Liftboat Overview
LIFTBOAT DESCRIPTION - What is a Liftboat?
Liftboats are self-propelled, self-elevating vessels with open deck area, crane, and living accommodations to support offshore petroleum or wind development activity. Upon arrival to a designated work site, a liftboat will lower its legs until it makes contact with the seabed. Thereafter, the liftboat's hull will rise out of the water due to upward force applied on the legs by the vessel's jacking system. Once a liftboat reaches the optimal elevation, it will cease jacking operations, and the crew can commence work.
The following terminology is also used to describe a liftboat in the maritime industry:
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Self-Elevating Support Vessel (SESV)
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Multi-Purpose Self-Elevating Platform (MPSEP)
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Self-Elevating Work-Over Platform (SEWOP)
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Mobile Offshore Unit (MOU)
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SEP (Self-Elevating Platform)
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Jack-Up Barge (JUB)
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Wind-Turbine Installation Vessel (WTIV)
LIFTBOAT HISTORY
While offshore on a welding assignment for a seismographic crew in Southeast Louisiana, Lynn Dean had to wait several hours before he could perform his job. About 75 workers were idle on a floating vessel, waiting for seas to calm, so that they could perform their duties.
Upon seeing this tremendous waste of labor, Lynn inquired as to what was the problem. He was informed that the wave action on the seismographic vessel could cause the spuds that held the vessel in place to bend. The situation was too dangerous, and the spud repairs too costly. Therefore, the job was shut down.
The party chief on the job explained to Lynn: "If you could build a boat that could work in waves like that, you could make a fortune." Hearing that statement and having many hours offshore to ponder this new concept led to the creation of an "elevating boat," as Lynn Dean called it. This new type of boat would revolutionize the way oilfield service activities were performed and paved the way for a new marine industry - the liftboat industry.
Lynn went on to build the first liftboat named the JEHU in 1955; it utilized a cable jacking system, 12 -16 gauge material, a second hand engine, and cost roughly $22,000. After seeing the positive response to the JEHU, Lynn went onto found EBI liftboats (Source: 1999 Oil & Gas Journal).
As offshore exploration trended into deeper water in the Gulf of Mexico, the demand emerged for liftboats with greater leg lengths. Typically, the charter rate of a liftboat is positively correlated to its maximum achievable water depth. United States liftboat companies considering a new construction sought maximum returns on their investment by building liftboats with legs to service client's deeper oil fields.
CRITICAL SYSTEMS
Liftboats share the same critical systems as any ship but with the addition of cranes and jacking systems. Propulsion and maneuvering systems are of particular importance on liftboats due to the close proximity required during offshore platform approaches.
Jacking systems are made by various manufacturers and models but can generally be separated into two categories: pin & hole (P&H), or rack & pinion (R&P). R&P is more commonly found on liftboats, which is either electric or hydraulically driven. One reason that R&P is more common is due to the higher “leg speed” these systems provide relative to a P&H system. Leg speed is a measure of how fast a liftboat’s legs can descend to the seabed once a Captain initiates vessel elevation. The faster a vessel’s leg speed, the less time it is freely floating next to a platform and exposed to the risks of a collision.
Cranes are equipped on many vessels; however, the high-capacity and high-utilization of cranes on liftboats make their operation and maintenance especially critical. Liftboat cranes are certified to limit their usage only once the vessel is in an elevated state. Liftboats servicing the petroleum industry generally have cranes of 500 tons or less. Whereas, the offshore wind industry utilizes liftboats with cranes of 1,500 tons for installation of foundations, towers, and turbines.
GOVERNING BODIES
The organizations with the authority and responsibility to regulate liftboats vary widely between: Flag States, Port Control, Class, and Marine Underwriters. Liftboats function as a ship while in transit and are similar to a jack-up rig while in an elevated state. Hence, the regulatory requirement imposed on ships and Jack-Up rigs are often both applicable to liftboats. Cranes fall under a separate compliance structure as most liftboats are not certified to allow their operation underway. Thereby, the cranes on liftboats are required to comply with varying non-maritime industrial standards.