I'm still not clear if you want a powercat or a sailcat with twin engines.
The price of motion is accidents.
The Great Lakes have short steep waves, like all lakes. I think because the water cannot escape but always has a shore to hit so cannot dissipate
Deciding on the seaworthiness of a design is always tricky. Should it be according to distance (time) from a safe haven? Often used by commercial rules. Or dependent on sea state (as in RCD for example). Portland Bill is usually rougher than anywhere else in the English Channel, yet the worst waves are only 1/2mile from shore.
In a powerboat it is the range under power that is the usual determining factor
But this is a long way from your original question. As always, don't get too bogged down with one factor of the design. Look at the broader picture, as Adhoc is saying.
Having said that, I don't like flat bottomed bridgedecks. I prefer them to be slightly Veed. Eve a small amount makes a huge difference to the amount of slamming. I like a 45deg angle at the bridegdeck edge as it spreads the loads and, unlike a rounded section, is easy to make and steps down into the hulls are generally safer
My structures lecturer said in my first lecture as a yacht design student. "Static objects (buildings, bridges etc) are easiest to design. Moving objects in one fluid are also relatively easy (cars, spacecraft, planes). The hard things to design are "interface vehicles" things that move in two mediums at the same time, like a boat in air and water. "
Think about it - few planes break up in the sky, it's landing, when they become an interface vehicle, that is challenging. Even more so with space craft which, when in space, have no loads and only one atmosphere pressure to resist.
That's why I wrote any article entitled "Rocket science isn't rocket science but yacht design is"
Richard Woods of Woods Designs
www.sailingcatamarans.com
