Liftboat

A liftboat [46CFR90.10-20] is a self-propelled, self-elevating vessel with a relatively large open deck capable of carrying equipment and supplies in support of various offshore mineral exploration and production or offshore construction activities. A liftboat also has the capability of rapidly raising its hull clear of the water on its own legs so as to provide a stable platform from which maintenance and construction work may be conducted.

If registered to the United States, liftboats structures and their machinery are covered under Title 46 of the Code of Federal Regulations. Liftboats are usually outfitted with at least one crane; marine cranes are usually designed to API specification 2C or the equivalent classification society guidelines.

Liftboats are commonly used to perform maintenance on oil and gas well platforms. The liftboat usually moves on location on a side of the platform where no obstructions or pipelines are observed, lowers its legs and jacks up out of the water. Because the pads of the liftboat are setting on a muddy, unstable seafloor, most liftboats practice a safety measure called a preload, where the boat jacks up a few feet out of the water, fills its holds with water for weight and allows the boat to settle in the mud for several hours before dumping the water and jacking up to work height.

If the mud of the seafloor gives way under the liftboat, it can fall into the water and put the lives of the crew in danger. A complete site survey prior to moving on location is an important safety measure to ensure that all seafloor features (canholes, pipelines, etc.) are known before choosing a final location.

Dixie Patriot

Built by SEMCO, LLC. in Lafitte, LA, the Dixie Patriot is largest liftboat ever built. Capable of working in depths up to 200 feet, it is outfitted with 11,000 square feet of usable deck area and two Seatrax 200-ton capacity cranes. It is so large that it has a helipad for crew changes and equipment shipments, virtually unheard of on liftboats.

References

External links

* http://www.access.gpo.gov/nara/cfr/waisidx_06/46cfr90_06.html

* http://www.bollingershipyards.com/liftboats.htm