Simple question on prop shaft zincs

[Frank Langer]

Hi,

I normally place two zincs on the prop shaft of our E30+, and they last about 5 months before needing replacement. They are now needing replacement, but I'll be hauling the boat in mid-February for survey, bottom paint, etc. I know I can't go til Feb. without zinc protection, but the water here is very cold, even with my wetsuit, so I don't want to be in there any longer than necessary.

If two zincs normally last 5 months, would one zinc last half that time, or longer or less time? Would a single zinc protect the propeller the same as two zincs, as long as the single zinc lasts? Or do I need to bite the bullet and spend enough time in the water to add two zincs like I usually do?

Thanks for any advice on this!

Frank

 

[Loren Beach]

sacrificing some zinc

I believe that as long as there is significant zinc present, it provides protection.
There is, however, a plan B. I note that Bob in Port Angeles really swears by submerging a good-sized piece of zinc over the side while in his slip. This is on a wire that in turn is attached to a fastener that is wired from the stern laz. to the dc ground on his boat. He will probably see this thread and correct my description where needed.

Cheers,
Loren

 

[Frank Langer]

Thanks, Loren. I would also really like to understand how the zinc over the side works. I sail year round, so can't attach a zinc over the side to the prop shaft (I would have to empty and then climb into the cockpit locker to undo it from the shaft to keep it from winding up tight). Does it protect the bronze propeller if the zinc over the side is simply attached to the ground on the engine? I wish I understood better what causes the corrosion and what really prevents it. In the meantime, I guess I'll keep replacing the zincs (at least one--thanks, Loren), until someone can explain the zinc over the side.

Thanks again!
Frank

 

[missalot]

Frank,

You could use a shaft brush to make the contact to the shaft. The shaft brush would be connected to the zinc you throw over the side, or where ever it goes.

 

[missalot]

Frank,

You could use a shaft brush to make the contact to the shaft. The shaft brush would be connected to the zinc you throw over the side, or where ever it goes.

 

[Carefree Sailor]

Hi Frank, I've seen somewhere on the net about over-zincing; however, I can't seem to find the particular site. A search has turned up the following thread started by Maine Sail. You might find it helpful.

http://forums.sailboatowners.com/index.php?threads/anode-installation-best-practices.175835/

 

[supersailor]

Zinc "Fish"

Hi! About six months after I bought "Terra Nova" I had to rewire her. That story has been told. One of the results was that I wired a "heavy" ground to the instrument panel area. The purpose was to collect all of the aft grounds in one wire. I ran a stub ground to the aft cockpit where I made a stud that I could attach a "fish" (large zinc on an electrical cable) to the engine ground. I suspended the Zinc from the instrument panel area over the side at about the position of the prop. The zinc attaches at the stud with an alligator clip (stainless) so that it can be removed. The fish needs to be pulled out of the water when sailing. I normally raise it and place it in a one gallon freezer bag.

The result is a set of zincs (2) went from 5-6 months to 1 1/2 years with one shaft zinc totally destroyed and one about 1/2 destroyed. I had hired a diver to check the undersides after clobbering a rock while heading north (different story). The big danger letting a set of zincs go is a destroyed prop. The diver indicated that the prop was in great shape.

The secret here is in insuring that the ground is in direct contact with the "fish". That gives the "fish" the same effect as the shaft zincs with a lot more surface area. The biggest minus I see here is that the "fish" gets crud on it and when it is raised, it needs to be put in a freezer bag so it doesn't crud up the cockpit. Raising it to go sailing just means pulling up on the wire attached to the "fish". When one 120 footer pulled into the Guest Dock ( I'm located right next to it) the fish went from cruded up to clean very quickly. That boat was obviously leaking very badly. Does it work. I vote a very positive yes!

 

[Frank Langer]

Thanks, guys. Bob, your suggestion sounds very promising. Today, I put on my wet suit and tried to replace the two zincs, thinking that what I had always done was probably the most appropriate solution. But try as I might, it didn't work today--water in the goggles so I couldn't see well, water was very cold, and nothing seemed to go the way it normally might. So I left the two existing zincs in place--they are a little more than half worn--and added a prop shaft zinc over the side attached to a gound stud in the engine compartment.

I'm hoping that it might approximate the solution you have developed, Bob. I'll keep an eye on this over the next couple of months to see if it begins to show signs of corrosion, meaning it's working as a replacement for the prop shaft zincs, and also the zincs themselves. If one of the two falls off, I'll know I have to bite the bullet and get in the water again and do my best to replace them.

Thanks for your ideas so far!

Frank