‘Voluntariness’ is a particular term in relation to the law of contract which basically means that no consideration has been given by the promisee in return for the promisor’s offer. In other words, although a person may have agreed to or accepted an offer made by another party, this will be a ‘mere agreement’ and, of course, unenforceable in a court. Indeed, it is actually a pre-requisite of salvage that the services should have been rendered ‘voluntarily’. Thus, if the ‘salvage service’ has actually been rendered in return for consideration i.e. was actually a contract for rescue, then although the rescuer will be, of course, entitled to his contractual reward, it is not strictly correct to say that this was, in fact, a salvage operation. The requirement that the service must be given voluntarily does not preclude the salvor, i.e. the one who performs the service, from making the service the subject of a voluntary agreement and this in practice is often done. To avoid the requirement of voluntariness and thus defeat a claim for salvage it must be shown beyond doubt that there existed a duty to render the service wholly and completely and, also, that duty was owed to the owners of the property saved.  For example, the actual crew of the ship in distress or a pilot on board are usually unable to claim salvage, unless the services rendered are outside or beyond the scope and bounds of their duties under contract.The San Demetrio (1941). A tanker was severely damaged in the North Atlantic by gunfire from a German warship. She was fully loaded with a cargo of petrol (gasoline). The Master gave the order to abandon ship. The whole crew left in three lifeboats. Subsequently the tanker caught fire after being hit again. The following day the tanker, still on fire, was sighted again by one of the lifeboats. Under command of the Second Officer, the crew re-boarded the ship and, with great skill and courage, brought the vessel several hundred miles through bad weather to safety on the Clyde. The crew claimed salvage award. It was held that the vessel had been properly abandoned under the orders of the Master. Therefore, under the circumstances, the vessel’s own crew were entitled to claim salvage.