(a) Prelaunching period. The amount insured during this period will be the cost of material destined for inclusion as a part of the vessel at risk at the shipyard of the builder, plus the cost of labor, other direct charges, overhead, and profit not exceeding 10 percent, all as determined from the builder's records.

(b) Postlaunching period. The amount insured during this period will be:

(1) An amount not in excess of the difference in amount between the total amount of war risk insurance obtainable from companies authorized to do an insurance business in a State of the United States and the contract price of the vessel plus the cost of the materials and equipment furnished by the owner and not included in such contract price, or

(2) An amount not in excess of the contract price of the vessel plus the cost of materials and equipment furnished by the owner and not included in the contract price: Provided, that no war risk insurance is obtainable from companies authorized to do an insurance business in a State of the United States.

(c) Maximum liability. The amount of any claim for damage to or the total or constructive total loss of the vessel adjusted, compromised, settled, adjudged or paid shall not exceed the amount insured: Provided, that the amount payable hereunder shall not exceed the maximum sum which the Maritime Administrator, as Underwriter, is authorized to pay under any applicable Acts of Congress: Provided, further, that where MARAD is an Excess Underwriter, the amount payable under this insurance for damage to or the total or constructive total loss of the vessel, after all sums due and payable under primary and excess insurance written by commercial Underwriters have been exhausted, shall be the balance, if any, of said claims.