Catamaran design help

[Devooo]

Im in the process of buy some catamaran hulls that i want to make into a cruising cat(powered by 2 outbaords NO sails) Im looking for any suggestion who will help me on the design and hopefully answer my questions along the way any thoughts on the hulls would be great If anyone know what plans they were from that would help out alot Thanks

 

[fhrussell]

Any details?..size, intended use, pictures...?

Your question is a bit too general for a helpful reply. I'm sure if you could fill us in, you'll recieve plenty of replies from this knowledgable bunch.

Good luck!

 

[Devooo]

Thanks for the reply The size is approx 30 ft My intended use is a cruising cat simialar to versacats.com I will be attached a pictures of the hulls as soon as i fugure out how to do so Right now im trying to find the best way to connect the hulls, Im either thinking aluminium or wood Thanks again

 

[Devooo]

Here is a link to the pictures of the hulls http://catamaran.connpro.com/gallery.html
What do you think would be the best way to join them together?

 

[nero]

Probably the hardest information to find on the net is how to build or design a bridge deck structure for catamarans.

If you are needing just two beams, then this can be done by beam method.

If it is a big structure, then it seems that others have simply built bid deep trusses that are covered with plywood and burried into the bridgedeck structure.

 

[nero]

Just looked at your link to the photos. Yours will be with bulkhead/trusts going from hull to hull. All this coverd with a bottom skin and top decking.

Basically the edge of the flair gets extruded across to the other side. This skin or planking will be structural in several ways. There will be slamming loads, racking loads, twisting loads, and a whole bunch more.

This is the most difficult type to design.

Adding a deck house also?

 

[Devooo]

Thanks for the replies Yes i was planning on adding a deck house, That part seems easy in comparision to the beams or trusses, What material would you recomend for trusses I was thinking of glu laming marine plywood Thanks

 

[nero]

The bottom planking or skin needs to be the same material as the hulls are made of. The glass orientation might be 0/90/45.

Making a glulam of plywood won't work well. The top and bottom flanges of your truss/beam need to be uni-directional fiber. uni-glass has been used. Can not find it now, but I saw an example of where the truss was scabbed by plywood and extended past the top and bottom edges. This made a gutter where uni-glass was wetout, roled up and vaccumed bagged into it.

Following something like this could give you to solid trusses to handle the most forces between the two hulls. The bottom planking and deck planking will handle the sheer forces between the two hulls. Torsional forces will need other considerations.

This is on my too do list this summer for my cat. If only I could find the time for it. Next summer is when I have to build this part so something will have to happen soon. smile

 

[Devooo]

I was wondering if you knew of any picture of such a design , I found it difficult to find any detai on the internet

 

[nero]

All my bookmarks are on another computer on the other side of the atlantic. Will try to surf a bit to see if I can remember how I stumbled on to those sites to begin with. Kinda thinking one of the guys was in finland or sweden. The other site of interest is australian. Both have to do with men building their own boat.

 

[Devooo]

I think i saw the one of the australian building his own boat but i thought it was stitch and glu Maybe it was not the right one

 

[fhrussell]

The link seems to not be working....? I keep getting images of powerline towers.....!?

 

[Devooo]

sorry here is the new link http://catamaran.connpro.com/services.html I was thinking of building something on the lines of versacats.com Still trying to figure it out,

 

[nero]

The guy from austrailia, used strip planking below the waterline and then plywood sheeting for the rest of it. No luck on finding the link that took me to his sight. May have to do the unthinkable and ask my wife to look thru my bookmarks. smile

 

[Devooo]

I talked to a guy guy today that recomended making the trusses out of alumium z-bar I posted a couple of picture of what im talking about here http://catamaran.connpro.com/services.html I have a piece of the z bar and it seems to be a nice material Thanks again