remote cable

There should be 2 power wires to your head unit.... Always on, which is your memory wire, and a switched power wire, which should connect to your ignition.

Run them both to the battery, but somewhere nearby your head unit, put a switch (obviously one rated for marine use) inline. That way to get playing power, you just turn the switch on.

Now that I stop and think for a second, check your ground. May not have a good connection... this is how to find out if you have a good ground.

It's the black wire btw