rudder shaft corrosion

[Troy Scott]

Jim,

After giving it some thought, I believe you're right. Now I have to learn about hull zincs.

John,

I'm glad to hear you agree with me about painting that area of the shaft. I will certainly continue to study this problem and try to get it right.

[John Stone]

Troy,
I'll be interested in what you learn about polishing and barrier coating. I am rethinking the pitting I have. Though I am confident mine is from stagnat water, polishing the pits and barrier coating may provide some protection.

Regards,
John

[Oswego John]

I am rethinking the pitting I have. Though I am confident mine is from stagnat water.

Regards,
John

Don't anyone ever underestimate the damage that stagnant water can cause. For about the last year and a half, our eighty five and a half foot schooner has been on the hard.

She had been tied up in stagnant water for years. The 1/4" steel plating below the waterline had developed 1/8" craters all over the underwater surface, including the steel rudder. It looked like it was hit with giant buck shot. The USCG condemned the hull and we are in the process of replating the hull.

Various sections of the damaged steel were sent to a metallurgical lab for analysis. They reported that the trouble was caused by micro biological organisms (whatever the heck that is) caused by stagnant water. I should remember to add that we sail in sweet water, not salt. I don't have a clue if that had any effect.

Btw, the corrosion occurred underneath an excellent bottom paint program. Go figure. It would be beneficial to delve deeper into this problem, if for no other reason than to discover the cause, the effect and the cure for future occurrences of this sort.

Good luck,
O J