When your boat has damages everywhere it may make a better sense to give it a new body. PVC pipes are cheap and easy to work with. You can keep the undamaged part of the boat and use it with the PVC pipe frame. Yo can even create a rescue boat this way.
You may trim off the damaged body parts and do a transplant:
PVC pipes can be used to assemble a frame which holds the motor and the electronics but make sure all openings are sealed with hotglue:
The receiver and the ESC together with the battery should be kept inside a plastic box. It is not possible to seal it 100% so you better use water-proof electronics. The brushed motor may expose to water without significant problem.
You may need to pad the bottom to ensure it won’t submerge too much.
This is a “shorter” version:
