For the purpose of this part, when reference is made to the phrase interest of the United States, it shall mean:

(a) As to vessels constructed or sold with construction-differential subsidy and/or national defense feature allowance under Title V or VII of the Merchant Marine Act, 1936, as amended, the value of the construction-differential subsidy allowance, plus the allowance for national defense features;

(b) As to vessels constructed or sold under Title V or VII of the Merchant Marine Act of 1936, as amended, and adjusted in price pursuant to section 9 of the Merchant Ship Sales Act of 1946, the difference between the pre-war domestic cost and the statutory sales price as defined in the Merchant Ship Sales Act of 1946.

Vessels subject to the provisions of this part are:

(a) All vessels which may in the future be constructed or sold with construction-differential subsidy allowances and/or national defense features allowance under Title V or VII of the Merchant Marine Act 1936, as amended.

(b) All vessels which have previously been constructed or sold with construction-differential subsidy allowances and national defense features allowances under Title V or VII of the Merchant Marine Act, 1936, as amended;

(c) All vessels which have previously been constructed with construction-differential subsidy allowances or national defense features allowance under Title V or VII of the Merchant Marine Act of 1936, as amended, and later adjusted in price pursuant to section 9 of the Merchant Ship Sales Act of 1946;

(d) All vessels which are subsidized under operating-differential subsidy agreements.

(a) All construction-differential subsidy agreements and mortgages relative to vessels covered in § 289.2(a) shall provide, wherever possible, that the Maritime Administrator may, in his discretion, require the owner to insure, with commercial underwriters, the interest of the United States.

(b) All future construction-differential subsidy agreements and future operating subsidy agreements shall require that owners insure vessels covered in § 289.2 (a) and (d) in amounts acceptable to the Maritime Administration.

Owners of vessels covered in § 289.2 will not be required to arrange commercial insurance to cover the interest of the United States, exclusive of its mortgage interest, but the United States reserves the right to require, whenever the contracts so provide, that this be done at some future date, should it deem it necessary.

The United States will self-insure its interest, exclusive of mortgage interest, as defined in § 289.1.