Shaft Zinc

[FlySwat]

I just splashed a "new boat" in the yard where I purchased it in New Jersey. They people who run the yard are very knowledgeable and don''t at all strike me as "flaky" or "incompetent".

However, they splashed the boat last week. I noticed on my bill that they had not added a shaft zinc. When I questioned them about that, they told me that the exposed shaft area was only about 1" between the cutlass bearing and the prop and there was no room to put a zinc on. They told me to check the engine zinc very carefully and replace as necessary (I have a Yanmar 2QM15).

I think this should work. As long as zinc is being eaten and not other metal I guess it doesn''t matter where it is (or does it?). Anyway, I''ve never heard of a boat not having a shaft or external zinc. The yard says they have had several boats over the years with this situation?

Am I ok by just checking the engine zinc and replacing as necessary? Or, are the telling me a tall tale?

Thanks.

[Silmaril]

There are some special zinc configurations out there. There is a "hockey puck" shaped zink that is a little under 1" thick. Not something the average yard would have, but readily available at most well stocked chandleries.

You don''t "Need" to have your zinc on your shaft. You can use a hull or keel mounted zinc IF your vessel is bonded. You can also hang a zinc "fish" over the rail, as long as you are connecting it to to a BONDED part of your boat. To protect your shaft and prop with this method, you will need to have it as part of the bonded network. You will need a bonded copper shaft brush, which rides on the shaft, making the electrical connection to your zinc.

[FlySwat]

Has anyone shaft mounted a "hockey puck" zink inside the hull? between the coupling and stuffing box?

[FlySwat]

Scratch my last - wouldn''t create the circuit.

[JohnVT]

By the way, the 2QM15 has two zincs.
Some say that if you leave the zincs off your shaft and prop you will not have as much marine growth fouling. Let us know.

[darrellt2]

I own a ''71 Hallberg-Rassy 35, and the space for the zinc is about 1". To complicate matters, the shaft is metric--made in Sweden. I found a Canadian company that supplied metric donut zincs, but they were 1" wide. So I had to take them to a machine shop to have them cut down to 5/8" wide. I got a perfect zinc, but each cut cost me $8, so I added $16 each to the cost of the metric zincs. I have no idea whether I''m saving my shaft on a mooring in Maine, but I figured that it was a small price to avoid having to replace the shaft/prop.

I''ll dive to check mid-season.

[Sasha_V]

Just as a suggestion to that. Wouldn''t it make more sense to buy the zinc that is just shy of 1" wide and with the shaft hole slightly smaller then the metric shaft you have, and then to make a one-off investment in the correct sized metric drill bit?

You do not even need a drill press. The existing hole will pilot the bit nicely. Just drill and then sperate the donut and fit it to the shaft.
The cheapest of cordless drills will do the job.


Sasha