Welcome to RCT!
Depending on how much air you have inside the electronics compartment of the boat, you might need dual water cooled ESC's (Electronic Speed Controls), and each will need to handle the voltage and amp load for your motors.
You also might want water cooling jackets for your motors. This depends on a number of factors. The load on the motors, the air space inside the electronics compartment, etc will all determine how hot things get. You may need a water pump as well to cool the electronics, since I am assuming this boat won't be moving very fast. So a water system like on speedboats where the water is fed via holes in the rudder won't work work well for your application. Again, just something to think about in the planning/building of the boat. If you build it without water cooling, and later find out you're running hot, you might have to add water cooling jackets to the motors, and swap out the ESC's for water cooled ones. So maybe plan for that.
To make dual ESC's work to steer the boat, you are going to need a radio that supports "channel mixing". This feature will connect two channels together and allow your steering to control how the two throttle channels operate, where center steering allows the throttle channel to work as normal for both motors. Turning the steering wheel one direction will lower the pwm signal for one motor to lower its RPM, and does the same for the opposing motor when turning the other direction.
You're likely going to want a rudder, and I would probably set that up on a second steering channel so you can adjust the servo endpoints (servo limits that stop the servo from tirning past the mechanical linkage). So for that you will need a servo. A standard size servo should do fine, but you can also look at 8th scale servos for a little more durability. You don't really need that big of a servo for a boat though I wouldn't think. But being such a big boat, maybe it would be more durable in the long run to go bigger.
Next you need a radio system (Tx and Rx - where Tx stands for Transmitter and Rx stands for Receiver) There are a number of surface radio systems (radio with a steering wheel) on the market that can handle this. But the only radio I have ever messed with channel mixing on is the
Radiomaster MT12. It's a great radio, but it has a pretty steep learning curve. But it has a ton of features, and can do everything you need.
Or you could use a stick trsnsmitter (radio with two sticks). Each stick would control one motor in this scenario, but you would still use channel mixing to tie the two throttle channels and steering together.
Hope this helps.
