Help! Boat question

My boat has currently started building this white powdery substance almost like corrosion and our prop is rusting. The white powdery substance is on trolling motor and and the jack plate. Any ideas on what is happening?

Aluminum oxidation.

I've read something about bad grounds in battery's will make that way worse.

Electrolysis

How do we save the prop? And fix the white stuff?

Sacrificial anodes need replacing?

It is corrosion. Aluminum corrodes (the white powdery stuff) and steel corrodes (the orangish/reddish stuff, aka rust). The engine probably does have some sacrificial anodes somewhere that need replacing. These are usually made of zinc and will corrode in place of the motor parts. This looks as though you are using the boat in salt water and not cleaning it, or you are coming into contact with some other substance that is accelerating the corrosion. There could also be some kind of battery/ground issue, although I think that is unlikely--but it is possible. Do some research on how corrosion works and apply the knowledge to your situation. Remove the electrolyte, clean and protect.

It is the trolling motor causing this problem. There is a bad ground somewhere and or the brushes need adjusting. I had the same problem on one of my boats years ago and swapped out the trolling motor; problem solved. The electrolysis travels between the two farthermost metal objects on the boat which is trolling motor to the prop.

Boris Marine is the best at solving this problem. Also have the blocks changed out at the same time to get a fresh start. Prop can be rebuilt and put through a heating process to get a fresh start on that also. It is expensive.

^^^ This is correct.

What is the best way to clean it?

Specifically the prop, best way to take rust off?

WD-40 if it is just surface, get it off quick. If it has aleady broken the surface And created pitting, you'll not be able to keep it off.

Fix the source of the problem first!

I'm not going so far as to recommend this, but I once read to install a common negative ground wire/cable between the trolling motor batteries and the starting battery. I did do that and had no problem with electrolysis. I no longer have that cable connected now and so far (knock on wood) still don't have a problem. My problem, though less serious, is lime accumulating on the lower unit, from the hard water in the river system/lakes down here. A 50% mix of water and vinegar helps remove it.

Thank you guys for your help.

good morning,

cleaning stuff like that is on youtube ............ just saying...............

good luck,
PURA VIDA,
bluebonnet2

My lower unit was so bad it had to be repainted. The paint wouldn't stick; so they run an electrical charge through the lower unit the second time and no more problems. The paint held. The same thing will need to be done to the prop.. I don't believe cleaning will solve the problem. The rust will come right back. The electrical charge puts something back right to take that electrolysis out. You may even find that some of the wiring under the calum. and around the batteries have this white powder. It needs to be cleaned off also. If not it will harden the rubber coating on the wires and they become bridle over time.

don't heat the prop.
send it to josh at steves custom props and just have it sanded and buffed.


do you keep your boat around any chemicals (pool chemicals,etc?) that will cause it in a second.

Take prop to prop shop and have them buff it. I would definitely check out troll motor for problems..sounds like the source of it.

That is electrolysis. You can see one of the sacrificial anodes on the bottom of the engine bracket and it does not seem to be affected.

I would guess either your trolling motor or outboard is allowing a small amount of electricity to leak. The trolling motor is showing affects on the skeg, probably the only part that the paint/coating was knocked off.


Just curious but is there any wire going from the starting to trolling motor battery?

No, we went to Decker lake. Power plant lake. Then to Roberts. Lewisville is our home lake. Last two weeks noticed on trolling. Then went to squaw Friday. And the prop was stained/corroded after fishing there. We have some wires that aren't capped on telling motor that used to be connected to a ducer.

We started to try and diagnose the source. What we found is that the trolling motor was giving off about a half of a volt when running at 90%, it would fluctuate based on the speed of the trolling motor.

When testing the voltage to the motor we found that it was drawing almost 8 volts when we were testing it with the trolling motor battery (not cranking) so therefore there is some way the motor is drawing power off of those batteries.

Thoughts on where to go from there?

Make sure your motor and trolling motor are not sharing a ground. This usually happens when you use cranking battery to support your trolling motor. If you have a 12 /24 plug it could go bad at the plug and you could have issues.