Zincs...

[sentientcj]

Bought a boat, it's on the hard. Where are the zincs usually found? And for that matter, what do zincs accomplish/why are they necessary?

Figured I'd change them before putting the boat in the water, then realized I a) don't know what I'm looking for, b) don't know where to look and c) don't know what they are actually used for.

[GaryMayo]

Zincs or sacrificial anode are for:

http://www.yandina.com/electrolysis.htm

Coursity Google

[gts1544]

sentientcj, While you don't mention what type of boat you have, the zincs are usually found attached to your inboard propellor drive shaft(s) and to your rudder(s), if they are metal. The purpose of the zincs are to be a sacrificial metal with respect to electrolitic corrosion of the metal parts of your boat with respect to the water. The zincs will corrode instead of your expensive metal boat parts. They should make a good electrical contact with your boat and be replaced as necessary. Hope this helps! gts1544

[noelex 77]

I would get someone to point them out on your boat.

They will be a dull silvery unpainted metal below the waterline but the shape is not important so this can vary
There is also sometimes one inside the engine
Here are photos to give you an idea .

They are easy to miss. For example the first photo has 2 zincs one on the end of the prop and one between the prop and the sail drive leg. The second photo has 3 one on each of the prop shafts and one on the rudder.
The last one is three different sized engine zincs, but you can only see the brass outer casing when its installed

[sentientcj]

Thanks guys, much appreciated. Now to look for these little buggers.

[Teknav]

This website explains the role of Zinc in electrolysis; a very well written article. Electrolysis