If you could pump a lot of water at high pressure and release it just off the bank where the boat is stuck you might be able to scour away the underbank while a

If you could pump a lot of water at high pressure and release it just off the bank where the boat is stuck you might be able to scour away the underbank while at the same time creating a slightly higher hydraulic head, kind of a standing wave or mound of water, that may float that end of the ship higher. The hydraulic jump may cause suction or cavitation that would make it harder to free the boat though.