Relay With 12V Switch and 24V Load
Assuming that you are not controlling the trolling motor, this should work just fine (simplified of course, the LED in the diagram is the entire unit, including internal resistors or whatever circuitry allows it to run directly from 24VDC):







simulate this circuit &ndash; Schematic created using CircuitLab

The relay you linked is rated for up to 20 amps at 27VDC, which is quite a bit of current. The 12V side of the relay doesn't affect the 24V side of what you are switching. One is the coil rating, the other is the contact rating.