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SHIPLIFTING AND DRYDOCKING SYSTEMS Better Equipment Increases Profitability —A Review— Most U.S. shipyards are in the process of increasing their efforts to expand repair and conversion work, both commercial and military. As many of these projects include dry- docking, the efficiency of a ship- yard's shiplift/transfer systems plays a vital role in the profitabili- ty of any contract. " The editors of MR/EN asked the leading designers, manufacturers, and users of these systems to tell us about their latest developments and experiences. The following re- view is based on replies that we had received at press time. FOR MORE INFORMATION If you wish to receive additional information on any of the products or installations described in this re- view, circle the appropriate reader service number(s) listed under each company's name, using the postage- paid card bound into the back of this issue. AMIRIKIAN ENGINEERING Circle 80 on Reader Service Card Amirikian Engineering Company of Chevy Chase, Md., recently an- nounced the development of a revo- lutionary drydock that features a new concept of stabilization for floating craft. Called "Stabilized Buoyancy Lift Dock and Shore Transfer System," the new floating dock, consisting of a compart- mented pontoon and complemented with a stabilizer, can lift a ship out of water and raise it to the needed level for direct roll-on shore trans- fer. The drydock, installed in a berth adjacent to a pier, bulkhead, or a corner of a slip, is operated by com- pressed air—without the aid of winches, cables, or chains, and needs no second flanking pier. Thus, the dock being free of obstructions of such adjuncts, drydocking access of a ship can be made from the side or an end; after elevated lift, the shore transfer is likewise accom- plished sideways or endwise. Fur- thermore, no limitations are im- posed on the dock's lifting capacity. It can raise and shore-deliver any floating craft—whether it be a small fishing vessel, an ocean liner, a su- pertanker, and even a giant aircraft carrier. The entire operation can be carried out through a programmed remote control. The stabilizer consists of a spe- cially devised structural framing that is fitted between the inboard face of the dock and the flanking pier or bulkhead. It serves the same stabilizing function as do the side- walls in a conventional floating dry- dock; that is, to restore equilibrium after a disturbance due to an exter- nal force. However, in a floating drydock, restoration of equilibrium is obtained through jerky motions of pitch, roll, and yaw, while in the lift dock the stabilizer resists such rota- tional motions to occur, and at the same time provides guidance for free vertical movements under both tidal rise and fall, as well as in oper- ational ascent and descent, thus keeping the deck of the dock in a horizontal plant at all stages of op- eration. The stabilizer was conceived by Dr. Arsham Amirikian, presi- dent of Amirikian Engineering, who formerly served in the U.S. Naval Facilities Engineering Command as chief designing engineer and chief engineering consultant. Upon re- tirement in 1971, he established the firm to render private consulting services, specializing in drydocking facilities. BARDEX HYDRANAUTICS Circle 81 on Reader Service Card Founded in 1963 as an engineer- ing-oriented organization having the capability to develop and manu- facture sophisticated hydro-me- chanical systems, Bardex Hydra- nautics is headquartered in Goleta, Calif., with offices in Houston, Lon- don, and Singapore. The company designs and manufactures heavy- load moving equipment for offshore and shipyard-related activities, in- cluding systems for applications ranging in size to more than 50,000 tons. Bardex systems are specified by the major designers, drillers, oil companies, and shipyards around the world. These systems meet the exacting standards of all certifying and classifying agencies, including the American Petroleum Institute, the U.S. Coast Guard., American Bureau of Shipping, Lloyd's Regis- ter of Shipping, and Bureau Veri- tas. Bardex has supplied rig-skidding systems for 95 percent of the major offshore platforms in the world, and is said to be the only major shiplift manufacturer whose equipment has a flawless safety record. The compa- ny is also a supplier of main deck structure lifting systems for off- shore drilling rigs, and pioneered highly flexible, low-cost hydraulic shipyard systems for transferring ships from the water to berths on shore. Bardex Hydranautics products are to be found virtually wherever there is a requirement to move a heavy load, such as ship and drill rig building and repair, offshore oil and gas drilling and production, and heavy construction. Where heavy loads, such as ships, must be lifted with precision and safety, a Bardex chain jack lifting system is employed. The key ele- ment in this lifting system is the hydraulic chain jack, which consists of a vertical jack that lifts its load by pulling one or more chains upward through two sets of locking pins in precise steps of one chain pitch. As in other Bardex Hydranautics sys- tems, the number, size, and design of the assemblies vary with custom- er load requirements. Chain jacks may be used individ- ually, but are normally employed in sets of two or more, and can be con- trolled by one operator from a single control station. Other system com- ponents include the hydraulic pow- er unit, chain, load equalizer-com- pensator assembly, and the inter- connecting high-pressure hydraulic hoses. The key element in a Bardex skidding system is the jacking as- sembly that the company calls a gripper jack. It consists of a double- acting hydraulic jacking cylinder (the jack) mounted to a patented hydraulic locking device (the grip- per), which clamps the flange of the beam on which the load is resting and acts as a movable reaction point for the jack. For rapid turnaround in high-use areas of a shipyard, BH provides wheeled transfer systems (bogie trains). Lifting and lowering of the ship to and from support blocking are performed with a self-contained hydraulic system on the bogie train. With this system the side transfer pit is eliminated, allowing free movement of vehicles and foot traf- fic. The gripper jacks are normally used on skid beams, but transfer systems using roller beams are also available. These require less jacking force than skid beam systems, mini- mizing initial equipment costs. Where moving heavy loads over relatively unprepared surfaces is re- quired, a BH Translift "walking" system may be used. The basic Translift system consists of a center load support, connected outer load supports, and an onboard control console. If desired, remote control of all units in the system can be achieved by using a portable pen- dant console. Translift systems can rotate in a full 360-degree circle, and can "walk" a load using the simple principle of weight transferrence be- tween the center load supports and the connected outer load supports. Some recent installations of BH equipment in the shipbuilding and repair industry include the follow- ing: Hyundai Heavy Industries in Ul- san, South Korea is equipped with a shiplift system and a horizontal transfer system. The shiplift plat- form is approximately 400 by 66 feet and has a capacity of 4,100 metric tons. The new $200-million shipbuild- ing and repair complex of PNOC Marine Corporation at Batangas Bay, Philippines, is equipped with a hydraulic shiplift system and hy- draulic wheeled transfer system. The platform of the elevator mea- sures 566 by 100 feet, said to be the largest hydraulic-actuated elevator in the world. The floating drydock used at Daewoo's Okpo yard in Korea is equipped with a Bardex roller beam transfer system capable of moving ships or sections weighing up to 6,000 metric tons. The same hy- draulic system is also used on fixed or portable beams located in the yard to move offshore structures and jackups as well as ships and sec- tions. Bardex Hydranautics hydraulic gripper jack. 16 Maritime Reporter/Engineering News
