Prop anode - first year in saltwater

[Guinevere]

We moved our Guinevere (#243) from Lake Michigan to Narragansett Bay in the fall of 2013. Last season was her first in salt water.

In Lake Michigan, I used a magnesium prop anode on our Maxiprop and, while I replaced it after every season, it only displayed minor pitting on the surface of the anode.

Last fall, when we pulled her for the winter, the attached picture shows all that was left of the zinc anode.

So, I'm looking for suggestions on adding anode volume prior to this season.

There is not enough clearance on the shaft to add a donut type anode.

A couple of ideas (I'm not a big fan of either):

- Drill the hull, bond two threaded studs, and attach a bolt-on teardrop type anode
- Hang an anode over the side while in the marina and clip it to a bonded stay

Does everybody just dive and replace these half way through the season in salt water?

Thanks for any thoughts-
Bob

[saileagleswings]

To me six months is pretty good. But I think your zinc should have been replaced before it was that far gone.

I hang a zinc fish over the side attached directly to the engine block. A diver checks the zinc monthly and replaces it if it is more than 1/2 depleted.

If I plug my boat into shore power at my house, my prop zinc lasts about a month or two. I bought a reference electrode from BoatZincs.com and ran all the tests in the manual supplied with the electrode. I found nothing wrong. Unplugged, the zinc lasts much longer. I have solar panels so I don't need to keep the boat plugged in to keep the battery charged.

[JohnForr]

I have a diver that will replace the zinc if necessary. It has been 7 months since the zinc were replaced. We have an auto prop and it uses a cone shaped zinc. Since I supply the zinc and he is cleaning my bottom monthly he said he would only charge me an additional $10 to change the zinc. I also live in Punta Gorda, Fl and my current zinc has been on there since last July (7 months). The diver was here yesterday and he said I had at least 2 more months on my zinc. My diver recommends that I don't keep my boat plugged in and I have only plugged in once in the last 4 months. Also, our boat is in a slip behind the house. All the neighbors boats are on lifts so I don't need to worry about negative effects from them if that is possible. We have a generator and the company, Phasor, recommended that I run it for half an hour a week under load. So about every 10 days or so I run the generator and the battery charges in about 2 minutes.

[saileagleswings]

Also in Punta Gorda: Eagle's Wings, Impulse, Salty Dog and Kai Lani