SeaGul

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

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44 minutes ago, teamvmg said:

Remember that if you cant the mast, you can't play or dump the traveller any more. this is a performance and [most importantly] a safety issue.

Can see thats a problem.

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10 minutes ago, Multitrail said:

Canting with run on a separate traveler not interfering with the main sheet.

.. dont get this? Main sheet is one thing - but the traveller will get an angle to the mast - so when you let the traveller go it will be stopped by  the main sheet - that has to be eased at the same time. This boat has a long curved traveller-track, and we use the traveller a lot for adjusting mainsail. 

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15 hours ago, SeaGul said:

...really? - a pull in the red line - from the cockpit- with the big block doubles the force bec the thin rope is fast one end in the shroud-base - other end of the thin rope is also in the shroud base. Makes it 8:1.

 

But there will be forces to the shroud-base going backwards - but not too much - given the 8:1 gearing.

2:1 only.

https://en.m.wikipedia.org/wiki/Pulley

 

image.png

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I fall backwards and crawling at the floor.... 

but the pic came from a pro.... 

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Hi Seagul 

The set up we are considering is a block system with the tail lead to the cockpit and through a constrictor clutch - directly across the trampoline. I am also thinking that the rig should be canted the wrong way before a tack, rather than winching it to windward under load. I am think that pulling on the chain plate in the fore-aft plane may promote leaks so maybe consider setting up the control line athwartships rather?

 

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http://www.harken.com/content.aspx?id=13779

 

The eye is the central point were both ends of port and starboard shroud are both connected as a loop at the centerline of the mainhull,

With a 6:1 on both sides of the car the eye can be moved to port/starboard, canting the mast the opposite way startboard/port.

The end of the track that the car is running in shall set the maximum canting degree allowed, center point is mast with 0 deg, canting (normal position).

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On 9/24/2017 at 7:57 AM, SeaGul said:

...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? 

I don't think the DF amas are as big as they look when taken as a % of the weight of the boat? Any DF owners out there who could verify?

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Seagull,

Can you tell me what is the maximum flat water breeze your Tri can take with the working rig?... ie, central hull lift off.

Also what is the length of your mast? And the width of your amas? 

Thanks. I am doing some fag packet theoretical number crunching.... And the reason for asking is that there appears to be some discrepancies in your sail diagram.... Look at the sheeting dimensions closely for starters. Millimetres?

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On 29.9.2017 at 8:14 AM, Morpheus said:

Hi Seagul 

The set up we are considering is a block system with the tail lead to the cockpit and through a constrictor clutch - directly across the trampoline. I am also thinking that the rig should be canted the wrong way before a tack, rather than winching it to windward under load. I am think that pulling on the chain plate in the fore-aft plane may promote leaks so maybe consider setting up the control line athwartships rather?

 

We wasnt thinking of adjusting the forstay - too complex.

Was also thinking of leading back to cockpit along the ama and rear beam. 

But there certainly is many thing to it - so we may optimaze other things first.

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9 hours ago, Rob Zabukovec said:

Seagull,

Can you tell me what is the maximum flat water breeze your Tri can take with the working rig?... ie, central hull lift off.

Also what is the length of your mast? And the width of your amas? 

Thanks. I am doing some fag packet theoretical number crunching.... And the reason for asking is that there appears to be some discrepancies in your sail diagram.... Look at the sheeting dimensions closely for starters. Millimetres?

The amas are 500mm wide - at max, the mast is 16,85m tall - we tend to let the car out a little when the wind pics up - so it a little hard to tell when it lift - and according to where the people are on the boat. But we feel it handles better in more wind that one could think - we see others have trouble and we can go really fast upwind at times. Think thats bec the speed pics up easy and there isnt much resistence.

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2 hours ago, SeaGul said:

10ms -I would say. 

I think that's about 19.5 knots in 'real money'? I never could understand the Scandis' obsession with the metric system ;-)

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10ms or 19 kn is close hauled - if we bear away it will never do 29kn - but  maybe semi foiling...   

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FWIW
I was bemused by the varying opinions of the value of a canting rig so I have had a fag packet play with some geometry. It is based on the T35 and can only be as accurate as the North Sails profile drawing, which seems to have a little distortion and some errors, which I have adjusted as best as I can with the limited information to hand.

First, a canted mast in itself adds righting moment, which must add load to the structure eventually, somewhere. In the case of the T35, it is an extra 400kgm or 8% increase for a 15 degree cant.
 
Secondly, the actual "lifting" benefit depends upon how the canted sail plan CE relates to boat CG. To get the leeward ama to lift, the CE needs to be to leeward of CG. Windsurfers, foiling moths, twin trapeze/ hiking rack performance beach cats/tri's all can/do. The further to leeward, the greater lift for a given cant with Sail Rocket 3 and Kitesurfers being extreme examples.
 
In the case off the T35 and I suspect most conventional offshore multihulls, the CE will be to windward of CG and will provide additional heeling moment. 15 deg cant gives an additional 10% heeling moment to the T35. Which if you want to fly a hull sooner to reduce drag has some benefit. As you shorten sail, eventually, there might come a time when CE crosses over to leeward of CG and heel becomes lift if you can stack enough weight to windward.
 
Also to highlight my earlier points re headsails, attached is a sail shortening prediction for the T35 main and each of the three foresails. The green rig being the self tacker, the red rig being Seagull's new furler and a blue rig as per Mighty Merloe. There is basically only 3 knots wind strength difference between the self tacker and the 42m2 larger blue flyer. Loads are another matter.
 
Seagull, PM me with your Email address if you would like a copy of the originals.

image.jpeg

image.jpeg

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.. - some work there from Rob - as an old windsurfer I experienced the lifting forces og canting the rig - but didnt think that can come into play for the T-35. 

But thinking about it - theres is some possibilities -but that is another rig I think. 

 

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I do not understand all the dynamics in play, nor do I have any data to support the following statement, however I have a F32 SRX which has both a canting rig (15 degree) and curved foils. We definitely are able to push the boat much harder with the foils and the canting. There is a sugnificent change in the boats handling with the canting, the boat seems faster and feels safer.  We rake the mast fore and aft, this gives us the ability to balance the boat so the helm is always nutral,  the canting system give us the ability to tension the shrouds, this is a very nice feature when sailing in slops, reefing, etc. there are also some other benifits we found, bottom line is that I am very happy with having the ability to canting the rig.

The canting/rake system is hydraulic and added 60lb, there is a redundant system which allows us to lock over ride the hydraulic system in case of a failure or to take the load off, most of the time the canting is done using a bypass and gravity/wind prior to a tack/jib, it does add one more thing to think about before a tack, bit I think it is worth it. 

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I can't disagree with you. Extra heeling moment in itself isn't slow. In lighter conditions, it might be an advantage. If you have significant dihedral, maybe your effective cant is only (say) 10 degrees. CE will move to leeward more than CG when heeling. As soon as a vertical mast starts heeling, it loses heeling moment/power. The exception being in extremely light conditions when the benefit to sail set can be better than power lost.

It could be extra RM from the canted mast is more than the extra HM because your CG is close enough to your canted CE.  

Do you stack the weather ama with crew? What is it like if the curved  boards are fully up and play no possible part in lift?

There are also other benefits to canting masts, including reduced tip vortices because more air is directed down which increases again if you have an effective base endplate.

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Interesting to hear about experience with similar boat. One expert friend also recommended hydraulics - not that complicated according to him.

I can clearly see that adjusting the forestay is an advantage - ref the windsurfer experience.

The SRX ; Have you testen the imact of the mast vs the curved foil? Looks very fast that boat - what is the boatweight ?

To get lifting forces; when the mast in canted  to windward - there will be lifting forces - the boats CG will depend on where the people sits - in a situation with lots of wind they will sit to windward - and the boat CG will be somewhere to windward - the sail CE will be close the the CG - but there will be lift in general - but maybe not so much on the leeward ama? 

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5 minutes ago, Multitrail said:

Just a small additional daggerbord foil add very little weight and force to the structures, but add lift and stability.

 

 

2017 10 02 004 (480x640).jpg

cut little fin there ...  If we attach somehind like that on the daggers - we need to take them out by sinking them - we dont othe take then out... but dont you need a form of adjustment for angle of attack? - or if not they need to have a lot positive attack and will give som drag? 

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You never had problems with foils give negative lift -in big waves or when pressed bow down? How much lift are we talking here at 15kn - these are rather big?

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I am not sure I understood or understand what is being contemplated. I think what is being proposed here is that the mast will stay to the windward side under sail. That is not the case for my boat and I assume for most “conventional” boats. Once we are powered up, the mast is always past vertical to the lee side, for us to fly the main hull we are heeling a fair amount. I do not think we are ever in a condition where the is vertical lift from the sail.  I think in order to get vertical lift from a “conventional” boat, you would need much more canting then 15 degrees. This is a very different story on a truly foiling boat, but we are not a foiling boat, we have foils that provid some lift to help keep the lee ama from getting overly depressed. I think having more canting on a conventional boat could be risky ( beyond geometry issues), as the boat powers up more, the mast/ sail becomes more vertical you would loss the “vertical lift” you would first gain horizontal force and the as it passes to windward you would gain downward force, along with a movement of the balance point, I think you would find the windward ama depressed very hard very rapidly, I would think in my boat, we would go over. Again in a foiling boat where the foils increas lift as they are depressed more, the issue may go away, I think, all speculation on my part 

I would post a picture but I am not sure how to reduce the size, here is a link to a photo on ian’s site; http://www.f-boat.com/pages/News6/F-32SRFlying.html

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Nice pic - and there is the mast canted 15deg? Optimal sailing - must be - beating a Gun 66 by that much.... ?

32 miles - is that naut miles - 1.852m og miles 1.604m? The average will be 12+ or 14+kn - in 4-6ms wind - faster that the wind.  The T-35 would also be very fast in those conditions.   

Even lifting and canting - it seems the ama has a good job to do - how big volume is the ama?

I can see that the rig probably will be 90deg or canted wrong way when pressed.

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If you adjust the T35 cross section above to get a 15 degree canted mast vertical, you have to fly the main hull at least 300 mm above the water. Windward ama would be roughly 1600 above water and the CE would be over 700 mm higher. So pretty much like the F32 photo.

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25 minutes ago, Rob Zabukovec said:

If you adjust the T35 cross section above to get a 15 degree canted mast vertical, you have to fly the main hull at least 300 mm above the water. Windward ama would be roughly 1600 above water and the CE would be over 700 mm higher.

Yes I think the T-35 - at 8,2 wide - the F32 is  7,2m -  it dont heel that much.  

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Never had negative lift problems; think it is an old wives tale? Have buried a few times but that is punching into and through wave backs - but foils always do their job - and also stop the stern lifting out with T rudder. This is Groucho and Sid.

grouchosamira copy.jpg

sid and mlletboat.jpg

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23 hours ago, Groucho Marx said:

Zero for rudder foils, 3 degrees for float asymmetric foils

groucholightairs.jpg

Is there a T-foil on this? If so what is asymetric - the daggerboard part?

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It's an earlier photograph when I had inverted V foils on the boat. The inverted Vs were asymmetric as were the upper dagger shafts. They worked perfectly but later I changed to L foils..

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On ‎2017‎-‎10‎-‎02 at 11:07 AM, SeaGul said:

cut little fin there ...  If we attach somehind like that on the daggers - we need to take them out by sinking them - we dont othe take then out... but dont you need a form of adjustment for angle of attack? - or if not they need to have a lot positive attack and will give som drag? 

The fin is detachable by bults to remove boards, adjustment for angle of attack, see vid.

stab1.mp4

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On 2 October 2017 at 7:35 PM, SeaGul said:

.....To get lifting forces; when the mast in canted  to windward - there will be lifting forces - the boats CG will depend on where the people sits - in a situation with lots of wind they will sit to windward - and the boat CG will be somewhere to windward - the sail CE will be close the the CG - but there will be lift in general - but maybe not so much on the leeward ama? 

If you had all 3 crew at 100 kilos each sitting on the canted rig T35 windward aka, you get to the CE/CG neutral point at about 12 degrees of heel. Heel a bit more, and you are in ama lift territory, but the vertical lift component is so small as to be meaningless and at 15 degrees is gone.

The real advantage is that if the mast was conventionally heeling at 15 degrees, the rig produces a downforce, making the ama dynamically heavier than it would be otherwise, with more sink and resistance/drag, even though it is a righting moment in itself and the overall heeling moment is significantly less than vertical. So if you fly a canted rig T35 at 12-15 degrees heel, you have no main hull resistance/drag, no additional dynamic ama sink resistance/drag and negligible/zero ama uplift.

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"So if you fly a canted rig T35 at 12-15 degrees heel, you have no main hull resistance/drag, no additional dynamic ama sink resistance/drag and negligible/zero ama uplift."

So the advantages comes from:

1. The weightcentre of the rig is more to windward - like you move one fat guy from the lee trampoline to the middel.

 

2. The attach centre of the sails moves away from the lee ama - which when you fly the main hull is the gravity centre of the boat.

But it will also be higher so that will counter this to some degree. 

 

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16 hours ago, Multitrail said:

3. Downforce from sails eliminated.

 

...I was thinking that was a part of 2.... 

 

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Hello, 

Admittedly know precious little about Tris but have enjoyed reading some of the above discussions.  

There is a lot of first hand knowledge about the technical aspects of Tri constuction here so I though I would ask: anyone have any thoughts, ideas, suggestions about converting an older carbon/kevlar Ultimate 30 to a Trimaran?  Terrible idea?  Too expensive?  There is one available for a really good deal. 

Looking for something fun and fast that could be sailed without a crew of 8...Idea of the Tri would be to provide more stability and space so could be used for pleasure day sailing as well as some racing.   

Has 900 lb swing keel, 8' beam.  

This is the boat I'm taking about...

 

u30pic009j_small.JPG.c6764e3de3da543c960d1482fb27abf3.JPGu30y.JPG.7e7c7046c158e2a27347ee44c36b906b.JPG

 

 

 

 

 

 

 

u30brook2.JPG

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The ultim 30 looks look a fun boat for experienced crews...  As you say the thing with cats and tris is that they have buildt in stability and dont need a big crew. 

The typical tri-main hull  i very slim - the more performance the slimmer. Its usually not a good idea to convert a mono to a tri...

It seems easy to add some floats to the racks and make the U30 an easier boat to sail even singlehanded. The connection of the racks to the rail need probably to be reinforced - they will get lift on that point. If you can get some cheap old beach-cat floats - it could be a U30 with training wheels- with little effort and money - and if not a success it can be converted back. 

 

Best regards Tom  

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On 9/20/2017 at 12:49 AM, msouth said:

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 

I read som post again now - and think about this one. Our assymetric daggerboards is very strong (break off the ama)  and they have good cases etc. so to make a lifting foil on them could be possible - not to lift above water but something like the C-foils on some tris.  

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The Grainger 8m for sale in this post has electric powered winches doing the canting rig.

I think the owner says the canting rig gives a bigger performance gain than the C foils. Unless you are going full foiling, the C foils increase the safely margin in high wind conditions.

 

 

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