46 C.F.R. § 98.30-19
Supervision by person in charge
(a) No person may connect, top off, disconnect, or engage in any other critical product transfer operation unless the person in charge designated in § 98.30-17, personally supervises the operation.
(b) No person may start the flow of a product to or from a portable tank or IBC unless instructed to do so by the person in charge.
(c) No person may transfer a product to or from a portable tank or IBC unless the person in charge is in the immediate vicinity of the transfer operation and immediately available to the person transferring the product.