Need to clean the bottom of the Baja. Even after using muriatic acid it feels like it's not clean. There seems to be some debate about what's best for the bottom. Some say polish and wax. Other say sand the last couple feet that are in the water at high speed. Some say sand across the bottom, some say sand with direction of flow. With all those options, I was thinking about a hydrophobic coating.
What is the real gain from sanding on a boat that currently runs 70+ with plans to double the hp.
Polish and wax or hydrophobic would probably stay the cleanest. But I'm intrigued with the sanding. It supposedly breaks up the "suction" of the water on the bottom of the boat. Wouldn't a hydrophobic coating do the same thing considering water is repelled from contact with it?
Opinions please.

I thought wax was a good idea but was told that was the worst thing for increasing efficiency in a boat. I suppose it may keep it cleaner but it was a lot of work. I also believe that it is probably worn away pretty quickly. I don't know what the "hydrophobic coating" is so no comment. I did see someone applying a "go fast coating" to the bottom of their fountain but I don't know if it worked or not. I did use a scotch brite pad on the transom once and that is now a sh!tshow to keep clean.

Smitty,

On our model boats, some guys have been known to do a final coat of graphite infused epoxy and not apply a clear coat on the running surfaces. Something we picked up from the unlimited hydroplane guys, I think.

About the sanding…. On our outriggers, we will do a crosshatch pattern, on about a 45deg angle in both directions from the direction of flow. We lay 1000 grit sandpaper on a very flat surface and drag the sponsons across it a couple of times; just enough to take the gloss off the clear coat. I’ve seen this done at the race site and the boat gain 2-3MPH from this alone. I’m not sure it would scale up for our full sized boats or not.

Thanks. Brad.
(937)545-8991

An earlier thread in the "Fiberglass and Paint section". As I stated in this thread this thread, the white hull would get dirty and stain easier once the pores of the gel were opened.
https://www.offshoreonly.com/forums/...om-finish.html

My gel coat bottom was pretty dirty when I bought my boat.
I washed it twice with muriatic acid, then simple green.
Then I laid under the boat, compounded it, polished and then 2 coats of wax. 2 years later it’s just starting to discolor if left in over night. I don’t think it affected speed. The best my boat ever did with merc 5 blades was 94. I saw 92.9 with half a tank of fuel, 2 people and all the gear and spare parts I carry.

This link is for a PWC, but they do have a suggestion for "hull finishing". However, it doesn't address speed, but says it's for better tracking of the hull.

https://groupk.com/index.php/polaris-1050-engine/

I've personally had great results using CLR...this product has worked where others, including muriatic acid, have failed. I know others that swear by The Works cleaner. I've never tried The Works on my boat (though it DOES make great aluminum foil bombs...or so I am told). I have started using these 'ceramic' coating type waxes and have used them after doing the CLR clean with good results.

muriatic or oxylidic acid to clean…it will leave the surface chalky. Wet sand and buff until it’s shiney.

finish with a ceramic coating. we use carpro quartz. there are many brands. wax does not hold up and will break down. Our boat is almost 30 years old and the bottom looks better than most new boats. it doesn’t brown, water beads even after 2 years, goes in salt water…

I keep mine in freshwater. That said I use "the works" and hydrogen peroxide mixed 1 to 1.. I tried a commercial cleaner boat shops use but found it can cause fading if left on more than a few minutes.

I run in fresh water and boat is kept at home on the trailer. I've had it a few years. Redid some of the flooring in the rear. Worked on neatening up the wiring and a bunch of other little stuff. This year is for working over the outside of the boat. I'm kind of leaning towards buff/polish/ceramic coat. Just for the sake of it staying cleaner longer. No matter what I do it'll be a major chore due to physical limitations. But I'll get it done.

Thank you all for your input.