Zinc wastage and electrical leaks

[rwc]

I noticed yesterday that my zincs, which were replaced about two months ago already have noticeable deterioration (maybe 15%). My neighbour said that the water in the marina frequently tests high for voltage due to people having grounding issues leaking electricity into the water.

Is there a way for me to make sure it's not me that's leaking the electricity? I'd at least like to try and make sure I'm not the source of the problem...

[Phillbo]

It's easy. Boats that are leaking electricity typically experience strange rumbling noises when under way as well...

Don't swim in that marina.

[rwc]

lol.

Thanks Phillbo. I asked the same neighbour who told me about the electrical leaks if he swam in the marina to check things. My plan was to go tug on random things to see if anything was loose that shouldn't be loose.

His response was "Sure! I've got a mask right here if you want to borrow it. But... make sure you wash yourself off with the hose after - there are things in there..."

Electricity notwithstanding, I'm no longer terribly eager to go in the water.

[mmwjr]

Originally Posted by Phillbo

It's easy. Boats that are leaking electricity typically experience strange rumbling noises when under way as well...

Don't swim in that marina.

Say what!

[mmwjr]

Originally Posted by rwc

lol.

Thanks Phillbo. I asked the same neighbour who told me about the electrical leaks if he swam in the marina to check things. My plan was to go tug on random things to see if anything was loose that shouldn't be loose.

His response was "Sure! I've got a mask right here if you want to borrow it. But... make sure you wash yourself off with the hose after - there are things in there..."

Electricity notwithstanding, I'm no longer terribly eager to go in the water.

There is a probe you can buy that connects to a DVM, you lower it into the water to measure stray currents. The marina wiring could be faulty as well.

[rwc]

Originally Posted by mmwjr

There is a probe you can buy that connects to a DVM, you lower it into the water to measure stray currents. The marina wiring could be faulty as well.

So nothing I can measure on the boat then to see if it's mine? I was thinking maybe I could measure differential between draw on the main and the charger with everything else off, but I have no idea if a leak would be significant enough to register or not.

[mmwjr]

Measure all metal that is in contact with the water on the millivolt scale to DC ground.

[Phillbo]

Without knowing what kind of boat you have I will still venture to guess the it's the larger boats in the marina that are the cause of the electrical charge... In my marina we have hundreds of 75' + boats that bleed electricity like crazy.

[shrew]

Keep in mind that stray current electrocution from swimming is a concept around FRESHWATER marina's, not saltwater. You should be able to detect small amounts of stray current using a good multi-meter. The source can be anything from ungrounded boats, to shore cords in the water.

[rwc]

I finally got around to checking into this. The zincs on my drive leg in particular were wasting rapidly. When I got in and started poking around, I discovered that the two grounds between the drive and the engine were both disconnected (one upper, one lower).

I reconnected them and also hooked them together with a larger zinc I had installed last time the boat was out of the water, and a valve that was not grounded. So now, most metal bits are all grounded together to one post on the back of the engine.

Now I'm concerned that maybe there was some legitimate reason the drive grounds were disconnected. Is anyone aware of a reason they would be? Did I do the right thing connecting everything together?

Is it possible that the rotation of the shaft in the drive might create a charge that would consume the zincs given that the drive was not grounded to anything else? I couldn't find any differential with DVM, but it seems odd that the drive zincs were so wasted while the trim tab zincs were not if this was an external leak from another boat.

[mmwjr]

The drives bonding wires are required to ensure all pivoting components are tied together and at the same potential. No reason not to do this.