On a hull you want to have protrusion instead of intrusion meaning outward dimples over inward this will break the suction instead of inducing it. Jon mentioned dolphin skin, but Mako shark skin is a better example because it is irregular. One thing to remember the fastest fishes have the smallest scales. This translates into more smaller irregularities are much better than less larger ones. In the Bejing olympics alot of airtime was spent on the shark skin bathing suits that were worn, duplicating that in glass would be hard. Aluminum on the other hand is a can do substance. The two methods I've looked into are knurling like you learned in the metals shop of high school. Very labor intensive. and checkering like a gunstock again very labor intensive. Will it work yes is it worth the effort don't know. Water creates 52 times more drag than air. as far as the dimpling of a golf ball and it's areodynamic enhancement ability. 2case I have personally worked on 1 was a set of bow tie aluminum heads the other was a crower small block chevy crank. The heads produced 9% better airflow up to .550 lift and 7% better over .650 lift under 28hg of vacume. The crankshaft had no way of testing but it looked cool. Lexus has put a panel under the car that is dimpled it has increased fuel mileage as well as reduced the interior noise level in that model SRP has produce a piston with ridges with dimples that creates a cleaner more complete burn that the same compression ratio smooth piston That translates into more air velocity during the squish. Making the mixture better for combustion