Unless otherwise stated, the term "attending vessel" refers to any vessel which is operated by the owner or operator of an OCS facility located in the safety zone, which is used for the purpose of carrying supplies, equipment or personnel to or from the facility, which is engaged in construction, maintenance, alteration, or repair of the facility, or which is used for further exploration, production, transfer or storage of natural resources from the seabed beneath the safety zone.
33 C.F.R. §147.20