Bilge Flooded - Wires/Shunt Immersed in Salt Water

[hdhr289]

Here is my question...Should I replace all of the wiring and battery monitor shunt that were immersed in salt water when my sailboat's bilge flooded up to the floor boards? I've rinsed all of the immersed wiring and connectors with fresh water, cleaned with electromotive cleaner and applied dielectric grease wherever conduit and connectors are exposed. All appears to be OK now and is functioning correctly but my gut tells me corrosion is going to be unavoidable.

Now, for the rest of the story...While away from our boat for a couple of weeks a series of unfortunate events transpired. Apparently the HVAC thru hull filter froze overnight and cracked. The bilge flooded to just under the floorboards. This immersed the DC negative battery monitor shunt and a 110vac connector located just below the floor boards. I suspect the bilge pump was trying to keep up but the combination of the bilge pump and DC refrigerator killed the batteries once the shore power isolator tripped out and the battery charger stopped.

I was surprised that the flooding stopped just below the floor boards, but glad that it did. It did not overtop the battery boxes below the floor nor did it get up above floorboards where battery switches, fuses, breakers, electronics, etc are located.

 

[Don S/V ILLusion]

I doubt anyone can definitively know what, if any, residual water penetrated the connections or insulation. It's a guess either way.
You could remove one or a few, strip the insulation and inspect and make an assumption about the rest. Since you live where you won't be using the boat for a while, I'd make it a winter project out of it and replace everything for peace of mind.

 

[dlochner]

What Don said. You were thinking about rewiring your boat, weren't you?

Now that you know that these critical parts are located in vulnerable places, it may be time to rethink the location and move them to higher ground (so to speak).

 

[Bill Roosa]

While replacing everything at once would be maximally prudent I would make the following observation; if it does corrode it will take a while and there is no positive proof that it will corrode.
sounds like you have made all the corrective maintenance that can be expected. I'd go with replacing things as needed (after you see an actual corrosion problem) and keep an eye on things. You should probably be doing that anyway with electricity in the bilge! Now you have another good reason to do so.

 

[jssailem]

While Don is correct about Peace of Mind, (an important thing while you still have all your faculties), I'm with Bill regarding the timing. Salt water is definitely a corrosive fluid. But it does not happen over night. You have taken good steps to minimize any impact. If you can accept that you need to watch the wires and inspect them each time on the boat then you'll buy some time before the expense. If you were about to head out on an extended ocean cruise and be at sea for months, then maybe it is time to change the wires. But if like many of us you are near a harbor 95% of the time, then monitoring the area to see if a problem develops makes sense. Thinks about the fishing boats that go out every day. Salt water splashing, fishing guts flinging, and their wiring for the winches exposed to more than the water in your bilge. They keep going year after year till the green crud on the wiring breaks or becomes unreliable, then they swap out for new and go back at it.

 

[dlochner]

Wait and see might be OK for some of the circuits, especially those that are seldom used such as LED courtesy lights. However, even a little corrosion on the terminals will increase resistance which will cause excessive heating and possibly a fire. A low amperage DC circuit is not that much of a risk, but the AC circuit when plugged into shore power could well be.

Are the terminals and connectors sealed with heat shrink terminals? Is the wire marine grade tinned wire? If the answer is no to either question, then the problem is more serious and deserves a quicker response.

 

[Ralph Johnstone]

All of the above, but for any re-newed joints that MUSTbe left in the bilge, consider sealing them with glue lined heat shrink.

 

[Benny17441]

There are salt water deposits under the sole. The boat's wiring is already exposed to salts by being in close proximity to those deposits. The job that you have done by rinsing, chemically cleaning and applying dielectric grease to the connectors may actually improve the condition of the wiring. I would not spend money or effort until I got a clear sign of a corrosion problem attributable to this incident. "All appears to be OK now and is functioning correctly" If it is not broken, do not fix it.

 

[Ralph Johnstone]

This immersed the DC negative battery monitor shunt and a 110vac connector located just below the floor boards.

This often reveals itself as:

 

[njlarry]

Key considation, are those circuits energized while you are away from the boat. You are lucky it wasn't a lot worse. What stopped the water?

 

[Maine Sail]

I am assuming this happened last year because it's not been cold enough to freeze this year?

That said some strainers are better served for below water applications than others. Most of the ones I see used below water you can not pay me to install. For below water strainers the Perko Bronze or Groco Bronze strainers are the most robust you will get. I have seen far too many of the cheap plastic ones split at the threads or just split even when they had a lo concentration of AF in them. Some real cheap ones are actually made brittle by antifreeze.

If a boat is left in the water in NE then it must be properly winterized and all seacocks should be closed after properly winterizing them. Heck they really should be closed each time you leave the boat, but I know many owners try to justify not doing this..

In a perfect world there should/would be no open connections made below the cabin sole. In fact the only terminations that should even be down there are bilge pumps and shower sumps. Open connections in a bilge can lead to RAPID DC CORROSION if or when the terminations become submersed in an electrolyte (salt water). By rapid I mean below water metals being eaten & destroyed in as little as 24 hours.

If or when battery cables must run under the cabin sole they should be contiguous runs with no terminations. If or when batteries are below a cabin sole, on a sailboat, don't....

Builders do numerous stupid things to save cost and deliver you a boat at a reasonable price, some times dangerously stupid things.. Unfortunately it is up to the owner to do the research and to make it right. Heck even properly made bilge terminations would be made above the cabin sole level unless you had a really, really deep bilge..

Take this opportunity to correct the poor wiring layout & not just throw a Band-Aid on it..

 

[hdhr289]

Thanks everyone. It was a plastic bowl that cracked near the threads. I'll add that to the list of items to replace.

 

[jssailem]

HD
Still thinking about your problem, got me wondering what type of wire and connectors are involved. Are we taking about marine grade wire and marine grade adhesive heat shrink connections? or were they automotive wire and Automotive grade crimp terminals with PVC sleeves as insulators?