saling catamaran wave making

[pops]

Hello, I'm new here, so this may have already been discussed although I haven't seen anything in my looking so far.
My interest is to seek a way to eliminate, or greatly reduce, the "slamming", or "pounding" of waves on the wing deck underside (or the innersides of the hulls also) on a 40 ft sailing cat. I experience this on my boat, an Apache 40, as well as on another newer French design 42 ft cat.
George

[tspeer]

It sounds like you don't have enough bridgedeck clearance, which is going to be really expensive to change!

Some modern catamaran designs have a large fillet between the inside of the hulls and the bridge deck. You might try putting in a large temporary wedge, say made of foam, between deck and inside topsides to see if that helps. Instead of waves getting channeled by the topsides to hit the bridgedeck square on, the wedges would turn the flow and soften the blow. It doesn't help for crests that rise up in the middle of course, but just reducing the slamming frequency would probably be a big improvement. If the temporary wedges worked, you could glass them in as a permanent solution.

[pops]

Hi Tom
Thanks for your suggestions.
The Apache cat has a wedge on each side under the wing deck, but I think you're correct that the wing deck clearance is too low.
I am considering adding a false bottom with something like C-Flex wirh a mini keel similar to what newer cats like the Lagoon 42 have, to increase the tunnel clearance with the added buoyancy.
Possibly a wedge in the forward center of the wing deck might help also.
pops

Originally Posted by tspeer

It sounds like you don't have enough bridgedeck clearance, which is going to be really expensive to change!

Some modern catamaran designs have a large fillet between the inside of the hulls and the bridge deck. You might try putting in a large temporary wedge, say made of foam, between deck and inside topsides to see if that helps. Instead of waves getting channeled by the topsides to hit the bridgedeck square on, the wedges would turn the flow and soften the blow. It doesn't help for crests that rise up in the middle of course, but just reducing the slamming frequency would probably be a big improvement. If the temporary wedges worked, you could glass them in as a permanent solution.