Probing the depths: Dive vessel provides a base for subsea workers

After delays caused by Hurricanes Katrina and Rita, the 220-foot dive vessel Epic Explorer left Bollinger’s Larose yard in February for its maiden entry into the offshore market, providing divers for a well-intervention project to plug and abandon certain downed platforms in the western Gulf of Mexico.

Epic Explorer has a host of various projects to perform in the Gulf of Mexico, primarily conducting riser repair, installations, pipeline tie-ins, ROV projects and subsea tie-ins.

Divers are housed for the duration of the job in two- and four-man saturation tanks that contain all the supplies they need for up to three months. The air in the tanks saturates their blood with helium, which blocks nitrogen from entering. (The formation of nitrogen bubbles in the body is the cause of decompression sickness, a potentially fatal ailment.)


Senior dive technician Kerry Mahoney checking pressures in the transfer tanks and transfer lock. [photo by Brian Gauvin]


The divers access the dive bell by way of the transfer lock. The bell is lowered through the moon pool by a winch. An umbilical cord carries the proper gas mix to the bell. The divers work for 10- or 12-hour shifts at depths of up to 1,000 feet.

When submerged, the divers can use an excursion umbilical to work away from the bell. The dive bell has a backup gas supply and can surface on its own if the umbilical should fail or be cut.
Because helium and time are expensive, the decompression chamber on the aft deck is used to isolate a single diver from the tanks when it is necessary to bring him back to surface pressure.

Epic Explorer is the former offshore supply vessel Flood Tide III, purchased from Tidewater in June 2005. The boat was converted to a four-point anchor vessel with an integrated saturated diving system (SAT).

The decompression tank on the aft deck. Divers work 10- or 12-hour shifts at depths up to 1,000 feet. [photo by Brian Gauvin]


Julie Rodriguez is the chief executive of Epic Divers, which was founded by her parents, Lawrence J. “Pie” Rivet and the late Marion Soniat Rivet King, in 1972.
Rodriguez explained that cost was a major factor in deciding to go with a retrofit rather than a newbuild. “However, time was also a factor,” she said. “With the time required to do a newbuild —approximately 18 months along with the engineering time of six to eight months — and with the anxious need to get into the market, a rebuild seemed the best approach.” •

By Professional Mariner Staff