[Raticon]

Originally Posted by Sailor Steve

Actually drag is worse on the surface due to wave resistance. As the hull moves through the water waves build up along the waterline, and the waves create more drag.
http://www.mecaflux.com/en/ship%20Hydrodynamics.htm

Is this mimiced in SH3 or with GWX in some kind? My first thought is the Schnorkel, and by using that you should technically be able to save lots of fuel for long voyages.