[hellosailor]

Went through the same thing five years ago and found connectors from an outfit called Buccaneer (I may be misspelling that) sold through electronics houses--not chandleries. They'll take up to two dozen separate lines with reasonable power and come with o-ring sealed caps to cover them when disconnected. Your VHF can run separately with a "bulkhead" type dual-female extended connector simply glued into the deck with 5200 or epoxy, as you choose.

While they aren't common, connectors like this ARE used commercially and they ARE out there. Why the small craft business refuses to admit that, I just don't know.

You will need to solder each of your wires to a pin in the connector, the pins in turn are cast and sealed into place.

 

[hellosailor]

Kinda like a wad of chewing gum surrounded by a compression collar. The wires go through the chewing gum, the compression collar keeps it squeezed tightly against the wires, and Bob's your uncle.

(Whatever does that mean, anyway?)

 

[hellosailor]

asdf-
If you have no reverse polarity protection and you want to add it, you can usually do that effecitvely for under $5 in parts. You install a zener diode just before the point where you want protection (i.e. on the DEVICE side of the plugs) and then install a fast-blow fuse just upstream of that, closer to the battery, in the positive line. (Although either line would do.)

You choose a zener that has a reverse-voltage rating just high enough so it doesn't conduct in normal use. Then if the cable that has the zener installed in it is connected backwards, the diode conducts, acts like a short circuit, and blows the fuse.

This is called a "crowbar" protection circuit, because it literally acts like someone has thrown a crowbar across the power lines and blown the fuse. the hardest parts are finding just one zener diode at a reasonable cost, and installing it correctly. You get it backwards, you blow the fuse immediately, you reverse the diode and now you know it works.(G)

OR, it your device can tolerate a little less than full power supply, you can install a simple full-wave rectifier (bridge rectifier) in the device side of the cable. That way you are pretending the cable is supplying AC, and ensuring that only the "correct" DC will get to the device, no matter how it is plugged in. That's another $2-3 part, the onloy drawback is that it will reduce your DC supply voltage by something like 1/2-1 volt.

The crowbar appraoch doesn't reduce your supply voltage at all.

If any of that sounds like Greek to you, any marine radio or radar tech should be able to come install it for you in 1/2 hour or so, any tv repairman if you can still find one of those.