It seems you need all new electronics. The transmitter (Tx) should not be hot. Servos should hold steady as long as they are powered.
FlySky makes a good, inexpensive set of electronics. Many sailors use the FS-i6 Transmitter. I got mine together with a FS-iA6 Receiver (Rx), at $53. This Rx is a circuit board with cardboard cover. Better Rx is FS-iA6B, $16. I got this from Amazon.
Sail servo could be Hitec HS-765 $39 and Rudder servo Hitec HS-485 $17. These are most popular.
The boat should be great.