What is the current thinking on painting underwater metal parts (propeller and shaft) as part of a bottom job?
Dan Dickison resonds:
Thanks for your question. There are a couple of approaches to this topic. The folks who commission many of the new Beneteau boats here in the Charleston area do paint the shafts and props along with the rest of the hull that sits under the water, but first they coat the metal appendages with an epoxy barrier to avoid any electrolysis that might occur between the copper in the paint and the bronze or stainless steel in the shafts and props.
I'm not a big fan of this approach myself because I prefer to be able to see the prop and the shaft surfaces, and I don't find that it's too much trouble to occasionally dive down and wipe them off. Your boat might reside somewhere where that's not advisable, in which case, painting the prop and shaft is probably the better option. I hope this answers your question.
If you'd like aditional information regarding this and other boat maintenance topics, I recomend that you consider purchasing a copy of Nigel Calder's Boatowners' Electrical and Mechanical Manual. It's a very useful reference and it's easily available in the SailNet Store. Best of luck to you.