Switching to larger seismic workboats

Seismic workboats keep getting bigger. Several factors drive the move to larger boats. One is a need to move crews of up to forty passengers safely. One is a need to re-provision in larger amounts. But the main driver is technology changes, which create the need to transport larger items of equipment and make in-water cleaning of seismic cables possible. That needs a safe, which means large, work platform.

Minimising space on crowded decks

Seismic workboats were typically up to 7 t in weight, but today there is already demand for 15 t SWL davits. Usually at this size davits need to be twin arm with two falls, but Vestdavit has been able to bring the safe handling and simplicity of single arm davits up to this capacity. Single arm davits are easier for the boat crew to engage and disengage and enable boat handling in heavier sea conditions than twin arm davits. That means more time on task as the boats can be used in higher sea states. The davits also occupy less space on the crowded decks of seismic and seismic support vessels.

Seismic support vessels often need to handle the workboats of different seismic ships they support. That means they require a davit which can lift and stow a range of boats. Single fall davits are ideal for this.

Supporting PGS’ seismic vessels

Vestdavit has already supplied eight single arm PLR-15000 workboat davits, including two for Norway’s Sanco Shipping. Sanco is a leader in designing and operating seismic support vessels. These davits are able to lift workboats up to 15 t with one wire fall and will be used on vessels on long-term charter to support PGS’ seismic vessels.

The new PLR-15000 davit is delivered in standard configuration with shock absorber, self-tension, control desk, wire hauler and hydraulic end stop. The davit has two cylinders for pivoting the davit for extra safety. The winch is C-606, specially developed for this davit’s SWL, built in accordance with the LSA code for lifting of personnel.

The davit is versatile with its multi-boat cradle, adaptable to various boat sizes and hull shapes.

Adapted from press release by Cecilia Rehn

Read the article online at: https://www.oilfieldtechnology.com/exploration/04122014/switching-to-larger-seismic-workboats/