Corrosion

[1sinbad2]

I am considering a 2000 crestliner Sportfish 1750 and the paint on the aluminum plate around the perimeter of the bow is blistering. Should I just remove the paint and polish the aluminum or install some sort of sacrifical anode. I'm a newby--but is a "zinc" a sacrifical anode? I am not a corrosion engineer. How or where should the sacrifical anode be placed.

 

[DJ]

Re: Corrosion

It all depends on WHY the paint is peeling. Is there corrosion undernreath? If not. the zincs are not needed.<br /><br />If so, the zincs will help. They need to be attached to hull so that they are NOT insulated from it. Bolting or riveting is best.<br /><br />First off, make sure there is NOTHING electrical, in the boat, grounded to the hull.

 

[1sinbad2]

Re: Corrosion

Thanks for the feedback. I'm still debating purchasing a 2000 Crestliner that has had been used in salt water. The paint on the surface around the boat that the cleats and grab rail mount to is blistering and will need to be repainted. I am concerned that there may be a problem with galvanic corrosion. I plan on using the boat in fresh water. Does gavanic corrosion occur above the waterline? If I install zincs, should they be mounted inside the hull?

 

[snapperbait]

Re: Corrosion

Sounds more like simple corrosion from salt spray than anything else... Previous owner did'nt wash the boat down good? ... Add some corrosive action between dis-similar metals (stainless vs. aluminum) in the mounting hardware for the grab rail and cleats.. If the corrosion starts and sneaks in under the paint somewhere like where a hole was drilled for a bolt, that, with the salt spray, will definately cause the paint to peel..<br /><br />I'd doubt that anyone would leave an aluminum boat like that in saltwater for any length of time in a marina or docked where galvanic corrosion from stray shorepower curret can run rampant... If it's been trailered, and if none of the electrical system is grounded to the boat, you can probably rule out galvanic corrosion.. <br /><br />Zincs go on the outside..

 

[1sinbad2]

Re: Corrosion

The engine has only 61 hours on it and the boat appears to have been trailered. Is it necessary to isolate the cleats and other hardware from the hull? How do you determine if any electrical component is grounded to the hull?

 

[akriverrat]

Re: Corrosion

paint on aluminum, in salt especially, will get nicked and corrosion forms blisters in the paint trapping moisture. if left alone they grow and the metal pits. doesn't need any galvanic action but adding dissimiliar metals or stray current will make it worse quicker. no paint may be ugly to many but it is much less maintainence.

 

[Fly Rod]

Re: Corrosion

This may help you to understand electrolysis better. Go to www.marinesurvey.com Scroll down to corrosion and also corrosion in marinas.<br /><br />It also has a bunch of other articles that make for good reading.