29 CFR 1918.84: Bulling cargo.

(a) Bulling cargo shall be done with the bull line led directly from the heel block. However, bulling may be done from the head of the boom when the nature of the cargo and the surface over which it is dragged are such that the load cannot be stalled, or when the winch actually does not have sufficient strength, with the purchase used, to overload the boom.

(b) Snatch blocks shall be used to provide a fair lead for the bull line to avoid unnecessary dragging of the bull line against coamings and obstructions.

(c) Snatch blocks shall not be used with the point of the hook resting on the flange of a beam, but shall be hung from padeyes, straps, or beam clamps. Snatch blocks or straps shall not be made fast to batten cleats or other insecure fittings.

(d) Beam frame clamps shall be so secured as to prevent their slipping, falling, or being pulled from their stationary attachment.

(e) Falls led from cargo booms of vessels shall not be used to move scows, lighters or railcars.