With the first offshore well drilled from a moored tender assist MODU (Mobile Offshore Drilling Unit) in 1947, the need to handle mooring system’s anchors, buoys and mooring lines for drilling, construction and pipe laying barges was born. In the early to late 1950s in the Santa Barbara Channel, California, coring units and MODUs with small anchors and only 4 to 6 mooring wire ropes were handled by standard tug boats with their normal towing winches. Corresponding conventional anchor handling tugs were used in the Gulf of Mexico and Mid East for construction. As construction and pipe laying barges increased in size as did MODUs, their mooring system components also grew in size and complexity necessitating larger purpose built AHVs (Anchor Handling Vessels) with more horsepower fitted with gantry cranes, open stern decks with the bridge on the bow, and “stern rollers” to help lift equipment on the deck. In the ‘60s and early ‘70s the development of multipurpose vessels (AHTs, Anchor Handling Tug Supply Vessels) appeared that could handle mooring equipment, act as a supply vessel and also tow MODUs and construction barges. As mooring line components further increased in size, weight and length due to increased water depth requirements and more severe operating environments, it became necessary to develop better seamanship and even more capable AHVs with large bow thrusters for maneuverability, sophisticated navigation systems to set/retrieve anchors, and innovative deck equipment to handle the larger mooring equipment. Further development led to AHTS’ that could also carry large quantities of liquid mud as well as dry bulk material. Today AHVs and AHTS’ have grown into ships with some over 250 ft. long, bollard pulls of over 200 tons, over 20,000 Hp with twin controllable pitch (CP) screws, and double winches that can each pull and brake over 1,500,000 lbs as well as conduct dynamical payout with long work wires to handle large anchor and chain loads.
Recognizing the pioneering efforts of the following individuals and organizations that contributed to this technology:
William (Bill) Bright, Dino Chouest, Laney Chouest, Burt Keenan, Charlie Slater, Nolty Theriot, Ken Waldorf, Tony Wilbraham, Edison Chouest Offshore, Farstad Shipping ASA, Maersk Supply Service, Offshore Logistics (Bristow Group Inc.), Offshore Supply Association Ltd., Smit-Lloyd (now Smit International N.V.), Tidewater, United Towing (now Maersk Supply Service), Zapata Marine Services (now Tidewater).