I've always believed that catamarans are displacement boats. I sail a G-Cat and I cannot see ANY way those super-deep-V hulls could plane.

However, I also own a monohull and am on an E-mailing list with other owners, and we were discussing the hull-speed theory. I tried to explain how catamarans circumvent this theory with their super-narrow hulls, but all I got for my troubles were some nasty e-mails saying that these boats just get on a plane to go so fast.

So what I need is some really technical information that proves catamarans are not planing vessels, or a good smack upside the head if they really are...