1) Avoid connectors exposed to weather at all costs.

2) Bolt two crimped on ring terminals together. But do it below deck.

Any connections that have to be made outside in a marine environment should be crimped and covered with heavy duty heat shrink tubing - the kind that has hot melt glue inside. And a second layer of heat shrink on top of the first layer.

For my wind generator I have done just that. Up inside the pole the connections are permanent and heat shrink sealed. The cable then passes through the stern and ring terminals are crimped on. Extra cable length is provided so when I need to remove the cable it can be cut and new ring terminals put on. The hole through the stern is just large enough to get the wire through.

Don't forget the drip loop. The connection point should never be at a low spot. Both wires should go up to a higher point for the connection. That way if water does get into the boat the water will not drain towards the connection. Then the connection requires less diligent waterproofing.

The solar panels are similarly wired. Watertight boxes are part of the panels (these are Shell solar - no longer made). The panels are paralleled and the heavy wire out of the last junction box is lead below with no external connectors. It is pretty amazing how well the connection boxes have stood up over the years - some are now 20 years old.