slicker surfaces tend to make water stick, more rough surfaces do aerate it, but there is much more to it than just hitting it with a flatboard. if you take the corners off your strakes and chine you can make the boat handle horribly.

On my lowers i have sanded them for years and keep them satin with the pad. never went over 220 paper and only used that to try to smooth the surface out only to go over it again and make it rough...(Following me?) has it made a differnce, I have to say yes, as i just put a new lower on one side and got the fastest speed ever with sanding and scuffing both, but i alos think its a progression of all the little things i have done combined.

Yes! And the same would hold true on a lower unit.

Problem is that the slick hull or drive creates surface tension between the object and the water. Example that was given to me, lots of years ago, was to take two pieces of glass, wet them, place them together, try to pull them apart. Try it and tell me how that works out. When you rough up the surfaces you lessen the surface tension, the two then release much easier. This is the base principle of why a vented hull is faster than one that is not. The air becomes the release agent allowing the hull to move thru the water with less resistance and run faster with the same power. Years back racers of small hydroplanes would paint their hulls with flat black paint, not a very slick surface, with the understanding or hope, that it would then run faster. If you look to Merc's hi po drives they are not done with slick paint. They are not so slick castings, ever wonder why?

Problem for most of us here is that a slick hull looks better and is easier to keep clean and looking good. How much faster would it be if was wet sanded? I have no idea, just keep mine clean, don't waste my time waxing it, and let the Reggie bottom do it's job.

So why is a bottom painted boat a no no.
Besides lookin like crap, I've heard from a bunch that it scrubs major mph.

Seems like bottom paint has enough texture to airate perfectly.

Cool thread. Think ill rough up my lower a bit.

MD

My 02 ct.

I dont think just sanding a lower will make any differance in speed. now re-shaping a drive to make it "true" is a different story..

I do sand mine to keep them fresh looking... but not doing it to expect any speed gain.

You won't notice...

True. But it is a ***** to keep clean. Just sanding doesn't do much if anything. Flip the hull and blueprint it.

We picked up 2 mph with proer hull and skeg sanding. We laser edged all hull edges and got another 3mph.there is a new hex film. Similar to golf ball technology we are going to try.

What kind of boat?

5 mph net is pretty DARRn good for some elbow grease.....
What's the secret hex film called...?

Better put motor in before you bother sanding your lower. Just sayin. LOL