Cat Design
 

After reading the Cobra post it got me to thinking... Is there a ratio for length to beam measurement for a well design cat hull. In my limited experience it seems wider is better. Is this always the case? Let's here from you cat experts even the the old out dated ones.

I think you are right. But do you want to keep it trailable? My Cobra at 8'6" would really be something if it was 6-12" wider.

Very interesting question. There are certainly many factors that effect the handling/ride of a boat, and with cats it is not only hydronamics, but aerodynamics (to a much greater extent than vees) as well. This should be a VERY good thread!:)

Shane......waitng, as always for an obselte members answer;)

Here's come excellent reading I've found on the subject:
http://boatdesign.net/articles/tunnel-hull-design/

And the people who wrote the book on tunnel boat design:
http://www.aeromarineresearch.com/

What we generally use as a rule of thumb in this instance, atleast as a starting point is the width to be
1\3 of the length. Use that as a starting point, and then you fine tune depending on weather the boats purpose is a cruiser you may go a little wider for room . If Its a race boat your building you may go a little narrower to get less weight & wetted surface area. If your doing a cat its much the same you would figure the width based on what the use of the boat may be. Just my opinion hope its helpfull

Ken Adams Jr.

Ok so far we have a 36' cat with a 12' beam. Or a 30' boat with a 10' beam. What would be the relationship between sponson width and tunnel width? Assuming we are talking about a race or fast pleasure boat. Does anybody remember how wide a 32' malstrom cat was? As I recall it was a wide beam boat for its day.:frog:
Thanks Ken. I am not tying to build a boat this is just an interesting excerise in design.