(a)
An employee of the Corps of Engineers, Department of the Army, engaged in floating plant operations may be furnished quarters or subsistence, or both, on vessels, without charge, when the furnishing of the quarters or subsistence, or both, is determined to be equitable to the employee concerned, and necessary in the public interest, in connection with such operations.
(b) Notwithstanding section 5536 of this title, an employee entitled to the benefits of subsection (a) of this section while on a vessel, may be paid, in place of these benefits, an allowance for quarters or subsistence, or both, when—