odd galvanic corrosion problem.
Posted: Jun 2nd, '08, 21:44
Men - had a small issue last fall that could have been much worse...
when i pulled the boat, i found that the zinc anodes on the shafts were completely gone (unusual...in past years, they were pretty bad, but always there). I found some pitting on the prop blades. The odd thing...the zincs in the engines, and the large zinc on the transom, and the zincs on the trim-tabs were all in good shape. (i should say "normal" for end of season).
My boat does not have any plastic "shaft savers" or other devices...just steel flange, bolted to steel flange.
Boat sat for several weeks late in the fall at an old dock(wife had our first baby in October...couldn't just leave to go fishin) ...and i'm suspicious that there was some bad stuff floating around that caused this...on the other hand, i did not leave the boat plugged into shore power.
Anyway - the damage to the props were "cosmetic" accorind to my prop guy and the shafts and the rest of the fittings looked good - but, i'm wondering why i had the issue with just the shaft zincs and not the others...and what can i do to make sure it doesn't happen again...and...is there some sort of test that can be done to check if the issue is somehow with my boat?
I've read over Cap't Pat's article...i'll double check the entire system...but...i'm stumped on why it only happned to the shafts (and my expensive props)
thoughts?
J
when i pulled the boat, i found that the zinc anodes on the shafts were completely gone (unusual...in past years, they were pretty bad, but always there). I found some pitting on the prop blades. The odd thing...the zincs in the engines, and the large zinc on the transom, and the zincs on the trim-tabs were all in good shape. (i should say "normal" for end of season).
My boat does not have any plastic "shaft savers" or other devices...just steel flange, bolted to steel flange.
Boat sat for several weeks late in the fall at an old dock(wife had our first baby in October...couldn't just leave to go fishin) ...and i'm suspicious that there was some bad stuff floating around that caused this...on the other hand, i did not leave the boat plugged into shore power.
Anyway - the damage to the props were "cosmetic" accorind to my prop guy and the shafts and the rest of the fittings looked good - but, i'm wondering why i had the issue with just the shaft zincs and not the others...and what can i do to make sure it doesn't happen again...and...is there some sort of test that can be done to check if the issue is somehow with my boat?
I've read over Cap't Pat's article...i'll double check the entire system...but...i'm stumped on why it only happned to the shafts (and my expensive props)
thoughts?
J