i'm designing a catamaran

[aero]

hi, I was wondering if anyone on these forums could give me advice on designing a catamaran.

I've modeled initial concepts, such as hull shape (stitch and glue) using rhino.

My main difficulty is resolving details such as beam to hull connections. also what would be better, daggerboards or long keels.

The purpose of the catamaran would be mostly just for the day out and occasional weekending possibly.

please view attachments and offer criticism and advice. I would greatly like to build something like this from own design.

I'm curently building a 15' dinghy using patterns generated from rhino so i know that part works.

cheers

[nero]

Daggerboards take up interior space. Keels do not. Keels make the boat stronger. From what I gather ... no practical experience, keels do not alow the boat to tack as well as a daggerboard.

Talk to Rob Denney. He is experienced and knowledgeable on multihulls. www.harryproa.com

Was thinking about a hardchined, stich and glue catamaran with a flat bottom pannel. Then I thought about bonding some foam to the flat bottom pannel and making a round bottom. This would make the boat unsinkable.

Do not have time at present to play with this idea.

beams need to go thru the hull touching both sides. Sitting on top or next to a bulkhead to bring the forces down to the keel / keelson. Torsional loads have to be countered. Maybe a bigger front beam structure with some foam in it. This would help the cat to float higher if flipped.

looks like a fun project

[bazza]

for some very different ideas on beam attatchment look up james wharram designs. very strong and cost effective.have built and owned wharram designs and can attest to strength and ease of construction. the system really works, however there is a serious designe flaw in the conversion from ketch to sloop rig.

[rkpshenoy]

aero i hope you can help me with my project having done some prior work on cats.
I have already done preliminary design of my catamaran design the way conventional ships are designed by following similar steps but for sticking to the required L/B , S/L ratios for catamarans. Having done that i saw that the lines plan i chose is inapplicable to my design. The CB of the hard chine hull form is far below the required value for the displacement calculated.Later i learnt from some other guy in discussion forum that my approach in fixing the dimensions itself is wrong.
If so plz tell me how to fix the main dimensions like planing length..., trim, lift required etc for catamarans.Also if you can suggest me any catamaran or a planing hull specific book it would be gr8.
Id let you know about the details of my project after anybody has replied.
Suggestions of all kind are invited.