determining distance between catamaran hulls

[Thai]

Hi everybody!
Now I want to build a catamaran. But I don't know formula to calculate distance between two hull. Could you guide or show doccument for this issue
Thanhk
B.V.Thai
HochiMinh City - Viet Nam

[wingsails]

There is no set formula that I am aware of, it depends on how stable you want it to be and how much of a problem being too wide is eg on a trailer behind a car.
Years ago width was 1/2 of length, but now wider boat are more popular.
That is only the start of your problems though, take advice and think things through trying to imagine how it will all come together.

[Hisham]

be care the larger span the larger bending moment

[Thai]

I agree with Hisham. This distance keep eye on bending moment and shear force effect vertical wave. So I want a detail formula. Could everybody help me ?, Thank
B.V.Thai
HochiMinh City - Viet Nam

[JonathanCole]

The width of a catamaran depends on many things. What kind of speeds you travel, what kind of sea and wave conditions you regularly expect, what the length is, etc.

Catamarans create diverging waves between the hulls . These waves can interfere with and sometimes assist the forward movement of the boat. This depends on many other design issues including the symmetry or lack of it in the hull design, the fineness of the bow in pushing through the water, the angle of the bow to the waterplane, and the speed that the hull is moving.

At some speed the waves actually can assist the movement of the boat by something called constructive interference. There is no set formula because all of the catamarn hull design characteristics effect the wave interference.

I think the most common point of view among experienced designers is wider is better than narrower. The wider the better, until you start getting so wide that you can't find a berth for the boat.