Multi-hull Construction Problem

[8knots]

This may be better posted in construction threads but poses a design issue too so please bear with me!
Living about 40 miles from the nearest deep water launch point and wanting a large boat I have a engineering/design question.

Would anybody even consider building a powercat in 2 sections or possibly 3? as it is I am restricted only by height (17') so it would be something like..
1 stbd hull
2 port hull
3 wing deck
4 stbd deck
5 port deck
6 center deck and super - less fly bridge
The transport of the "modules" would require a fair amount of sacrificial structures and bracing But could be done! With the proper engineering I think it could be done safely without the un-easy feeling in the back of your mind "This thing is held together with bolts and epoxy" as you fight the sea!

I am a fledgling to multihull thinking and wonder how much "wring" these vessels endure. Say quartering into a head sea I "know" one hull is going to respond to the pressures of the sea at a different rate than the other at any given time other than at rest. This I think requires carefull engineering of the wingdeck structure. Most of the cat designs I see are a great big cave in the middle with little room below deck for structure. Granted most are sandwitch FRP, bagged with a carefull laminate schedule.

The "module" method lends itself to easier construction I think
smaller units of tooling = less manpower to do the layup
easier units to de-mold with smaller facility and lifting equipment.

In a nutshell...."would you put your name on it?"
any ideas and cautions welcome
8Knots

[BrettM]

I say why not? Boats are full of welded joints, secondary bonds and bolted connections. Plenty of boats/ships have modules made by different organisations and then joined together (with the hope that they fit). The 84 ft yacht in the boatbuilding thread has the same problem - can't fit under powerlines on its trip to the water.

Would I put my name on it? Not if somebody else planned it...
Brett

[gonzo]

I assume you also have some width and length restrictions. At least the need to stay within DOT regulations. It would be easy to build a modular boat. There are very succesful designs that use flexible mounts. They make the movement of the boat much easier. If the hulls are transported side to side it would make it simpler. However, you haven't specified any size, so they may have to be one behind the other.

[Not A Guest]

You may several problems with this approach. The big ones are:

Finding a work space, moving these large pieces into assembly position, and preping the surfaces for assembly.

Aside from those issues which all have solutions, the engineering is doable.

[8knots]

I have contacted the permit office here in AK and for $34.50 US I can obtain a permit to transport 80' long X 16' wide X 16'6" tall. I talked with the lady there and she said 22-23' wide is no problem with 4 pilot cars in the daytime. This tells me a 40-50' monohull would be not much problem except for height. The modular method for multi-hulls is a easily done too!

Gonzo, can you enlighten me on the flex mounts you are talking about?

In my new found multi-hull studys I have not decided on FRP or ALU Unfortunatly I think AL will be the answer. Keeping a 60' by 100' shop consistantly warm for good FRP construction will cost me a small fortune, It is -34 at my house this morning! Ahhhh Alaska
The cat I'm doodling on is 50' but with a little more study I may drag her out to 56-57ish. I don't know enough to really decide yet.
My customers all have cranes I can use with the promise of a fishing trip!
Plus they all think I am a mad man and get a kick out of my office walls plastered with sketches and math calc's.
Keep em sharp 8Knots

[gonzo]

So this is a one time transportation problem. I thought it was supposed to be trailerable. The flexible mounts are used in all James Wharram cats. They are sailing cats, but their handling is outstanding.