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Re: Other: Trimaran
By:Etiennemuller Muller Ireland
Date: 7/27/2011, 3:47 am
In Response To: Re: Other: Trimaran (Bris Paul)

: It would be great to be able to rake the mast backwards as speed
: increases like we do when windsurfing.
: I'll work on that one .
: Thanks Et, I'll keep you posted.

: Regards - Bris

With direct dynamic handling of the boom by a human the entire rig is moved backward. The problem with my fixed rig setup is that if the mast is pivoting around a fixed point at the boom cutout, as the foot goes back, the head goes forward.

I found an easier solution to the quandary was to alter the centre of resistance by having a pivoting centreboard rather than changing the centre of effort.

If the old kayak is definitely surplus to requirements, I would consider putting in a centreboard case and going the whole hog rather than using a lea board. Upwind performance will be much better.

You would still benefit from a mast track though, for different rig sizes and trim adjustment. I find that I tend to push the mast-foot to the front of the track I installed most of the time. I may install a second track further forward sometime. It is all experimental with something like this, because with more downhaul pressure the centre of effort moves backward, so there are many variables. Find the longest track you can. The more modern boards have shorter tracks, so the longer ones are cheaper anyway.

I stayed the mast the way I did, using the top sections of two broken carbon masts and an old boom clamp, because it was the only way I could think of that would still allow a modern windsurfer rig to behave as it is designed to. It worked out quite well, as gusts hitting the rig drive the extra force down onto the forward leeward cross member rather than pulling at a shroud on the windward side. In practice this puts far less strain on the points where the cross members are attached to the central hull.

The boat does not accelerate as immediately as a windsurfer and that extra inertia puts what feels like quite big strains on the whole setup when one is hit by a gust. Of course it is possible to ease the sheets to compensate somewhat, but a cambered rig tends to pull anyway, and one can only sheet out so far when broad reaching or going downwind and then you up against the shrouds.

I had a lot of fun building this boat and puzzling through all the options. Definitely a good way to while away some fun time.

Messages In This Thread

Other: Trimaran
Bris Paul -- 7/25/2011, 2:39 am
Re: Other: Trimaran
Craig Robinson -- 7/25/2011, 4:53 am
Re: Other: Trimaran
Mike Savage -- 7/25/2011, 5:24 am
Re: Other: Trimaran
Bris Paul -- 7/25/2011, 6:03 am
Re: Other: Trimaran *PIC*
Etienne Muller - ireland -- 7/25/2011, 2:40 pm
Re: Other: Trimaran
Bris Paul -- 7/26/2011, 4:40 am
Re: Other: Trimaran
Etiennemuller Muller Ireland -- 7/26/2011, 5:34 pm
Re: Other: Trimaran
Bris Paul -- 7/26/2011, 7:16 pm
Re: Other: Trimaran
Etiennemuller Muller Ireland -- 7/27/2011, 3:47 am
Re: Other: Trimaran
Bill Hamm -- 7/29/2011, 10:25 am
Re: Other: Trimaran
ancient kayaker -- 8/3/2011, 11:14 pm
Re: Other: Trimaran
Bris Paul -- 8/4/2011, 12:16 am
Re: Other: Trimaran
Etiennemuller Muller Ireland -- 8/4/2011, 5:02 am
Re: Other: Trimaran
Mike Savage -- 8/4/2011, 8:37 am
Re: Other: Trimaran
Bill Hamm -- 8/5/2011, 3:18 am
Re: Other: Trimaran
Mike Savage -- 8/5/2011, 5:52 am