stinky

DC Designs

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dude...I want a DC.

 

Given you're in the US just PM Steve Clark, John Kells, Chris Maas, ICYM..... those guys will give you all the info you need to get you into this awesome class

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dude...I want a DC.

 

 

Talon,

 

I think that Stinky is in your neighborhood. Perhaps there could be some colaboration. This is great news for the Left Coast!

 

Please pm me if there is anything that I can do (short of building another boat).

 

John K

USA-244

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Gybing boards! A favorite subject of mine! Whenever I have used them, the boat I have been sailing has had an advantage to windward, compared with the fleet. This raises more questions than it answers, so I will try to be more specific.

 

I owned Steve Benjiman's 505, Grace, when it was still in its prime. At the time in the UK, the 505 fleet were not using gybing boards. I will never forget the first start I did in that boat - flat water, 10 knots. We won the pin and I knew it was a drag race to the lay line so I just buried my head, determined to sail as hard as I could for what I knew would be a fair distance. We sailed a fair distance before I looked up, over my shoulder and I was gutted. There was nobody there which I thought meant they had all tacked off and my lay line tactic was simply wrong. Then I realised that everybody was sailing for the layline but we had simply gone from being furthest left to furthest right and had at least 100 metres on the fleet. There were a few top guys missing but I can honestly say that was one of the best ever feelings I have had while sailing. So, what do I think happened? To this day, I am unsure whether what made Grace so incredible upwind was that we pointed higher for the same speed or that we simply made less leeway. I suspect it was a combination of both.

 

On a completely different type of boat, I changed to a gybing board. This time it was on a National 12 (small, 2 person underpowered UK hiking dinghy) The before and after was very noticable. Having never won a race at one of the major opens, we won 2 in a weekend and finished 2nd, on discard. All our gains were upwind. For much of the weekend, due to the wave pattern, on one tack you had to foot off while on the other, you had to pinch. The boat worked. A few weeks later I went to the national champs with a new crew. Our first 2 races were poor due to bad boat handling and then we got our act together. The we came 4th o/a, compared with my previous best of 12th. If we could have discarded both of the first 2 races (20th and 18th), we would have won by a big margin! Again, we were simply quick upwind. I used that same board in 2 other 12's and each time, we were uphill flyers.

 

However, was it just the gybing board. The same board maker had done other gybing boards for 12's, but mine was different because the case of my boat was 4mm narrower than most. Could that have been the difference?

 

For a long time I believed that one of the biggest factors with gybing boards was that the people who could make them properly were the finest foil makers anyway. Therefore, gybing or not, I always felt at an advantage by having one of the best boards in the fleet. These days of CNC moulds rules that out. In addition, locking the board off properly, like Trevor can do, was something not very common, On top of that, I have never had somebody to 2 boat test with, both having the same board with the ability to stop gybing. One of the only people I know of who has probably done comparisons is Trevor B and I hope he can shed some light on the matter.

 

I am sorry if these comments are a bit rambling. If I was sailing a class that allowed them, I would use a gybing board from a top class foil maker, not because I am convinced it is faster but because I am convinced it isn't slower!!! Maybe gybing boards suit my sailing style. Maybe it's phsycological. Who cares! It seems to work for me

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i know, I know, but you can't just sign on a dotted line somewhere and have a DC. my original plan was to strip the seat and mast off my old IC and build a new DC hull to put them on, but my seat carriage was built for the days of wider boats than the DC's! Besides, I am not sure at all if my mast (which Steve C told me could be the oldest surviving carbon dingy mast in exsistance) can deal with a narrower shroud base.... and the time and patience (not to mention dough!) to build it all is suspect at best in me. So I will continue to loiter and try to vulture other people's boats until I figure out how to make it happen...

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i know, I know, but you can't just sign on a dotted line somewhere and have a DC. my original plan was to strip the seat and mast off my old IC and build a new DC hull to put them on, but my seat carriage was built for the days of wider boats than the DC's! Besides, I am not sure at all if my mast (which Steve C told me could be the oldest surviving carbon dingy mast in exsistance) can deal with a narrower shroud base.... and the time and patience (not to mention dough!) to build it all is suspect at best in me. So I will continue to loiter and try to vulture other people's boats until I figure out how to make it happen...

 

 

Building an IC takes time. There is no way around it. 90% of boat building happens after the kids are tucked in. In building an IC more than half of the time goes into the little bits, (foils, seat, carriage) and the hull is relatively easy. The seat & carriage are tricky bits that need to be light, STONG, and built to tight tolerances.

 

 

 

Start with the little bits as time & $$$ allow, and it will all fall into place. Much of the build cost is: sails, hardware & the rig, all of which can wait until the end of the build. The biggest expenditure up front is 50 yards of the black stuff, 5 gallons of the sticky stuff, and some core material to get started. It you can split a 100 Yard roll with someone; you will get the best value on the Carbon. Shopping around is worth the time to get the best deal.

 

Best

 

John K

USA-244

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Jim:

Ignore hull drag and lift for a moment.

Assume your board requires 3 degrees angle of attack to provide the necessary side force.

IF the fore and aft centerline of the board is aligned with the fore and aft centerline of the hull, both will "sink" 3 degrees. Or there will be a 3 degree difference between the direction the boat is headed ( based on the fore and aft centerline) and the direction the boat actually goes. The difference between Course Made Good (CMG) and Heading is leeway.

Now assume that you rotate the centerline of the board such that it is + 3 degrees to the centerline of the hull. Now the board's CMG is the same as the boat's heading. The result should be that if two boats are sailing the exact same compas heading,the one with the gybing board will end up to windward of the boat without a gybing board.

There are other effects on apparent wind and hull drag that may not all be positive and are probably class and condition specific.

Hope this makes sense.

SHC

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The result should be that if two boats are sailing the exact same compas heading,the one with the gybing board will end up to windward of the boat without a gybing board.

 

Is that what happens with gybing boards? I was under the impression that the normal state of affairs was that boats without gybing boards point higher and make leeway, while boats with gybing boards point lower but don't make leeway - because the gybe in the board means that it's presented at a positive AoA. I.e., they don't sail at the same compass course, but they do make very similar CMGs.

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If I remember the gist of the conversations on the gybing boards for the 14's

 

There was speculation that the board allowed the sails to free up a couple degrees and therefore get more power for the same board AoA.

 

However, there was also a lot of chat on whether the complications were worth it for the mortals in the fleet.

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Gybing boards:

The boat sails because the two sets of foils in fluids (fin and rig) work against each other with an optimum slight angle which results in maximum forward thrust/ angle to wind (VMG).

If the drag and efficiency is high that angle can be very fine and the boat can sail high (C Cat), If the foils are flat planks and the sails are bags then the angle is wide and the boat sails wide angles (Mirror Dinghy).

If the fin is rotated relatively to the hull, then this angle is reduced and for the same fin and rig the forard force will be less, and the boat will go slower. If however the sails are sheeted off a little at the same time, the angle is maintained and the boat moves back to its optimum VMG. The fact that the hull is better alligned with the real course probably means the hull drag is reduced and so a very slight speed gain results.

 

So just cranking some gybe into the board is exactly the same as sheeting the sails in closer by the same angle except that the hull experiences less lee way. Reducing leeway on a long narrow boat might reduce drag more than on a short wider boat like a 505 or I14 so maybe there could be some benefit.

 

BUT:

 

The New Light Canoes are frisky enough to make you very busy just keeping everything upright and going the right way. Despite all the string Chris has on his boat I believe he very rarely touched any of them while racing, he was too busy.

 

Keep it simple, Build some light canoes and join the fun.

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The New Light Canoes are frisky enough to make you very busy just keeping everything upright and going the right way. Despite all the string Chris has on his boat I believe he very rarely touched any of them while racing, he was too busy.

 

Keep it simple, Build some light canoes and join the fun.

Sorry, Phil, but what has that to do with gybing boards? I have never had a gybing board that you need to do anything with, other than fit it to the boat. The I14s developed a system to automatically stop the board gybing downwind and they could, if desired, lock off the gybe but that would most likely be something you do before the race.

 

There is no reason why a gybing board shouldn't fit your definition of simple, light and rarely needing to be touched. Having said that, I am not sure I would have one on a canoe, unless somebody else was building it because that is where the pain is!

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The big reason that the I14's turn the gybe off down wind is that having to fight the spinnaker and keep the boat on its feet is quite enough without having the boatd gybe suddenly and then have the boat jump one way or the other. You also like leeway if it is a W/L course. Going to weather there is always presure on only one side of the board so it stays to one side or the other. I remember the way my 505 would feel going down wind with the board gybing. It made keeping the boat on course a little interesting at times. You can stop a lot of this in a 505 by pulling the board up a bit. On an I14 it woulde depend on how your cassette system works. I tried it on my Swift and it worked OK except for the gusher of water coming out of the DB trunk when I got up on a plane. If it blew hard enough, it could almost reach the boom. That couldn't be fast so I changed to a standard style and tight trunk.

 

I can't tell you exactly how they work but I remember overstanding the windward mark too often right after getting a new Waterrat board. I'd tack on what used to be the lay line and end up way to weather by the time I got to the mark and have to ease off more than I'd liked.

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I think what is a big deal with the canoe is getting everything right and sorted. A gybing board is another thing on the list, and lets face it, we all struggle to find the time to sort our boats out. Spending time on improving your rig and sails and making sure you can sail a regatta series without any kind of equipment failure is probably time better spent than messing with a gybing board. (But not as fun!!!)

 

The other thing I sort of hinted about in my last post is that a simple but good conventional board is better than a badly designed and/or built gybing board.

 

If you have a 100% reliable setup (and you can stop congratulating yourself about that while sailing) I don't see that it will detract you much while sailing though.

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whats going on with the carbon tube on the deck.

To me it looks like a variant on the self-tacking jib, copied fom rc-yachts. The forward red line would work like a vang.

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To me it looks like a variant on the self-tacking jib, copied fom rc-yachts. The forward red line would work like a vang.

Correct. I think Alister was the only canoe at McCrae with such a system. The boom keeps the foot at set tension and the line ahead of the luff keeps the leach tight. RC yachts simply move the luff forward of the pivot/deck fitting, but full size loads make that a structual issue.

Some other canoes had circular tracks for self tacking jibs but most were sheeted each side like most other boats.

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Correct. I think Alister was the only canoe at McCrae with such a system. The boom keeps the foot at set tension and the line ahead of the luff keeps the leach tight. RC yachts simply move the luff forward of the pivot/deck fitting, but full size loads make that a structual issue.

Some other canoes had circular tracks for self tacking jibs but most were sheeted each side like most other boats.

 

Can't remember if I've met Alistair Warren, but to me it seems Monkey is one of the other elephants in the room. Here he is duking it out with the top guys on a boat that no one else seemed to like, but the boat is going really well, with its funky boom vang and all. Boat may not be to everyone's liking, but you can't argue with results.

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It looks like Alastair has taken the smarts from the Challenger Trimeran and RC yachts and put it to good use on the jib.

 

Looks a bit odd, it must add a fair amount of windage to the whole rig. Kudos to the DC guys for having the guts to go to the far reaching corners of the envelope.

 

JB

post-5485-1202265866_thumb.jpg

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Can't remember if I've met Alistair Warren, but to me it seems Monkey is one of the other elephants in the room. Here he is duking it out with the top guys on a boat that no one else seemed to like, but the boat is going really well, with its funky boom vang and all. Boat may not be to everyone's liking, but you can't argue with results.

 

You're right. Alistair was consistently near the top and was especially fast in the lighter stuff. His starts were usually excellent.

His hull shape is so different from mine and at times so fast that I'd rather not think about it too much.

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Just to add a little fuel to this fire, the numbers crunchers have been looking at the times for the DCs at McCrae with the intent of establishing a Portsmouth number. What they come up with is 860-865. This compares with the IC at 905 and the AC at 873. The FD at 879 and 505 at 902 are both slower. The Musto Skiff ( 875) can also look forward to the canoe, Only the RS700 has a lower rating at 856.

This seems like a pretty aggressive number, and a bigger step forward than I thought was going to happen. But if it's really indicative of how fast the new boats are, I'll take it.

SHC

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Just to add a little fuel to this fire, the numbers crunchers have been looking at the times for the DCs at McCrae with the intent of establishing a Portsmouth number. What they come up with is 860-865. This compares with the IC at 905 and the AC at 873. The FD at 879 and 505 at 902 are both slower. The Musto Skiff ( 875) can also look forward to the canoe, Only the RS700 has a lower rating at 856.

This seems like a pretty aggressive number, and a bigger step forward than I thought was going to happen. But if it's really indicative of how fast the new boats are, I'll take it.

SHC

And this is just the first generation of boat to the rule. They will most certainly get faster.

Awesome ride!!

 

Steve, How is the model design going?

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Steve, How is the model design going?

post-738-1202336626_thumb.jpg

Good and not so good.

This one is based on the front 2/3 of your bottom panel and some different topsides.

The back 1/3 tries to do Chris's stern and is mostly there, but not quite.

post-738-1202337495_thumb.jpg

I generally like the shape, but it wouldn't measure in because I got the topsides angle wrong when I taped the seams.

The bottom is too deep and not beamy enough.

It might actually be close enough such that I could start with some big sheets of plywood and fake it from here, but I also have another variation I want to try

post-738-1202336655_thumb.jpg

The problem I have with this isn't a problem I have in particular. I can build in deep space as well as anyone, but if I'm going to tell someone that "this works" I have to be sure that I have got enough controls in the system such that the boats are pretty damn repeatable.

SHC

post-738-1202336640_thumb.jpg

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Any one else want to try a model like this.

 

Start with the Hollow Log ply shape (from Hollow Log Plans) and increase the bottom panel width aft of the max beam to emulate the String Theory stern. The chine edge of the topsides will need some minor adjustment to accommodate a different S curve to follow the chine to the centre line.

 

Steve's model looks longer than I use: 1/10 scale or about a half metre is good enough with 1/32 in or 0.8mm ply.

 

To get the right chine angles Steve needed to spread the shell wider (see HL plan for dimension) before taping the seams. This bends the bottom panel harder near the chine when the gunwales are narrowed and gets the chines low enough to measure in.

 

If it all sounds confusing wait till Steve gets his design sorted.

 

Have fun.

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this looks like a fun little project. But given how quickly Steve is doing it, I might just wait....

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Can't remember if I've met Alistair Warren, but to me it seems Monkey is one of the other elephants in the room. Here he is duking it out with the top guys on a boat that no one else seemed to like, but the boat is going really well, with its funky boom vang and all. Boat may not be to everyone's liking, but you can't argue with results.

 

 

Alistair Warren had a very good regatta. With a new & untested boat, he finished all of the races, and to the best of my knowledge avoided using any epoxy all week (something that I wish I could say). He managed good starts, and sailed smart. There are a few design features on Monkey that you would think might not be fast: transom-hung rudder, jib boom (because of the weigh forward, and the height of the jib foot) and a square stem that shoots spray up like the spout on a whale. None if it slowed him down at all.

 

Another thing to note is that Alistair’s hull could easily be built of ply of you could keep the weight down

 

Well Done

 

John K

USA-244

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Just to add a little fuel to this fire, the numbers crunchers have been looking at the times for the DCs at McCrae with the intent of establishing a Portsmouth number. What they come up with is 860-865. This compares with the IC at 905 and the AC at 873. The FD at 879 and 505 at 902 are both slower. The Musto Skiff ( 875) can also look forward to the canoe, Only the RS700 has a lower rating at 856.

This seems like a pretty aggressive number, and a bigger step forward than I thought was going to happen. But if it's really indicative of how fast the new boats are, I'll take it.

SHC

 

 

I don't have a lot of experience sailing on PH, but these numbers look like the DC is faster than an AC. Was the differences in the course length taken into account as the AC's were on WL courses with longer legs? Time will tell if we can race to this number up in Ottawa next June.

 

John K

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I don't have a lot of experience sailing on PH, but these numbers look like the DC is faster than an AC. Was the differences in the course length taken into account as the AC's were on WL courses with longer legs? Time will tell if we can race to this number up in Ottawa next June.

 

John K

 

The PY comparisons were made (by me, I can't speak for the UK ones on the IC Forum http://www.intcanoe.org/forum2/viewtopic.php?t=736 which came up with very similar results) comparing the AUS Yardstick and using the times to calculate a Yardstick for the DC. AC's yardstick has little relevance as they do not sail a triangular course (and DC's don't sail windward leeward). However around a triangular course the numbers (and pre-worlds) indicate that a DC will beat an AC, gut feel is that on a windward leeward course (so long as the AC can fly the kite) the DC will get beaten.

 

For Aussies, I came up with a Yardstick of 91 for the DC

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Hello everyone

Well as I hope you are all aware the vote on the adoption of apendix four, adopting the box rule as main class rules and essentially making the DC the new IC, is coming up in march. It is absolutely CRUCIAL that everyone vote on this. It is the biggest thing to happen to the Canoe class since Uffa Fox. Go to the US site and it should be obvious how to vote. To vote you need to be a member and a boat owner, thats the criteria. If you aren't from the United States vote through your nations Federation/organization/whatever. You can download the ballot of the site, fill it out on MS word, and send it to John Kells. You can also email him and he will send you a ballot, his email address is listed on the posting.

 

Let me just restate how important this vote is. All the great activity we haver been seeing because the DC will go for nought if we do not vote.

 

Thanks

Willy

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So I cannot see a gybing board making a difference on a single sail boat.

 

But given a two sail boat my ears suddenly prick up... Becase with a jib and a main both located on the centreline the angle of the hull relative to the wind suddenly gets very significant indeed... Our in aerodynamic terms canard wings relationship is changing significantly as the hull is rotated relative to the wind... As the board gybes the jib/main relationship changes. I'm struggling to explain this... here's a graphic with a very exaggerated gybe angle. Blue has the board centrelined, green is gybed. The true wind to sail angle is the same for both, but the width of the slot is very much greater for the gybed boat... It seems to me there are a lot of possibilities there...

 

 

we need a gybing boards thread!

 

Thanks, Jim - i was hanging out for someone to make the point that you have - and with a diagram.

 

i too suspect that it is a rig issue, not hull drag. so how hard would it be to lay a bit of track across the boat @ the jib tack; tack to a traveller and put some control strings on. then:-

Experiment 1. try letting the jib tack 'down' to the position that a gybing board would 'put' it (see previous comments about how a gybing board effectively "rotates" the boat to leeward) - and see if you actually do get better VMG, or "climb", or however u want to call it.

 

but why limit the exercise to just that? drop it down further (this may prove to be the saving of the fat Nethercott bow) - is that even better? see? you can play around with the effect of a range of angles far wider than could be 'induced' by a gybing board.

 

if this works it will be proved that the gybing board affects the rig properties rather than hull drag issues.

 

and so to Experiment 2. Pull the traveller to windward for the offwind legs.....

 

i predict that the difficulty will be in getting the jib sheeting right - it is hard enough to get the clew in the critically correct position when the tack stays put!

perhaps Alistair's system on Monkey would help - though from my experience on radio models i perferred to run the boom attitude control string down the leech as it added to, rather than subtracted from, the luff tension then. of course you need a strong boom pivoted from a point behind the tack - but surely carbon fibre technology makes a decksweeper easy and elegant?

 

please excuse the style - ive been up all night following this thread!

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Hello everyone

Well as I hope you are all aware the vote on the adoption of apendix four, adopting the box rule as main class rules and essentially making the DC the new IC, is coming up in march. It is absolutely CRUCIAL that everyone vote on this. It is the biggest thing to happen to the Canoe class since Uffa Fox. Go to the US site and it should be obvious how to vote. To vote you need to be a member and a boat owner, thats the criteria. If you aren't from the United States vote through your nations Federation/organization/whatever. You can download the ballot of the site, fill it out on MS word, and send it to John Kells. You can also email him and he will send you a ballot, his email address is listed on the posting.

 

Let me just restate how important this vote is. All the great activity we haver been seeing because the DC will go for nought if we do not vote.

 

Thanks

Willy

 

Does the link to the ballot work for you? I tried it as well at school but I got nothing. I e-mailed John Kells to get it so I should get it relatively soon but I was just wondering if anyone else was having problems.

 

TC

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Does the link to the ballot work for you? I tried it as well at school but I got nothing. I e-mailed John Kells to get it so I should get it relatively soon but I was just wondering if anyone else was having problems.

 

TC

You'll still need to email it back through your National body, but all the details can be found here: http://www.internationalcanoe.yachting.org.au/?page=34766

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Frank,

 

I'm not a believer, but maybe that's just because I haven't seen any results from it. We haven't seen any results from it because of RRS 54:

 

54 FORESTAYS AND HEADSAIL TACKS

Forestays and headsail tacks, except those of spinnaker staysails

when the boat is not close-hauled, shall be attached approximately on

a boat’s centreline.

 

I'm not sure how much you can push the "approximately" but there is some opening for interpretation there.

 

I think I remember some arguments in the IOM class, where someone attached their forestay at the hull bottom and let it pass through an oval hole in the deck.

 

That boat apart, the model boats are actually doing the opposite, pulling their tack to windward because of their jib boom setup. If that really had an adverse effect on performance I think they would have found another way to sheet their jibs.

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I think the answer to the gybing board question has to do with the course made good not in the relative angles of foils to the sails. Not that they aren't affected, but.....

Consider the boat sailing close hauled on the starboard tack heading 180 degrees.

If the board requires and angle of attack of 3 degrees to provide the necessary side force,

the boat should be making 3 degrees of leeway.

In which case it's course made good is 177 degrees.

IF you rotate or gybe the board 3 degrees, and the board is still delivering the necessary side force at 3 degrees AOA, then the boat should be making 0 degrees leeway.

In which case the course made good is 180 degrees.

You haven't "climbed off the top" you have just not slipped sideways at the same rate.

The boats will sail at the same heading, but end up in different places.

 

Oh and if you have an IC, please vote.

 

SHC

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The boats will sail at the same heading, but end up in different places.

Are you thinking 90 rather than 180 degrees Steve?

Anyway, I see what you're saying, but I still can't put all of it together... I really must sit down and puzzle this one out deeply. Not at the expense of getting the boat finished though! In one case the course made good is 180 degrees, in the other 177... Isn't the actual heading of the craft relevant to the convenience of the navigator? If one were to imagine a foiling boat (sailed vertically) the "heading" of the boat relative to the wind is irrelevant... Supposing the foil must have three degrees of sideforce to make a given course then that's what it must have... And unless the theory above about side force from the hull is correct (perhaps it is) then isn't the optimum upwind performance gained at the optimum angle between hull and foil? Does it matter ... For me to argue with SHC about technicalities of high performance boats is pretty damn stupid... Maybe I've just had too much in the way of epoxy and polyurethane fumes lately... Should be back on the water by the end of the month now:-))

 

Can anyone think of any attempts to introduce gybing boards in single sailed boats? Did it work? It would be interesting to know.

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Steve,

If gybing the board simply improves the course made good by a few degrees, by in effect narrowing the angle between the rig and the centreboard by those few degrees, then you should get exactly the same effect by sheeting the sails closer and pointing higher by the same angle. But that usually has a negative result, slower and less VMG?

I still see the only benefit of the gybing board in the hull having no leeway.

 

And Yes I have voted for the DC rule to be the IC

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Does the link to the ballot work for you? I tried it as well at school but I got nothing. I e-mailed John Kells to get it so I should get it relatively soon but I was just wondering if anyone else was having problems.

 

TC

 

The download link is fixed now.

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Gents.

The reason that gybing daggerboards work (if done properly) is this:

 

The sideforce that opposes the forces from the rig and propels the boat forwards is provided by the daggerboard, but also the rudder (usually by virtue of a couple of degrees of weather helm, as the rudder operates in the downwash of the dagger), and the hull, which usually has a lateral area of comparable size to the dagger.

Whilst the dagger and rudder are fairly effective lifting devices (high - ish aspect ratio, good section shape) The hull is a highly inefficient lifting surface (very low aspect ratio, dodgy shape) and as such cannot produce anything near as much side force for its area as the dagger or rudder. More importantly, the induced drag penalty of such an inefficient body when dragged at a yaw(leeway) angle is huge when compared to deriving the equivalent amount of lift from the foils.

 

A boat with non gybing daggerboard sails upwind through the water, with the hull and dagger making a course a few degrees lower than the heading (the leeway angle) The yaw angle or leeway is necessary to have an angle of attack over the lifting bodies and produce sideforce. If set up properly, the rudder should have some weather helm, such that it is carrying some of the sideforce, unloading the dagger and hull somewhat. The foils generate lift fairly efficiently, but the hull will have a proportionally massive induced drag for its modest contribution to the total side force.

 

The benefit of a gybing dagger is that, if correctly designed, the dagger gybes a few degrees each side of centreline meaning that the dagger can experience an angle of attack while presenting the hull at zero angle of attack - i.e no leeway.

This means that all of the lift creating the sideforce is generated by the (efficient) foils, and none by the (inefficient) hull, which now has no induced drag.

This net reduction in drag means that the boat can either go faster at the same heading, or higher for the same speed. The latter is usually far more valuable in a fleet racing context..

 

Whilst gybing the board means that the foils are slightly more highly loaded, and thus run slightly higher lift coefficients than if using the same foils fixed, it is inconsequential in the context of the reduction of induced drag from the hull

 

For this system to work well, the amount of daggerboard gybe has to closely reflect the leeway angle, which varies from class to class.

Furthermore there has to be a mechanism to "centre" the dagger downwind, else it will slop around pointing in a different direction to the heading of the hull, thus creating unecesary induced drag between the two bodies again, not to mention control probs.

 

Obviously there are some tricky things to get used to when first using a gybing board - little or no leeway meaning that conventionally foiled boats "fall away" to leeward Also, where people have had good judgement of their boat's abilities on laylines, the addition of a gybing board will prove tricky at first!

 

 

As for the track of boat / sheeting angles - I think that optimum sheeting angles should be made with respect to the track of the boat, rather than the centreline of the boat. This would infer that a boat with gybing dagger should sheet a little freer than the non gybing boat, by an equivalent amount to the leeway angle of the non gybing boat.

However, optimum sheeting angles are generally a function of the efficiency of a boat, with mirror dinghies sheeting far wider than IACC yachts. As the boat with the gybing dagger has improved its efficiency, it could go to a closer optimum sheeting angle, thus negating somewhat the previous paragraph.

Basically, I reckon amidst the general noise and variables oif dinghy racing, the last 2 points cancel out.

 

Dan

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Gents.

The reason that gybing daggerboards work (if done properly) is this:

.... [snip] ....

 

Dan:

 

Very clear and concise explanation. Well done.

 

It's nice that the DC folks soldier on keeping on an interesting topic while the bulk of us swarm Doug Lord out of boredom and frustration. I wish this level and type of discussion happened more frequently.

 

As for the track of boat / sheeting angles - I think that optimum sheeting angles should be made with respect to the track of the boat, rather than the centreline of the boat. This would infer that a boat with gybing dagger should sheet a little freer than the non gybing boat, by an equivalent amount to the leeway angle of the non gybing boat.

However, optimum sheeting angles are generally a function of the efficiency of a boat, with mirror dinghies sheeting far wider than IACC yachts. As the boat with the gybing dagger has improved its efficiency, it could go to a closer optimum sheeting angle, thus negating somewhat the previous paragraph.

 

I'm not entirely clear on this point. I would think that sheeting angles are made with respect to the apparent wind, not the centreline or the track. I'm certainly open to accepting your thesis - but I don't think I sheet based on anything but apparent wind. When in doubt, I look at flow over the sail on telltales and adjust, not track or centreline.

 

OFP

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Be careful OFP,

Please do not mention HWSNBN or PHOILING on this thread, we do not want its purity contaminated.

 

I think what Danny has said tallys with my thoughts on gybing boards. So logically the gybing board would be more benefit on a long skinny boat (canoe) than a wide flat boat (505) because the drag from leeway angle on the narrow hull (without gybing board) would be greater.

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The reason that gybing daggerboards work (if done properly) is this:

You may well be right, but have you any evidence, tank test or whatever, to back these statements up... We've had several pretty convincing posts about what could be going on (they've convinced me anyway), and on the face of it yours could be just another unless you state the background. We've got some pretty technical sailors in the topic who don't believe its a hull factor...

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Obviously there are some tricky things to get used to when first using a gybing board - little or no leeway meaning that conventionally foiled boats "fall away" to leeward .....

 

Mentally challenging on the start line when sailing a gybing board among a fleet of non-gybers is letting the boat go bow down by 3 degrees or so... it looks like you're driving down into the guy to leeward, when its just that your hull is at a different angle but your actual path through the water is parallel. Big temptation to pinch up, then you go slow.

 

Phil

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REALLY STUPID QUESTION whats a gybing daggerboard? (the gybing part) this is coming from someone who has only sailed 420s

 

 

 

 

ok flame away

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Frank,

 

......t because of RRS 54:

 

54 FORESTAYS AND HEADSAIL TACKS

Forestays and headsail tacks, except those of spinnaker staysails

when the boat is not close-hauled, shall be attached approximately on

a boat's centreline.

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......t because of RRS 54 FORESTAYS AND HEADSAIL TACKS: Forestays and headsail tacks, except those of spinnaker staysails when the boat is not close-hauled, shall be attached approximately on a boat's centreline.

 

spoilsport i'national b'crats! (i would have thoight that this should have been left to the class rules.)

OTOH i'm happy to avoid the general introduction of another complication for marginal gain.<BR>

 

BUT i would still like to see someone try it and get some data on getting the jib away from backwinding the main to windward.<BR>

 

the other trial id like to see is the effect of grooves down the c/b to simulate the (adverse) effect of having a flap. (i just can't understand how the bladerider gets away with a 4mm gap!)

 

sorry - had trouble posting this reply - hope it gets thru ok now

 

f!

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BUT i would still like to see someone try it and get some data on getting the jib away from backwinding the main to windward.<BR>

 

the other trial id like to see is the effect of grooves down the c/b to simulate the (adverse) effect of having a flap. (i just can't understand how the bladerider gets away with a 4mm gap!)

 

f!

 

If the rig you're talking about is like the pivoting model yacht rigs, it's been tried on a canoe, and it was completely unmanageable. I seem to remember a great story about Rod Mincher literally not being able to point the boat downwind with the thing, or something like that.

 

Flapped daggerboards have already been tried but with respect to hinge gaps, canoe foilmakers appear to be smarter than all moth foil makers except Bill and Phil, who sail canoes also so they cancel themselves out of the analysis :P

 

Sure the hull is an inefficient lifting surface but a) the leeward angle of a canoe, which goes to weather better than any other boat I have sailed, is much smaller than on other dinghies, so whatever amount of drag is coming from the hull moving sideways through the water is probably a lot less than on other dinghies. So you are reducing that drag by x percent, but that drag might be a pretty small number to begin with. I think this is why conventional boards have not been completely overtaken by gybing boards in the IC, whereas they seem to be standard issue in the 505: the 5-0 makes a lot more leeway than a canoe, so the hull drag is a lot more of the total in a 505, and the potential benefit of shifting that lift to a more efficient surface (i.e. the gybing board) is greater. But I have no formal training and this is sheer conjecture.

 

Everybody go nominate Chris Maas for Seahorse sailor of the month over on that thread. I think he deserves it.

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OFP,

Sorry I probably wasn't clear enough on the sheeting angles. What I was referring to was the optimum sheeting angles when the sails are pinned in sailing upwind, i.e when the helm is steering to the telltales with the AOA of the sails constant with respect to the centreline. The optimum sheeting angle would be the optimium jib lead angle for a sloop where upwind generally the main will be centred to keep the slot open. For Una rigged boats this angle is the boom to centreline angle (Una rigs i.e finn, laser)

A mirror dinghy will have a fairly wide jib sheeting base, whilst an IACC yacht will be down to about 6 degrees.

Similarly with Una rig boats, a finn usually sails with about 9 deg until it gets windy. I you tried that on an oppie (Less Aerodynamically and hydrodynamically efficient) you'd go slow and sideways. Similarly an nice efficient A class cat would have a fairly narrow sheeting angle.

 

Obviously this is different to sailing off the wind where the course stays largely the same apart from when hunting waves, and the sails are trimmed to the apparent.

 

JimC

Can't remember off the top of my head where I got my info from the last post but it will probably be hidden in some textbooks like Aero/Hydrodynamics of sailing by Marchaj or Sailing Yacht Design Theory/Practice. I did my Nav Arch degree at a Uni where the consultancy wing do a fair bit of AC testing, so I'vbe got a reasonable handle on why stuff works in that respect.

 

With regards relative leeway angles, I think that most dinghy classes with non gybing daggerboards will actually be suprisingly similar in this respect, just with more efficient classes making the same amount of leeway whilst pointing higher and/or going quicker.

Sizing of foils is quite important - too big and you will be incurring too large a penalty from the extra wetted surface, too small and the induced drag penalty from running too high a lift coefficient will start to bite.

For boat shaped foils operating at boat reynold's numbers, there exist optimal angles of attack at which the optimum balance between the induced drag ( increasing with smaller foils) and the friction from the wetted surface ( increasing with bigger foils) is found. This is a simplified explanation and will depend on things like foil section shape, aspect ratio and a bunch of other factors.

This is blurred a bit for quick dinghies that plane upwind, for which freeing off 10 deg and going a fair bit quicker doesn't hurt the VMG too much. The sideforce generated by the foils remains the same assuming that the crew continue to generate the same righting moment, but since the speed has shot up, the lift coefficient will be much lower, meaning that the boat will now be making less leeway, and have more than the optimal amount of foil in the water.

 

Dan

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This is blurred a bit for quick dinghies that plane upwind, for which freeing off 10 deg and going a fair bit quicker doesn't hurt the VMG too much... but since the speed has shot up, the lift coefficient will be much lower, meaning that the boat will now be making less leeway, and have more than the optimal amount of foil in the water.

 

Dan

 

That is the point I was trying (inadequately) to make. Canoes move through the water fast enough to make less leeway than other boats, so there is less drag from hull sideslip for the gybing board to reduce. In fact, at higher speeds, wouldn't a gybing board be better locked on centerline? Seems like you might start inducing positive sideslip by pushing the boat sideways through the water to windward otherwise...I guess that's why it is hard to come up with an angle to set the thing to. Perhaps an auto-trim feature is needed, like a rudder/tiller setup with a bungee on it that decreases the AOA as the side force on the foil builds. Have it auto-depower progressively as it exceeds max righting moment. Probably this is insane but I had the idea so I thought I'd mention it.

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Steve

I see your are developing "String Theory" style hulls from sheet ply. Does this mean you have gone away from roughly symmetric waterplane areas?

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Steve

I see your are developing "String Theory" style hulls from sheet ply. Does this mean you have gone away from roughly symmetric waterplane areas?

I am doing this mostly as an exersize. I haven't necessarily changed what I think, but am doing the grunt work, as it were, to demonstrate that you can build a String Theory like boat using Hollow Log building technique. Whatever results I probably won't consider "my design" because it will be so highly derived from Chris' and Phil's boats. The goal is to get to a easily constructed competitive boat within time and budget of as many people as possible. Just trying t forward the world wide revolution.

SHC

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Danny Boy- there is also the issue of the circulation around the two foil system, that is the system creates more lift and less drag than a single foil. Does the gybing foil change the effective stagger because the surrounding flow direction is effectively changed? Seems there was something Seahorse about this viz AC stuff. So which is the foil in upwash, and does the gybing board change the relative aoa ratio between the two, or even them out, which if I remember my biplane theory, is advantageous? Anyway, NACA's studies of biplane cells back in the 20's-40's pointed to keeping the chords of a biplane cell parallel for best efficiency.

 

Paul

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post-738-1202336626_thumb.jpg

Cool model, Steve. But if you put Chris's stern on both ends, rounded off the front one (in planform) within the 45 degree limit, and flattened the bottom, you'd have a pretty cool scow! I know I know. It would be wrong. Really really wrong.

 

Paul

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Does the rule say which plane the point needs to be in?

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I've looked at the proposed dc rules and looked at the proposed dc rules, and I can't figure it out.Paul

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That is, I think the 45 degree inclusion rule applies to both ends. I think.

 

Paul

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I've looked at the proposed dc rules and looked at the proposed dc rules, and I can't figure it out.Paul

 

I'm not a builder but it reads pretty clear to me:

The projection on to a horizontal plane of the line of greatest beam shall be a continuous curve, and at bow and stern shall lie inside lines which are

at 45º to the centre-line and which pass through the centre-line not more than 25mm beyond the extremities

 

That the above means that the bow and stern along the line of the beam need to come to a 'canoe like' pointy bow and stern. This to me says that looking down at my boat (i.e. overviewing the beam) my boat should taper to points that lie inside of 45 degrees to the centreline.

 

But if in doubt I'd refer to rule 3:

SPIRIT OF THE RULES

The International Canoe has a long and vital history; these rules frame parameters for continuing development of the sailing canoe.

The individual values and dimensions within these rules are based on historical precedent and current best practices. These rules endeavour to offer designers and builders significant opportunity for innovation while maintaining continuity with the past.

 

Which is kind of saying - yes we're all about development but our roots are as canoes. So when in doubt your boat should look canoe-like.

 

Have no idea if this helps, when it doubt just design something and check with your measurer before you build

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The rule is pretty clear on pointy ends. You can twist words in your head if you like and create something which you interpret as complying, but you have to convince the measurer who is a canoe sailor and knows what the rules mean to canoe sailors. Is it worth the effort.

 

Why bother with a scow anyway. The moth class moved on from scows to skinny canoe shaped hulls about 15 years ago. Now on good days the top foil moth finish three laps roughly in the same time as the good skiffs finish two laps and the remaining scows finish just one lap. The world has moved on a long way from scows in 2008.

 

The 11ft long skinny skiff moths would peak out at about 17 kts. The 17ft skinny, light weight canoes feel similar to sail but are much more stable, and being so much longer, with not a lot of extra weight, should have a top speed quite a bit faster than that, they are already proving faster than the quite quick Nethercott canoes and development has only just started.

 

So get building and come along for the ride.

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post-738-1202336626_thumb.jpg

Good and not so good.

This one is based on the front 2/3 of your bottom panel and some different topsides.

The back 1/3 tries to do Chris's stern and is mostly there, but not quite.

post-738-1202337495_thumb.jpg

I generally like the shape, but it wouldn't measure in because I got the topsides angle wrong when I taped the seams.

The bottom is too deep and not beamy enough.

It might actually be close enough such that I could start with some big sheets of plywood and fake it from here, but I also have another variation I want to try

post-738-1202336655_thumb.jpg

The problem I have with this isn't a problem I have in particular. I can build in deep space as well as anyone, but if I'm going to tell someone that "this works" I have to be sure that I have got enough controls in the system such that the boats are pretty damn repeatable.

SHC

 

Steve, let me know if you come up with something workable. My brother and I are keen to try and build one and put his new CST rig on it and see how it goes against my new (your old) boat.

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I have just spent a ittle time modifying my old model of Hollow Log. The freeboard is cut back to what everyone else thinks is right for a canoe. I might widen the stern tomorrow after I see what if looks like with all the clamps off. I think people's perceptions of the hull shape will be diferent without the high sides and pinched in foredeck. Photos tomorrow.

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Danny Boy- there is also the issue of the circulation around the two foil system, that is the system creates more lift and less drag than a single foil. Does the gybing foil change the effective stagger ... ................. ..............

 

Paul

 

Back to gybing boards - again!

 

- "STAGGER"

 

thanks Paul - that describes what i was trying to grasp. only i am thinking of the change in stagger between main and jib (not c/b and rudder) when the board is allowed to gybe.

i have the feeling that it would be advantageous to move the whole jib a bit to leeward when closehauled (only they tell me the big boys won't allow it)

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i have the feeling that it would be advantageous to move the whole jib a bit to leeward when closehauled (only they tell me the big boys won't allow it)

That's one of the rules that can be changed by class rules if the class so desires. Its not an exception in th IC rules though.

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The rule is pretty clear on pointy ends. You can twist words in your head if you like and create something which you interpret as complying, but you have to convince the measurer who is a canoe sailor and knows what the rules mean to canoe sailors. Is it worth the effort.

 

Why bother with a scow anyway. The moth class moved on from scows to skinny canoe shaped hulls about 15 years ago. Now on good days the top foil moth finish three laps roughly in the same time as the good skiffs finish two laps and the remaining scows finish just one lap. The world has moved on a long way from scows in 2008.

 

The 11ft long skinny skiff moths would peak out at about 17 kts. The 17ft skinny, light weight canoes feel similar to sail but are much more stable, and being so much longer, with not a lot of extra weight, should have a top speed quite a bit faster than that, they are already proving faster than the quite quick Nethercott canoes and development has only just started.

 

So get building and come along for the ride.

 

Oops.

 

Paul :unsure:

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Here is my old Log model cut down to 2008 freeboard:

Bow On:

 

post-8573-1202798925_thumb.jpg

 

Stern on:

 

post-8573-1202798879_thumb.jpg

 

And if it was extended and then cut, what it would look line with a String Theory stern (Black Line) FWIW?:

 

post-8573-1202799010_thumb.jpg

 

I need to build a new model and amend the building instructions to match a low freeboard version and sloop rig. I really need someone near me who wants to build one, so I can refine the model details at full size like I did when building Hollow Log #1.

 

Any takers?

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Gawd this is the tech thread of tech threads: hull shapes, gybing boards and sheeting angles.... Danny Boy had the correct explanation of the gybing board (not that the others were wrong). Bethwaite (senior) mentions in HP Sailing that you should define your heading as the the direction of the chord of the centerboard in other words he ignores the hull in doing his velocity triangles because he's considering gybing boards. Regarding sail sheeting, I've convinced myself that if you sail at the same boatspeed in both cases (I don't think there's any reasons why that shouldn't be the case unless you trying to use the gybing board to puch you upwind too much) that the AWA is smaller and the AWS is faster so you should want tighter sheeted and flatter sails. This agrees with the intuition that the boat is more efficient (although my arguement is circular)...

 

As to whether the gybing boards are good idea that's something that the class needs to determine on a competitive basis. I don't recall how the I14s lock the board downwind but my guess is it won't complicate the IC too much but i wouldn't imagine that IC sailors want a stringfest like a 505 or FD.

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The 14 I'm sailing on has the DB in a cassette, in a box in the hull. When going downwind there is a little delrin bushing that pops into the front of the box, locking the cassette in place. There are some lines led out to drop it down. Since I've only sailed her twice, we've just locked it in place before the sail and haven't used it, yet.

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The 14 I'm sailing on has the DB in a cassette, in a box in the hull. When going downwind there is a little delrin bushing that pops into the front of the box, locking the cassette in place. There are some lines led out to drop it down. Since I've only sailed her twice, we've just locked it in place before the sail and haven't used it, yet.

I believe the I14s and 505s use tension in the kite haliard to lock the board to centre.

I think Oliver had a manual control on the DC, as if there is not enough to do just balancing things. Del had an automatic flap system on Donkey which used the jib sheet tension to pull the flap to leeward.

Phil in Sydney

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Not to be out done by Phil,

Two ideas I have modeled with different chine heights forward,

post-738-1202935802_thumb.jpg

One has wing details as per Chris Maas, which as I see it will be a pain to build, and the second has enough beam in the way of the chain plates to avoid the trouble.

post-738-1202935817_thumb.jpg

Both have String Theory ass ends.

post-738-1202935781_thumb.jpg

Both will be water tight enough to do something at Bill Beaver's day job, which might look like this:

post-738-1202938126_thumb.jpg

SHC

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post-8573-1202938728_thumb.jpg

I am inspired to build another canoe. The number of new ideas means that modifying the Hollow Log is un economical in dollars and time. So if someone near Sydney wants a cheep entry into Canoe sailing please contact me by PM

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Not to be out done by Phil,

Two ideas I have modeled with different chine heights forward,

One has wing details as per Chris Maas, which as I see it will be a pain to build, and the second has enough beam in the way of the chain plates to avoid the trouble.

Both have String Theory ass ends.

Both will be water tight enough to do something at Bill Beaver's day job, which might look like this:

SHC

 

Pretty cool Steve.

Can you torture ply into those shapes? For what it's worth I think String Theory's stern is cut off at about 40 degrees. The new boat will be 33degrees.

 

Yes the wings are certainly a pain to build. But your boat Josie has a shroud base of what, 730mm? Compared to ST's 810mm. Your mast seems to stay up okay. My new boat will still have the wings, though smaller, but I don't think you'd need to push too hard to get rid of them.

 

Can Bill Beaver throw some waves at those models?

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Can Bill Beaver throw some waves at those models?

 

Either tank can send waves, if you wanted to get really funky you could run both models side by side in waves and video it in the big tank.

On the other hand you could get some good numbers from the little tank.

 

I spent entirely too much time down there.

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Both will be water tight enough to do something at Bill Beaver's day job, which might look like this:

post-738-1202938126_thumb.jpg

SHC

 

Ah, the Puppet. I get all teary-eyed just thinking about her - traveling the world without me, having trysts with strange men on foreign beaches, and now cruising tow tanks in my absence. Did I mean so little? Will she ever come back to me?

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Atypical, what were your 2 best days with her? :lol:

 

Paul

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Trysts with strange men on foreign beaches?!? Who are you calling strange Dr. Karl?? :P Besides that, she knows of the "other women" in your sailing harem ;)

 

The puppet is a truely fine beast - albeit slightly weighty compared to the latest generation of DC exotica, she still punches well above her weight... 6th in the McCrae pre-worlds.

 

Uncle Boat, if you do wind up tank testing your Log Theories could you please post some photos as I am interested to see how the cut-off stern effects the wake of the boat.

 

Jon

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I've heard rumors that the Lusty lady arrives mid week next week...I assume she is to be chained to a post the backyard awaiting your return to the right coast. As for Sheet Metal...alive and well no major parts have fallen off. And last but not least...Hungry Beaver #3 has emerged from the molds quivering and still covered in PVA.

 

Had the Clockwork out for a sail recently?

 

-GMS

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I've heard rumors that the Lusty lady arrives mid week next week...I assume she is to be chained to a post the backyard awaiting your return to the right coast. As for Sheet Metal...alive and well no major parts have fallen off. And last but not least...Hungry Beaver #3 has emerged from the molds quivering and still covered in PVA.

 

Had the Clockwork out for a sail recently?

 

-GMS

 

There are some handicap races on for this spring so I'll likely get her out for a couple of those, just to stay in practice. Still have to glom the seat back together but that will be simple.

 

Otherwise, I have been too busy working, buying crap for the shop, fighting with the DMV, figuring out how Joomla works to rehab the IC site, rebuilding your hand-me-down, 1946 WWII surplus $50 blue-light-special Welch DuoSeal, reinventing my flap and wand linkages, undoing the last of the road rash damage that I-70 inflicted:

 

post-7499-1203043509_thumb.jpg

 

making little carbon bow protectors to replace where the sand in the dolly was eating my boat:

 

post-7499-1203042567_thumb.jpg

 

and otherwise getting ready for the regatta this weekend. This is over and above staging for the first foil layup, which involved having a router, and convincing it to cut things it would rather not. Fortunately there are lots of machine shops around here, and therefore lots of machine shop supply stores that sell little tools capable of cutting damned near any material you care to name at virtually any rpm and travel rate you want to cut it at, subject to my rather humble spindle limitations of course!

 

I finally have a vise lagbolted to my bench, which is such a nice change from holding things in my teeth that I am almost speechless - the things I took for granted in Arnold! The molds are ready to spray after another go of sanding - roof leak in the big rain storm two weeks ago and MDF does not like water one bit! Fortunately they are covered in gelcoat and only one edge lifted. I will get some materials cut tonight but probably nothing in the bag till next week. Resin, disposables, carbon check check check.

 

Anyway it is all still a work in progress but I feel like I finally have most of the things on hand that I will need to do some work and come away with nice looking parts. Mailed you guys twenty rolls of tacky tape two days ago in support of HB#4 and future efforts. Lemme know if you need more Nomex.

 

The shop is nearing liftoff, the Moth seems functional, the foil project is nearing critical mass, and I am broke. Now if I can only remember how to sail...oh wait, I never really learned how to sail...don't mind me I'll just be over here lecturing people on power to weight ratios ;)

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Atypical, what were your 2 best days with her? :lol:

 

Paul

 

Day I bought her, and day I sold her except - wait - I never sold her! Sent her to Australia but in some sort of boomerang effect I hear she's coming back!

 

I guess the most satisfaction I got from the boat was keeping up with the really good IC sailors in a few races. A number of things on the boat are dodgy, but if you can avoid planting the seat or getting the mainsheet stuck in the cleat or ventilating the rudder you can really move in that boat. I guess I was surprised to hear that she only weighs 65kg; a pretty good number for such an old and well-used (abused?) boat, particularly as minimum weight was 83kg or more when she was built. I think the seat is really heavy also. 65kg is heavy compared to what everyone else was sailing in DCs in AUS, but she was built before there were DCs, and at 65kg you would not even be able to correct up to class legal IC weight with 10kg of lead. So the boat was really ahead of its time in more ways than one. Figuring out how to make her go fast in all conditions was a very satisfying process.

 

Someday I will chronicle all the stuff I replaced on that boat to get it where it is. Most of it was stuff Dan Edwards made, that failed in one way or another while I was sailing the boat. Since I am waiting for some resin to kick, I guess someday is now. Each failure has a story of course.

 

Vang lines and attachment to boom (replaced entire boom eventually with a cast-off preproduction braided carbon J24 spinnaker pole)

-and-

Daggerboard

 

The failure of these two items left my girlfriend at the time bobbing around in West River to be picked up by a passing powerboat. I was still trying to get to shore when she came cruising by, looking like Jackie O in her big black glasses and windblown, dark hair, in a lounge chair on the aft deck. I would say it was the beginning of the end, but for there to be an end, there has to be a beginning, which there really wasn't.

 

Rudder

 

This failed on me in 15-18 just outside the entrance to New York Bay on Sugar Island in the St. Lawrence river. I had a backpack filled with camping gear strapped to the aft deck, which loaded the rudder up a lot. The post sheared off at the cassette, causing the boat to head up radically and drop me into the water right next to the rudder blade, which was floating merrily next to me. Later inspection would reveal that this post was constructed of two or three layers of lightish fiberglass wrapped around an aluminum tube, or perhaps "draped" around is a better term. The aluminum tube looked as though it might have begun life as a ball point pen, or an automotive fuel line. Some nice Canadians spotted me flailing and towed me up to the island - some awesome boathandling by this 30-something woman who had grown up there. Lucky me or it would have been curtains for certain on the rocks.

 

Mast

 

This didn't so much fail as simply outlive its usefulness. It was the original round braided carbon spar from Ted's shop. It was real bendy, so I ran a bunch of uni down the front edge, and wrapped it in mylar tape to kick. This was done with a minimum of skill and in a rush the night before some regatta, so I hit it with the heat gun at about 1am. Consequently, when I took the tape off, all the glue from the tape stayed on the mast. Thereafter, whenever I put the mast down in the lawn to rig, it would always pick up grass clippings until it looked like a giant pipecleaner, or a furry javelin. It retained this property for years and was known for it. People would take one look at it and start checking to see if any boogers were hanging from their noses. I eventually replaced this mast with a new one. The mast that went to Australia was the new mast, as of about 2005.

 

Paint

 

This started flaking off at some fundamental level despite Dan's excellent application of some form of Interthane just before I bought LP from him. There were four layers on the boat: Sea Mist Green, some sort of royal Blue, a Red from a former life, and the white. I sanded all this off and hit it with duratek, which I then faired so the woodgrain showed through on the high spots when the boat was wet and the weather sunny. I fancied it quite leopard-like in appearance. I later sanded all this off, completely refaired the boat with three cycles of fairing compound in Rod Mincher's shop while setting the CO alarm off with the propane heater, and primed it again.

 

Carriage

 

This only failed because the seat leash pulled out of the cedar crossmember in the back, whereupon the seat slid a few inches too far outboard following a tack. The carriage was cutting edge 1985 technology, with sides fashioned from an old street sign and c-shaped clips on the guwales to hold the seat. When pulled slightly too far outboard, the seat would act as a giant lever on the windward side of the carriage, forking the aluminum plate away from the rest of the boat with giant crunching sounds, allowing one to finally decipher the message on the sign: DANGER...FAL....

 

Daggerboad Trunk

 

This was a c-shaped piece of commercial carpet, hard glued by Dan into the nice square trunk Bill put in the boat, rendering use of any other board impossible, at least until I spent a morning chiseling everything out of there after Dan's board failed.

 

Rigging

 

The paucity and dilapadation of rigging on this boat when I bought it are difficult to exaggerate. Apart from the vang, various other bits required replacing (or placing), including but not limited to the mast step, all deck fairleads, blocks and cleats, a mainsheet tower, mainsheet cleat rotating arm, shrouds, spreaders, spreader bracket, adjustable shroud tackle, gooseneck, outhaul - you name it, it got replaced.

 

Sails

 

It goes without saying that this boat had really crummy sails when I bought her. One was the main Lars Guck used at Worlds in San Francisco in about 1993. I know because I have seen the video. It is the same sail.

 

Dolly

 

This is actually pretty amazing. Dan Edwards went to the hardware store and bought some metal electrical conduit, which he aligned in a big V. He constructed a series of bunks for the boat which he then fiberglassed to the V and coated with carpet. He then mail ordered a trailer axle and springs from God only knows where, and bolted it to the underside of the conduit at the top of the V, and attached a ball receiver hitch to the point of the V. One lighting kit later, he had a trailer, which was light enough to use as a dolly also. This contraption, after prophylactic wheel bearing replacement by Dave Gilliland in Texas, made it all the way to Ohio and then out to Annapolis at 70+ mph without trouble. Big G later found a discarded trailer frame at work, which I combined with the Edwards mail-order axle and springs to form a new, better trailer. This served me well until, one fateful evening in September 2007 (the 8th as I recall), one of the springs failed, at which point the tire on that side hit the fender and rocketed aft beneath the trailer at about 65mph, while the other side of the axle remained attached to its spring. The trailer was vaulted into the air, landing on its side but mainly on the wing bar of my new Moth, with my shiny new IC on the bunk below it. Suffice it to say I have a new trailer now.

 

This was all pretty spectacular stuff, and it got me to thinking: One cannot deny the pattern here. Is there a Curse of Dan Edwards? Should I have just paid him the extra $500 for a boat that was worth much less than I actually gave him? Will I continue to experience catastrophic sailing equipment failures until I procure the services of a medium and exorcize the bad karma from my life? Did the failure of my new Van Dusen mast have something to do with the Curse, and has the Curse now transferred over to Jon, who was sailing the boat when the mast track ripped off? Maybe the boat just doesn't like being sailed by other people? Surely there is some explanation for what is happening here in the vast history of maritime folklore. Or maybe I've finally broken the last thing in my posession that was made by Dan Edwards. You decide.

 

And Dan, if you're reading, you now know how it all played out.

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Any ideas on sloop vs una at this stage...?

 

Andrew

 

So far the cat rigged Hollow Log has proven below standard upwind but fast downwind. This could be due to the unstayed rig rather han the lack of a jib, I hope to find out over the next few months when I add some diamonds to stiffen the side bend.

 

Its not that far off. Before McCrae I found I could hang in there upwind with Seth who came third in the IC WC but could not pace Hayden who won, Then I could not stay with the top 6 or so DCs at McCrae. But Downwind I think the Log was as fast or faster than anyone.

 

I understand from the UK sailors that Andy Patterson's cat rigged boat goes well upwind so I have hopes of improvements.

 

I think it I was starting again I would go for the sloop rig.

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Any ideas on sloop vs una at this stage...?

 

Andrew

 

I have seen two una rigs compete in large regattas against two sail boats and both times the una rigs have seemed subpar. Phils boat in McCrae was bloody fast down wind but upwind it was a question of hanging on people rather than pasing them. I felt as if I had to beat Phil to the windward mark because if I didn't he would be so far ahead by the leeward mark that I would never see him again. He usually did well enough up wind that he was able to make up the ground downwind and then some but I do wonder what he could have done with a standard rig because I think the hull is excellent.

 

Dad sailed a una rig AC at the 2005 worlds in England. This was a stayed rig on a Nethercott hull but, like Phil, it was more him trying to stay with the good guys upwind instead of hoping to pass them. Strangely enough the boat also proved above average downwind though, if I remember correctly, he was using a larger spinnaker than anyone (typical dad).

 

I would really like to see Andy's boat go becuase it is to date the only una rig DC that has a stayed mast. It is supposed to be fast upwind which might be evidence that the rig has to be stayed to be effective upwind but, who really knows?

 

Willy

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From personal experience, I think that a una-rig is far more effective downwind than the same amount of sail area in a sloop rig. With a una-rig, all the sail area is experiencing the full breeze without any kind of interruptions, where as on a sloop rig the jib often has air that is more turbulent than the una-rig due to it being in the wind-shadow of the main. Also, with a jib it is harder to achieve an effective sail shape as you would be able to with just a main as the canoe has such a narrow sheeting angle. One way to see if this idea in fact "works" is to compare Steve's downwind speed with the jib stick compared to his speed without it.

 

TC

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I can not see why the una rig can not be made fast upwind. Foiling moths or ACats show how fast upwind Una rigs can go.

We just need to refine the execution of the theory a bit, and still have speed to burn downwind.

 

After some mental analysis I do not think the unstayed rig is correct. I think the hugely varying power as you move out along the seat makes it hard to get leach tension consistant over the power range. I could get it pretty good in light stuff when sitting in at the hull, and at times it was Ok when fully powered up at full seat, but in between it was very difficult to match cunningham and vang to desired mast bend while controlling sail depth and twist. It all gets messed up further in waves. The last day at McCrae with the big waves and little wind was a nightmare upwind.

 

I guess it works on Finns, OKs and Lasers because they have a much narrower hiking/power range. The Finn and OK sails are also highly developped over decades.

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I guess it works on Finns, OKs and Lasers because they have a much narrower hiking/power range. The Finn and OK sails are also highly developped over decades.

 

 

Two Una rigged just out of the box IC's are a pretty small sample to compare against what must be one of the most highly refined small sloop rigs out there. I think some iterations are needed. Think about what the Finn rig looked like when it came out and compare it to the Finn rig of today.

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I can not see why the una rig can not be made fast upwind. Foiling moths or ACats show how fast upwind Una rigs can go.

We just need to refine the execution of the theory a bit, and still have speed to burn downwind.

 

After some mental analysis I do not think the unstayed rig is correct. I think the hugely varying power as you move out along the seat makes it hard to get leach tension consistant over the power range. I could get it pretty good in light stuff when sitting in at the hull, and at times it was Ok when fully powered up at full seat, but in between it was very difficult to match cunningham and vang to desired mast bend while controlling sail depth and twist. It all gets messed up further in waves. The last day at McCrae with the big waves and little wind was a nightmare upwind.

 

I guess it works on Finns, OKs and Lasers because they have a much narrower hiking/power range. The Finn and OK sails are also highly developped over decades.

 

What were your mast deflections? And the weight(s) you used for them?

 

I was doing some half-assed Bethwaite foot/pound guestimates on the Finn & OK, and it seems that theres a what? A 3, 3 1/2ish foot lever for a Finn/OK going upwind at 5 degree heel(?) if you assume the point of lateral bouyancy moves 1/2 foot to leeward . The Canoe would be what, 6-7 foot/lbs. So if you take your usual Finn 220lb sailor that's 660lbs. If you take a canoe sailor to be 175lbs, that's 1050lbs. Almost twice as much! Is any unstayed mast stiff enough for this? Well, except for the early Finn aluminum Needlspars. :blink:

 

Paul

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After some mental analysis I do not think the unstayed rig is correct.

 

Its interesting that Andy P built an unstayed Una rig for the old Nethercott he used as a development platform and very rapidly elected to redesign TT for shrouds... An unstayed fully battened rig is very much an odd beast when you think about how the battens need to work. Moths of course abandoned unstayed rigs a long time ago.

 

For me the two sail rig is an easy decision because I'm not as talented a helm as the Andys, Steves and Phils of this world, and I reckon that the twosail rig is shedloads easier to get in and stay in the groove upwind, but downwind does worry me. I should build a jib stick setup.

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For any one who is interested The Hollow Log mast comprised:

2.75m of 63.5 ID 2.1mm wall carbon with extra side wall thickness, and a 0.6m long 2.4mm thick sleave at deck to goosneck area, +

2m of 58 ID x 1.8mm WT

+1m of 50.8 ID x 1.8mm WT +

Tapered stiff sailboard section from 50dia to 30dia about 1.2m

All parralell tubes from CTech NZ, board sections from broken spars.

The top two splices were glued in and the lower one pulled apart for storage. All overlaps were about 200mm.

 

I initially tried a lighter mid and top section which would not hold me up at full seat. These went onto an unstayed moth rig which was also a bit soft but came to life when I fitted diamonds.

 

I think there are some disadvantages in the windage of the big section.

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my thinking is that a Uni rig should be faster upwind but I think it'd need to be stayed. Downwind a sloop should be faster if you can get the jib working especially on the reaching triangle course you guys use because the jib should give a higher lift coefficient on the same area because of the flap effect. I think that you'd need to be able to sheet it more outboard to give it a better shape though. Probably the best way I can think of to do that on a canoe would be a jib-boom because a jib track with no end support might be bad structurally although I guess you could do some kind of support off the hull

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my thinking is that a Uni rig should be faster upwind but I think it'd need to be stayed. Downwind a sloop should be faster if you can get the jib working especially on the reaching triangle course you guys use because the jib should give a higher lift coefficient on the same area because of the flap effect. I think that you'd need to be able to sheet it more outboard to give it a better shape though. Probably the best way I can think of to do that on a canoe would be a jib-boom because a jib track with no end support might be bad structurally although I guess you could do some kind of support off the hull

 

 

Isnt part of the issue with the una rig on a canoe the mast height/luff length limitation? i.e. its hard to get the most efficient sail shape as you cant fit a 10m sail on that mast height with the aspect ratio that you really want?

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What if you were to fit a wing mast like an A has with diamonds. The shrouds can be loose so you don't have to counter so much compression and a square top main. The thing I have to get my head around is getting the kicker to let go durring a tack or gybe so that the mast will rotate easliy. Cats have the advantage of the sheet controling leach tension because of the wide sheeting angle. Maybe you'd set something up like you guys have for the jib on the kicker so you can release it just before the tack and re tension it after the tack.

 

Since you don't have to have internal haliards, you might be able to put some carbon stiffeners cross ways inside the mast separating foam that also acts as the mandrel when you lay up the mast. I saw an early high speed windurfer mast that was built this way and it seemed to be a good idea.

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Willy is right and wrong about the Una rig on Blue Meanie.

The kite was standard AC size, but the mast was a meter taller.

The theory was that the taller una rig would go upwind faster than a sloop and be just as fast down wind.

The goal was to simplify the AC concept and make it mare affordable.

I don't think I hit those goals.

The boat went fast enough to finish in the top few on occasion, but wasn't the break through I hoped for.

post-738-1203517456_thumb.jpg

Seen here, it is was hard for me to figure out why this rig with a better aspect ratio wasn't that quick.

I figured out that I was not getting very good flow on the lee side of the sail in the bottom half, so I tried using a traveler to sheet further outboard, but that didn't help. I then over-rotated the mast ( which was round) to try to eliminate any separation bubble behind the lee side of the mast. I also tried fairings, but that didn't help much either.

By the time I was finished, Ibelieve that I should have shortened the spreaders radically to induce more bend to weather below the spreaders and that might have lowered the angle of attack enough in the bottiom of the rig to lively up the flow.

Paul Cronin was having similar problems with the Bongo rig and we compared notes quite a bit.

My next move would have been a custom wing like mast, but that would have negated the simplification and cost reduction goals of the program.

In any event, the idea of a taller rig with Kite didn't seem to answer the question the way I hoped it would and the class was not receptive to that alternative, so I shelved it and Sam reverted Blue Meanie to IC mode.

SHC

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