3Hulled triangular sailboat

I am thinking about the (dis)advantages of a sailing boat with three hulls in a triangular fashion.

Some examples of fast craft with 3 hulls in this arangement exist but the type in general has never become popular. I have doubts about performance in waves but don't clearly know why. Perhaps the frontmost, least boyant hull, should be able to rotate in the vertical plane to "ride" over waves? i can see (dis)advantages in this also.

Any thought,suggestion or comment is welcome.

Here some links to designs with 3 hulls

http://www.hobiecat.com/sailing/TriF...trifoiler.html

http://foxxaero.homestead.com/indsail.html

More examples are very welcome.

In these designs speed was the ultimate goal, i my design ease of handling is more important but an easily driven hull is part of that (smaller sail - easy handling - lower weight etc......)

The configuration of the three hulls, 2 at front or 2 at back, large central one or small frontmost one, anything is possible. But i have not found many good reasons for either one of these options.

[yipster]

that are some hefty samples, i've seen many dozens of all sorts of interesting tri and sail configurations but where...
f.e. something from "multihulls" magazine site or so but links are broken

[grob]

The 3 modular hull configuration that you have shown is something that I have been thinking about, there used to be a picture on my site. www.fourhulls.com. I will have to dig it out

The advantages are,

Inexpensive as the hulls are small and so easy to tool up.
Good stability
Low wetted surface area
Good for storage

Disadvantages are,
High wave resistance, due to the relatively short fat hulls.

The reason for these designs having speed as the ultimate goal, is that the short hulls do not work to well at low speeds (hull speed) because of the higher wave drag. But they work very well at higher speeds once you get over the wave drag hump.

If you are talking about a sailing craft I would go for two at the front and one at the back, as it would give better stability, perhaps you could then use the rear hull for steering. I use a similar modular hull concept but with 4 hulls instead of 3. So there are some hulls available should you want to try the concept . I haven’t got time at the moment.

All the best

Gareth

Thanks for your reply Grob, nice boats on your site,

I made an illustration of the 2 hulls at front option, and i like the idea of having just one rudder aft. Creating a frame connecting hulls and mast without obstructing crew will be a challange. What i liked in the 1 hull at front option was that the beams seemed better placed to resist wave impact.

If i understood correctly in with an hull aspect ratio of over 1:8 (like most catamarans), the "hump" in resistance when you go from displacement to planing does not exist.

[tom28571]

No matter which end you put the center hull on, there will be a large fore and aft shift in CE when it heels. Much less control when the center hull is forward because of momentum. The more successful ones are mostly like proas with the main hull reduced to two in line hulls like Yellow Pages. The Hobie has a large center hull so it is different.

Thank you tom28571 for your clear answer.

I am more convinced now that 2 hulls at front with a small hull that contributes only a little to the lateral plane at the back is the way to go.

More conciderations are very welcome.

[yipster]

did look for ya, there are / where some sites with more info on various configurations but cant find them back

Peter Lynn in NZ is a kiteboat pioneer. When he first got into kiteboats he used a three hull configuration: two hulls aft; one in front. You can see a picture of it here; you'll have to scroll down almost to the end:
Peter Lynn Kites - Newsletters 2005
http://www.peterlynnkites.com/web/1a.../news/2005.htm
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More pictures:
Flexifoil Buggy Boat at Prokites.Com
Address:http://www.prokites.com/bugboat.htm

[grob]

Originally Posted by zeevonk

If i understood correctly in with an hull aspect ratio of over 1:8 (like most catamarans), the "hump" in resistance when you go from displacement to planing does not exist.

That hump does exist at aspect ratios of 1:8 although you can still get over it, even in displacement mode, given strong enough wind and or big enough sails. The hump gets less significant as you get longer and slimmer.

How big are the hulls/boats you are thinking of. That hull configuration is easily modelled using Michlet if you want to see the effects.

Gareth

Michlet, great tip.

I will try to educate myself on the "hump shift when longer and slimmer" issue.

Size is not important yet, i would like to keep the discussion as open as possible.

Using a kite as power supply crossed my mind, a kite powered boat has less heel, solving the lateral plane shift.

Thanks Lorsail.