Surface corrosion,pitting-aluminum boat

[motownbob]

I have a 1997 crestliner,and have recently noticed several spots that have tiny blister like rough areas and some spots that the paint is starting to flake off. The dealer says that it could be caused by salt,but i never use it in the winter, in fact it is covered completly. Any idea on what is causing this, and how to stop it?

 

[SeaDawg]

Re: Surface corrosion,pitting-aluminum boat

I would look to be sure that another type of metal (like stainless steel) is attached to the aluminum near the pits. You could have galvanic corrosion.<br /><br />If it is not factory paint, it could also be the paint. Certain types of paints and sealants will eat up aluminum.

 

[motownbob]

Re: Surface corrosion,pitting-aluminum boat

There are spots of corrosion that are not close to ant other metals, and where stainless meets the aluminum, there is no corrosion.

 

[DJ]

Re: Surface corrosion,pitting-aluminum boat

motown,<br /><br />You didn't say if the boat spends any extended periods moored in the water. If so, the area that it is tied up in could be "hot". That is, stray electrical current in the water.<br /><br />Also, make absolutely certain that nothing in the baot is grounded to the hull. And, make sure the zincs on your engine are clean and not painted over.

 

[SeaDawg]

Re: Surface corrosion,pitting-aluminum boat

Yea, I guess what we are trying to say is that it sounds like you are experiencing some type of galvanic corrosion, which is caused by electric current (very small amounts, usually too low to measure) passing through your hull.<br /><br />It is usually caused by two dissimmilar metals coming in contact with a good conductor liquid (like saltwater).<br /><br />But it could be caused by something at your boat dock too.<br /><br />This is different thqat just plain oxidation, which is what happens when steel rusts.

 

[motownbob]

Re: Surface corrosion,pitting-aluminum boat

My boat is only used in fresh water, sits on a trailer, and is never in a well, any ideas?

 

[Uncle Dave]

Re: Surface corrosion,pitting-aluminum boat

Mo town;<br />Just where on the boat is the problem area. The more you can describe a problem on these boards, the better the answers.<br />If below the water line, then you may have serious problems<br />Mr. Fitz.

 

[motownbob]

Re: Surface corrosion,pitting-aluminum boat

THe corrosion is all above the water line, mostly on horizontal surfaces. Most of the spots are say dime size, there are a few spots on vertical surfaces. When i scrape my finger nail on the spot, a whitish powder comes off.

 

[Luna Sea]

Re: Surface corrosion,pitting-aluminum boat

Oh boy, I can relate to this one! I have a 20' Lund and keep getting little corrosion spots on the transom if I leave it in more than a couple of days, right where the deck meets the transom. 1st solution was cover the battery, with a box, cause on a drizzly weekend the first time it happened. Patched with JB Weld. More spots, drilled into transom and installed studs for big bolt on zinc. And again????? Stuck my meter's black to an engine bolt and threw the red lead in the water, .5 volts! I'm a salt water trailer boat but have a mooring, if I could find the problem...... Only wires out of sight are for bow light, may rip them out cause somethings doing something to the hull....... Good luck!

 

[DJ]

Re: Surface corrosion,pitting-aluminum boat

motown,<br /><br />Since your "spots" are on a horizantal surface, I think you can rule out galvanic action.<br /><br />Horizontal spotting is caused by water or a foreign substance sitting on the surface. It is much like acid rain used to effect vehicles before the advent of clear coat paints.<br /><br />If the water that you boat in, or you clean up with is extremely hard, as it is here in AZ, I believe that's your issue. Hard water will damage paint.

 

[motownbob]

Re: Surface corrosion,pitting-aluminum boat

Concerning the water here in the detroit area, it is considered to be medium hard, about 5 grains, city water not bad...it is actually pretty good water compared to other parts of the country.

 

[DJ]

Re: Surface corrosion,pitting-aluminum boat

motown,<br /><br />How about the water you boat in? Being from Michigan myself, I know that there are a lot of mineral rich lakes and rivers there. Not to mention pollution.

 

[motownbob]

Re: Surface corrosion,pitting-aluminum boat

I boat only in lake st clair, erie, and huron.

 

[Lark40]

Re: Surface corrosion,pitting-aluminum boat

Is the boat covered? Does it sit in the open where tree debris can fall on it?<br /><br />Something is getting on it to start the corrosion. Cover it up.<br /><br />My Crestliner is 44 years old and has barely any trace of corrosion. But, I keep it covered and as dry as possible when out of the water.

 

[motownbob]

Re: Surface corrosion,pitting-aluminum boat

My boat has a full snap on cover from bow to stern, and the boat and trailer are covered completly in my driveway from november to the end of march!

 

[Lark40]

Re: Surface corrosion,pitting-aluminum boat

Is your cover breathable? Can the moisture underneath evaporate out?