All these ideas are good ones. I used a block of styrofoam, and trolling motor, and car battery. For the forward and reverse, I used an aluminum plate with the servo in the middle of two 12v momentary switches. Now I use a 51" deep vee hull I build with an electric motor and a motorcycle batt. I use regular gas hardware but convert it to take an electric motor. It is also easily switched to gas to "play". For the bait I attach a short pole to the boat, with a close pin glue to the top. A quick tug and it releases. Also with electric, you can tie your line to the boat with 2lb test. This way you can move it and fish at variable depths.
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