SeaGul

Fast tri 35tf, canting rig, foil assist or t-rudder

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35ft light (1300kg) 53m2 main + 19m2 self-tack jib. 8,2 m wide. Has big assymetric daggerboards on the amas and one rudder.

What would be the most buck for the money/speed option if you want to improve the boat?

Its a point to not add too much strain on the construction so my guess is that canting rig would be nice - also the t-rudder could be fine - but the foil assist - easy version is to keep the boards but add a smaller lifting foil close to the amas bows. But that will generate more strain.

 

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Does she pitch much? Rudder foils really stabilize pitching, keeping the rig more efficient...

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Yep, I had a thread here about rudder foils a while back, opinions generally are pretty positive.

i haven't done it (yet) because mine is a kick up rudder, so need to design a sacrificial preventer pin to avoid turning it into a water brake

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Do you want increased speed at lower wind strengths or increased top speed? Anything you do increase top speed will almost certainly make you slower at lower speeds. And vice versa.

Increased speed in itself will increase strain. Do you regularly fly 2 hulls? If not, anything you do to lift will add strain, especially locally.

 

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Tricky to steer with one main hull rudder when flying two hills.

a canting rig should be easy. Add 4-5 feet to the side stays, splicing or somehow attaching a ring about 8 feet above deck. To that ring attach a secondary side stay that would go to a block on the aft aka, then towards the main hull where it can be put in a winch. With a spinlock clutch somewhere between the winch and the aka block.

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3 minutes ago, EarthBM said:

Tricky to steer with one main hull rudder when flying two hills.

a canting rig should be easy. Add 4-5 feet to the side stays, splicing or somehow attaching a ring about 8 feet above deck. To that ring attach a secondary side stay that would go to a block on the aft aka, then towards the main hull where it can be put in a winch. With a spinlock clutch somewhere between the winch and the aka block.

Agree... canting rig

New boards (creating some lift) would be good

Ama rudders 

It's all just money

Nice boat BTW

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30 minutes ago, PIL007 said:

Agree... canting rig

New boards (creating some lift) would be good

Ama rudders 

It's all just money

Nice boat BTW

Wouldn't disagree with any of your comments..... I was thinking of maybe some more basic things.

No obvious prod or bowsprit and presumably no flying lightweather headsail/screecher. Practical but not fast recess in the side of the main hull for the outboard. Old style ama shape.

Or if you are not flying 2 hulls, just sail the boat harder.

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Cool boat.  No expertise on this but I thought I would clarify the saying that we use in the USA.  I realize you are in Norway.  The saying is: "most bang for the buck"  Buck being dollars and bang being what ever it is you want to optimize.  

 

Fair winds

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Would generally agree with the others:

Float rudders would allow a smaller main rudder and 2 hulls flying.

Angled daggers would reduce disp.

Canting rig helps with righting moment.

T foil rudders are nice but increase complexity, if there is good pitch stability and no tendency to pearl then maybe not worth it.

Lifting foils in floats will, as noted, increase beam and float loading. Also fragile. 

Along the light/heavy wind tradeoff, maybe a masthead screecher and CZ with runners.

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5 hours ago, eric1207 said:

Cool boat.  No expertise on this but I thought I would clarify the saying that we use in the USA.  I realize you are in Norway.  The saying is: "most bang for the buck"  Buck being dollars and bang being what ever it is you want to optimize.  

 

Fair winds

 

 

...hehe... yes -I kind of know - bang/buck ...

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it can be sailed one one float but is not designed to do that - the design is from early 90s and the floats are original. And we intend to keep it "original" as we think the design is very successful - it looks good if I might say so - Im not the designer - but we bought the boat because of the good look and light build.

If you start to change the amas - you have to beef up the beams -etc etc- full rebuild.

So the canting rig option seems like an relatively easy way to go as a start - next the rudder - both think seems to not put extra strain on the boat.

As one say - a T-rudder will increase drag - and you have to use more power to get the same speed . Canting rig has no such disadvantages - just the handling of the system.

Been thinking of angle those existing boards - but that will add some strain? - ore is it more strain when the ama digs in deeper?

We had an issue with the board break of the ama from the beam - so there is a lot force here already - its fixed and stronger - but fast sailing with full board is not smart.  

 

bild 8 rykande kryss 2 2004.jpg

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On what points of sail and what breeze are you trying to improve?  What is your competition?  I am finding after a lot of trial and error on my tri the biggest improvements are removing weight and keeping it simple so with 3 crew we are concentrating on boat speed and tactics not fiddling around with stuff. A bigger Genoa also helped a lot in 7 to 14 knots of breeze. I actually removed the code zero for short harbour courses and just use one gennaker

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It has screetcher and code 0 on a pole. 

To optimice the things that is already there - yes - some to do there . 

Keep the weight as low as possible for regatta. Specially in the light - 2 max 3 people. 

That is the old mainsail - we got a M32 mainsail thats higher aspect.  

Also a genoa for the light upwind - it will give us a rating higher than a Maxi 100 - but we go for line honor.

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So now that we know more about your Tri, it looks like:

1) Maxing out your fore triangle for light weather (see below)

2) Canting rig

3) Float rudders and no main rudder would be good, less drag, but not possible with existing floats..

 

image.jpeg

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4 hours ago, Rob Zabukovec said:

So now that we know more about your Tri, it looks like:

1) Maxing out your fore triangle for light weather (see below)

2) Canting rig

3) Float rudders and no main rudder would be good, less drag, but not possible with existing floats..

 

image.jpeg

 

Yes thats is correct - the configuration with big assymetric daggers on the amas may create som turbulence for ama-rudders? Theres no centerboard so the center rudder is in "clean"  water. Also these board is effective even in light airs (and the big rudder). As the boat is - its very fast in the light stuff - but should not be pushed too hard in heavier stuff. 

One thing - the construction is abit flexible - as the SeaCart30 one could have waterstays to take som of the loads - but that could maybe create som loads on the beams that they are not designed to take - any views on that? 

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Increased performance, however you try to achieve it will increase loads. Even a canting rig.

Increased loads means reinforcing areas of the boat, adding weight, which in itself adds loads.

All of the above comes at a cost rate way in excess to the increased performance gained so maybe you have hit the wall?

Get a bigger light weather genoa, loading up the boat to its max earlier and then just keep reducing sail area to keep the loads at the max acceptable to you.

You need a good multihull designer, preferably the original designer to tell you how much more load you can take and where. Or how much reinforcing will be needed and where.

There are no easy (load) free solutions. Good Luck........

 

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Agreed, it doesn't - and if you have angled foils and T rudder, there is also less drag and loads on platform because, aside from sailing faster, it is lifting the boat higher from waves and water drag. An inverted T rudder also reduces pitching and stern dragging (and turbulence over rig).- many people do not seem to be able to comprehend this basic fact.

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Additional rigging, pulleys and control systems equals more weight and load. More vertical pull on the weather chainplates, and extra load around control systems, mast pivot etc possibly means more reinforcing which is extra weight and load, especially as you can carry more sail at higher wind strengths.

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Okay, more weight because of pulleys, like on Sid, maybe 1 kgs at most with today's light blocks  ...  and you can pivot and also quickly tension the rig. Take your choice. More vertical pull on chainplates and control system and mast pivot - something I have never noticed or had breakages from. My chain plates are glass and carbon tows around thimbles, have never had breakage problems, also lighter and stronger than metal. And if you are sailing faster you do not need extra sail area, on the contrary, you need less. Win, win, all around?

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it all just needs to be thought through for each specific case..... but the chances are that there will be some extra weight and load, in places that may not have been originally designed for it.

Unless the adjusting control system is entirely mounted on the shroud, including locking off, there is a turning block somewhere which increases attachment load significantly and depending on where the block is located, puts either the crossbeams or the mast under increased compression and in any case the mast step under increased shear.

And what you can do on a boat which is less than 10% of the weight of the boat which we are talking about is entirely another matter. And is your boat ever likely to go offshore for extended periods?

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2 hours ago, rattus32 said:

Is this the original Tornblom T35?

 

It is indeed.... also owned by Marstrøm at a time...  bought it after mr. Ahlinder had flipped it and couldnt agree with the insurance...

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6 hours ago, EarthBM said:

How warm does the water get during the sailing season (3 months?)

 

...here in Oslofjord it can get over 20 C - but summer is various - you usually dont need sun protection over the cockpit... put the light is good - in good weather it dont get too dark...

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As for the mods - I get that what ever you do - there will be some loads here and there. 

But also - some mods can ease the loads - by getting the lee ama going lighter in the water - so at same speed less loads. 

Same with the T-rudder - motions and less digging in can give total of positiv effects. 

About the weight - the boat with all tings weight 1300kg - so which boat is 10% of that - it must be fast...

This is a coastal boat - and will not go offshore for extended periods - just to pass certain areas - if the weather is good. 

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Have you raced against a Seacart 30? If so did you beat it and what conditions was it? If not what is your relative rating currently?

From my experience in that size boat the canting rig works well but only in limited conditions.  in the light airs you'll just go slower,  as mentioned it's extra weight and no speed gain until you are fully powered up. The loads increase because the maximum righting moment increases.  

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1 hour ago, Samin said:

Have you raced against a Seacart 30? If so did you beat it and what conditions was it? If not what is your relative rating currently?

From my experience in that size boat the canting rig works well but only in limited conditions.  in the light airs you'll just go slower,  as mentioned it's extra weight and no speed gain until you are fully powered up. The loads increase because the maximum righting moment increases.  

 

In Lidingø Rundt 2006 there was Seacart30 and T-35 as well - that was a gusty race and as the pic shows the T-35 was reefed. Before the start of the race a SC30 flipped - but was rightenes and started in the race. I tried to find the results but didn. T-35 was sailing home  when they flipped - not paying much attention as the only used the jib. 

But the boats have about the same rating, SC30 is lighter but smaller and narrower - they strong point is to sail on one hull - doing that the will be faster - but the T-35 is probably faster in lighter conditions. SC30 is a totally rigid plattform that can take anything - thats the force - T-35 must be nursed a little.  

The SC30 that was sailed was top with sails and people - T-35 more low budget amateurs...  we have sailed against a SC26 with the best sailors aboard a couple of time and always beat them. But SC26 is not the quality of the Marstrøm buildt SC30.

Lidingö runt 2006.jpg

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7 hours ago, SeaGul said:

........About the weight - the boat with all tings weight 1300kg - so which boat is 10% of that - it must be fast...

This is a coastal boat - and will not go offshore for extended periods - just to pass certain areas - if the weather is good. 

Groucho's boat. My mistake, it is 230 kilos, not lbs, so 18% of your weight. And 8.5 m LOA.

 

image.jpeg

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1 minute ago, Rob Zabukovec said:

Groucho's boat. My mistake, it is 230 kilos, not lbs, so 18% of your weight.

 

image.jpeg

 

Is that the next AC boat?  230kg is LIGHT (ref M32 at 480kg) ..... and that look like an effektive wing...  abit hard to understand the scale of it - how lang/tall/wide?

  

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28 minutes ago, SeaGul said:

 

Is that the next AC boat?  230kg is LIGHT (ref M32 at 480kg) ..... and that look like an effektive wing...  abit hard to understand the scale of it - how lang/tall/wide?

  

Next AC boat? Not to my knowledge. It is 8.5 metres LOA with an 11.5 metre long mast which weighs roughly 30 kilos. And I wouldn't want to go offshore in it.......

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7 hours ago, Rob Zabukovec said:

Next AC boat? Not to my knowledge. It is 8.5 metres LOA with an 11.5 metre long mast which weighs roughly 30 kilos. And I wouldn't want to go offshore in it.......

Next AC boat will be a return to the dark ages, even with Guillaume Verdier designing it. But the mono advocates are very gleeful and full of gloating with the change from "them multicocks." to proper boats. But most enlightened people see it as a retrograde step and actually pretty stupid one; like how are they going to rotate the heavy swing keels without a stinker.

Correct, Sid is no offshore boat, never was intended to be, just a fun foiler harbour sailer. However the boat has handled some savage wind against tide conditions and has held up well.  Here is the prototype Flash Harry.

flashharrybeat.jpg

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T35 =Sc30 in speed.

My add on foil to the daggerboard end is not adding much strain, but also add lift even when daggerboard is not fully submerged,

So it creates lift sailing fast with say 50 % or less dagger down 

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1 hour ago, Groucho Marx said:

....Correct, Sid is no offshore boat, never was intended to be, just a fun foiler harbour sailer. However the boat has handled some savage wind against tide conditions and has held up well.  Here is the prototype Flash Harry.

Don't worry Gary, I like Sid and the way you have a go at some pretty radical stuff. I have sung your praises on other forums: https://proaforum.com/forum/viewtopic.php?f=5&t=212

The offshore comment was simply to highlight the fact that what works for a 230 kg harbour foiler may not be appropriate for a 1300 kg Tri with at least the potential for offshore work.

 

image.jpeg

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That second proa you've designed is interesting Rob, maybe beyond interesting, flying the windward float at rest? Rob, the other one, Denney might be a little miffed by you stealing his steam?

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21 hours ago, Samin said:

......From my experience in that size boat the canting rig works well but only in limited conditions.  in the light airs you'll just go slower,  as mentioned it's extra weight and no speed gain until you are fully powered up. The loads increase because the maximum righting moment increases.  

I rest my case.

Ditto T foils. They are heavier with extra load on the rudder fittings, and in light winds, when not lifting, they are extra drag. Pitch reduction is important, especially on a boat like Groucho's, where  the weight of the extra tall mast is 13% of light displacement. On the T35, that would equate to a mast weight of over 200 kilos. I know of a 9.5 metre Proa with a mast weight of only 2%.

And if a T foil allows you to drive a boat harder/faster in heavy conditions, that must put extra load on in other places as well.

It sounds like the T35 is already on the load limit?

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....ok -we save a lot of work and money here...   just trim the thing optimal and sail it as lightweight as possible - others have said the same .... but of c halv the fun is planning radical stuff - not always so fun to actual do it (work money little gain). 

The mast is rather light (ca. 100kg)  - its a 300mm sandwich carbon mast - made here in Norway by "locals" - the TRT people. It has stee-rod on double spreaders - that is some weight.

We bought it with a carbon Marstrøm mast - that was in two pieces after the flip - sold that to a danish F-31 builder - was much heaver than the sandwich mast.

Things that are a bit heavy is the big boards - guess 30kg each - 2,3 m lenght- but they have proved to be strong.

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4 hours ago, Rob Zabukovec said:

And get a larger light weather genoa......

 

Have that - but didnt test - 40+ m2

 

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Looking forward to hearing how it goes. For the benefit of my data base, what do you reckon your top speed upwind is/will be, your absolute top speed and how you compare against the SeaCart 30?

Thanks in advance.

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That will be next season - soon winther. Its no active SC30 around now that I know of.

 

24kn is currently the best -last owner - the boats real strengt is easy doing 17-18kn in 6-7ms reaching.  

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2 minutes ago, SeaGul said:

That will be next season - soon winther. Its no active SC30 around now that I know of.

 

24kn is currently the best -last owner - the boats real strengt is easy doing 17-18kn in 6-7ms reaching.  

And Upwind?

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A t-foil on the rudder may create some drag, but onthe other hand it can be placed so that it is surfing on the backwave crested by the main hull in lower speeds sah less than 9 knots, then it actually behaves like if the main hull was a bit longer in the waterline

And move the deplacement speed up a bit.

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Hei Hei Seagull

If our "fat" dazcats can nearly do 24 knots then I think try harder is the phrase...........? Where in OsloFjord does she live and once you have worked out how to sail her do come and do Fastnet

Hilsen

Bruce 

 

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1 hour ago, Rob Zabukovec said:

And Upwind?

It can take quite some wind close - 13-14kn in good wave conditions.

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1 hour ago, msouth said:

A t-foil on the rudder may create some drag, but onthe other hand it can be placed so that it is surfing on the backwave crested by the main hull in lower speeds sah less than 9 knots, then it actually behaves like if the main hull was a bit longer in the waterline

And move the deplacement speed up a bit.

Very interesting that T-rudder solution - but you need an advanced adjustable rudder to get it optimalized, so theres some work and money there. 

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34 minutes ago, Bruce Sutherland said:

Hei Hei Seagull

If our "fat" dazcats can nearly do 24 knots then I think try harder is the phrase...........? Where in OsloFjord does she live and once you have worked out how to sail her do come and do Fastnet

Hilsen

Bruce 

 

Fastnet isnt the perfect match for this boat - we have many good races here - that is abit more sheltered. 

Dazcats kan be sailed like there no tomorrow - so maybe more usable top speed. But this is fast if we get a little angle - and can use big sails in moderate conditions. 

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2 hours ago, PIL007 said:

I still maintain ... Cant rig... easy and cheap if thought out and float rudders for sure

That's interesting as my 28ft racing tri has float rudders which are awesome reaching in heavy breeze but I'm not sure they are actually faster overall especially in windward leeward racing. I canted the rig slightly to Port on the fixed lashings for a long port tack coastal race 10 months ago and only just bothered centering it as no noticeable difference tack to tack. The sister ship to my boat has a full canting rig setup and doesn't use it,  the gains aren't usually enough to loose 20 seconds in a tack and miss a shift.  On the other hand my old tri with little floats the canting rig was a lot quicker,  so I think it depends on the boat and courses raced as to the best optimisation.  In any case racing not many people would argue that keeping it as light and simple as possible is generally the fastest unless you race with the same crew every week to make the most of the sail wardrobe,  car positions,  canting- rotating rig, Gib and main Cunningham,  inhauler, outhauler peeling from mast head kite to screeched to fractional kite to number 2 putting a reef in adjusting the centre boards tweaking the batten tension choosing light or heavy air main, cleaning the bottom each race etc plus just getting around the course on the favoured side while avoiding cruise ships and keel boats....

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21 hours ago, SeaGul said:

It can take quite some wind close - 13-14kn in good wave conditions.

FWIW, the fag packet flat water speed prediction formula in my data base give you a max upwind speed of around 12.7 knots and around 25.4 knots top speed. So you are sailing your T35 at nearly full potential. The only real improvement to come should be with a big flying Genoa in light up winds and medium reaching winds. With a 40 m2 flying Genoa, if you can carry it in enough wind, could give you around 14 knots and 28 knots respectively.

Standard jib only SeaCart 30, you should be about the same or slightly faster. Ditto Dazcats, depending on which one and which rig, but they should be faster upwind in big waves due to greater RM and huge inertia. Both of these boats can carry really big flying genoas/screechers.

But as Samin has pointed out, a lot depends on how well a boat is prepared and sailed......

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It is fag packet stuff... Basic physics. Just waterline length, displacement and sail area. Not including wing masts.

Texel, MOCRA and OMR basically work along similar lines, albeit with their own versions of factors for mast, sail, prop(s) and foil efficiency, plus bias for boats with headroom/accommodation.

if you want to work it out for yourself in more detail, do a trial Texel rating. It will give you speeds and sail carrying predictions. Play with your sail areas. You will get different speeds and different stability predictions which you can interpret or adjust using your own experience of  the T35.

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7 hours ago, PIL007 said:

I still maintain ... Cant rig... easy and cheap if thought out and float rudders for sure

One of the guys on SF Bay rigged his Multi 23 up for a canting rig. Pretty simple conversion actually.


Worked pretty well, too well one day.   He was reaching out for a start (I think it was the Bridge 2 Bridge) and somewhere between the city front and Alcatraz, rig canted over, he caught air, and going upwind, flipped over backwards.....  Said his crew didn't help matters as when the bow started to lift, they all scattered back...

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There was a newer Dragonfly that flipped backwards in a British regatta - didnt find it now.

About the calculations: center of effort, stability - how wide and the type/size of floats - and how you distribute the movable weight - must be important parameters? 

 

 

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38 minutes ago, SeaGul said:

There was a newer Dragonfly that flipped backwards in a British regatta - didnt find it now.

 

 

No kidding? Wow. I was impressed with the multi23 - but it's kinda a crazy machine. Dragonfly's actually have usable interiors, for the most part.

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20 minutes ago, msouth said:

In the T-35 case, make sure you use open mesh nets.

Yes - the mesh is too fine as its now - when wet - the wind can come under the trampoline - and lift.

 

And the 100kg - + one less crew in case of light wind sailing, then its 200kg.  

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5 hours ago, SeaGul said:

....... About the calculations: center of effort, stability - how wide and the type/size of floats - and how you distribute the movable weight - must be important parameters? 

Of course they are..... With regard to centre of effort, one of the reasons a lot of fast multihulls (see Mighty Merloe above) have got vast flying genoas with a very long foot measurement is that it lowers the overall CE so the heeling effect of adding a lot of sail area is not so great. Any loss of aspect ratio efficiency is more than made up for by brute sail area. Even monohulls are doing it.

With regard to your North Sails info. I gather 40 m2 sail you have bought is the red one? As you already have it, see how it goes. But I was thinking along the lines of a genoa which fills the basic triangle of the blue screecher (again like Mighty Merloe).

 

image.jpeg

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Just as a reference, I was just reading the racing rules for cayak boats, they are open to use any build material but foil mounted on rudder is not allowed, this may be an indication that the drag is not an issue using rudder foil.

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5 hours ago, SeaGul said:

.... And the 100kg - + one less crew in case of light wind sailing, then its 200kg.  

And for the record, increasing sail area by 10% gives a better speed return than reducing weight/displacement by 10%. If you can do both.... Happy Days.

And not relevant here, but if you could increase effective (ama) waterline length by 10% the speed increase would be almost double 10% weight reduction.

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11 hours ago, Rob Zabukovec said:

It is fag packet stuff... Basic physics. Just waterline length, displacement and sail area. Not including wing masts.

...

Americans, don't be alarmed. "Fag Packet" = cocktail napkin this side of the calm pond. ;-)

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3 hours ago, rattus32 said:

Americans, don't be alarmed. "Fag Packet" = cocktail napkin this side of the calm pond. ;-)

More correctly/literally, it means rough calculations done on the back of a cigarette packet..... Fag being English/Australian slang for a cigarette.

Although I have designed buildings on a cocktail napkin...

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33 minutes ago, Rob Zabukovec said:

Although I have designed buildings on a cocktail napkin...

 

...they say the best building are...

 

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"With regard to your North Sails info. I gather 40 m2 sail you have bought is the red one? As you already have it, see how it goes. But I was thinking along the lines of a genoa which fills the basic triangle of the blue screecher (again like Mighty Merloe)."

 

These are the jib and two flying sails - code1 or schreechers ... we got them and use them - works fine - but also - the races here is upwind-downwind - seldom reaching - so what about a spinnaker - or other sail that can go real deep? 

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11 hours ago, Rob Zabukovec said:

And for the record, increasing sail area by 10% gives a better speed return than reducing weight/displacement by 10%. If you can do both.... Happy Days.

And not relevant here, but if you could increase effective (ama) waterline length by 10% the speed increase would be almost double 10% weight reduction.

Sail area - in light conditions - then all the fast mono har 5-6 sail they use for every 1-2ms change - we have a very solid jib that doesnt work very well in the light - so here we can do something - but rating will rocket. 

Longer amas - yes -designet today - they would be bigger/longer - but then one have to beef up the beams and other stuff - and heavier...

These amas - as you see on the reefed pic - ere slim and with very fine last section - the SC30 amas is more like planing fat end.

The amas tend to go a little deep and can nosedive wile using the big code 1, so that why we look at some cheap compensations.  

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If you are going to have a flying furling light weather genoa, I would have made it as big as possible, ie the triangular area fixed by the blue screecher head tack and clew. By all means have a specialist sail for deep downwind as well. And your rating will be even higher again.

if you can save 100 kg weight, the principle is that if you used that weight saving to increase the size and change the shape of your amas plus add some carbon to your crossbeams to get back to the original weight, that will give you double the speed return than just losing 100 kg of weight and as a side benefit, should not change your rating, whereas losing 100 kg will. And if you can fly 2 hulls now, maybe the beams don't need much reinforcing, because a smaller ama deeper in the water is more drag than a longer more buoyant one? Especially if you are nosediving already and waves are hitting the beams. I am aware that it is not on your agenda, you would need specialist advice and would cost a lot anyhow.

Over to you. Nothing more I can usefully add.

 

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A canting mast should dramatically reduce the load on the floats. On your boat I think it could be on the order of 500kgs or so. That's like removing 7 people from your leeward float. The hard part is making it effective for the type of racing you do, especially if it is short courses.

Edit: Just did some back of the envelope math, its closer to 200kg because this boat is so light. and that would be the maximum effect.

Edited by Mizzmo

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18 hours ago, EarthBM said:

https://youtu.be/bMoHhilUSoU

Overcanvassed and they never let the main go! Nothing to do with a canting mast.

I find this sequence worth looking at a bit. First shot the frac kite is drawing, leeward float has nearly completely sunk, double reefed main? just below hounds. Then the float is completely immersed up to the main hull, kite is released, main still on. Then float still immersed, main eased but boat starting to rotate on float due to unbalanced plan. As boat rotates the bow of the float is visible as it keeps heeling further, wind catching the tramps. Dumping the main before the kite, given the misalignment, might have helped, mast probably would hold.

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I sailed past that boat as she was going over (RIB was on site already). If memory serves they caught a lobster pot (we couldn't see it, I was told about it afterwards) which slowed them down and the true wind pushed them over - aided possibly by fine mesh nets. Conditions were 25-30 knots true and we were towards the back of the multi fleet with a large genoa and no main. We were doing 15 knots on Strontium Dog (43' tri). The DFs were flying past us with their kites up like we were standing still (not a situation we were accustomed to) but I thought the conditions were too savage to fly a 150 sqm kite. But then again, I never win races...... 

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On 9/22/2017 at 0:52 AM, Rob Zabukovec said:

More correctly/literally, it means rough calculations done on the back of a cigarette packet..... Fag being English/Australian slang for a cigarette.

Although I have designed buildings on a cocktail napkin...

Since we can't smoke anywhere anymore (thank doG, Big Brother did something right for a change), the cocktail napkin has been our "fag packet" for the past 2 decades at least.

Our best thinking comes from behind a cocktail in any case.

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2 hours ago, rattus32 said:

Since we can't smoke anywhere anymore (thank doG, Big Brother did something right for a change), the cocktail napkin has been our "fag packet" for the past 2 decades at least.

Our best thinking comes from behind a cocktail in any case.

Cocktail napkins, cigarette packets, beer mats, backs of envelopes, corners of newspapers.....I have used them all.

And Is often when, preferably with a drink in hand and no time pressures, no people to liaise with or entertain or urgent things to do that you tend to wander off into all sorts of what ifs you wouldn't normally contemplate and find a Eureka moment. Commuting on trains/planes and especially late at night were/are also still good for me.

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On 22.9.2017 at 4:24 PM, Rob Zabukovec said:

If you are going to have a flying furling light weather genoa, I would have made it as big as possible, ie the triangular area fixed by the blue screecher head tack and clew. By all means have a specialist sail for deep downwind as well. And your rating will be even higher again.

if you can save 100 kg weight, the principle is that if you used that weight saving to increase the size and change the shape of your amas plus add some carbon to your crossbeams to get back to the original weight, that will give you double the speed return than just losing 100 kg of weight and as a side benefit, should not change your rating, whereas losing 100 kg will. And if you can fly 2 hulls now, maybe the beams don't need much reinforcing, because a smaller ama deeper in the water is more drag than a longer more buoyant one? Especially if you are nosediving already and waves are hitting the beams. I am aware that it is not on your agenda, you would need specialist advice and would cost a lot anyhow.

Over to you. Nothing more I can usefully add.

 

The 100kg on the boat would be things that used in touring - not regatta. Sailplan - with no regards to rating - just sail fast - and maybe take line honors- most important are more area upwind - its often that this been a problem.

To start change the floats - big job - and like to keep the boat "original" as possible. Then the canting mast will be the thing.  

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11 hours ago, Morpheus said:

I sailed past that boat as she was going over (RIB was on site already). If memory serves they caught a lobster pot (we couldn't see it, I was told about it afterwards) which slowed them down and the true wind pushed them over - aided possibly by fine mesh nets. Conditions were 25-30 knots true and we were towards the back of the multi fleet with a large genoa and no main. We were doing 15 knots on Strontium Dog (43' tri). The DFs were flying past us with their kites up like we were standing still (not a situation we were accustomed to) but I thought the conditions were too savage to fly a 150 sqm kite. But then again, I never win races...... 

....going closer to the edge - lot to gain there - but also can end in disaster - but lobster line is bad luck. Still - how can they totally submerge that big volume ama? 

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On 22.9.2017 at 5:28 PM, Mizzmo said:

A canting mast should dramatically reduce the load on the floats. On your boat I think it could be on the order of 500kgs or so. That's like removing 7 people from your leeward float. The hard part is making it effective for the type of racing you do, especially if it is short courses.

Edit: Just did some back of the envelope math, its closer to 200kg because this boat is so light. and that would be the maximum effect.

I have got several indications that canting mast can be a good gain - specially on this boat with slim amas. Will try to calculate the effect on the amas. 

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ehh - well - did som napkin calculations - by 10 degrees you can get the centre of effort moved about 1,7m out of centre - measured to the waterline. 

The rigg with all and sails maybe weight in at 200kg - so that will be 340kg - at 15 degrees its about we talk 500kg (2,5m out of centre) - as Mizzmo said before.

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