With offshore activities continuing their inexorable move into deeper waters and more challenging conditions, the need for anchor handling tug supply (AHTS) vessels to have increased reliability and efficiency has become paramount.

At the same time these vessels also are increasingly required to run with lower operating costs and better environmental performance.

For AHTS vessels—designed mainly to anchor and tow rigs and installations but also increasingly multifunctional to also handle duties including oil recovery, rescue and firefighting—the need to carry out their work on the deployment, recovery and shifting of subsea mooring patterns as quickly and safely as possible is particularly crucial.

Downtime is a dirty word in the offshore industry at any time but especially in today’s tough environment, and AHTS efficiency is a sector that has become a key focus for oil companies looking to further improve their offshore operational uptime and productivity.

With this in mind, Wärtsilä of Finland recently launched a new design focused on simplicity, efficiency, low fuel consumption and a reduced environmental impact.

The company has targeted the design with equipment solutions suitable for medium- to large-size AHTS vessels, where one of the key components is a two-speed gearbox system selected to meet the design targets of reduced costs and less complexity without compromising operational safety.

Less fuel

Wärtsilä estimates the new design can provide a reduction of 20% to 25% in fuel consumption compared to conventional diesel mechanical twin-engine solutions, with 17% of that saving contributed by the two-speed system, the company said.

The hybrid (diesel-mechanic and diesel-electric) two-speed gearbox Power Take In (PTI) solution can switch from one operational mode to another, with changing propeller speeds producing no loss in PTI power.

The AHTS design features bollard pull options of 180 tonnes, with options for 150 or 220 tonnes, and a hybrid propulsion system. The vessels are also fully compliant with ABS regulations.

Wärtsilä, known mostly in the offshore sector for its power and marine LNG solutions to the market, recently outlined its continued ambitious growth plans for the offshore oil and gas market, including in the offshore service vessels sector, at a briefing at its facility in Rotterdam, Netherlands. Solutions it is offering in the sector now include ship design, propulsion and auxiliary engines, electrical systems, propulsion systems, thrusters, automation systems, bridge systems, and remote monitoring capabilities.

But it also flagged up the growing global gas and LNG market as a key area for its future expansion plans, including small- and medium-scale liquefaction solutions.

Vessel Facts:

Sector: Anchor Handling Tug Supply

Owner: Wärtsilä

Vessel Design: WDS 4826

Size (length): 83 m (272 ft)

Deadweight: 3,500 tonnes

Top Speed: 15.6 knots

Bollard Pull: 180 tonnes

Deck Area: 670 sq m (7,212 sq ft)

Power Range: 2-13 MW

Operating Arena: Worldwide

Classification: ABS: +A1

Accommodation: 31 persons

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