Launch hire in foreign and domestic ports will be accepted by National Shipping Authority as vessel operating expense, subject to the provisions of Article 5 of GAA 3-19-51 and BAA 9-19-51, only under the following circumstances:

(a) When incurred by the Master of an NSA vessel, or by an agent of NSA or by his sub-agent, for the purpose of properly conducting the owners' activities and business of NSA vessels;

(b) When incurred in transporting liberty parties to or from an NSA vessel with the approval of the Master or the General Agent as properly for account of the vessel owner; and

(c) When incurred for the transportation of workmen required aboard the vessel, if the contract for the work provides that such service shall be for account of NSA, and the launch service is authorized by the representative of NSA or the agent who ordered the work to be performed for account of NSA.