When I hauled my boat in the fall of 05 my zinc was just about gone. Other boats at the dock had reasonable deteriotation. I belevied my broblem to be a 36' power boat just 3 slips away. This year that power boat stayed on the hard. I added a shaft coller zinc as a back up; the last thing I needed was for my Max prop to be destroyed. My big zinc was gone and the shaft coller was badly deteriotated. I plan to purchase a galvanic isolator which I understand should solve the problem. What brand do you suggest and are there any other measures that might prove helpful?
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Zinc deterioration reply
I have a Beneteau 361 that also had zincs deteriorating at a remarkable rate. While the stray currents could be from another boat near you, chances are it may be your boat's dockside shore power connection or something internal to your shore power system that is the culprit. Check the bondng connection of the shore power ground wire (green) to the engine; it should be tight and free of corrosion at both the engine connection and the crimp-on connector. Check and see if unplugging the shore power cable when you are not onboard helps the problem. If it does, have the marina maintenance folks check the power pedestal on your dock for corrosion free connections and correct wiring. The galvanic isolator may help but check the cheap sloutions first. In any event, generally it is best to leave the shore power unplugged dockside unless you are using it. Also a marine electrician would likely be able to diagnose and tell you more vis-a-vis stray AC current and the quality of your shore power connctions.
I have a Beneteau 361 that also had zincs deteriorating at a remarkable rate. While the stray currents could be from another boat near you, chances are it may be your boat's dockside shore power connection or something internal to your shore power system that is the culprit. Check the bondng connection of the shore power ground wire (green) to the engine; it should be tight and free of corrosion at both the engine connection and the crimp-on connector. Check and see if unplugging the shore power cable when you are not onboard helps the problem. If it does, have the marina maintenance folks check the power pedestal on your dock for corrosion free connections and correct wiring. The galvanic isolator may help but check the cheap sloutions first. In any event, generally it is best to leave the shore power unplugged dockside unless you are using it. Also a marine electrician would likely be able to diagnose and tell you more vis-a-vis stray AC current and the quality of your shore power connctions.
Not as big a problem as you may think
Although adding a galvanivc isolator may help, it may not. What it sounds like you did was put a Maxprop zinc on the prop hub as you should but didn't bother to also place one on the shaft. There is a common problem with Maxprop zincs of which you may not be aware - that being the mounting holes are so close to the perimeter of the zinc that they corrode faster than the more massive portion of the zinc and simply fall off long before the zinc actually gets eaten away. In other words, it may not be as big a problem as you think. We routine;y put zincs on both the Maxprop and shaft and invariably only the shaft zinc remails after a season. I'd suggest adding a shaft zinc in the spring and maybe try another trick - paint only the mounting holes on the Maxprop zinc with nail polish to avoid the mounting points from premature deterioration.
Although adding a galvanivc isolator may help, it may not. What it sounds like you did was put a Maxprop zinc on the prop hub as you should but didn't bother to also place one on the shaft. There is a common problem with Maxprop zincs of which you may not be aware - that being the mounting holes are so close to the perimeter of the zinc that they corrode faster than the more massive portion of the zinc and simply fall off long before the zinc actually gets eaten away. In other words, it may not be as big a problem as you think. We routine;y put zincs on both the Maxprop and shaft and invariably only the shaft zinc remails after a season. I'd suggest adding a shaft zinc in the spring and maybe try another trick - paint only the mounting holes on the Maxprop zinc with nail polish to avoid the mounting points from premature deterioration.
shaft zinc
I did use a shaft zinc this past season and as you stated it took a hit but was still there. The idea that because of the outer rim is smaller the zinc just falls off makes a lot of sence. I will coat the holes as you suggested. I will also check my dockside power and the boat as you all suggested. Thank you guys, so much for your all input. Steve
I did use a shaft zinc this past season and as you stated it took a hit but was still there. The idea that because of the outer rim is smaller the zinc just falls off makes a lot of sence. I will coat the holes as you suggested. I will also check my dockside power and the boat as you all suggested. Thank you guys, so much for your all input. Steve
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