When i bought my boat, I failed to get a zinc anode for the prop shaft
for about a year but there was no harm as I found no corrosion (was a
zinc in the engine block). However, when I had it hauled, I installed
a zinc and immediately my prop began fouling badly. Later, while
cruising to S. Florida, I stayed at a dock with bad grounding for the
power systems (I have no ability to use shore power) and when I jumped
in the water to de-foul the prop, I felt a tingling all over and saw
that the Zinc had dissappeared in less than a week. I got out of the
water fast thanking God for making me so cheap I never wanted shore
power (Idda been electrocuted through my own shore power by means of
the bad ground of the boat next to mine). Failing to reapply the zinc
for another year (I didnt worry about bad ground causing corrosion
cause I almost never stay in marinas) I noticed again that there was
almost no prop foulage. Hmmmmmm....... My theory is that the copper
in the bronze prop that should suppress fouling is prevented from
going into the water and forming a layer of Cu ions near the prop by
the more electronegative zinc to which it is electrically connected
via the shaft.
I read awhile back about a guy who was copper plating props to
prevent fouling but it didnt work well and my theory is that once
again, the action of the zinc suppressed the copper ions. SO, here is
my idea:

Coat the prop blades (just the blades) with a thick layer of
non-conducting epoxy paint. Put a thin layer of conducting epoxy
paint over this (yes, it exists, I use it at work for stuff).
Electroplate a layer of Cu over this about .005" thick. Done right,
the electroplate will conform to the shape of the prop with no
whiskers or anything else to affect the prop balance. NOW, the outer
Cu layer is electrically isolated from the zinc so it suppresses
fouling. When the outer Cu layer is eventually breached, the
underlying layer is protected from corrosion by the zinc. The coating
would probably have to be renewed every couple years.

Any thoughts on this?

(Parallax) wrote in message om...
When i bought my boat, I failed to get a zinc anode for the prop shaft
for about a year but there was no harm as I found no corrosion (was a
zinc in the engine block). However, when I had it hauled, I installed
a zinc and immediately my prop began fouling badly. Later, while
cruising to S. Florida, I stayed at a dock with bad grounding for the
power systems (I have no ability to use shore power) and when I jumped
in the water to de-foul the prop, I felt a tingling all over and saw
that the Zinc had dissappeared in less than a week. I got out of the
water fast thanking God for making me so cheap I never wanted shore
power (Idda been electrocuted through my own shore power by means of
the bad ground of the boat next to mine). Failing to reapply the zinc
for another year (I didnt worry about bad ground causing corrosion
cause I almost never stay in marinas) I noticed again that there was
almost no prop foulage. Hmmmmmm....... My theory is that the copper
in the bronze prop that should suppress fouling is prevented from
going into the water and forming a layer of Cu ions near the prop by
the more electronegative zinc to which it is electrically connected
via the shaft.
I read awhile back about a guy who was copper plating props to
prevent fouling but it didnt work well and my theory is that once
again, the action of the zinc suppressed the copper ions. SO, here is
my idea:

Coat the prop blades (just the blades) with a thick layer of
non-conducting epoxy paint. Put a thin layer of conducting epoxy
paint over this (yes, it exists, I use it at work for stuff).
Electroplate a layer of Cu over this about .005" thick. Done right,
the electroplate will conform to the shape of the prop with no
whiskers or anything else to affect the prop balance. NOW, the outer
Cu layer is electrically isolated from the zinc so it suppresses
fouling. When the outer Cu layer is eventually breached, the
underlying layer is protected from corrosion by the zinc. The coating
would probably have to be renewed every couple years.

Any thoughts on this?

For Marion Fannaly:

Several years ago, i experimented with various preparations that could
be applied underwater as a temporary antifouling (temporary being
months). I finally used a Creeping Crack Filler (a sort of green waxy
material) into which I mixed a lot of copper powder. This worked
fairly well.
Another good material was the black roofing cement that can be applied
cold mixed with copper powder, it can be applied with a putty knife
and smoothed.
I actually did a patent search on this and found some very early
patents on such material and there is even a current british product
but I cannot remember the name of it.