Waterproof battery and electrical panel

Jul 26, 2017
MacGregor Venture of Newport 23 Aldie, Virginia. Chesapeake Ba
How can I waterproof ship's battery and electrical panel?
Venture of Newport 23 trailer sailer
Electrical panel is only 10 inches above bottom of bilge, and underneath main hatch, 20 or 30 wires.
Two bilge pumps will not work if battery shorts out, so a major leak or knockdown could sink the boat.
Waterproofing the AGM battery could be simple, just smear liquid rubber over both posts (or appropriate electrical insulation).
I could wire the bilge pumps direct to main battery, bypassing panel.
But how do I waterproof the back of the electrical panel?
May 29, 2018
Canel 25 foot Shiogama, japan
Two bilge pumps will not work if battery shorts out, so a major leak or knockdown could sink the boat.

In the case of a major leak or a knockdown I would suggest NOT relying on your bilge pumps.
Make sure you have a couple of sturdy buckets aboard.
In truth, the small 12 volt bilge pumps that are fitted to trailersailers are to get rid of the small amount of water that may be swilling around the bilge.
They are in no way capable of emptying a swamped 23 footer.
The battery will run down, the pump will clog or give up way before the job is done.
Also, the discharge being underwater means the pumps have to operate AGAINST a positive (resistance ) pressure thereby greatly reducing their efficiency.

So, after that , my answer is
a good waterproof handheld VHF to call for assistance.
sail safely to avoid a knockdown or swamping
dillegent maintainance to ensure the hull, centerboard pocket, rudder mounts are sound

AND a couple of good buckets.

Apr 22, 2011
Hunter 27 Pecan Grove, Oriental, NC
Oct 22, 2014
CAL 35 Cruiser moored EVERETT WA
If you somehow swamp your Newport 23, it is time to go back to basics. One is to empty water as fast as possible. Buckets manual pumps what ever. Most boats have some flotation (air pockets, styrofoam blocks).

You have personal flotation on so that if the boat sinks you can float on the water.

One of the ways to prevent the boat filling from splash or waves over the stern is to close the companionway hatch and all lazarets/hatches that give you access into the boat. This will help to keep the inside of the boat dry. If water starts filling from inside the boat, then you find the hole and plug it as soon as possible. If it is a thru hull you pound a wooden plug into the hole. It may not stop all the water but it will slow down the leak while you man the buckets and manual pumps. There is also a putty called "Stay Afloat" (My Site) you can buy to plug leaks temporarily.

Since you are thinking about it make up a plan to keep water outside of the boat. Your time will be better spent on that than to worry about electrical systems. If you are worried about the battery, then you might be able to relocate the battery to a higher location. Note that raising the battery to a higher location raises a heavy weight above the boats center of gravity. This may be worse than dealing with water in the boat. It is all a compromise when considering changes to a boat.
Jan 4, 2010
Farr 30 San Francisco
I don't think it is as bad as all that. Even underwater the battery won't "short out" there will be some current flowing in the water, which is lost to you. Be an interesting experiment.
Oct 10, 2019
Signet 20 0 Ithaca
Not to sound snotty, but if you want to keep water out of your electrical panel, and it's 10" off the bottom of the bilge, you should move the panel. Otherwise, good luck sealing around all of those 20 or 30 wires...
Oct 24, 2010
Hunter 30 Everett, WA
Consider this. In the event of an actual knockdown the surface area of the conductors of your battery are very small and you would experience very little energy loss through salt water with that small of contact area. I would venture to conclude that it would be a non-issue even if you do submerge it in salt water. Just make sure to clean it up afterward. If it were high voltage it would be a different answer but we are only talking 12 volts here.
  • Like
Likes: jssailem