Fish-Hawk.Net

I have a 70 hp. outboard on my boat and a 12V trolling motor . I would like to have 1 battery for starting , 1 for house and 1 for trolling motor.
How do I go about wiring all 3 to be charged by 70 hp motor ?

Research "battery combiner" or charge/charging relay. I've used ones from BLu Sea and Keyline. They all work the same.
Charging the trolling battery is not too common,.. more for the house/electronics. Maybe one of the companies offering these products has something similar that does more than one extra battery.
Cheers,