46 CFR 35.35-42: -42 Restrictions on vessels alongside a tank vessel loading or unloading cargo of Grade A, B, or C—TB/ALL.

(a) No vessel may come alongside or remain alongside a tank vessel in way of its cargo tanks while it is loading or unloading cargo of Grade A, B, or C without permission of the Person in Charge of the transfer on the tank vessel.

(b) No vessel may come alongside or remain alongside a tank vessel in way of its cargo tanks while it is loading or unloading cargo of Grade A, B, or C unless the conditions then prevailing are acceptable to the Persons in Charge of cargo handling on both vessels.