Which word describes the action of stopping or locking something away aboard a ship?

The term that best describes the action of stopping or locking something away aboard a ship is "secure." In a nautical context, to secure an object means to fasten it or make it safe to prevent it from moving, potentially causing hazards on board. This is a crucial practice in maritime operations to ensure the safety of both personnel and equipment, particularly in rough seas or during maneuvers.

"Turn to" generally refers to changing direction or a shift in tasks, which does not pertain to the action of securing items. "Swab" is associated with cleaning the deck or surfaces on a ship rather than securing items. "Topside" refers to the upper part of a ship, specifically the deck area, but it does not imply any action of locking or securing items. Thus, "secure" is the most appropriate term in this context.