RV64

new trimaran under 20

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Hello everybody

After 2 years designing and  building  I had the big pleasure  of sailing my very  very square small trimaran (unnamed yet !)

5,8 x 5,8ml ; 300kg all up, sail 21 m2 including 8 ml carbon wing mast 

she is a joy , stable,  fast and easy to pilote 

 

IMG_0116.jpg.223f0d6ab9971583abfa7d760541a5e4.jpgIMG_0152.thumb.jpg.e0cff11b6295c10f60b4b47c0f2d3cbe.jpgIMG_0187.thumb.jpg.e341c60d3ba4e54ff5b4107a400c90b6.jpg  IMG_0089.jpg.ed1df072b3aea746cd6978ed7baf6a3f.jpg

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OH no not a pulse 600 please! but same program

No gennaker-screecher? not yet  but soon to be  32M2  flat spi and 17 m2 gennaker 

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Nicely done.  Looks similar to my new SeaRail 19.  Might want to consider using a self tacking jib unless your jib overlaps the mast to balance the sailplan.  I take it you are planning on flying the main hull since you put the rudders on the amas?  Is there a daggerboard?

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Hi Tom you are right  i should be using a self tacking jib but I wanted to be sure of the balance of the overall design : There is 2 daggerboards on the amas as well and i wasn't sure of their positioning /Sail plan 

and yes i think she is flying 1 hull  because of the "vvvvvvvvv" i can hear suddenly when she kicks off

good luck with your sea rail as soon as you get back your sail

IMG_0097.thumb.jpg.da6850a4eb10400fd8123c3d6d5912a0.jpgIMG_0098.thumb.jpg.9a972e748728d643318995b40a566d43.jpgyou are right IMG_0087.thumb.jpg.cfce88e57d42805fd2afbf8d6faf4e4e.jpg

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Looks awesome.  In particular I like the very purposeful bow treatment.

Any guesses on the total rigged weight?  Which ama flotation percentage did you settle on?

Would love to see some video when you get a chance.

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the TOTAL rigged weight is 300 KG  with DM20 max rigging

the amas are around 875 lts so about 300%

i don't have any video yet and I am currently building the bowspirit so not to soon IMG_0107.thumb.jpg.1e318f8fd471905c59ac8432d6441163.jpg

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8 hours ago, RV64 said:

Hi Tom you are right  i should be using a self tacking jib but I wanted to be sure of the balance of the overall design : There is 2 daggerboards on the amas as well and i wasn't sure of their positioning /Sail plan 

and yes i think she is flying 1 hull  because of the "vvvvvvvvv" i can hear suddenly when she kicks off

good luck with your sea rail as soon as you get back your sail

IMG_0097.thumb.jpg.da6850a4eb10400fd8123c3d6d5912a0.jpgIMG_0098.thumb.jpg.9a972e748728d643318995b40a566d43.jpgyou are right IMG_0087.thumb.jpg.cfce88e57d42805fd2afbf8d6faf4e4e.jpg

If you add a spin at about 20 sq m. your boat will give a Pulse a run for its money based on Texel calcs with 2 aboard.  Of course, numbers are one thing, sailing is quite another (or else why are we so passionate about it?).

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Curious about the beams... they look so thin, especially considering the huge RM with the big beam and floats. Can you comment on material and design?

I'm impressed, those in the know, isn't 2 years really fast? This is not a simple project. It even folds

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Considering the weight, relatively short mast, and 5.80 m beam, you will need plenty of wind to lift the mainhull !

my Tri is 6.10 x 5.10 m with similar weight and I need more than 15 kt to lift the main (just kissing !). I needed very strong waterstays

to keep the boat stiff, and also back stays to avoid collapsing the mast (which happens to the first one !).

 

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19 hours ago, eastern motors said:

Looks awesome!  Two years of full time work?

 

no but surely 6 months between designing ,time for "how am i going to to this", finding bits and pieces at the local gumtree or craiglist ( le bon coin for us) and sanding,sanding,sanding...

 

10 hours ago, sail(plane) said:

Curious about the beams... they look so thin, especially considering the huge RM with the big beam and floats. Can you comment on material and design?

I'm impressed, those in the know, isn't 2 years really fast? This is not a simple project. It even folds

80 x 4 mmCarbon tube reinforced with 1kg ud  carbon top and bottom  for the front ones

180 x 74 x 2mm carbon mast of which i cut the gooseneck, add a flange (foam +ud carbon) in the middle , closed it and same as above

main hull is 4mm plywood with 300g biaxial glass both sides + ud carbon where it needs 

floats are Hobby miracle 20 heavily modified( wider, higher minus 13 kg for each of them)

all carbon work is vacuum bagged

10 hours ago, patzefran said:

Considering the weight, relatively short mast, and 5.80 m beam, you will need plenty of wind to lift the mainhull !

my Tri is 6.10 x 5.10 m with similar weight and I need more than 15 kt to lift the main (just kissing !). I needed very strong waterstays

to keep the boat stiff, and also back stays to avoid collapsing the mast (which happens to the first one !).

 

Hello patzefran you are right what i meant was just main hull just  kissing . the first time was supposed to be 8-10 KN. in fact 10-15 then 15 to 20, and i called it a day  at 16h when the golfe du Morbihan was more white than blue.  we never had to be on the trampolines but we were both of us really  back the second time 10-15kn and i do feel she is under powered because everything is so easy and not physical. I am thinking of adding 1,5 mt to the mast so it will be around 28 m2 

about the stiffness , the problem was longitudinal with only 2mt between the 2 arms so i decided to go split shrouds with 8:1 at the front .this is lifting the amas about 25mm each side and it is very very stiff.

Thank you all for your comments , i really do appreciate with no false modesty

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there is a traveler but no rail. i am using a  DM 20 max bridle (like a Laser) and and 2:1  sheave for the traveler but it is not working as well as it's supposed to be: i find it really hard to tension the bridle as i want without putting too much load on the main hull because there is only 45 cm between the bome and the bridle  and i have a 8:1 57 harken  carbo for the main sheetIMG_0177.thumb.jpg.2688a7c5f1ec427bd8e8ad9bbfb20bbc.jpg

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You might want to consider a dual mainsheet in lieu of traveler.  A little more complicated, but gives you the whole width of the boat to adjust.  And yah, more expensive since you have to have more blocks and cleats. 

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i do not understand what you mean Tom Here is a foto of the bridle and blocks the traveler are not on but go from the bottom bock to the little red cleat.the problem is the length of the bridle where the bottom block glides It is to long 2 meters and the boom to low. I might go for a rail because i did not save any weight there is 2 more blocks on the big bottom one for the traveler and 4 more to adjust the tension of the bridle to the side of the main hull (previous foto) can you tell me more about what you think()i will answer tomorrow )

 

IMG_0191.thumb.jpg.fa3df19c7180679e705e3aa7b0e2114a.jpgblock 

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Here's one way to do it on the attached.  Another way is to use a single triple (or more) on the boom and run the one mainsheet through the boom block over to the other block on the opposite ama.  Then you adjust the upwind mainsheet for main tension and adjust the downwind mainsheet for traveler position.  Mike Leneman (MultiMarine) loved these things and eschewed use of the provided travelers in favor of this setup.  Be careful, though, since this adds to the compression load athwartships on the main hull. 

double-mainsheet.jpg

Edited by MultiThom
Warn about compression load.

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thank you tom now i understand it better. I don't think i will use this set up despite it being quite interesting

the traveler does not need  to be more than1,5 mt altogether . i never had to let the main going further than that 

the two mainsheet seems a little bit complicated to operate but it might a question of being use to it

the load on the boom will be  to much( it is only a reinforce all carbon windsurfer mast or though i could add some more carbon

anyway you give  me to think about it  good on you

 

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Hi, RV64 !

Any records of your 2018 sailings ?

Here is a photo of my Strike 20 on Sanguinet lake. My rig is now a Hobie cat 21 mast, so the mainsail luff is short !

20180831_143801.jpg

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sorry for the hijack, but maybe this thread could become the official meeting place for the "homebuilt <20ft trimaran in France" community

here are a couple of pics of mine: 19' plywood hull, floats from an F18 (Alado) and brand new carbon beams + mast

the program is daysailing and camping around the Golfe du Morbihan 

 

 

 

 

IMG_20190318_140922.jpg

IMG_20190318_140934.jpg

IMG_20190318_140946.jpg

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5 hours ago, french do it better said:

sorry for the hijack, but maybe this thread could become the official meeting place for the "homebuilt <20ft trimaran in France" community

here are a couple of pics of mine: 19' plywood hull, floats from an F18 (Alado) and brand new carbon beams + mast

the program is daysailing and camping around the Golfe du Morbihan 

Nice job !

What is the overall beam ?

If you keep it light, you can lift the centerhull. In this case you should put the rudders on the floats. When there is enough wind, I install  rudders on the floats of my Strike 20, so I keep control when the mainhull is lifted.

Please, keep us informed of your progress.

 

 

 

IMG_20190318_140922.jpg

IMG_20190318_140934.jpg

IMG_20190318_140946.jpg

 

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19 hours ago, french do it better said:

sorry for the hijack, but maybe this thread could become the official meeting place for the "homebuilt <20ft trimaran in France" community

here are a couple of pics of mine: 19' plywood hull, floats from an F18 (Alado) and brand new carbon beams + mast

the program is daysailing and camping around the Golfe du Morbihan 

 

 

 

 

IMG_20190318_140922.jpg

IMG_20190318_140934.jpg

IMG_20190318_140946.jpg

Looks great!  What is the design of the main hull?  Never heard of the F18 Alado?  Looks like a Hobie Tiger?  Keep us updated with more pics!

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@patzefran overall beam 4.5m, I will use the rudders from the F18, so on the floats they go, and the single daggerboard is a carbon board that would have been used on a Marstrom 20 if it had passed quality test.

@MultiMacGreg I designed the beams without waterstays and they were built like the mast by Axxon Composites www.axxoncomposites.com/en/  

@dave202 the main hull is my design. The Alado is an F18 designed by Jacques Valer (who now designs the JPK range) and you are absolutely right, Hobie liked it so much they bought the shape to do the Hobie Tiger !

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23 hours ago, french do it better said:

@patzefran overall beam 4.5m, I will use the rudders from the F18, so on the floats they go, and the single daggerboard is a carbon board that would have been used on a Marstrom 20 if it had passed quality test.

@MultiMacGreg I designed the beams without waterstays and they were built like the mast by Axxon Composites www.axxoncomposites.com/en/  

@dave202 the main hull is my design. The Alado is an F18 designed by Jacques Valer (who now designs the JPK range) and you are absolutely right, Hobie liked it so much they bought the shape to do the Hobie Tiger !

Looking at the mainhull, it seems it is flat bottom dory shape, like my Strike 15 (Richard woods used this option to simplify buiding) . It has a tendency to slam going to windward in chop (which could be also related to its short length). So I asked Richard Woods to desigh a veed forward bottom on the Strike 20 , and I found the behavior much better to windward.

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"RV64" and "French do it Better" - both of those designs are really fantastic - can you let us know what the sail plans are derived from or are they bespoke?

Are outline plans available for either of them?

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@Vantage475T thanks ! the concept is to use as many parts as possible from the donor F18 cat, so the mainsail is an original dacron main from the late 90's, with small flat top. The class F18 jib at 4m2 is too small and not the right shape, so I am having a 7m2 jib built. For now I will use the F18 21m2 spinnaker and I have a 16m2 code 0 from a previous boat that will fit nicely.

The first upgrades will be a more up to date F18 mainsail, and probably a bigger spinnaker.

I work from a 3d model of the full boat so I don't really have 2d drawings to show. I think it is a good concept, there are loads of Alado 18 / Hobie Tigers out there, so if enough people show interest, maybe I will stop procrastinating and actually put some 2D drawings together or why not a set of construction plans.

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People shy away from tension ply but it is not a difficult build process - and it is fast. This design originally was 21 odd feet (6.5m x 6.5 beam) a little larger than 20 feet but close. And you end up with a very light but very stiff hull.

frog2 copy.jpg

froglines.jpg

frogstern.jpg

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cool building process and I like your boats, but you still need a mould right ?

I went for plywood sharpie construction because I wanted to go stitch-n-glue. I'm on a budget (not paying for the carbon bits B))

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No mould needed. I start with the double central bulkhead which dictates the cross section shape, then bow and stern and connecting gunwhales, keelson and stringers plus a half frame forward. Scarf the ply and glue it to keelson, (slightly tricky to get rocker shape central) wait for it to cure and then start bending to attach to gunwhales. You have to make a couple of diagonal cuts each side in the forward ply sections where the cross section shape of central areas start changing to the slightly sharper bow. This, (along with gaining rocker)  is the trickiest part, getting it fair and smooth.

frog6 copy.jpg

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Hats off to you folks with the patience and skill to build a boat.  I have a general question for you guys.  How do you decide on things that are tough to fix after you build.  For example, mast placement fore/aft; centerboard placement fore/aft, rudder size; jib size and sheeting angle (along with expected mast rake (so you get the right length forestay).   Speaking of rudders, do you design them to be straight down, raked forward or raked aft?  I've spent a year with a new boat shaking down...I can't imagine how long it takes after building one before you have everything dialed in.

  

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Take a look at the latest Sodebo (definitely not home designed or built) and look at mast placement well aft of the near centrally placed cabin/cockpit. Lock Crowther did this decades ago with his mast position on Twiggy 32 design. On multihulls the old rules seem to have changed. You only rake a rudder forward  or aft to get the right helm balance feel. Too far forward and it can become imbalanced and have a mind of its own, too far aft results in strong weather helm - (it's not weather helm but feels like it).

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@MultiThom In my case choices are made easier because I am working off an F18 cat so a lot of these choices are already made.

I have chosen to line up the transoms of the floats and main hull (which is a touch longer), and my beam positions are fixed by the mouldings on the floats. For simplicity I wanted to have the mast on the forward beam.

Rudders come from the cat so that's one choice less to make

There are rules of thumb for centre of lateral resistance position relative to centre of effort of sails, but they really apply to monohulls which heel. I have studied a couple of trimaran designs of which drawings are available online, and from my job I have access to a lot of sailplan drawings, some of them also showing CLR position. Put all this together and came out with a compromise. However, I have allowed for a few degrees of centerboard rake fore/aft, and the mast rake can also be adjusted if necessary.

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14 hours ago, MultiThom said:

... How do you decide on things ...

If you are really indecisive, you have to make everything adjustable.

I couldn't decide how to do that for the crossbeam positions, but I managed for several things...

Broomstick_BrokenFoil_8-26-09.jpg

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hello Patzefran and every one

2 square is on a boy in the golfe du morbihan and i have been out 4 times for the last 2 weeks.

today was best with 16 kn up to 23. my wife and I did a coville planté ; she got a bit scared but all was fine: 2 square put itself up again on its own .

still no video or photo but soon I will get an droite phone with sailfreegps apps so I will be able to report on speed and other things. help to improve?

and well done french do it better (by the way i am not so sure that 's true, being an ex OZ boy)

hope to see you soon around  Arradon for a ride ...

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hello French do it better

how are things going?  any other photos?

alsoi have in my garage a kevlar F18 top square main that will go very very cheap  !!! (better on your boat than in my workshop...)

i live in Plougoumelen  PM me if you are interested

some news of 2 SQuare with  brand new trampolines ( so much nicer than nets) and soon to be coming the ""bout  dehors"" gennaker ad asy  

 

IMG_0154.JPG

IMG_0155.JPG

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Your boat looks very nice, RV64. Could you give details on its dimensions , weight, kind of mast and sailing performance ? Did you built yourself the outriggers or they come from a donor cat ? This the third seaso now for my Strike 20 and I have invested in a 29 m² asymmetric spi, not tested yet.

20180831_143801.jpg

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