Dave Mac wrote:

Hi I was wondering if anyone knows if you need to have zincs on your
prop shaft in fresh water?The one on mine looks original(20+ years)
and still appears 99% intact.
Thanks Dave


Pure "fresh" water does not conduct, and will not foster
elecrolytic corrosion. Therefore, in theory, you do not need zincs.

All water contains some dissolved salts, and those loose ions do
permit corrosion a slow as you like.

Zincs won't hurt, magnesium is better for fresh water, but if they
don't dissapear, don't replace them.

They won't work at all if they have been painted.

Terry K

Yes, don't replace them if they don't disappear, but *DO* do the following:

- Inspect for signs of corrosion, especially in areas where there may be
junction between two metals or an air gap. Rivets and the connections on
your bonding circuit (grounds) are in particular susceptible ...loose rivets
means corrosion likely exists and bonding circuit connections should remain
clean. They should also be sprayed with something like Corrosion X to keep
them clean and corrosion free.

- Once a year or so, remove the zincs (or magnesiums) and wire-brush them
and the boat where they mate up. It doesn't hurt to use a wire brush them
on the outside too if it looks like crud or paint is preventing good water
contact.

Brian D



"Terry Spragg" wrote in message
...
Dave Mac wrote:

Hi I was wondering if anyone knows if you need to have zincs on your
prop shaft in fresh water?The one on mine looks original(20+ years)
and still appears 99% intact.
Thanks Dave


Pure "fresh" water does not conduct, and will not foster elecrolytic
corrosion. Therefore, in theory, you do not need zincs.

All water contains some dissolved salts, and those loose ions do permit
corrosion a slow as you like.

Zincs won't hurt, magnesium is better for fresh water, but if they don't
dissapear, don't replace them.

They won't work at all if they have been painted.

Terry K