460 electrical corrosion

[David Young]

I've got some (galvanic) corrosion on my mast foot on my 460 and have the yard checking on the source. Hull #2 - other 460 owners might want to look out for the same thing happening on other boats to see if there is a common problem. Once the cause has been found, I'll let you know what it was. If you've experienced this already or have suggestions as to where to look first, please let me know.

 

[Gordon Myers]

Zinc's ???

Have you looked at your Zinc (or Zinc's) on your drive shaft. If the zinc is gone, look at your prop. The big boats need a min. of three and poss. five zinc's on the drive shaft to get the surface area needed. The mast is "bonded" to the lead keal. The keal is "bonded" to the motor, the motor is "bonded" to the drive shaft - get the picture ? Zinc is used since it is the 1st to go. Aluminum is eated (corrosion) before steel or cast iron (engine), then brass and bronze (prop). Therefore, if the zinc is gone, the next thing to be sacrificed is the aluminium or aluminum alloy mast.If the aluminum has corrosion and the zinc is good, then check the connection form the mast to the keal. There needs to be a good connection between the mast and the keal for lighting. Then also make sure that there is a connection between the keal and the drive shaft. There needs to be a good connection between all and sufficient amount of zinc to protect all parts.The amount of zinc (or lack of it) can be checked using a Corrosion test Meter.

 

[warren feldstein]

corrosion

See the West Marine catalogue. There are several diagnostic testers and books on the subject listed therein.

 

[Dan Arsenault]

Stray Current?

Dave, you might want to see if you're experiencing stray current corrosion as opposed to galvanic corrosion. Charlie Wing's Boatowner's Illustrated Handbook of Wiring has a good treatsie on the two subjects and is a good overall reference to keep around anyway.Good luck,Dan ArsenaultSerendipity Too

 

[David Young]

corrosion check.

Thanks - looks like a little reading and a trip to the boat ASAp to investigate electrical systems if the yard does not find something - it's great to have a warranty still.Had my zincs replaced a short while ago so I suspect they should still be good (if they are still attached). Probably not the problem...

 

[Gordon Myers]

Zinc's Plus

You say you had you zincs replaced a short time ago. How long ago ? How long were they on before you replaced them ? How many ? What did they look like when you replaced them & were they attached ?The corrosion could have taken place prior to the last time you added zincs.

 

[George Kornreich]

Galvanic Isolators

Hunter put galvanic isolators on some but not all boats. Look behind the electric panel for one on each of the green ground wires coming from each shore power line. If they are not there (mine had none) consider installing them (called "Zinc Savers"), one on each line. but watch out for this: With everything disconnected from the power inlet to the ground buss, I had continuity between the 2 green wires, showing that something was connecting the two between the shore inlet and the power panel, that I couldn't find. I connected the zind savers just after the shore inlets in the cockpit aft locker. This way, it was before anything that was combining the two ground leads, as it must be.