Sanding dried algae from bottom of boat, need pointers!

[Modified]

Well, I've been using 150 grit and it seems to be working but it takes forever. Should I use 80 or so to knock the big stuff off and then come back with 150? I have also tried some barnacle and algae cleaner but it didn't work on the bottom. My main concern is how do you tell when you have sanded too far and need to apply some kind of protecting coat? It seems as if the algae has kind of "pitted" the bottom of my boat and I want the smoothest surface for less drag in the water.

Needless to say this boat has been in the water for 2 years and hasn't been cleaned.

 

[gcboat]

Re: Sanding dried algae from bottom of boat, need pointers!

Have you tried a good pressure washer? If not then you should give it a whirl. Something around 4,000 psi with a turbo tip will remove just about anything stuck on there. The barnacles will need to be hand scraped. Don't use anything that's too stiff, it improves your chances of gouging the bottom. As far as digging into the gel coat is concerned as soon as the white color starts to turn a gray or milkish tan then you have indeed gone too far. Then you will need a good barrier coat followed with your anti fouling paint. If there are a lot of osmotic blisters they must be cleaned out and completely dry before any other products can be applied. It's all in the prep. This is another one of those processes that you just can't be in a hurry to finish. The products to use are many and varied - let your wallet be a starting guide but also let some common sense about your boat prevail.

 

[Modified]

Re: Sanding dried algae from bottom of boat, need pointers!

I haven't hit a grey or tan area at all, I may just knock the heavy stuff off and go test it on the river once I get my new tilt/trim rams.

There hasn't been any blistering that I can see.

 

[gcboat]

Re: Sanding dried algae from bottom of boat, need pointers!

Great - then go have fun !!!!!!!!!!!!!!!!!

 

[tashasdaddy]

Re: Sanding dried algae from bottom of boat, need pointers!

have a good pressure washer standing, after having it in the water. let the algae soak up that water, makes it easier to come off. there is also a product call ON/OFF that is reported to work well on algae.

 

[Sorrento 25]

Re: Sanding dried algae from bottom of boat, need pointers!

Well, I've been using 150 grit and it seems to be working but it takes forever. Should I use 80 or so to knock the big stuff off and then come back with 150?

Yes, but stop at the point where the 80 is starting to cut the gelcoat. That way when you go over it with 150 you make scratches no deeper than if you used 150 alone. I'm using 80 - 180.

 

[BillP]

Re: Sanding dried algae from bottom of boat, need pointers!

Like mentioned already, try ON/Off. Use it when all others fail and you don't want to sand. It will take most everything that gets on a boat bottom off and comes in a liquid or gel. Use gel for overhead work. It ain't cheap though.

bp