If it has a large silver speed control, that is the old Dumas speed control which is nothing more than a variable resistor working with a servo, replace it with a modern electronic speed control, that old speed control is the worst piece of equipment in the business, it even uses more power when the boat is not moving, has a low power limit also, I use a $40 Proboat electronic speed control (ESC), IT HAS A (bec) battery elimination circut, so you don't need a reciever battery to run the reciever, it pulls power from the main batteries, its water proof, and handles a lot of power. The two problems I have experinced are the slowest speed is faster than I like with a tug boat, I cant get that very slow almost idel speed, and sometimes I have to redo my turn on sequence. 1) turn on Transmitter on ( always turn transmitter on first and off last) 2) hook up batteries, 3)turn on esc switch. There are times when the esc does not work and I disconnect and have to redo everything, good luck.