Power Trimaran

[DaveB]

Originally Posted by BayouDude

I am taking a course at the University of New Orleans and am going to design a power trimaran. I would like to do something about 80-100 foot with a 20-30ft beam, a range of 1000 miles and a cruising speed of 20kts. I was thinking the vessel would be used for a live aboard dive boat or possibly a yacht. I was intrigued by the trimaran hull and was wondering if anyone had any suggestions? Any input would be appreciated.

I don't know for sure, but 30ft doesn't seem like much beam on a boat of that length... I am under the impression that it's important that the wave patterns don't interfere constructively between the hulls. There are some packages like michlet that can help with this type of analysis... I think this might be why some tris have short outer hulls...

Sounds interesting...

Cheers,

Dave

[marshmat]

On the power tris:
30ft beam on a 100ft tri does sound rather narrow. I've seen monohulls with that length-beam ratio. The interactions of the wakes of the central and outer hulls would probably be a pretty important thing to watch for. I don't think it would be an easy analysis to do.

On the radar stuff:
(perhaps we should start a new thread for this?...) The slight angles you see on stealth ships work well at sea. On an aircraft, where radio waves can propagate in all directions, the 48-degree angle is most effective at reflecting the beam in a different direction than it came. On a boat, the shallow angles you see on stealth corvettes reflect marine radar signals so they do not return in the direction they came from; radar from aircraft is reflected into the ocean where the waves cannot propagate. It is a matter of intended purpose and surrounding media that dictates the design of a stealth vehicle.

[kach22i]

Originally Posted by marshmat

radar from aircraft is reflected into the ocean where the waves cannot propagate.

I thought radar waves bounced off of water surface, not went through it. Guess I'm wrong.

A new thread?

Sure, but I have to go right now. Cheers George/kach22i.

[marshmat]

depends on the angle they hit- like all electromagnetic radiation, radar waves are reflected at some angles and not at others. the way light reflects off of waves is a perfect example; it's the same type of radiation as your radar just with a much higher frequency.

[FAST FRED]

"On the power tris:
30ft beam on a 100ft tri does sound rather narrow"

The power tri would not have the usual loading of mast and sail , so the amas would merly be "Training Wheels ". The main hull would have an L/B ratio of 8-1 up to 15-1 .

so an overal beam of 30 would be quite generous , and only needed for a small % of the hull legnth.

With no need for a help pad the vessel might even be narrower overall than 30ft.

With many travel lifts limited to 20 ft , with relativly short far aft amas , a small yard should be able to service her.

FAST FRED