Sprintjet brushless issues

Lots of back flow out of the nozzle then cavitation. Works better in reverse than forward. Throttle set to 50% and it can move but barely, anything else causes cavitation and I can’t figure out how. No water inside of the hull when opened up after test

Surpass 2s esc with 5800kv motor Shapeways stator housing, ride plate, and nozzle Water cooling plate on esc