Rob:

The guys are right. Unless your boat is a real ancient driftbarge, most any Class I or Class II hitch will tow it just fine.

I use a Class I on my LeSabre (only thing available) and it hauls the Clacka (likely heavier than an Alum boat) just fine. The 3.8L V6 in a heavy 4 door Buick is a bit underpowered for freeway speeds unless I've got the boat cover on, but with it on I can run 60 all day, still get 25 mpg. and arrive in 1st Class style .. \:D

Mike