Ultra Dynamics, which makes the UltraJet range, claimed that waterjets are currently a favored choice of propulsion for some wind farm workboats mainly because of their increased maneuverability.

The increasing number of offshore wind farms is proving to be a valuable source of orders for waterjet manufacturers. Ultra Dynamics, which makes the UltraJet range, claimed that water jets are currently one of the favored choices of propulsion for some wind farm workboats mainly because of their increased maneuverability and the ability to hold station while work is being watercarried out — a key requirement when servicing offshore wind farms, especially in very rough sea conditions.

Additionally, waterjets can also be serviced quickly, often without drydocking the boat, which means less downtime and cost savings to the end customer, according to the company —an important issue when a vessel is operating in an area where there are no facilities to undertake extensive repair work.

To back up this claim, the company — based in Cheltenham, England — recently took orders from South Boats Special Projects Ltd., including eight boat sets comprising twin UltraJet 451 waterjets with a flybridge joystick control and display to propel a series of 15.43 m alloy wind farm service vessels designed for crew transfer and logistical support at various wind farms in the U.K. and Europe.

The first of these vessels, due for launch last February, has twin Scania DI 12M EMS diesel engines rated 441 kW at 2100 r/min coupled to ZF360 transmissions with a 1.237:1 reduction ratio driving twin UltraJet 451 waterjets. Following on from these vessels, a further three boat sets using twin UltraJet 575 waterjets with joystick controls are also on order to propel a series of larger and more powerful 20.4 m alloy wind farm vessels, which will match MAN D2842 LE410 EDC diesel engines rated 809 kW at 2100 r/min via Twin Disc MGX5147SC transmissions with a 1.48:1 reduction ratio.

The South Boats hull combines a number of advantages including a chine-shaped aft(a relatively sharp angle in the hull), which gives stability in following seas. The company said that to prolong the vessels’ service life, the aluminum structure and shell are constructed to a high safety factor to withstand pressures exerted on a vessel of this type.

Standard design principles include symmetrical underwater sections and asymmetrical wet deck knuckles and spray deflectors. The hull also maintains a parallel waterline beam through the length of the vessel to allow good weight distribution around the vessel.

The sea-keeping capabilities of the catamarans have been proven in service when transferring engineers to wind farm turbines in conditions in excess of 2.5 m significant wave height, the company reported. The UltraJet JetMaster Joystick control system offers maneuvering power, and a specially developed digital programmable logic controller (PLC) network converts the joystick commands to boat movements.

This system offers features previously only available on more expensive systems such as electronic steering synchronization for catamarans, vessel steering by use of proportional interceptors, combination lever and joystick control, auto-steer (a topilot) interface, steering and reverse position indicators and helm-mounted display for setup and diagnostics, said the company. It also incorporates a complete secondary backup control system.

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