Legal Issues

Admiralty Law is the governing law, where maritime operations are concerned. The taking of a ship to sea, falls under that heading. Even if the ship is just a boat, Admiralty Law applies. Regardless of the contract between the Captain and owner, Admiralty Law has precedence over it's provisions.

The Captain is an agent of the owner. His contract with owner need not be in writing.
The Captain has the power to encumber the ship(cause a lien to occur). He can bind the owner by acts done within the scope of his authority. There are many ways this can occur, some accidental, some deliberate, but most legal.

The Master, as agent for the owner is obligated to the crew:  to provide food, medical care, protection from violence and to not abandon them in a foreign port.

Master is entitled to extra wages for service outside the line of duty, for money advanced by him to the ship, care and cure for injuries. Lawfully in charge until suspended.

Crew members are entitled to certain rights which the owner and Master can be actioned against, if disregarded. This can include fines, even jail for some offenses. The crew is entitled to a voyage to the destination and in a timely manner, originally agreed to.

Crew have certain legal obligations to the ship and Master.
    Not to abandon the ship till the voyage is over. This is pretty hard to enforce as a practical matter. On the other hand, in a foreign country the authorities can and have forced crew to put to sea with the ship even when they wanted to leave.
    To obey the lawful orders of the Master.

There are many other provisions in Admiralty Law, it is a wise owner who engages a knowledgeable Captain.

In Summary