Using a stereo jack & plugs, you can wire it as a jack to charge your receiver battery, and with a separate plug wired correctly, inserting the plug completes the circuit to power up the receiver. Mounted into the deck of the boat eliminated the need to upen it up to turn on the radio.
Why not just use a Dubro Kwik Switch/Charging Jack?
That picture must be a newer version of the quick switch w/ charging jack. The idea I has was much simpler.