If grounded aboard a small powerboat, which is a method to free yourself?

Firstly, do not try to revive the boat engine, it will make mud to enter the engine and clog it up. Drop the sail and try and find out where the deep water lay, so that you will not allow the boat to go that way. Determine the current tide of the water, kedge the boat and try to ease it out of the water in the direction of the tide. If all these fail, call the towing service.