Motor sailor - not at all.
I remember once sailing my very fast 31ft Twiggy against a 40ft Harris. It had a 8 to 1 length to beam ratio main hull - that thing was like a Cross - a nice fat main hull and a nice rig on it - and we could barely catch that thing in the 7-8 knots conditions we were in - she could sail really well in light winds. Not a
motor sailer at all, she could sail!
The OP may have been thinking about putting a super fat main hull on a tri - which is dumb because this has already been tried in the 60s. Designers like Nicol, Horstman and Cross all worked out that if you got past about 8 to 1 length to beam ratio then you couldn't go to windward.
The Harris sailed really well in light winds due to its fatter hull shape in lighter winds - Designers know that wetted surface is a primary drag factor in light winds - and fatter hulls have less wetted surface than thin hulls - that is why a Laser can beat a Tornado in a drifter.
Due to the fact that you are often slowing down a fast multi - and that tris like the Harris and Cross sail well in light winds - they are great cruisers. When they start producing large hull waves in 15 knots and 9 knots of
boat speed then everyone is slowing down because of conditions anyway.
As for the flare on modern tris - yeah sort of. When you go aboard a highly flared tri and share the space with another person, there is an awful lot of "excuse me" and pardon me stuff happening. This is because the
cabin sole is rather narrow. Sure there is room above the waterline but to pass another person in the boat requires each person to stop and move. Much more than on a mono.
And then you have the issue of a higher immersion rate because of the thin main hull - so the boat can end up with an immersed transom and goes slower than it should. It takes a real sailor to keep the weight down on a faster tri. We cruised slower on our fast trimaran than with our slower top speed cat - because the tri was so weight sensitive.
A 40ft Cross or Harris can be an excellent cruiser if kept on its designed waterline (which is much easier than with a thin tri). The one in the video I linked to was kept light and did good
multihull averages - at much less cost than a similar cat.
I spent about two years designing my own 40ft trimaran. It had a 9-1 ratio main hull a centre
cockpit like the
Searunner and flare like a Spoon Bay. It was almost finished when I realised that a cat would make a much better cruiser for our
family, so I built a cat instead. As much as I love tris (and I owned two and built one) building a tri when there are nice ones out there to buy secondhand is a silly thing to do.
Nice "Fat hulled" tris that sail well are
Harris 40
Liahona (Simpson)
Bruce Balan on Migrations - a 45ft Cross which has been his home for years - a great boat and cruising couple
https://migrations.brucebalan.com/
Go the fat hulled tri.
At the risk of turning this into a treatise - the
Hughes designs linked to are not great designs in my eyes. They show a problem that is very subtle yet important - (for one the larger tri has its transom immersed - so it will be slower than it should).
But Hughes designs full bottomed floats that are immersed in the
water. This is nota good idea. If you look carefully at the Harris, Simpson and Cross floats you will notice a nice veed bottom on the floats. This is vital in a cruising float as the float plops in and out of the
water all the time, especially on a beam reach. Highes floats will bang, and that will get old really really quickly. Sure you will go a little faster at top speed, but what a penalty, and the crew will just want to get off.
If you look at a fabulous seaboat tri - the Cirrostratus, drawn by the legend Robin Chamberlin, look at the deep vee section of the float. Robin was a great
designer who knew that float design was critical in making the crew feel safe. When I built a 38ft Newick - Dick Newick told me of the competing ideals of comfort (more vee) and rounded bottoms (more top end speed). Cruisers don't care for top end speed so make sure the floats have lots of sharp vee on their bottoms.
https://www.boatdesign.net/threads/m....62361/page-38
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