What's Eating My Boat?

[Slab]

I'm guessing this is Galvanic Corrosion. But why all the sudden is it so aggressive. There is a sacrificial anode on the motor. The only thing I've done recently is add a 24 volt Terrova trolling motor. I don't remember seeing this much corrosion before at all. This is after one trip on the water and I was only out for 2 hours.




It's eating the Terrova too


This is another thing I added now that I think about it, a Jack Plate. This corrosion is all over the boat under the water line; on the motor skeg, on the sacrificial anode, on the hull, on the terrova. It's everywhere!

Could it be stray current corrosion. I noticed that my hull is connected to the ground of the battery. I see online that some are, some are not. I don't want to put it into the water till I figure this out. Do I have to hang Zinc Anodes all over the boat? And while I'm on the subject, are magnesium anodes better? I thought magnesium blew up when it touched water! lol

["G"]

Battery grounds.....all other grounds should go to the Neg. battery post. Battery ground should be made to the engine block not the hull....The engine is isolated from the hull by rubber bushings inside the steering pivot point. Grounding to the hull will eventually destroy the boat. I got this info from my boat mechanic and verified it with the folks at Minn Kota. Minn Kota even said that my onboard charger should not be mounted directly to the boat....to mount it on starboard or plywood to isolate it from the boat. I don't think what you have is galvanic corrosion....I think it is being caused by electrolosis from the ground you have to your hull.

[backtocrappie]

Possible that.., the zinc became insulated with dirt and no longer touches the motor. 2nd guess is acidic water is finding all the weak spots in the natural oxidation of alum which serves as a permanent protective coating on a micro level.

[Cane Pole]

I agree with G. Some people use the hull to ground accessories such as lights. The lamps work, but this type connection causes undesirable loop currents via the hull.

[skiptomylu]

Well a few years ago you may remember when I couldn't get my boat out due to water dropping and I waited as long as I could before trying to take it out. However when I went to get my trailer the boards were rotten as all get out and I didn't have time to fix/change them out. I learned that they put just boards on trainers now and not treated boards because the stuff/chemicals they use now will eat your aluminum boats up via chemical reaction when wet! So I needed up buying UV Plastic boards for my trailer! I didn't want to need to Change them out every 3 years which is how old y trailer was when the boards rotted apart!

not positive it's what is wrong with yours, but sure would check it out for that!

[skiptomylu]

One other thing is I always was told if you have you big motor in the water when charging, that will set up electrolysis?

[Slab]

I don't think my boat is used for the negative for accessories (everything I see has two wires going to it). I think the hull is grounded due to the motor being grounded and attached to the boat. It does not have an insulator between the motor and the boat, at least none that I see.

[Slab]

Well a few years ago you may remember when I couldn't get my boat out due to water dropping and I waited as long as I could before trying to take it out. However when I went to get my trailer the boards were rotten as all get out and I didn't have time to fix/change them out. I learned that they put just boards on trainers now and not treated boards because the stuff/chemicals they use now will eat your aluminum boats up via chemical reaction when wet! So I needed up buying UV Plastic boards for my trailer! I didn't want to need to Change them out every 3 years which is how old y trailer was when the boards rotted apart!

not positive it's what is wrong with yours, but sure would check it out for that!

Wouldn't that just eat the boat where the chemicals from the boards were touching the boat?

In any case, my boat has rubber rollers. No boards here. Thanks for the suggestion Skip.

["G"]

The isolator is inside the steering pivot Ed. All grounds should end up on starting battery neg post......neg post of starting battery should go to the engine block. Even though outboard is bolted directly to boat kit is rally not connected due to isolator bushings in the turning pivot......you cannot see them but they are there.

[Slab]

The isolator is inside the steering pivot Ed. All grounds should end up on starting battery neg post......neg post of starting battery should go to the engine block. Even though outboard is bolted directly to boat kit is rally not connected due to isolator bushings in the turning pivot......you cannot see them but they are there.

Just did a continuity test. The engine is connected to the hull/transom. It's a tiller steer, so no other connections from motor to boat except the battery and the motor mounting hardware. But that does not mean that buried in there is not a ground wire connected directly from the battery to the boat hull. I'll have to follow wires and look for that. An easy test might be to just completely disconnect the battery and see if the motor is still electrically connected to the hull. I'll go do that.



Disconnected all wires from battery, and the motor and hull are still electrically connected via a continuity test. At least with an evinrude tiller steer 40hp it's not insulated via that steering pivot "G".