[striper-chaser]

I have noticed on the bottom of my boat some little white powder spots that is rough that i assume is corrosion. how do you get rid of this and keep it from coming back?Its the aluminum thats not painted. Thanks for any info.

[Forktail]

Sounds like electrolysis. The only other thing it might be is salt water that has dried.Electrolysis is an electrical-chemical reaction with the aluminum that causes the corrosion. It will weaken the aluminum over time. The only way to avoid it is by installing zinc plates on the hull below water line. The electrolysis will attack the zinc fist, before the other metals.You could scrub and acid wash the aluminum, then seal it again with aluminum marine paint to help the corrosion you already have.Make sure you have zink plates on your outboard too.

[KCLOST]

Striper Chaser,Forktail is right on the money on this one....Normally every boat should have a zinc component to attract electrolysis to it so it won't get to the boat.On my boat (bass tracker) the trim tab on my outboard is got the zinc properties and does the job.... Never had any corrosion like you have described (I assume you mean "battery-like corrosion"). And this boat was in the water for 3 years straight.So check and make sure you have or haven't lost the trim tab (assuming you have a motor on the boat). Make sure it isn't painted, it should be raw metal. That could be your problem..If they are small spots that are evenly distributed on the entire submerged hull surface, it's probably not corrosion at all. It's more than likely lime deposits. This is common if the boat is kept in the water for a long time. You can get it off with Acid cleaner for aluminum hulls (wear rubber gloves and safety glasses). After you remove and you see that the aluminum has not been harmed, it's lime. My boat had this.It will come back over time however..

[striper-chaser]

Thanks for the info.It has a zinc plate on the motor and the boat .You may be correct on the salt water .I will wash it off and see if it comes back.

[KCLOST]

Let us know how it goes...