My Favorite Questions seem to be corrosion related, so here’s another!

We recently pulled the boat out for the winter. We noticed a disturbing amount of white popcorn style corrosion along the front keel (where paint had been rubbed off due to beaching the boat). However, we even noticed this popcorn corrosion coming through the areas where there was still paint. The corrosion really attacked the bare areas hard though. What we discovered was apparently, the front bilge switch was not working and was submerged in the bilge water. The bilge pump switches I was using were called “Bilge Mate” made by Bocatech. They are not the typical float switch as they operate electrically, not mechanically. Once the water gets to a level where water makes a connection between the two probes on the switch, it makes the connection and the pump runs. As a related note, I also had to remove the same type switch for my rear bilge pump last month as it just went on by itself (no water in bilge) allowing my pump to run for hours whilst I was not there. My questions are:

1. Could this front switch sitting in that bilge water cause that corrosion in such a short time?

2. Is my assumption is the switch was activated but shorted out and throwing 12 volts into the bilge potentially correct???

3. What switches are you guys using? The problem I have is the V is so narrow on the 26’ boat there is not much room for a pump let alone the switch.

4. Is there a pump you guys are using that can get closer to the bottom of the boat? Even with my Rule I still leave 1.5-2 inches in the bottom.

5. Lastly, I plan to soda blast the hull this year and see what damage is really done after this episode. I plan to leave the hull bare aluminum as I plan to continue to beach and painting at our marina (or anywhere in the area) is not an option. My thought is that if I had another problem in the future (and there will be) that the corrosion would be dissipated over a large area and should not result in concentrated damage. Is this true??

Thanks you all.
Merry Christmas and Happy New Year!!
Bob

It's possible that your electronic bilge pump switch was leaking voltage into the water. I'd go with either a conventional float type (and don't worry about a bit of water left behind--they all do that). You could also use one of those irritating but effective pulsing designs that runs for a few seconds every few minutes, staying ON if water is present.

On the hull corrosion, the only way to be sure is blasting the paint off and seeing.

Jeff

If you want to get the last 2 inches of water out of the bilge, you need a diaphram bilge pump (noisy) that will allow you to plumb an inlet hose right down to the bottom of the hull. The hose needs to be cut off at a slight angle to prevent the hose from sucking itself on the hull. I put one of these systems in a large cruiser for a person who did not wany any water remaining in the bilge when he left after the weekend. With the automatic switch, the pump and labor, it cost about $900. Quite a price to pay to get that last little bit of water out.

Paul

True, there are cheaper and less convenient ways to do this, but this guy was not a Marinette owner. Money was no object - just so the water was gone from the bilge completely when he left the boat. And, it was.

Paul