I was surprised nobody mentioned the wind-jet (not to be confused with windjet) - a French production planing catamaran: http://wind-jet.com/uk/technologie.html

I think the 16 foot planing catamaran folks keep mentioning was called a Hardcore 16.

To plane efficiently a catamaran's hulls must have a lower load coefficient than displacement hulled cats have. Since load coefficient is proportional to 1/beam^3 it pays to make the hulls wider. Narrow hulls have higher induced drag when planing.

-colin