Section 103(1)(d) in The Merchant Shipping Act, 1958
(d)when a substitute is engaged in the place of a seaman who has duly signed the agreement and whose services are within twenty-four hours of the ship's putting to sea lost by death, desertion or other unforeseen cause, the engagement shall, if practicable, be made before a shipping master, and if not practicable, the master shall, before the ship puts to sea, if practicable, and, if not, as soon afterwards as possible, cause the agreement to be read over and explained to the substitute; and the substitute shall thereupon sign the same in the presence of a witness, who shall attest the signature.