On my previous boat, the A30, there was very limited space to put a zinc anode on the shaft, in fact not enough room for a standard collar (donut) zinc. My solution was to clamp the collar zinc to a 7/8” round bar, chuck it in my lathe, and undercut the ends. This allowed enough clearance to get water to the cutlass bearing (very important). As very few people have a metal working lathe at home, read on, there is a much better solution.

When I got the A37 there was even less room on the prop shaft, so the above solution was not an option. At the World Cruising Club in Toronto last fall, we had a presentation by a corrosion expert, so I popped the question, “Where the heck do you put a zinc on an Alberg 37?” The speaker was not aware of the lack of room on the shaft, and asked if anyone else had a solution. Another A37 owner said, “Prop nut zincs sold by West Marine”. This sounded like a good idea, so I did some investigating on-line and ordered the kit through my local chandlery. The brand name is Martyr and they are manufactured by Canada Metals (http://www.martyranodes.com).

There are 8 sizes to cover any possible shaft and prop nut size. See West Marine’s 2004 catalog, Pg. 485.

The prop nut zinc kit consists of a bronze castellated nut with the “castles” ending in a platform drilled and tapped for a ¼” socket head cap screw which holds the zinc anode.

The hollow bullet shaped zinc covers the whole nut and the streamlined shape should microscopically enhance performance, in theory at least.

My boat has a 7/8” shaft with 5/8” thread so the complete kit is PN: CMPNBZC11, and the replacement anode is PN: CMPNZB. The West Marine price for the kit is US$36.49 and the replacement zinc anode is $13.29. My A30 also had a 7/8” shaft, unless my memory has failed me once again.

For Canadian Alberg owners, the prop nut zincs can be ordered through Mason’s Chandlery. Speak with Mike Paulssen in case other staff has not heard of them. Mason’s is at 905 278 7005. Their C$ price was good in relation to West Marine; it should be as it is a Canadian product. The Martyr, Canada Metals product seems to dominate the zinc market so I’m sure any marine store could order them.