Catamaran resistance/power prediction

[Spiff24]

Does anyone knows about some algorithm to predict the resistance/power of catamarans. In particular large, fast, wave-piercing cat's with dwt>750 ton.
I really need an algorithm that acounts with the interference of the hulls on each other.
Another thing, does anyone knows where I can find a FORTRAN code with Holtrop&Mennen's method for resistance? The thing is, because I haven't had any success to now in finding such algorithm, I'm thinking of determining the resistance for one hull, multiply it by two, and eventually find (I guess I'll eventualy find it, lol) the formula(s) to correct the result for catamarans. The problem is that I've coded the H&M to fortran...and the results are ridiculous. I found out where the problem is - one of the coeficients in the wave resistance can't possibily be correct (the larger the ship...the coeficient tends to zero, this is the "dominant" term in the equation). So I need to check if this formula is correct or not...it could happen that there is an error in my copy of the article...or not
Thanks,
Spiff

[yipster]

i figger those maths are complicated. no algorithms in fortran but from multihulls freds calculator gives a rough idea.

[terhohalme]

Try this:

http://www.cyberiad.net/michlet.htm