Look familiar anyone...
Yet another one of these power cord/adapter failures. This is the third set I think I have replaced in about eight years. Luckily I have been aboard each time they failed and smelled it burning through. This particular failure burned the hot wire about four inches back from the adapter and melted the wire sheath inside the boat. It was a boat fire waiting to happen.
There are many things which cause this issue, in my opinion. Chiefly I think it is a design failure because these adapters/sockets do not have a thermal breaker and because these adapters are poorly suited for their purpose. What happens is:
+ You get low voltage (bad power) at a marina.
+ You get a small amount of corrosion inside the cord/adapter.
+ You run very close to 30 amps on the boat, and with the air conditioning turning on/off, you briefly go over that 30 amps on startup.
+ The cord itself gets hot in the sun.
+ You connect too many cords together because the distance from the hookup to your plug exceeds what a single cord can reach.
Over time, any or all of these issues cause the cord itself to get warm/hot. Heat causes resistance and corrosion. Resistance and corrosion causes more heat, etc until the cord begins to melt down. Because there is not a thermal breaker in the cord/adapter itself, you see the result. Now couple this with a cord set that in my opinion is at best rated for 30 amps and a connection mechanism that carries minimal surface contact, and you have a disaster in the making.
My suggestion is to avoid these cord types altogether (Marineco/Hubble). I see three different options. The first option is to up your cord set and adapter to 50 amps. The connection mechanism is better and higher rated. You will still keep your breaker on your boat at 30 amps, but your cord set and adapter will be much higher rated. A second option is to go with a Smart Plug.
These plugs were born due to the very issues I described. They have a thermal breaker inside the plug itself (so you will never burn down) AND the connection mechanism highly increases their contact/surface area. I have used one of these successfully for quite some time now. Interesting enough, I have that set running my air conditioners and I often put my hand on the adapter and it was always cooler than the Marineco plugset. A last option (and probably the best if you can in my opinion) is to avoid plugs altogether and hardwire the wires to your boat. The "big boats" do this. Using this method you will have maximum surface area and a solid, mechanical connection. When you wish to go sailing, simply unplug from the dock and pull your cord into the lazarette. Now, many boats are set up differently and this is not a viable option, but certainly something worth considering.