The spirit of 'Enterprise'
Seacat Services’ innovative 27.4m catamaran, ‘Enterprise’, has self-sufficiency at its core. It’s a characteristic that promises to make it relevant for emerging wind maintenance operations.
This High-Speed Utility Vessel is the first of a kind. Recently delivered by the South Boats IOW yard it “does what it says on the can” Seacat Services MD Ian Baylis told MJ. Enterprise has, he said, been developed in response to growing demand for carrying bulky equipment - along with a full complement of technicians - to increasingly remote sites.
The hull itself has evolved a little from the original South Boats form since Andy Page et al took the design lead: a slightly finer entry with a high wet deck clearance combines to reduce slamming and the buoyancy is carried evenly along the length.
However the robust 48dwt Enterprise still needs a good turn of speed. Therefore the engines are a pair of MTU 12V2000M72 s giving 1,450hp from each hull, 2,900hp total.
While the power was adequate, efficiency required a rethink on the propulsion system. Mr Baylis explained: “The extremely high bollard pull was the main design driver as we wanted the vessel to achieve 23kn at 75% loads... but the water jets struggle to get the boats up to speed on that kind of thrust curve.” So after a lot of evaluation, a pair of Servogear 1,175mm diameter CPPs were chosen. On recent trials this resulted in a 25kn speed when over 50% loaded, keeping everyone happy. Further, at this performance noise levels are sub 60bBa and motions have been recorded well below industry standards.
Interestingly, this is complemented by twin sets of Hercules Hydraulics HHBT45 bow thrusters. “Because of the large plane area and water profile, we initially thought the vessel needed more transverse power, so we opted to fit two in each hull,” said Andy Page. “That’s been a great success, although originally only for harbour use they were working so well they have been used for pushing-on manoeuvres during trials.”
But as Ian Baylis told MJ, this is only half the story: “A key feature of this vessel is that it can self-load and unload its own cargo."
Therefore central to Enterprise’s capability is a large, heave compensated Effer 275M crane: this can lift one standard 20ft box over another, allowing it to slot three side-by-side on the rear deck – plus there’s also the option of fitting another container across the bow. As naval architect Andy Page of South Boats IOW told MJ, the vessel has enough stability in its 9.62m beam and 1.55m draught “that even with the maximum load held at full extension, the heel angle still keeps to within around 3° or 4°”. As a result, the boat can reach across and pick up cargo from the quay. To add to Enterprise's general flexibility, the 128m2 deck area also retained space for an A-frame.
It is a pragmatic solution for an industry accelerating into distant regions with a high wind resource but little in the way of support. As Mr Baylis explained: “A delivery driver turning up at an isolated harbour in Scotland or Norway with a replacement turbine part won’t have to worry about getting it off the truck.”
Self-sufficiency is also the reason for a TMP 500L crane positioned on the bow, although this can help with cargo lifts its central purpose is to be able to change out Enterprise’s forward fender instead of necessitating a long, off-service diversion for maintenance.
The vessel also sports a rear fender allowing it to work from either end. As a result, Enterprise could potentially be called on to help with a turbine refit given benign conditions: “In calm weather, we could reverse onto a tower, drop the gearbox down onto the back deck and take it back to base for repair rather than waiting for the jack-up,” explained Mr Baylis. Mr Page added that being able to return a piece of machinery to shore “at 24 knots rather than 8 knots” is bound to add efficiency to operations.
Cargo aside, effort hasn’t been spared in creating a comfortable transit for the workforce: the vessel has SDC carbon-chassis, crash tested seats for up to 24 technicians; 16 on the main deck, and a further eight on the upper deck. Further, it has en suite sleeping berths for six, allowing for a complete crew rotation; as Mr Baylis pointed out, pair this with 40,000 litres of fuel capacity “and if you want to, you can just disappear offshore for days at a time” making the most of the vessel’s Category 1 designation.
Last but not least, the fendering has proved one of the most critical aspects of the whole project. Although Enterprise has retained the proven Danish RG Seasite unit, there’s a lot of engineering sitting right behind it.
Instead of relying on the material alone to soften contact forces, Enterprise has a dynamic, shock absorbing device backing it up, mitigating the peak loads on both tower or vessel and making pushing-on operations much safer for all concerned. This novel design, developed in cooperation with Seaspeed, compresses on impact then recovers enough to allow Enterprise to maintain a good level of friction against the landing.
It was, admitted Andy Page, not an easy job and necessitated moving from aluminium to steel. “The fender itself required a lengthy design period of six to eight months,” he explained. “It took a lot of investment, a lot of time and effort, but we hope we’ve developed a quality, marketable product that could find a home on other projects – including refits.”
By Stevie Knight
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