I did once experiment on my 130L Fanatic to check which surface is better for the board.
- sanded the bottom to the quite rough mat finish
then
- apply glossy white paint
i don't have definite answer myself, but there must be somewhere accurate scientific research result for this intriguing question.
What is the lower resistance surface for our boards:
- absolutely glossy ? when water could flow in undisturbed laminar manner ? but make 100 % adhesion to surface
- rough - where water molecules skip over surface limiting surface area contact ?
- hydrophobic - where molecules are actively repel off the surface ?
- maybe some composite micro structure like shark skin ?
- future possibly belongs to the super-conducting-magnets that repeal water implanted into board- but there without any other changes we could not keep balance with absolute zero resistance
or
there is nothing to improve as companies do already the best bottoms for their boards ?
Anyone else remember this?
3M made a stick on film that was used with the americas cup yachts
October 1993 - NASA RIBLETS FOR STARS & STRIPES
www.nasa.gov/centers/langley/news/factsheets/Riblets.html
Speedo has the "Fastskin" suit. Might be able to glue the fabric to the bottom. Also, what about spraying the bottom with the water repellent spray? Not sure for how long it would stick for but might be long enough to see if any difference is felt.
It's not illegal to kill sharks in Australia, right? Couldn't you just cut the skin off and glue it. :)
^^^ Please don't kill sharks for their skin...they're already being killed for fins, flesh & from fear.
Re; original topic, there was a board in the 80's (?) that had a dimpled underside, but didn't take off - probably thought it would work like a golf ball.
In my old joinery business I used to get kids always coming in wanting to buy offcuts (1200x400 ish) of laminate for their 'sandboards' for riding the local dunes (I never charged them, just happy that they were doing something outside - probably why I had so many come in). Anyway, I ran out of gloss offcuts one day & apologised as I handed over a 'Laminex dimensions' offcut ('dimensions' has a fine stippled texture & is/was the best finish for wear & tear). The kid came back with his mates the next week & told me that he blasted past all the other kids...I soon ran out of 'dimensions' offcuts as all the other kids followed.
I always thought that there would be a superior finish than simply smooth...but it would make sense that the best speedsailing board designers would've already researched this, so I'll stick with my 3m fine pad & turtle-wax once a year
.
been and done...
boardlady.com/fast.htm
here is at least one explanation of testing to date.
Well and truly done. I remember the "speed finish" fad about 1990 ish where lots of the the polyester boards were sanded back. $100 extra for a new board cos some guy did the bottom of the board with wet n dry for 10mins 
