soma

Gunboat 68

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3 hours ago, Greenflash said:

...Daggerboardsare designed to break before the cases that hold them do. We cannot create weak points for the board to more easily shear off. Here's why: Many high aspect boards have two UD planks, one of which is in compression and one in tension. Between the two there are shear webs that transfer the shear loads between the planks. Some manufacturers have voids in between the shear webs. The 68 actually does have foam. You have to keep the UD planks perfectly straight all the way down the board, any 'lines' or weak points will cause a stress concentration and cause it to fail. Back to my idea of just helping the board shear off if in doubt. VPLP have done enough of this stuff that they know what to put in the daggerboard cases to make them strong enough.

Thanks very much for that! Well written description - I can visualize a rough idea of that structure now.

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9 hours ago, harryproa said:

  

Do you have any evidence for 99.9% of 20+ knot collisions with massive objects (whales, containers, logs, reefs, rocks, etc) being non terminal?    

Nobody suggested centre boards, although they are what the Tornado cat uses, and it is still the fastest non foiling 20'ter.

At 18 tons for a 68'ter, there should not be any doubt about the "strength".  Or, at 5 million bucks,  whether it's a "fine boat".   There are, or should be, serious concerns around the appendages in a high speed collision. 

 

In my boat I hit something coming over the yellow bank at about 15knots. Took the tip off my board off, but no further structural damage. It did pop my board up and slowed us down about 10knots almost instantly. I have not hit a container or whale yet. The caveat to my boat is that we have sacrificial keels that protect both the saildrives and the rudders. Frankly I prefer that over a non keeled boat, but that's my preference. I've not read any stories of a performance multihull (cruising) hitting a whale/container and that event being terminal. Terminal meaning boat sinks or people get seriously hurt.

I personally feel that having kick up boards, rudders and saildrives are not worth the squeeze or added complexity for the off chance that you hit something. I believe that the additional complexity in 'kick up' adds more concerns than they address, hence my preference for mini keels, which also allow grounding.

As Greenflash noted, 20 knots whilst cruising is 'wicked fast'

 

 

 

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7 hours ago, Greenflash said:

Gunboat has gone down the kick up centerboard road before. After a few iterations they do work reliably. Without getting into too much history here the message from the owners, skippers and VPLP was very clear for the 68: In a balance between safety, weight, usability and performance - We want daggerboards. 

Eh, I for one would love it if you got "into too much history". Was the experience on the GB60 bad? Something else?

 

7 hours ago, Greenflash said:

Hitting something is an unfortunate event. Kinetic energy is a function of speed (Condor just averaged about 10 knots across the Atlantic, people aren't blasting around at 20 knots all day and night)  and weight.

Sure, but I think the point is that kinetic energy grows as the square of velocity and only proportionally to mass. Still I agree with you (and with GB and other pro-daggerboard people).

 

7 hours ago, Greenflash said:

The Gunboat 68 is not more susceptible to hit something than any other boat on earth, in fact I would argue it is less likely. If you do hit, redundancies and good engineering practice means you walk away from the incident with a story to tell. 

Exactly.

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I think it's unreasonable to expect no or minimal damage to ANY moderate size sailing boat with a 20 knot collision with a big log, container or similar, monohull or multihull. Maybe a steel destroyer will handle a log easily but I wouldn't want to hit a 20 T container.

Around here in British Columbia the most common insurance claim is for new stern drives when a medium/small size powerboat hits a log and rips off one or two drives. Sometimes the boat sinks too.

No,  you probably don't need a crane or forklift to replace a daggerboard - a halyard and a couple of beefy guys to hold it outboard until in the slot will do just fine. My boards were solid wood core so rather heavy but with my wife lifting the board on a halyard I could semi-easily push it outboard until it was in the slot. Since Gunboats have a bigger budget and longer heavier foils, get 2 big guys instead of 1. Maybe an outhaul and a snatch block with a line led to a winch if you need it.

Yes, building new rudders or daggerboards is costly if they are high performance types with lots of carbon. And yes, it will cost a few $$ to ship by air to some exotic location. Not the end of the world for a typical Gunboat owner I figure. I think Catana charged something like $12K Euro for a single new daggerboard for a 47...

 

But at the end of the day, we are seldom faced with 20 knot collisions with stuff. If you do, it's a bad day and you go on and fix things.

10 hours ago, Greenflash said:

PS - Zonker do you want a job? B)

You just want me for my speedy laminating skills, not my engineering brains don't you!

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49 minutes ago, Zonker said:

 

But at the end of the day, we are seldom faced with 20 knot collisions with stuff. If you do, it's a bad day and you go on and fix things.

 

Agreed, although most boats aren't faced with it ever because they don't claim to and can't go that fast.  In this context, the 20 knots is invoked as an illustration of what it means by those who say boards would not break.  Here, the better question is probably at what speed the boards, drives and rudders will break.  If that's below a scary speed, then impact injuries are no issue.  If it's within realistic cruising speeds ranges, then for anybody who does want to cruise far and wide it's worth thinking about.  when far from help, exposed foils like that are not that smart imho.  

All probably not an issue for GB owners because they're unlikely to be really cruising and have bought the boat for showing off.  Like their maserati, unreliability, high repair bills and depreciation are acceptable downsides of looking like the guy in the ad.

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1 hour ago, bigmarv said:

If it's within realistic cruising speeds ranges, then for anybody who does want to cruise far and wide it's worth thinking about.  when far from help, exposed foils like that are not that smart imho. 

Hell here I am siding with GB. If you are cruising far and wide on a cat, boards for me are almost a necessity. Having boards allows for a larger wind angle range...….that 20 degrees of added wind range is huge, especially if cruising far and wide. As you move faster that apparent wind whips around too. I find it's always on my nose or always behind me.....I must be crappy at picking my windows I guess.

1 hour ago, bigmarv said:

All probably not an issue for GB owners because they're unlikely to be really cruising and have bought the boat for showing off.  Like their maserati, unreliability, high repair bills and depreciation are acceptable downsides of looking like the guy in the ad.

As Greenflash noted there are a number of GB's out cruising for the love of cruising, not just for 'showing off'. There are also a number of GB's that race and want to be part of the GB camaraderie. Even though they cost an arm and a leg I'm glad that there are owners out there shelling out that type of dough to keep builders, captains, maintenance and vendors fed and happy. Spread the wealth I say. The 62's and the 66's have not really depreciated that much when considering all makes and models.

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6 hours ago, Whiskey.T said:

Eh, I for one would love it if you got "into too much history". Was the experience on the GB60 bad? Something else?

This is kind of a short history/issues that were dealt with.

1. Performance loss. With a kick up board, while it is down, you are left with a hole in the bottom of the boat that is the length/width/depth of the board. The faster you go, the more turbulence you create into the void. If you’ve been on small dinghys 420’s etc. there is a rubber seal that allows their centerboard to drop and keep the turbulent water out of the trunk at the same time. Allowing for a smooth underbody. Just wasnt possible to create something like that on a larger scale.

2. Can’t modify the boards for more performance. The trunk you build into the boat for the kick up boards limits any future modifications. With dagger boards? Make them as deep as you want, change the foil shape. All possible. With everyone pushing for taller rigs, larger sail plans, you outta be able to put the power down you below the waterline.

3. The GB60’s had hydraulic rams that controller the up/down of the boards connected with a “fuse” pin. Hit something at speed, pin blows, saves the board/ram. But replacing that pin is the fun part at sea. After all that, there would still be damage to the board.

4. If you need to pull the boards for repair, with daggers, attach a halyard and hoist. With kick up boards, requires a haul out to drop out from the bottom.

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1 hour ago, crashjibe said:

This is kind of a short history/issues that were dealt with.

1. Performance loss. With a kick up board, while it is down, you are left with a hole in the bottom of the boat that is the length/width/depth of the board. The faster you go, the more turbulence you create into the void. If you’ve been on small dinghys 420’s etc. there is a rubber seal that allows their centerboard to drop and keep the turbulent water out of the trunk at the same time. Allowing for a smooth underbody. Just wasnt possible to create something like that on a larger scale.

2. Can’t modify the boards for more performance. The trunk you build into the boat for the kick up boards limits any future modifications. With dagger boards? Make them as deep as you want, change the foil shape. All possible. With everyone pushing for taller rigs, larger sail plans, you outta be able to put the power down you below the waterline.

3. The GB60’s had hydraulic rams that controller the up/down of the boards connected with a “fuse” pin. Hit something at speed, pin blows, saves the board/ram. But replacing that pin is the fun part at sea. After all that, there would still be damage to the board.

4. If you need to pull the boards for repair, with daggers, attach a halyard and hoist. With kick up boards, requires a haul out to drop out from the bottom.

How long does it take to swap out the "fuse" pin, and is it possible to keep racing if you blow the fuse?

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11 hours ago, crashjibe said:

This is kind of a short history/issues that were dealt with.

1. Performance loss. With a kick up board, while it is down, you are left with a hole in the bottom of the boat that is the length/width/depth of the board. The faster you go, the more turbulence you create into the void. If you’ve been on small dinghys 420’s etc. there is a rubber seal that allows their centerboard to drop and keep the turbulent water out of the trunk at the same time. Allowing for a smooth underbody. Just wasnt possible to create something like that on a larger scale.

2. Can’t modify the boards for more performance. The trunk you build into the boat for the kick up boards limits any future modifications. With dagger boards? Make them as deep as you want, change the foil shape. All possible. With everyone pushing for taller rigs, larger sail plans, you outta be able to put the power down you below the waterline.

3. The GB60’s had hydraulic rams that controller the up/down of the boards connected with a “fuse” pin. Hit something at speed, pin blows, saves the board/ram. But replacing that pin is the fun part at sea. After all that, there would still be damage to the board.

4. If you need to pull the boards for repair, with daggers, attach a halyard and hoist. With kick up boards, requires a haul out to drop out from the bottom.

As I have tried to explain, kick up daggerboards are not centreboards.  They are dagger boards and are raised, lowered and removed the same as non kick up boards.  The only difference is the back of the case and the hull do not have to be bulletproof, but the case has to be extended aft a couple of metres at floor level (and a little longer than normal at deck level to allow the board to pivot) at deck level and a fuse included behind the board and lower bearing.  

Sealing the back of the case is trivial, supporting the board at floor level critical, but far less material is required to do this than making the case and hull bulletproof.   

There are many more high tech options but even if the open slot was filled with cheap foam and lightly glassed, it would be a better solution than sheering the board.  

If you want longer boards,  extend the cases.  The further the board kicks up, the lower the sideways loads, so this is more of an interior layout problem than a structural one.  Board section change is not a problem.  

Greenflash,

A daggerboard will not sheer off fore and aft at anywhere near a pre-ordained speed.  It will vary enormously depending on whether the contact is at the tip or just below the case, whether the boat is hard on the wind, reaching or running, stripped for racing or loaded up for cruising and how much of the safety factor was used up by the build crew.   

If you posed the question to your owners as:

If it meant the boat was lighter and faster, and you hit something substantial at high speed would you prefer to: 

1) have crew crashing into furniture at high speed, a dagger board sheered off and the remains jammed in the case, 2 holes in the hull where the sail drive and rudder used to be, no sailing for a couple of months, and a substantial bill to tow, slip and repair the boat?

or

2) spend 10 minutes resetting fuses and continuing?

you might get a different response. 

If you ask your designers, shareholders, lawyers and insurers the liability question Big Marv asked in Post 381, they may also respond differently.  

There are faster, safer, cheaper and less likely to lead to litigation solutions than dagger boards which don't kick up,  fixed rudders and  exposed sail drives.  

You evidently do not think this is correct, so I guess we have to agree to disagree.  

The boat looks great, seems to sail well and you have orders for more.  I wish you well. 

regards,

Rob Denney

www.harryproa.com

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2 hours ago, harryproa said:

As I have tried to explain, kick up daggerboards are not centreboards.  They are dagger boards and are raised, lowered and removed the same as non kick up boards.  The only difference is the back of the case and the hull do not have to be bulletproof, but the case has to be extended aft a couple of metres at floor level (and a little longer than normal at deck level to allow the board to pivot) at deck level and a fuse included behind the board and lower bearing.  

My fault in not reading more carefully what you wrote.
Can you explain a little further (or provide a diagram). I'm familiar with a kickup daggerboard something similar to the attached image

http://forum.woodenboat.com/showthread.php?187418-Pivoting-daggerboard

Can you explain the fuse behind the board.

I'm trying to visualize how you would build it. Damn cool looking proa by the way.

pivoting_daggerboard_phil.gif

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6 hours ago, harryproa said:

You evidently do not think this is correct, so I guess we have to agree to disagree.  

The boat looks great, seems to sail well and you have orders for more.  I wish you well. 

Hi Harryproa! I think we will agree to disagree, but I like your concepts (and would also like to see more) and I will explain why we don't do this. Thanks for the compliment! 

6 hours ago, harryproa said:

but the case has to be extended aft a couple of metres at floor level (and a little longer than normal at deck level to allow the board to pivot) at deck level and a fuse included behind the board and lower bearing.  

On the Gunboat 68 this would mean losing a wardrobe and a head and adding quite a lot of weight. It just isn't worth the downsides for us. We've already made the cases rather long so that people can play with canting systems in future.

6 hours ago, harryproa said:

1) have crew crashing into furniture at high speed, a dagger board sheered off and the remains jammed in the case, 2 holes in the hull where the sail drive and rudder used to be, no sailing for a couple of months, and a substantial bill to tow, slip and repair the boat?

Fortunately, None of this has happened  after numerous collisions with various objects over our 15+ year history. This isn't a problem we've been asked to solve. (Except the jammed board like Soma showed, which has a simple solution)

6 hours ago, harryproa said:

spend 10 minutes resetting fuses and continuing?

For centerboards at least, the reality is that it is a quite a bit more of a task, the crank arm is moving as the board moves with the boat. You need to get into calm waters first. replacing a pin in anything that is underwater while in swell will always be a tough project. Bear in mind the pieces are heavy. 250Kg boards, big gear, high loads. We don't want people to man-handle this stuff. 

Furthermore I don't quite understand how something 'gives way' and then you don't allow the object to move on to the more sensitive bits like sail drives and rudders. I'd take the hit on daggerboards every day of the week. 

Nice website BTW, you're really 'doing it' which I can respect! 

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5 hours ago, Greenflash said:

Nice website BTW, you're really 'doing it' which I can respect! 

Reality check?  Denney has been "doing it" for twenty years, yet there isn't the slightest trace of evidence that any Harryproa has ever delivered on his claims of high performance and/or seaworthiness offshore.  Pretty drawings prove nothing.  To give full credit (or blame?) where it's due, all the beautiful CAD work was done by others, not Denney:

Quote

Steinar Alvestad is an artist (Alvestad Arts) doing the styling and optimizing available space in the harryproa designs. Steinar was one of the first harry supporters, buying plans for a 20m/65’ter back in early 2000.

Nineteen years later, that boat still isn't finished.  http://harryproa.com/?p=726

Finally, a proa is the least suitable of all hull forms for carrying cargo.  Monohulls, catamarans and trimarans do a much better job at carrying weight for any given length.

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14 hours ago, harryproa said:

 

There are faster, safer, cheaper and less likely to lead to litigation solutions than dagger boards

Seems like a solution in search of a problem, unless I'm just not aware of how much litigation over daggerboard failures has been initiated over the past decade.  Do you know?

 

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On 4/12/2019 at 6:11 PM, Zonker said:

I helped write the specification for an aluminum fast 45 knot power yacht we designed. It read something like

"hull surface shall be fair such that the largest gap under a 1m long ruler placed anywhere on the hull shall be no more than the thickness of a #1 paperclip"

"this is to be the bare hull BEFORE any hull fairing compound is applied"

That's about 0.8mm over a 1m length. They are very good aluminum builders. We agreed on this standard before writing it in; don't want to put in something that is impossible/impractical.

I've found that about 1mm over 1m length is achievable by very good builders.

Yo Zonker, I thought I'd bite... 

I put a 1 meter steel rule on edge on GB6803 hullsides,  just demolded. I think I could push paper through some spots but not a paperclip B)

IMG_1712.thumb.JPG.c033890580f76895bc472d2cef691444.JPG

IMG_1714.thumb.JPG.e3e73c8a9109b6dbffb4001b128c72bb.JPG

You guys will have to wait to see the whole thing, but our composite team absolutely killed it on this infusion. Not a dry spot, void or wrinkle to be found. A little teaser of the most complex area ("breakthrough" near the transom outboard): 

image1.thumb.jpeg.733a040d9c1f7416a9db236ff2bde50c.jpeg

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15 hours ago, harryproa said:
36 minutes ago, Greenflash said:

I put a 1 meter steel rule on edge on GB6803 hullsides,  just demolded. I think I could push paper through some spots but not a paperclip B)

 

IMG_1714.thumb.JPG.e3e73c8a9109b6dbffb4001b128c72bb.JPG

You guys will have to wait to see the whole thing, but our composite team absolutely killed it on this infusion. Not a dry spot, void or wrinkle to be found. A little teaser of the most complex area ("breakthrough" near the transom outboard): 

 

 

That is indeed impressive. 

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Easy to do if you're starting with a mold to get it that fair (well pretty easy).  The 1mm/1m was for a welded aluminum hull before the fairing compound. THAT was impressive.

Nice work around the transom. Those are some deep recesses. Tell the designers to stop mucking around and make it easier for the poor builder.

 

In the top picture are there tiny imperfections in the surface finish? Or just dust - the weave looks huge so they are tiny whatever they are.

I think you should just clear coat the hull and call it a day. 

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7 minutes ago, Zonker said:

I think you should just clear coat the hull and call it a day. 

yup, that will do it for me!!!

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20 minutes ago, Zonker said:

Easy to do if you're starting with a mold to get it that fair (well pretty easy). 

The level of female mold surface finish is everything. The bike's nose piece is only 2 layers of 6oz Kevlar and 6oz carbon fiber. You don't want any filler or paint on a race bike that only has a 1hp engine.

story 14.jpg

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She made it to St Barths. Looks very cool...

 

 

20190417_163046.jpg

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I would love to see that Gunboat hoisted up on deck like that monohull sloop on the MegaStinkpot in the background! Maybe there wouldn't be enough room abeam for that even stinkier big GoFast on deck on the nearside.  

    This cat look so much better than Nigel's last effort for Gunboat. 

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5 minutes ago, Rasputin22 said:

I would love to see that Gunboat hoisted up on deck like that monohull sloop on the MegaStinkpot in the background! Maybe there wouldn't be enough room abeam for that even stinkier big GoFast on deck on the nearside. 

It's not a sloop, it's a motor boat but the mast behind it makes it look like a sloop at first glance. Still, pretty funny.

Edit: maybe I'm wrong.

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Just now, Whiskey.T said:

It's not a sloop, it's a motor boat but the mast behind it makes it look like a sloop at first glance. Still, pretty funny.

You seem to know a lot for a newbie. That big Megayacht is nearly a permanent fixture in St Barts. Forget the name but I've dinghied around it and they crane a 50 monohull sloop daysailer up on deck and I bet that Gofast to stbd is 60 foot or so. Have another shot (of) Whiskey.

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that's a good place to find wisdom

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15 minutes ago, Whiskey.T said:
19 minutes ago, Rasputin22 said:

I would love to see that Gunboat hoisted up on deck like that monohull sloop on the MegaStinkpot in the background! Maybe there wouldn't be enough room abeam for that even stinkier big GoFast on deck on the nearside. 

It's not a sloop, it's a motor boat but the mast behind it makes it look like a sloop at first glance. Still, pretty funny.

Edit: maybe I'm wrong.

You are not wrong.

ondeck.jpg.db28559401d56534b59537a8de0fff08.jpg

P.S.  Look at the headstay.

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No harm, no foul, Whiskey.  Le Grand Bleu 370'.  23 meter sloop and a 22 meter gofast on the other side. Roman Abravanich's old boat.image.thumb.png.6eacaf34d141d21841afde63ec884c5a.png

Here was the replacement but it is sold now too!

image.thumb.png.9bcbc49898254b0b7a735aa37c1d3f4b.png

 

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4 hours ago, olsurfer said:

The level of female mold surface finish is everything.

I'm unclear <pun intended> as to what your peccadillo with women's make-up has to do with anythi...  Oh, wait; my bad. ;)

 

 

<My standard peace offering: 689304321_marinepeaceofferingintraditionalformfromajuniormemberv2.jpg.c8e62540292c662b656e0d2a8ed3cd98.jpg; Ask DDW to explain it, if necessary>

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I knew I was in the weeds as soon as I wrote it but didn't know another way to say it.

I like to get the point across with as few words as possible.... ah jeez, i can't help myself....

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9 hours ago, MR.CLEAN said:

Seems like a solution in search of a problem, unless I'm just not aware of how much litigation over daggerboard failures has been initiated over the past decade.  Do you know?

 

I could swear I just saw an ad on TV for a class action lawsuit against dagger board failures. Or maybe it was about ear plugs. I lose track. 

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12 hours ago, Zonker said:

...I think you should just clear coat the hull and call it a day. 

Do I remember this right? There's a real issue with UV protection. The carbon is really sensitive to UV, and it's really hard to get UV protection into either the epoxy or a clear coat. Or am I wrong?

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No the carbon doesn't mind.it is the epoxy resin that breaks down with UV. The clear coat provides UV protection but eventually it fails too. 

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22 hours ago, Lat21 said:

She made it to St Barths. Looks very cool...

20190417_163046.jpg

Imagine her even sexier with a nice carbon boom furler:

 

Brenta 52_01.jpg

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4 hours ago, dcnblues said:

Imagine her even sexier with a nice carbon boom furler:

 

Brenta 52_01.jpg

You just couldn’t resist the stupid. 

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On 4/15/2019 at 9:45 PM, jackolantern said:

 

How long does it take to swap out the "fuse" pin, and is it possible to keep racing if you blow the fuse?

As greenflash posted, it all depends on the sea state. As there is no emergency “brake” mechanism to lock the board in place, it is free to move with the wave action on its pivot point, so there you are, in the bilge, trying to line up the fork of a hydraulic ram, with the top of the swinging board. Can be easy or could be very dicey, with potential for a finger tip guillotine. 

 

 

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On 3/27/2019 at 6:07 PM, Monkey said:

Did you not read what he wrote?  I’m not aware of a single modern vehicle out there with “gravity drains” in a moon roof. It’s a big rubber seal. 

You don't have a very good memory, do you?

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4 hours ago, Monkey said:

You just couldn’t resist the stupid.  

Well, at least I'm not the only one. There's me, and all those friggin retards at Hall Spars. We all sit around wishing we were as smart as you:

Quote

...she also represents the pinnacle of New Zealand’s marine engineering and boatbuilding expertise.

...A couple of easy-control strategies will help: a self-tacking jib, a German mainsheet system allowing the sail to be controlled from either helm, and a very slick Ocean Furl boom-furling system from Hall Spars.

Roger Hill 18.5m sailing cat Cation

 

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proa sailor,
Yawn. 
 
Mpenman and Green Flash,
Glad you like the boats and the web page.  
Drawing of one of several options (not the one I would choose, but it gives the idea) attached.  Deliberately basic as a) I am busy building the protoype of http://harryproa.com/?p=2944#more-2944 b) I don't have a drawing or layout of the GB 68 and c) I don't want to get into a discussion about the details of alleviating the problems of holes below the waterline and moving heavy objects under high loads, which in my opinion, are dopey ideas from the get go. 
 
1248060560_ScreenShot2019-04-18at6_12_19PM.thumb.png.56da43c3b4290e15e2d3002c55273396.png
Green Flash,
Kick up rudders and protected saildrives are no brainers. Neither is difficult.   
Manhandling of heavy objects at sea (and on land) is dangerous and was suggested by others, not me.  With smart design, there would be no need to touch the board, much less do anything to or with it.
adding a lightweight (only has to keep the water out) extension to the case, a fuse and an insert will be lighter than 'bullet proofing' the hull .  
The proa part of the proa wars have been over for a while.  One side is selling proa plans (2 x 50', 1 x 40', 2 x 32' and 3 x 25' and a couple of consultant jobs in the last few months) and developing new ideas and boats.  The other side, not so much.   The personal dislike still appears occasionally, but most of the haters realised it was helping sell harryproas, so gave it up.    Anyone wants to discuss this, maybe starting a new thread is a better idea than feeding the troll.
Clean,
Interesting question, thanks for asking.  Zero according to Green Flash, but the legal industry is apparently full of sleaze bags, so maybe it is only a question of time.  And why I said 'likely' to lead to. 
Until then, let's call these philosophical questions and an opportunity for you to show off your legal knowledge:  
1) If poor build (Oyster), poor maintenance (Cheeki Raffiki) and poor systems (the pro sailor injured getting off the boat into the tender) have legal consequences, does/should poor design? 
2) There have been sufficient other deceleration injuries to justify "don't sleep head forwards at high speeds".   Does 15 years without  a report of someone getting hurt in a collision absolve the high speed boat designer/builder from including safety features that will stop someone getting hurt when the boat does hit something?   
3) What is the situation If someone is hurt because the board didn't sheer off as designed (impossible to design for, so probable) in a 20+ knot collision with a large floating object?  Does this change if the designer/builder knew it would happen at some stage (WHEN, not IF, post # 342), and there is a known solution to the cause, which was ignored to gain more wardrobe space.  Do the hurt people have a case?   
4) If the board did sheer off, and the floating object then ripped off the unprotected outdrive and fixed rudder and it became a Rainmaker (or worse as the boat would be taking on water) situation, is/should there be any liability around the design choices?  Is it buyer beware, or do the designers,  builders and owners have some responsibility?   If it is buyer beware, do crew and passengers have legal options?
 
These are design questions that I had to resolve 20 years ago before I could start selling plans.  The early solutions weren't pretty, but were worth it for peace of mind.  Since then they have evolved to almost elegant.
 
By the way: I "knew you'd bite" at an unsupported statistic and  "get in here yappin'" so I could ask these questions. "Don't you love it!! "   :-)  Ref pg 6 of the Ultime thread.
 
 
 
 
 

 

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harryproa, 

  congrats on the new website.  It is good to have all the relevant pieces of info in one place.   B)

( although I am itching to see the exhilarator 40 drawings ? )

The kick up boards are a VERY good idea ;  & I think we will see flow on from your ideas very soon.

Lastly,   I cannot find the "page 6 ultime thread"   ?

Keep up the good work !

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On 4/18/2019 at 10:20 PM, dcnblues said:

Well, at least I'm not the only one. There's me, and all those friggin retards at Hall Spars. We all sit around wishing we were as smart as you:

 

They’re happy as hell to sell expensive kit to anyone willing to pay for it. There’s a reason most don’t. Same reason they aren’t building stainless steel hulls. 

With the exception of a wingmast, it seems like your goal in life is to push for all the things real life doesn’t like. 

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On 4/19/2019 at 2:09 AM, Zonker said:

No the carbon doesn't mind.it is the epoxy resin that breaks down with UV. The clear coat provides UV protection but eventually it fails too. 

Not so sure about that one Zonker . I've seen plenty of un- clear coated "A" class masts where the exterior layer of carbon turns quite white as if breaking down .

The sailers themselves don't seem to be too concerned as it's just the dress layer with all the work being done underneath by the varying amounts of uni and biaxials  I have been told .

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On ‎4‎/‎18‎/‎2019 at 3:09 PM, dcnblues said:

Imagine her even sexier with a nice carbon boom furler:

It is most definitely possible to do both. I've considered boom furling for the next boat and had in boom furling on the previous boat (St Francis, which was removed by the next owner). I'm assuming that in-boom furling has improved considerably but the two things I did not like were the luff of the sail in a track that had more and more friction as it was raised and then the critical angle of the boom vang. When the wind piped up, I never felt sure it would come down. If they could put the sail on cars (which I'm sure would bang up the boom furling, it would make it easier to lower without needing to furl the sail.

I'm gonna take a look at a few more systems to see what's happened over the past 10 years to improve on those two issues.

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On ‎4‎/‎18‎/‎2019 at 11:34 PM, harryproa said:
Mpenman and Green Flash,
Glad you like the boats and the web page.  

Interesting designs. Have not review much of a proa layout. 

On ‎4‎/‎18‎/‎2019 at 11:34 PM, harryproa said:
 
Kick up rudders and protected saildrives are no brainers. Neither is difficult.   
 

Definitely a solution that can be used. Not a bad one. Does consume a fair bit of space and the saildrive or shaft drive still needs to be protected. 

My personal preference is still to have smaller keels with boards. Solves most of the problems and allows you to put the boat on it's own bottom.

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8 hours ago, Justaquickone said:

I've seen plenty of un- clear coated "A" class masts where the exterior layer of carbon turns quite white as if breaking down .

Sure - but that's the epoxy resin breaking down, not the carbon fiber itself. Carbon fiber is essentially Carbon. 

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On 4/22/2019 at 11:41 AM, mpenman said:

It is most definitely possible to do both. I've considered boom furling for the next boat and had in boom furling on the previous boat (St Francis, which was removed by the next owner). I'm assuming that in-boom furling has improved considerably but the two things I did not like were the luff of the sail in a track that had more and more friction as it was raised and then the critical angle of the boom vang. When the wind piped up, I never felt sure it would come down. If they could put the sail on cars (which I'm sure would bang up the boom furling, it would make it easier to lower without needing to furl the sail. 

I'm gonna take a look at a few more systems to see what's happened over the past 10 years to improve on those two issues.

Yeah, I agree. I think Leisurfurl has the patent on putting the drum for the furling line where it ought to be: mounted to the front of the mast (no added weight to boom, and even strengthens the mast). So any solution would need to work out some compromise there for an ideal system (ideally where you buy the furling drum from LF and are free to customize the rest of the system). I also really like the combo of boom furler with rotating mast. I like the reduction in turbulence, and I really like the reduction / elimination of horizontal boom to mast angle.

And I think a system which used cars would slide up and down with an ease that isn't available today. I'm imagining a new car design in some rigid material which is engineered to break apart / unfold when subjected to the side forces of being rolled up (the upper cars would obviously need to do less than the lower ones). Yet when straightened, such a car would have the tensile strength to hold the (battened, full roach) sail to the mast. Conventional sails with the internal chord slotting into the fixed-mast mast groove seem archaic to me.  And it doesn't seem unsolvable to design a car which can perhaps separate enough to be folded.

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On 4/21/2019 at 3:12 PM, Rasputin22 said:

Why aren't they building SS hulls again? I must have missed that part.

a) most people (including myself) forget that without oxygen, stainless isn't really stainless and corrodes / cracks (so if you've ever put tape over any part of your standing rigging, you may want to dye test those parts), and b) it's weaker than painted steel and several times weaker than carbon (I thought it was around 1/2 the strength, but it's apparently more like 5x weaker. My bad).

Still, when SpaceX decided to switch manufacturing to SS because it's 60x cheaper than carbon and would do the job for a big spacecraft (even so far as to have a porous outer layer on one side to sweat out methane as an evaporative cooling technique), I thought it was interesting enough to share a link on this topic with the hot carbon boat and ask for clarification about the above facts. I probably shouldn't have. Sorry.

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On 4/21/2019 at 2:23 PM, Monkey said:

...With the exception of a wingmast, it seems like your goal in life is to push for all the things real life doesn’t like.  

Well, real life sure likes drain tubes in sunroofs and deck hatches. Works in cars, seems to work on the GB 68. I wonder why experienced sailors like yourself haven't created a demand for hatches with drains which would defeat the surface tension trying to otherwise make those hatches leaky? Hmm, I wonder whether it might be an attitude that condemns anything not done the old way as 'stupid,' and is arrogant enough to use personal attacks even when they can't get their facts straight. I'll tell you what, Sparky: You stick with tradition. I'll stick with innovation (and thank god you weren't anywhere near the design board for the GB 68).

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Hatches with gutters and drains are incredibly complex. I'm sure that they add weight and cost. I have molded gutters before (for Francis Lee), the beautiful Perry double-ender) and they were challenging and added weight without a structural benefit. I'd rather see other approaches.

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Structural benefit? They wouldn't be there for a structural benefit. They're there so that you don't have to mop up sea water out of your cabin or off of your bunk. And they are often raised above deck level in the hopes of making it harder for the water to get in. So it doesn't seem like rocket science to put a drain in that extra space off the deck. And the valid question would be what structural penalty would you pay for the drains? What added price? Me, I'd pay a lot. Car roofs want to be stiff and light too. But car designers don't seem to think they can fight off surface tension / capillary effect, so maybe boat designers should get on the same page. GunBoat did, and I think they deserve a round of applause for doing so...

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On 4/23/2019 at 4:50 AM, mpenman said:

Interesting designs. Have not review much of a proa layout. 

Definitely a solution that can be used. Not a bad one. Does consume a fair bit of space and the saildrive or shaft drive still needs to be protected. 

My personal preference is still to have smaller keels with boards. Solves most of the problems and allows you to put the boat on it's own bottom.

Ta. Harryproas are cheaper, lighter and easier to sail and maintain than a conventional cat, but they look different. Some see this as an advantage,  others as a crime.

With a bit of lateral thinking, the space required for kick up boards is not much. 

Saildrives and shafts under the water are draggy and numerous accidents waiting to happen.  If hitting something doesn't damage them, a crap pot, trailing sheet/halyard, someone else's anchor line a fishing net or other debris renders them useless.  Survive those and all you have to worry about is the seals, bearings, antifouling and corrosion.  Cruising is meant to be low stress and fun, not an exercise in damage control.   

Small keels increase the draft and the drag and for GB are probably an image problem.    My biggest concern with them is that if the boat drifts sideways onto a beach in waves, they are likely to snap off, followed or preceded by, the rudders.   Not a regular occurrence, but it only needs to happen once.  

Small keels still require kick up boards and rudders.

Peterbike,

Thanks.  More information, including the Ex 40 data will be posted soon.  

Ultime/G class development thread on Ocean Racing Anarchy.  Posts #524, 526, 528 and 559, which Clean did not respond to.  I mentioned it here as a gentle reminder, but it seems he is not responding to this thread either.  

Back on topic:

Re costs:.  From the HH site: the HH66 has 270kg (600lb) x 6m (20’) long daggerboards that are built from aerospace technology carbon and cost over $200,000 each.  The GB 68 ones weigh 250 kgs, no idea if they are aerospace tech or boatbuilding tech (or what the difference is), but either way, these are not items you want want to be sheering off very often.  Nor are 2 guys going to easily get them off the truck, carry them down the dock and instal them as suggested above.  

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Still on Dagger boards, I'm curious about the relationship of the sleeve to the board. I imagine that of course it needs to be loose enough to slide easily up and down, and to prevent wear on either surface, but the looser that relationship, the more prone the system would be to banging, especially in rougher blue water. An obvious solution would be some kind of cinches at deck and hull bottom level, but I'm not aware of any such system. So how is a modern system designed, and what is the current thinking on how you balance stability versus ease of use? Thanks.

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Well made cases and boards are built to pretty tight tolerances so banging is low

On our cat, the tolerances were pretty generous (which is a polite way of saying sloppy). At deck level I just applied a couple of wood wedges between trunk and board and that stopped motion. At bottom, I glued in some outdoor carpeting to make it a tighter fit. 

In rough seas they would bang a bit but not really objectionable. One was noisier than the other and right near our pillows so that one was often fully raised unless we were hard on the wind.

 

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The 2 Catanas I've owned from the last generation had the fit between board and case pretty tight. No banging with either, but the board were somewhat difficult to raise under load.

On the other hand,  I know some other Catana owners who used to complain about noise at anchor. The solution in that case is what Zonker mentioned (wedges).

The newer Catanas 59 and 62 have Delrin bearings that make the fit tight but with the boards sliding easily even under load.

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53 minutes ago, dcnblues said:

Still on Dagger boards, I'm curious about the relationship of the sleeve to the board. I imagine that of course it needs to be loose enough to slide easily up and down, and to prevent wear on either surface, but the looser that relationship, the more prone the system would be to banging, especially in rougher blue water. An obvious solution would be some kind of cinches at deck and hull bottom level, but I'm not aware of any such system. So how is a modern system designed, and what is the current thinking on how you balance stability versus ease of use? Thanks.

done right.., they don't bang or move around at all

they are raised and lowered with winches - powered in my experience

 

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14 hours ago, harryproa said:

Nor are 2 guys going to easily get them off the truck, carry them down the dock and install them as suggested above.  

Nope. Heavier than I guessed. My board was about 200 lbs. I'd guessed the GB one would be 400 lbs. At 600 lbs you'd probably have to round up a few other sailors in a marina for the 1/2 hr job to get it carried down the dock and into the case. Balance it on its side on 2 dock carts. 

I'd invite everybody that helped over for sundowners and a few snacks that evening.

If the boat is at anchor, get a truck with a typical extending boom crane like a Hiab to lower the board across the tubes of a dinghy. Hell just lower it into the water if you can't get the dinghy close enough. If it floats, tow it to the boat with the dinghy. If it's got so much carbon it's a sinker, tie a few fenders to it.

Thankfully because these boats don't seem to be breaking off boards that often you will not have to spring for the case of beer and a few appies too often.

Somehow I managed to move a 350 lb diesel from a trailer to inside my boat with 2 guys. I was above, hoisting it aboard using the mainsheet tackle. Friend was below, holding it away from the topsides. We are not talking huge weights here, just long and unwieldy. Ever seen a big mainsail being taken off a racing boat? Same story; bunch of guys and you all try to walk at the same speed.

I do think a skeg in front of a saildrive or strut is wise if you are going long distances. If you're more the local racey type, leave it off to save drag.

 

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Curved boards need to be inserted from the bottom. With significant positive buoyancy (I’m guessing comparable to weight, so 400-600 pounds) there is almost no way.

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4 minutes ago, Zonker said:

I do think a skeg in front of a saildrive or strut is wise if you are going long distances. If you're more the local racey type, leave it off to save drag. 

I agree completely with you (and @mpenman above). I had a boat with saildrives and no skegs, and lines, crab pot cables, etc, would always find their way to the propellers.

With skegs this has not happened in almost a decade. The skegs protect the saildrives and rudders from rocks or other immutable objects --that's a given-- but they also deflect other objects that can ruin your day (lines, nets, etc.). 

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Quote

With significant positive buoyancy (I’m guessing comparable to weight, so 400-600 pounds) there is almost no way.

Well unless you tie some weights to the tip and have a few divers guide it into place...

At Chagos I helped put a rudder back into place while the boat was in the water. Blade was 2m, and stock was 2m. It had a big s.s. stock so it was a lot heavier than my wood daggerboard.

We just put fenders on top, some dive weights lashed to the bottom and maybe a small spare anchor on the bottom until it was floating roughly vertical.  Took it by dinghy to the boat and guided it into place. A few lines to either side of the stern to position it. No divers, just snorkelers. I'll post a few pictures tonight. It may help people in a similar situation. Oh I think we lowered a string through rudder stuffing port and tied to top of rudder. Helped to get it lined up with upper bearing. Winched it in place with a topping lift for the last foot or so.

None of this is rocket science really, even with tightly fitting curved boards.

<edit> Just make sure you have a gallon / 4L or so of epoxy and a bunch of glass to fix things that break. I was quite shocked that most sailors that had sailed across an ocean had never even touched fiberglass and epoxy except to perhaps fill in a screw hole.

 

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6 hours ago, dcnblues said:

Still on Dagger boards, I'm curious about the relationship of the sleeve to the board. I imagine that of course it needs to be loose enough to slide easily up and down, and to prevent wear on either surface, but the looser that relationship, the more prone the system would be to banging, especially in rougher blue water. An obvious solution would be some kind of cinches at deck and hull bottom level, but I'm not aware of any such system. So how is a modern system designed, and what is the current thinking on how you balance stability versus ease of use? Thanks.

I think that machined bearings are common at the points that take the loads. I have seen and used Delrin and UHMWP for these and they were simple CNC machined rectangular blocks (to fit inside a rectangular trunk) with the foil shape machined into it. Holding it into the trunk can be a challenge, but making the bearings fit the foil and trunk isn't hard. I don't know how it is done on the Gunboats, but the size and loads on those foils is pretty massive as it would be on any type of foils on any multihull of that size.

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Probably the simplest daggerboard adjustment was Tom Rolands, NACRA rope friction side clutch, brilliantly simple.

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Looks like we didn't take any pictures of re-inserting rudder after repair. 

Step 1  - weigh down the bow of the offending monohull to get rudder stuffing box above the waterline

rudder-1.thumb.jpg.61bdab411854154387fdd2b22677dd7e.jpg

Step 2 lower rudder - all the ropes are because she was a sinker. So we lowered carefully until the top of the stock came free.

rudder-3.thumb.jpg.3e648960132f1e13d4fd256e2c0f279d.jpg

Step 3 - tow to shore and repair

Step 4 As they say in the Haynes Manuals - rudder re-insertion is reverse of above.

 

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As I've noted before, I'd take MacGyver, errr, 'Zonker' with me anywhere!!!!!

 

Only issue with his travel is that he's finding animals that bite his rudders and boards...….crikey, that was a big shark!!!

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Hmmm, found this. "...loud knocking noise of the old boards." So it does happen.

When I think of 'bearings,' I think of something with internal rotating parts but I'm getting the impression that in the context of trunks for daggerboards, it just means a slippery sleeve. 

Slim's new Daggerboards

*Almost forgot: ""shark finned" the last few feet so that when we snag a fishing pot line or something we have a chance of it just gliding off." Not sure how I feel about this as a benefit. Maybe a vortice reduction benefit? But it doesn't seem like it would help it's intended purpose much, and does seem like it would hurt hydro-dynamically as much as it would help (and it would add to draft).

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14 hours ago, Zonker said:

<edit> Just make sure you have a gallon / 4L or so of epoxy and a bunch of glass to fix things that break. I was quite shocked that most sailors that had sailed across an ocean had never even touched fiberglass and epoxy except to perhaps fill in a screw hole.

I'm curious: Hypothetically, if you went cruising with a GB 68, would you also bring some carbon fiber, or would the fiberglass just be a temp fix until you could do a proper job in a yard?

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I read the blog about Slim's new Daggerboards. Seems good to have the upper bearings at deck level, but going higher aspect on a cruising boat, I'm not so sure about. There are some amazing performing boats with very low aspect foils, which kind of "makes you think". My buddy Simon just built a new centerboard for Adagio. Adagio has been a top finisher in Mac and other races for 50 years. It has had many upgrades, but lengthening the trunk wasn't one of them. The board below the hull is almost square and this boat consistently finishes with the leaders. A 35ft trimaran finishing with the faster SC 70's etc. There's also the Tornado, which I think Rob mentioned. Those are low-aspect centerboards on a boat that has been unbeatable in it's class since '66 or something. I get it that high aspect is better, but at what cost? The loads sure go through the roof.

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    Russ, I'll have to show you a multihull board concept that I tried to use on my latest design. The builder would have nothing to do with it and I'm afraid that he will just put Seppuku style daggers in the cat. I tried to compromise with him by insisting on using the age old Dick Newick style 'crash box' which has saved me from serious grief more times than I care to admit. But the builder just blathers on about 'breakaway' tips and can only hope that the case doesn't get ripped open like what happened on the clients previous aluminum catamaran. That resulted in one hull flooded and sinking and the boat drifted on the reef during the night and was totaled by morning. The sad part is that the aluminum cat had been designed for centerboards but in the interest of time and money had gotten changed to daggerboards with no crash boxes by the previous builder and the same client. Some just never learn. 

    I digress but the board I want to share is inspired by the simple Tornado centerboard which I am very familiar with. My design is similar to a board that was used on an earlier obscure French production catamaran. It is a tapered dagger of sorts that due to the placement of pins in tracks in the case will pop up vertically and fold back upon impact. The geometry of the tracks and the taper of the board as it folds/retracts is such that the slot is always filled by the board through the whole range of motion. Hard to describe but I have an animation of it somewhere that I will try and find and post. It has the best qualities and few cons of both daggers and centerboards and for lack of a better term I named it the 'STAGGERBOARD' which sort of describes the odd motion from fully down to fully up. It would be very suited for a performance cruising cat for the reasons that you mention.

   Let me see if I can dig up the file or link.

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16 hours ago, Zonker said:

...

None of this is rocket science really...

<edit> Just make sure you have a gallon / 4L or so of epoxy and a bunch of glass to fix things that break. I was quite shocked that most sailors that had sailed across an ocean had never even touched fiberglass and epoxy except to perhaps fill in a screw hole.

 

Zonker I first noticed in a first year engineering course (mechanical lab – it was introduced to teach reality to paper engineers who did things like create drawings with hand welded joints specced in thousands of an inch)  ....I think there is a DNA / Mother’s milk thing that separates the mechanically inclined into those who need operating room conditions and central bank levels of capital equipment to produce a usable end product and those who can repeatedly produce satisfactory results with what they can find at hand wherever they are. You either can look at problem and see hundred ways to solve it our you reach for the manual and can’t proceed until you have all the listed tools arrayed in front of you.

You and those around you are lucky which of those two groups you fall into.

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Russ and Veeger,

    I found a link for the Staggerboard ®.

 

     Here is a link that will open a page in your web browser and after loading will show a simple animation of the daggerboard within its case as it retracts from fully down to a optimum up position for beaching and then further retracting before removal via an open slot at the top of the case. 

 
    It should advance through the frame automatically at 3 second intervals but you can use the page up and page down keys. Flip thought the page keys quickly for an old school card animation.
I didn't have a good software for animating this sequence when I first did this but think I will take in into Fusion 360 and do an improved animation/articulation there.
 

   I guess while looking closer at in now nearly three years later that I was also influenced my the long horn on the Finn centerboards. The nice thing about this board it that the slot is relatively short and is never left open which causes drag. After years of messing with Flying Dutchman gaskets in my youth and later with the Tornado board seals this is what gave me this obsession. This design concept was for a charter boat that gets beached and we surely didn't want sand and shells being a problem when beached. Looking closer now I note that the case is relatively big compared to the size of the board but the for interior of a charter daysailer this really wasn't an issue. I think that the top portion of the case could be minimised for a cruiser. 

   image.thumb.png.7c0577c2f047c3cd2adb0306e238e3f4.png

 

Actually the more I review this idea I am seeing a lot of merit so now that I have access to a 3d printer I may just print a small working scale model in ABS or PLA just to play with.

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Rasper, I like what I see.  Couple quick questions.  What keeps the board down? Ballast?  Most daggerboards have positive flotation.  As for raising the board, can I assume that there would be an attachment point at the apex /top of the board?  Might need more than gravity to push it down into position?

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on a performance cat - like a gunboat - the lateral loads on the boards can be pretty high

i don't think that setup can withstand significant lateral loading

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I had planned to use a pushrod like used on outboard motor tilts. But I could figure out if one of those would have a 'pop off' to let the board raise in a grounding/strike. The alternative would be to use block and tackle at the upper apex of the board sort of like I show in red in this screengrab. That apex needs to be a bit higher to stay above the waterline, not really but it would make sense. It would work fine manually but the client liked the idea of using an Antal Line Driver on the tackle system for push button use muck like on the SIG 45 and some of the more recent 'top shelf' cats. I had figured on scantling my board carbon use to where they would be just slightly buoyant in seawater. Should be plenty strong if that much carbon in the skins and web spar and with delrin roller pins in the tracks this board should raise and retract pretty easily. I'm going to rethink the idea in Fusion and would love for you to kibbutz if you are so inclined.

image.png.2d690d909769e356dbf662160c1296f6.png

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8 minutes ago, us7070 said:

on a performance cat - like a gunboat - the lateral loads on the boards can be pretty high

i don't think that setup can withstand significant lateral loading

Got a point there which is one reason I mention extending the apex in my reply to Veeger above.There is room in the case to get a deeper bury in the case to help with those lateral loads. 

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4 hours ago, dcnblues said:

Hypothetically, if you went cruising with a GB 68, would you also bring some carbon fiber, or would the fiberglass just be a temp fix until you could do a proper job in a yard?

I got seriously twitchy when I used up all my epoxy, all of my foam, and lots of my glass to fix that rudder. (It was a grounding on a reef not a collision). My wife found it funny but I was bugged that nobody had any significant anything in composites other than some Marine-Tex or ~1L of West with little pumps. I also carried 2 x 20L (5 gal) buckets that had tight fitting lids. They had colloidal silica and microballoons, though not quite full. These don't weight very much but a lot better trying to find any sort of filler in a Mexican fiberglass supply store.

I am reminded of Hal Roth who fixed the hole in the side of his Spencer 35 in a very isolated part of the world. I don't recall if he used what he had aboard, but my thought was always carry enough materials to fix a big hole in the side of a boat.

I did take some CF with me as I had some left over. It was useful in building small bits and pieces but for most folks it would be less useful. Little bit tricky to wet out and have to know what you are doing with it.

For a Gunboat, I would certainly take several yards of carbon biaxial and some wide uni. In making repairs in composites it helps to use the same type of materials as the original to avoid introducing stress concentrations where the material changes.

For the rudder I actually had a friend in Brittany who got in touch with the Waquiez factory. (Boat was a 48 DS). They send me a PDF of the rudder construction drawing so I could do my best to rebuild the laminate with what I had.

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2 hours ago, KC375 said:

Zonker I first noticed in a first year engineering course (mechanical lab – it was introduced to teach reality to paper engineers who did things like create drawings with hand welded joints specced in thousands of an inch)  ....I think there is a DNA / Mother’s milk thing that separates the mechanically inclined into those who need operating room conditions and

Yeah absolutely true. Some of the people I work with are very good with numbers and calculations, but you sometimes have to whack them on the side of the head and say "how can anybody really build that".  

I think it helped to have a semi-reliable car when I was growing up so I had to get my hands dirty fixing it. You'd get a good feel for how much force a 10mm bolt can take or why you need to think about access for future maintenance.

Good example - young engineer designs a s.s. tank to contain a corrosive liquid. Puts stiffeners INSIDE the tank where he could just as easily put them OUTSIDE. If they are outside, they can be mild steel and cheap. If inside they must be s.s.

I made him do it over again :)

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4 hours ago, dcnblues said:

*Almost forgot: ""shark finned" the last few feet so that when we snag a fishing pot line or something we have a chance of it just gliding off." Not sure how I feel about this as a benefit. Maybe a vortice reduction benefit? But it doesn't seem like it would help it's intended purpose much, and does seem like it would hurt hydro-dynamically as much as it would help (and it would add to draft).

Yes, smaller tips = smaller tip vortices. Look at modern race boat rudders.

When we snagged a fishing net (often) with our boards we could just lift them and glide over the net. Till they caught the rudder. We got fast with a boat hook to poke the net under the rudder as the boat started sailing again. If we timed it right we would not snag at least 1 rudder. We also caught kelp on the rudders lots but because it's slippery usually wouldn't stay on the boards. It would get caught in the small gap between rudder blade and hull

I'd say the tapered tip only works if the taper starts at the hull lower opening. Because in reality you will catch it on any straight section of board. You MIGHT be able to raise the board and free it then and have it slide off the board tip.

 

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19 minutes ago, Zonker said:

...

I think it helped to have a semi-reliable car when I was growing up so I had to get my hands dirty fixing it. You'd get a good feel for how much force a 10mm bolt can take or why you need to think about access for future maintenance.

...

You learn a lot about problem solving trying to get home on a rainy night in a car with Lucas electrical components!...(Fuel, air, compression, spark...what's missing and how to change that)...you also learn to park up the hill, if possible pointed down the hill (although bump start in reverse works well but still a bit more complicated).

I think about that as my kids are of an age to get their first car. I can afford for them the sort of reliable transport I never had until my late twenties...or do I get them something more interesting but less reliable that forces them to learn their way around something like:

51I+qC3YJ-L._SX383_BO1,204,203,200_.jpgalfa-romeo-giulia-spider-repair-service-

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Yes, all aspiring mechanical engineers should be given an old Alfa that they have to get running before they get into engineering school!

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1 hour ago, Zonker said:

...You'd get a good feel for how much force a 10mm bolt can take 

So much this. I feel sorry for the 95% of the population that has no knowledge or conception of basic hands on fixing things. I file it under the many failings of the way our culture educates it's young. I actually read a good article that said a very serious contributing factor to winning world war II was all the farm boys who were hands-on mechanics and who kept the equipment running without any training. The article went on to argue that competing armies didn't have the same advantage. Maybe it's true for cruisers too...

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1 hour ago, Zonker said:

... We also caught kelp on the rudders lots but because it's slippery usually wouldn't stay on the boards.

I had another thought regarding the GB 68, as it is a 5 million dollar boat. What a luxury it would be to have a lighted camera image available in the cockpit of the underwater center board and sail drive, and of the rudder... Both lights and cameras have become pretty small and fairly low power. It's a real pain that that would mean four through hulls, as I can't think of a better way to do it, but my God, what a luxury to be able to just switch that on (at night especially). Or, incorporating a power and video feedline through the existing thru-hulls maybe? Yes, perhaps even extending the existing through hull... And having a small but decent lens or lenses which could monitor both the board and look forward. How valuable would that be in shallow water? (Obviously only clear water). Just a thought. Way less work to put a GoPro on the end of a boat hook, of course...

Another thought is about the tiller. For people who order the option, do they get two or do they only get one and move it when tacking? Is it carbon fiber as well? I'm guessing yes. My thought is that one would also greatly benefit from a custom pole that would be longer and stronger than a conventional boat hook and customized to the curve of the hull and the length of the centerboard. Fishing nets and even clusters of kelp can be massive and while under way having something effective enough to pole under the center board And away from the boat might be highly valuable. (I'm thinking a solution that would be able to clear the problem without just pushing it down the hull to the prop and then the rudder).

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Hmmm,  hadn't seen that line driver before.  Now I'ma seriously in the 'want' mode...

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20 minutes ago, dcnblues said:

So much this. I feel sorry for the 95% of the population that has no knowledge or conception of basic hands on fixing things. I file it under the many failings of the way our culture educates it's young. I actually read a good article that said a very serious contributing factor to winning world war II was all the farm boys who were hands-on mechanics and who kept the equipment running without any training. The article went on to argue that competing armies didn't have the same advantage. Maybe it's true for cruisers too...

I’d be fascinated to see that article if you have a link or remember the publication ( - genuine interest, not passive aggressive doubting). Before giving too much credit to American farm boy ingenuity...which I’m sure made a contribution, I’d take a hard look at the German casualty figures on the eastern front...but I think we stray from our topic

GMR_GB68_05fev19_0322.jpg?gid=1

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2 hours ago, KC375 said:

...or do I get them something more interesting but less reliable that forces them to learn their way around something like:

I always liked the bit from Zen and the art of motorcycle maintenance where he meets the dad who is buying all the individual parts for a Harley for his son. And they both agree that the kid will know a lot more by the time he gets them all together. Of course that was the 60's...

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11 minutes ago, Veeger said:

Hmmm,  hadn't seen that line driver before.  Now I'ma seriously in the 'want' mode...

Deep pocket item. We were going to use one for each daggerboard and then a third for the mainsail traveller. Adds up in a hurry! Harken has something similar but the Antals still seem more up to the challenge. A number of Gunboats have used them and SOMA had found a offroad 4WD bumper winch that looked promising for a tenth of the cost but I think he has chickened out on those. 

Antal 1000 watt

LD1000_G_636910925977319449.jpg