On May 22, 4:06 am, nick wrote:
Joe wrote:
On May 21, 5:05 am, Chuck wrote:

I think something like that may be what
is happening, Joe. Two pieces of metal
in contact with some bilgewater or
cooling water could easily show a small
voltage between them.

After sleeping on it, I have another suggestion. It may be the bottom
paint he's using. Might be high in copper content. Could cause the
blistering of the paint and the barrier as he described, and in the
fashion it is occuring.

Joe

Chuck

Well, good ideas but my bilge is dry, so no bilgewater. I checked the
bilge pump by disconnecting it just in case.

The antifouling is Micron Extra which is indeed a copper based paint
though it is supposed to be OK for steel.... but I guess that's open to
interpretation. The steel was originally primed with two layers of
different primer then painted over with an epoxy paint before the
antifouling. As I bought the boat used, I cannot say how well it was
done, but from what I have been able to see while working on it, it
looks to have been done well...

I also considered the engine cooling water issue (actually my wife kind
of steered me there with a question about the different metals in the
cooling system - scary I know..). I broke the circuit if you like by
removing a section of the pipework between the hull inlet and the
engine. The exhaust is the rubber pipe with a plastic waterbox baffle
that exits above the waterline. So, that shouldn't be the cause. There
are only a few items that are mounted on the hull, such as the
instruments so they will be next on the disconnect list.

One good thing is that I did discover that one of my main battery leads
was chafing badly against an engine mount and I have been able to move
this before it became a problem...

Again thanks for the suggestions and I'll keep looking. It's going to
be a weekend job now as the boat is back at it's home marina which is
over an hour's drive from home. I'll certainly post any progress as who
knows, it might help someone else down the track.

Cheers,
Nick.- Hide quoted text -

- Show quoted text -

Next time you pull her get rid of the copper based antifoulant and go
with an ablative bottom paint.

I've done about 30 bottom jobs on steel from my 42 fter to 225 fter.
Here is what I suggest. Take it down to bare steel, coat with
Endsallrust a dow chem rust converter you can get it from Hillmans
marine in Texas. Then two barrier coats, most any good quality 2 part
epoxy. Then 2 coats of ablative bottom paint. You need to make sure
all paint is applied with zero moisture on the hull, never let the
bare steel sit overnight, and try to paint on a day with less than 20%
humidity. My last bottom job lasted 5 years.

The only way better is to have the hull flame sprayed or met coated,
then the barrier then the antifoulant.

Good luck.

Joe