My trolling motor works full power out of the water, but the minute I put it in the water, it basically dies (has little power).

It’s possible you’ve sheared the prop pin. Propeller pins are designed to break when the prop gets caught on debris or underwater obstructions. They are designed to break to prevent damage to the armature and other parts of the lower unit of the motor.

Replacing the Prop Pin

1. Remove the propeller by removing the nut and washer holding the prop in place.
2. The prop pin is located on the propeller shaft and is covered by the propeller.
3. The pin should slide out. If it does not, you will need to tap it out with a punch.
4. Slide the new pin in place.
5. Slide the prop on and seat it over the prop pin.
6. Replace the nut and washer for the propeller securely.