Trimaran design for family cruising

Hi longcours62

Thanks for the reply. In terms of the design I drew if you look at the cut away view you can see that waterline beam is only 5'4" (=1.62m) so it is actually thinner than yours. At the main deck level the width is comparable accomplished by a significant hull flare also visible in the cutaway drawing.

Your accomodation plan sounds about right for these narrow style boats so that's why I put the extra sleeping areas in the ama wings. You have standing room at the foot of the bed and about 3' or 1m of headroom so it should be quite comfortable for sleeping. I have reserved the central areas of the lower hull for the main bathroom and extra provisions so that there is still room for a central walk way without feeling too closed in.

I talked to a catamaran designer once and he said that you can use 3:1 as a good rule of thumb for determing bridge deck clearance. So if the ama span is 6' then you should have a minimum of 2' clearance to avoid excessive slamming. Having said that most big cats use 1m+. I think slamming would be less of a problem for a tri than a cat given that the main hull will normally lift the ama's as the wave progresses down the boat. In the event of excessive slamming into a head sea I suppose one can always slow down but its trickier in the surfing down wind scenario (and going into the back of the wave) where speed is harder to control.

Interested to talk more - do you have some drawings of your earlier design?

 

I think I have some 'hand drawing" somewhere.
But as I wrotte before , we made this drawing just for see what we could put in this type of boat, one French designer ' put an eye on' just for see if it is possible to do .But finaly we built our actual boat because we hopped to built sister ships (crazy !!)
And we was sure at this moment sold power trimaran was not possible.
On the mains lines we made (not hull lines we are not capable of doing that, must be done in my point of view by a specialist ,like Nigel Irens) 3 possible superstructures
- just wheel house (3,60m width) and the rest 'below ' the deck
- deck saloon and wheelhouse (4,2m width)and below just two cabins and toilette
- higher wheelhouse behin a deck saloon(4,20 width) and the rest below.
After that also two options for engine room and workshop
-under the wheelhouse (whit long shaft)
- aft with walk in engine room ( I like this possibility easy to work around engine,less noisy) but a lot smaller aft cabin
As soon as I can find an old drawing I will send to you.
I don't know Américan designer but 15 days ago I contact Kasten

 

I'm certain I read somewhere Olivier de Kersauson planned to build a 60ft version of Ocean Alchemist, to allow him to travel without crew, but don't know if he has actually build one or still have plans to build it. Might be worthwhile to check.

 

Yes, I also remember reading someone commenting along those lines on this forum. Apparently they met down in the Southern Ocean and took a photo of Ocean Alchemist and shot the breeze about future plans etc. Interesting encounter...

Unfortunately can't find any reference to such a boat online?

 

Sorry I just find

one 'brouillon' used for make some try on it .
But you can see (first why I need designer for doing the hulls lines !) and also the general form of what we looking for.
On this sample it is with the shorter roof just for the wheelhouse and the
arrangement below deck level.
But the roof with two (small ) levels first around 550 mm for keept the view outside and the second 750 mm for the wheelhouse (total) 1300 mm) may be look better because longer. Note in this case (two level or longuer roof) the roof is also beamier .

 

Hi Longcourse

Yes I see what you were talking about now - its clearer with the picture. I agree with you that a longer wheelhouse might look good. Kurt Hughes has a 60' tri design on his website that might really suit what you are looking for although it is very light compared to your original specification. Worth taking a look at at any rate.

 

Profil of longer roofs

Just for see the difference

 

Yes, those changes look better than the original sketch. I also redid mine based on some feedback here:
- wider overall beam
- less windage via removing the hard dodger

Interested in any feedback from others.