14 Comments

1. Charles Jenkinson on June 15, 2015 at 3:21 am

   Is the wooden mast epoxy-glass sheathed? This may provide the extra strength and stiffness required.

2. ian on June 15, 2015 at 8:00 am

   Hi Jerome,

   Very pretty boat, and congratulations for keeping the previous owner’s vision alive despite the lack of details…that’s quite a puzzle to take on and just getting it in the water and moving is a feat in itself.

   That amount of sail is definitely not small, but isn’t outrageously large either and is in line with many similar tris of that size…along the lines of a slightly larger than standard light air rig that may need more attention and early reefing in a breeze but is otherwise reasonably sized.

   I honestly don’t think sail area is the issue with pointing and steering as much as the lack of a proper board to provide lateral resistance and a centralized pivot for the rudder to work with.

   You are correct in thinking that the rudder is providing some lateral resistance; the entire underbody of any sailboat does so and has to be taken into account when you match a rig to it.

   Proper helm balance is the first thing to get right, and once that is moving in the right direction any needed big fixes should be fairly obvious…a sloop with a normal rudder and not enough keel area will have the center of lateral resistance aft of the rig’s center of effort and the result will be lee helm, which is not good at all.

   You don’t mention excessive weather/lee helm being a problem, and if it isn’t that noticeable perhaps the designer put the rudder farther forward to partially compensate for the lack of a traditional keel or other board…

   that’s one way to do it but it’s at the expense of crisp steering- if you consider the effect if the rudder was moved further and further towards midships, when it got to the middle of the boat it would work great as a keel but would have very little power to alter course quickly and would create lots of drag in the process of trying.

   The simplest way to tweak the CLR/CE relationship is to shift weight around and with sail trim…since the hull itself adds to the lateral resistance, making the stern or bow sink deeper will move the CLR, and obviously a slack sail develops less power. Since your boat is light and appears to have plenty of freeboard, you may be able to make a good deal of progress just by moving stuff around a bit or adding some trimming ballast…even seasoned designers don’t always hit their design waterlines at launch so it is very possible that what you think is the optimum stance for the boat at rest, isn’t.

   Easiest way to do CE changes more permanently is with mast rake (not bend), which is how sailboards with no daggerboards can go to weather…this is a pretty good overview on tuning for helm balance-

   http://johnellsworth.com/writing/nautical/balance_helm/balance.html

   Consider that most well balanced sailboats can operate under main alone, working jib alone, with either or both reefed, or with giant headsails without the boat becoming totally unmanageable…all of which is to say that the difference in sail area between the masthead setup you have now and a fractional rig probably won’t improve your issues to any great degree by itself.

3. Jerome on June 15, 2015 at 3:57 pm

   Hi Ian, thank you very much for your comment and link, it is very interesting and it opens up a field of knowledge I am not very familiar with. I understand however what you wrote regarding the CLR/CE relationship and it makes a lot of sense. I only did one proper trial in a very gusty 15-20 knots wind and didn’t have much time to try different combinations of sail and weight but it is what I should do next. It is good to know that the sail area will not make a massive difference, my plan is to trim slightly the main sail at the base so I can see, there is no boom so I will set up a simple reefing system – unused reefed sail will be simply furled up with small cords. I hope it will work. Before I read your comment, I was going to change the rig to a fractional 9/10 like I have seen on similar trimarans.. Now I think I will speak again with the sail maker and rigger and see what they say and also check the cost.. Thanks again , and I am also grateful for the comment from Charles who suggested to epoxy glass the mast. Regards
   Jerome

4. Stefano on June 15, 2015 at 6:01 pm

   Wellcome on board trimarans !

   Ian said already what is to say… from my experience I would say:
   1) build a very strong daggerboard case and kick-up daggerboard (a simple foil build approach is found on this blog in “little tri”). If you do not, with all that sail area you will find yourself with a broken rudder rather sooner than later. the place where to locate it is just behind the mast and actually it can make the mast step and partner sturdier.

   2) you can also derive a simple idea for trampolines form little tri pics. Connecting the akas with a stiff element would also help the ama from hobby horsing and providing too much leverage upwards and backwards. With all that sail, other than in the most gentle of the breezes, this is very likely to occurr in such a sleek and presumably fast boat.

   3) leave the rest unaltered and experiment with different jibs including smaller ones, then you will end up having a much clearer picture of what you eventually need when (and if) modifying the sail rig.

   Good luck and enjoy !

   Stefano

5. ian on June 15, 2015 at 8:30 pm

   Hi again Jerome,

   It’s hard to see it all in photos but the mast spar and standing rigging setup look to be something from another boat entirely and not originally intended for this boat; especially with the diamond struts and baby stay it looks a lot like a typical monohull daysailer/racer setup from the 50’s-60’s…you see similar newer fractional rigs with those things too, but that’s usually for bending purposes with metal or FRP spars.

   Fractional rigs are often used to meet/beat racing rules requirements too, and can easily be a handicap more than a performance enhancer.

   One other thing I forgot to mention is that with the big roached mains and full battens many tris of this size can’t use a traditional fixed backstay at all and use mast rake to position the upper shrouds to take up a lot of that strain, with running backstays used when they run spinnakers or other large headsails off the wind.

   the Crowther Buccaneer is a good example, as are a lot of older tris of that size like Norm Cross’s small tris-

   http://smalltrimarans.com/blog/wp-content/uploads/2010/07/buccaneer-24-trimaran-views.jpg

   Something else worth noting is that in that plan and a number of other Crowther and similar designs- the headstay chainplate is kept well aft of the stem, which is another way to shift CE aft without a major rig re-design…it’s very noticeable in the Bunyip and especially the Kraken 25 rig (which also has that antiquated spreader arrangement)-

   http://sailboatdata.com/viewrecord.asp?class_id=6865

   http://www.boatdesign.net/forums/attachments/multihulls/49249-lock-crowther-kraken-25-trimaran-kraken25.jpg

6. Jerome on June 17, 2015 at 2:30 am

   Hi Ian and Stefano, thanks for your comments and suggestions and links, I will check with Joe how I can upload more pictures to show a bit more details about the boat. Following Ian’s comments I have now decided to keep the masthead settings for now. On the pictures you will notice that there are 2 backstays and I think I don’t need positioned there, they are too far back. The mast was bending laterally in the gusts and I think that if I move these backstays more to the side, it should help. There is a fixation on each side at the aft for running stays too in case I need them. I need to find a way of tensioning more the forestay, it was very loose last time and not good, I am thinking of installing tensioners on the aft shrouds. The standing rigging is all in dyneema ropes by the way. I need to give more thoughts about the CLR/CE to help with the steering. Right now I can hardly tack upwind, the boat gets stuck. I didn’t notice hobby horsing but am planning to put trampolines on each side. A couple of times, the leeward aka went under water in a big gust, the boat slowed down, it seemed to handle very well.

7. Small Tri Guy on June 17, 2015 at 9:33 am

   Jerome,
   Just send me any pictures you want to add to this post. I’ll upload them, no problem.

8. Stefano on June 17, 2015 at 11:36 am

   Jerome wrote:

   “I need to find a way of tensioning more the forestay, it was very loose last time and not good, I am thinking of installing tensioners on the aft shrouds. The standing rigging is all in dyneema ropes by the way.”

   I would suggest instead to install exact length shrouds and a forestay 6:1 or 4:1 purchase, perhaps under deck (palan in french) as is seen in this video in the first minute: https://www.youtube.com/watch?v=BCJNdnHt6HE

   As for side stays, I would again link the two akas with a rigid bar, then connect the two ends with a ” patte d’oie” (a v shaped spreader i ignore the term in english) as seen here :

   https://www.google.it/search?q=haubanage+patte+do%27ie+trimaran&source=lnms&tbm=isch&sa=X&ei=mpOBVZ75E4v6ULW-gaAI&ved=0CAcQ_AUoAQ&biw=1280&bih=695#imgrc=Fohjyzi525iXYM%253A%3BCYKcpuU1c90CzM%3Bhttp%253A%252F%252Fwww.nauticaltrek.com%252Fimages%252F37%252F36553.jpg%3Bhttp%253A%252F%252Fwww.nauticaltrek.com%252F12533-decouverte-de-l%3B403%3B362

9. Charles on June 17, 2015 at 1:34 pm

   Hi Jerome,
   I think it’s safe to get on with making a foil profile leeboard while you continue thinking about CE versus CLR. What do you think?

10. Michael Mangus on June 18, 2015 at 2:26 pm

    Something noticeable in the pictures is the apparent asymmetrical ama shape. The original designer may have intended the amas to act as lateral resistance by developing lift towards the inside of the boat. The leeward ama would be deeper in the water and develop more lift than the windward ama, thus countering any leeward drift as the boat sails. That would account for the lack of a daggerboard/leeboard/centerboard in the design.

    If it isn’t working as intended, a center foil is the way to go. As noted above, it would be pretty easy to add a side daggerbox or a leeboard to the center hull.

11. Anthony on June 19, 2015 at 8:42 am

    Great looking boat – thanks so much for sharing!

12. Jerome on June 20, 2015 at 3:23 am

    hello, thank you all, I am grateful for your comments and for sending additional links. Michael, I think you are absolutely right and thanks for pointing this out, it does make sense indeed. I have sent more pictures to Joe so you will see more details about the boat. I had a good chat with the sailmaker and for now we are going to make minimum changes in the sail area and rigging and I need to do more trials. I am taking onboard all the suggestions received: daggerboard, pate d’oie stay.. I looked at the pictures that Ian sent and the trimaran from Meade Gougeon looks very much like mine.. the sail plan is interesting. My jib is much bigger than the main sail, and I think that eventually I will need to get a smaller one. I can furl it for now when I do my trials. I can’t wait to get the main sail adjusted (putting reefing eyes) to do more trials!

13. samuel vermeulen on June 23, 2015 at 10:30 am

    hello
    where can i bay tis plan from this trimaran snoowgoose
    greeting samuel

14. Small Tri Guy on June 23, 2015 at 10:35 am

    Hi Samuel,
    There are no building plans for this boat available.