Bonding?

[jfkal]

My P-bracket (Bronze) has a bonding wire back to the engine. Now I found corrosion at the engine block attachment of the wire. That made me think about the whole setup: The shaft runs in a cutless bearing. Now if I bond in the p-bracket I am actually only then creating a battery with steel and bronze connected through a wire and the saltwater acting as electrolyte. I am tempted to snap of the wire ??? Any thoughts.

 

[philip_stevens]

Do you have a zinc anode where everything should be bonded back to?

The p-bracket bonding and the engine bonding should go to a zinc anode. The shaft should also be bonded to the engine with a wire bond across any coupling device, be it plastic or steel with rubber inserts, or just plain steel.

regards,
Philip

 

[Guest]

Any corrosion at the engine has nothing to do with electrolysis. Electrolysis only occurs when the two metals are submerged in a conductive liquid. The "corrosion" at the engine will be due to a poor attachment job - perhaps they used acid core solder, or it is just plain oxidation of the copper and such.

On the other hand, if the shaft is stainless and the strut is bronze you might be correct in removing the bond. So long as there is no other electrical path, AND the cutless bearing is rubber, it might be better isolated.

You must have zincs on the shaft for protection. Are they deteriorating in less than a year? Have you noticed any corrosion on the strut itself?

These are the things you should be looking for. You can clean up, but ignore the corrosion at the wire to engine junction.

 

[jfkal]

Yep. The zincs on the shaft disappear at the rate of one per 4 month (no constant shore power and I use ground isolating diodes). Will check the voltage at the bonding. If I see substantial current I snap it of and use the cable to strangle the engineer who designed the thing )

Joerg

 

[jfkal]

Hmm it looks like this:

P bracket bonded to engine. Shaft has zinc and that's it.....No other zincs anywhere else.