Final answer:
In case of a jammed rudder, the crew uses sails adjustment and tacking technique, as well as differential engine power to control the ship's direction.
Step-by-step explanation:
When dealing with a jammed rudder condition, the crew of a ship has a few tactics at their disposal to maintain directional control. Historically, advances such as the introduction of the caravel ship design allowed for increased maneuverability due to the repositioning of the rudder to the back of the boat and the addition of the lateen sail. In a scenario where the rudder becomes jammed, the crew can make use of alternative sails and techniques such as tacking, which involves the adjustment of the sails relative to the wind, to change the direction of the ship. The use of the ship's engines, if available, in different power configurations can also assist in steering the vessel when the rudder is not functional.