Hull Sensor?

[Calivanos]

Guys I found a round, about 1 and a half inch diameter, thru hull that is constructed of bronze covered with a copper cap. It has DO NOT PAINT on it (it was painted) and a spot for a wire to connect on top (inside). What is it?

[jralbert]

I'd like to tell you it's a Capac sensor for monitoring galvanic corrosion but your description doesn't match. Capac units (on the exterior/ hull side) have a plastic housing approx. 10" dia and stamped "Do Not Paint" with the sensor about 3" in dia in the center. The sensor is actually the part to be left paint-free, it doesn't matter whether the rest of the housing is coated. The sensor is made of a silver chloride material, not brass. If you can gently remove the paint with a thinner solution - no abrasion - a cloth rag is ok - you might see that it's not brass. On the inside, Capacs have a post to which the meter lead is attached.

If it is in reality a Capac my guess is that its condition indicates it's past its useful life judging from the way a PO treated it.

And as I think more about what you describe (bronze, 1 1/2" dia), it's more likely that it's the business end of a sonar unit. That's the size of the sonar (depth finder/fish finder) on my former M. I was, though, able to paint the sonar with a special water based paint (sold at West Marine and others) to keep the barnacles away.

Next time we get queries like this a picture is worth...a lot.

[barkleydave]

DITTO Transducer


dave

[meltonhill]

On the older Marinettes the capac is about the size you describe. Mine is about 1 1/2 with do not paint on it. Trace the wire see where it leads

[Calivanos]

Here is a picture

[Supersport18]

I believe that is a thru hull temp probe.

[Calivanos]

I am just now reinstalling exhausts, tanks, generator and am trying to zero in on wiring. This weekend I will chase down the one wire that was attached to the top. I want to say it has to be part of a Capac but maybe it is some kind of transducer.

[barkleydave]

The Cathode for the CAPAC is coated with Silver/Silver Chloride as a ref. Cathode. It is fragile and can be damaged easily by scratching etc. The pic. of the "Think" does not appear to be coated with it.


dave

[meltonhill]

Was the bottom sandblasted? That's exactly what my capac looks like

[Calivanos]

Yes sir it was sandblasted. In that case it should be connected to the galvanic isolator right?