The PT 109 by Lindburg was our first RC Model. We built it one cold rainy weekend around 1980 I am not sure of the year and it doesn't matter. Originaly the model had some plastic gears turning the two shafts and propellers, being driven by a 400 size motor. Just set the rudders and it would go in circles, slowly. None of us thought much of its performance and the circles were pretty dull. So I set about learning about DC motors, speed controls, servos and Radio Control (RC).
First I tried some brass gears from Dumas Models and a heavy motor from Dumas as well as some drive dogs. Then we had to learn about batteries and chargers. That motor from Dumas was very heavy for a 30" plastic model and it was slow. The local hobby shop supplied a stock 27turn 540 size motor, that was very fast in comparison. It wasn't long before it chewed up those brass gears and I was looking for a way to get 2 motors in there, one for each propeller and shaft. At the same time I found Octura and their great boat hardware, and acquired a pair of 3 blade counter rotating brass porpellers that looked good. At first I tried wooden motor mounts glued to the hull of the boat, this proved insufficent to keep the "stock" 540 motors from moving around. I then set about making an aluminum bulkhead to be the motor mount and heat sink for the motors. When that was done it looked great and worked well too. I scratch built a servo mount and linkage for the steering that is still working. The first speed control was a three step resistave control. In other words at slow setting there were some big resistors to lower the voltage to the motor so the boat went slow. At medium there were some smaller resisters to drop the voltage for medium speed. The side effect of this method was the battery was working as hard when the model was going slow as it was when the boat was going fast, and the speed control was on high, where the battery was in effect directly connected to the motor. Those resisters got very hot and the run time was short. The battery was working all out all the time the model was running, not a great set up. And you could get burned from those resisters. The receiver needed its own battery pack and you had to be careful to insure there were fresh batteries in it or you might be swimming to retrieve you boat, or worse the boat took off at top speed for parts unknown. The alternative was an electronic speed control, and they were expensive. They did have a BEC "battery eliminator circuit" that ran the receiver, no more receiver battery pack. If you ran the boat too long and the voltage dropped in the battery beyond a certain point, the boat headed off on it's last heading with no controll, at least the battery was almost dead.--
It was all worth it to see that boat go where YOU wanted it to go, left, right, away and back to you. There was that learning curve about the steering was reversed when the boat was coming at you.
Next there were Brats and Frogs and RC10s and years of racing. Then one winter day I decided to design and build my own boat.