Various situations are presented with respect to employees rendering watchman or similar service aboard a vessel in port. Members of the crew, who render such services during a temporary stay in port or during a brief lay-up for minor repairs, are still employed as “seamen”. Where the vessel is laid up for a considerable period, members of the crew rendering watchman or similar services aboard the vessel during this period would not appear to be within the special provisions relating to seamen because their services are not rendered primarily as an aid in the operation of the vessel as a means of transportation. See Desper v. Starved Rock Ferry Co., 342 U.S. 187. Furthermore, employees who are furnished by independent contractors to perform watchman or similar services aboard a vessel while in port would not be employed as seamen regardless of the period of time the vessel is in port, since such service is not of the type described in § 783.31. The same considerations would apply in the case of members of a temporary or skeleton crew hired merely to maintain the vessel while in port so that the regular crew may be granted shore leave. On the other hand, licensed relief officers engaged during relatively short stays in port whose duty it is to maintain the ship in safe and operational condition and who exercise the authority of the master in his absence, including keeping the log, checking the navigation equipment, assisting in the movement of the vessel while in port, are employed as seamen within the meaning of the exemptions. The same may be true of licensed relief engineers employed under the same circumstances whose duty it is to maintain the ship's auxiliary machinery in operation and repair (see Pratt v. Alaska Packers Asso. (N.D. Calif.) 9 WH Cases 61).