Paint blistering on steel hull because of ground leak
 

Hi,

I'm having problems with underwater paint blistering on my steel hull
because of a ground leak (again)... I'll fix this leak definitely, but
I'm thinking what would be the best setup to prevent damage in the
future might a new leak occur.

Ideally I'd like to have an isolated engine which would make my dc
system completely separated from the hull (my RF ground is already
isolated by capacitors). It might be easy to do if you have the money
to buy a new starter motor, alternator and senders, but I'm currently
not in that position.

I'm now thinking of the second best option. Would it be good to put a
bonding wire from engine to the hull or not?

Currently there is no ground wire. That means that any ground leak
takes current through the seawater to my prop/shaft or engine
internals (via cooling water) and via the engine negative wire back to
the battery. It eats away my expensive parts and paint.

If I would ground the engine to the hull, any ground leak would follow
the steel of the hull to that extra ground wire and via the engine
negative back to the battery. Hereby I assume that the path via the
steel is more attractive than "outside" via the sea water. I'd say
this is a better situation than the current because no electrolysis
takes place.

Is there anyone who knows more about this topic and can comment on my
dilemma?

Thanks,
Joost

Paint blistering on steel hull because of ground leak
 

On May 5, 4:23*am, joost wrote:
Hi,

I'm having problems with underwater paint blistering on my steel hull
because of a ground leak (again)... I'll fix this leak definitely, but
I'm thinking what would be the best setup to prevent damage in the
future might a new leak occur.

Ideally I'd like to have an isolated engine which would make my dc
system completely separated from the hull (my RF ground is already
isolated by capacitors). It might be easy to do if you have the money
to buy a new starter motor, alternator and senders, but I'm currently
not in that position.

I'm now thinking of the second best option. Would it be good to put a
bonding wire from engine to the hull or not?

This is your first best option after finding the leak to ground. Yes
your engine should be grounded block to hull.

Currently there is no ground wire. That means that any ground leak
takes current through the seawater to my prop/shaft or engine
internals (via cooling water) and via the engine negative wire back to
the battery. It eats away my expensive parts and paint.

You just answered your own question. You can do severe damage to the
shaft, pumps, exchangers, ect not having a grounded engine. Also your
engine should have zincs.



If I would ground the engine to the hull, any ground leak would follow
the steel of the hull to that extra ground wire and via the engine
negative back to the battery. Hereby I assume that the path via the
steel is more attractive than "outside" via the sea water. I'd say
this is a better situation than the current because no electrolysis
takes place.

Is there anyone who knows more about this topic and can comment on my
dilemma?

You need to find the stray voltage. Get a good volt meter and check
the ground from your marina to the water. If you find more than 2
volts DC your marina has a short. Then go from your hull to the water.
Shut off everything and power up one circut at a time until your
isolate the problem. Make sure your zincs are welded to the hull, not
bolted, and replace after 50% loss.

The blistering could also be a sign of a bad bottom job prep.

Joe

Thanks,
Joost