46 U.S.C. § 53308

In this chapter— (1) if the net proceeds of a sale or the net indemnity for a loss is deposited in more than one deposit, the amount consisting of the gain shall be deemed to be deposited first; (2) amounts expended, obligated, or otherwise withdrawn shall be applied against the amounts deposited in the fund in the order of deposit; and (3) if a deposit consists in part of a gain not recognized under section 53306 of this title , any expenditure, obligation, or withdrawal applied against that deposit shall be deemed to be a gain in the proportion that the part of the deposit consisting of a gain bears to the total amount of the deposit.