Need advice on how to install of a battery cut-off switch in my Sea Hunt 17' with a Johnson 90 outboard. Battery is locate in aft compartment in front of the motor.

My Marina is requiring that it be intalled.

Thanks as always,
Dom

Use marine-grade wiring, locate the switch as close to the battery as possible. Put the switch on the positive side of the battery only.

Make sure the switch can handle the maximum current your battery can deliver, then increase that by 50% for a safety margin.

Buy a high quality marine switch from Blue Sea, Perko, or Marinco.

With an outboard, you don't need to be quite as concerned about ignition protection.