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Antony Robson, Captain of the new Turbine Transfers’ ‘Trearddur Bay’ is in awe of his new vessel. “It’s completely different to anything already out there, it’s not a prop boat, it’s not a jet boat – and, given what we need, it drives better than either,”
At 21m long, this 7m Beam support catamaran is a world first, says Rob Stewart of Aluminum Marine Consultants. With a build of this significant the team at Aluminium Marine Consultants have a wealth of industry knowledge and the experience need to carry the construction to successful completion.
Mr Stewart explained that the build has meant close cooperation between Aluminium Marine Consultants, Turbine Transfers, BMT and Voith: although the BMT Nigel Gee design had been tailored specifically to take the new linear jets, putting it all together was a challenge: “With anything new, especially with an innovative build like this, you are always going to have some tweaks between paper and cutting metal.”
While her size is impressive, what really gives Trearddur Bay its edge is her speed, a windfarm service vessel this sized often needs to keep a pace between 25 to 35 knots.
Trearddur Bay’s is fitted with a Voith Linear Jet. A world first, the Voith Linear Jet is a break-through form of propulsion that provides a unique and flawless solution to both high speed and zero speed power. “It’s a propeller in a shaped nozzle, with stators in the back so that the water flow comes out as a jet rather than having a circular motion,” explains marine superintendent Alistair Knowles of Turbine Transfers.
The 750kg, double walled stainless steel nozzles, which sit in front of a pair of Clements Rudders, are tailored to the vessel in a way that delays the cavitation point. This allows not only for effortless operation, but means the subsequent noise and vibration levels are kept extremely low, a feature which is enhanced by the resiliently mounted superstructure. When commenting on noise levels within the vessel, Mr Knowles said that the levels recorded were down to 62db, and that ‘’we could chat comfortably without raising our voices, even at high speed’.”
But it is not just smooth ride and well-adjusted acoustics that make the Trearddur Bay a world leader; it also yields huge fuel efficiency advantages.
During trials, the vessel exceeded itself, and the results truly speak for themselves. Mr. Knowles described the results as “phenomenal, it’s extremely fuel efficient for a vessel of its size, so able to run at 25 knots under reduced power and with consumption comparable to smaller less capable boat”.
While the vessels superb efficiency is indeed a key talking point, it is not the only thing to have benefited. ‘’’Originally it was calculated by Voith that it would perform at about 27 knots but during trails it was recorded at 32 knots’’ said Rob Stewart, Aluminium Marine Consultant’s Commercial Director. Further, because the vessel will be used to carry equipment, it was loaded with 7 tonnes, half on the foredeck half behind “and we still got a 30 knot speed with no loss of handling”, added Mr Knowles. “We’ve measured bollard pull of 12.4 tonnes whereas most jets of a similar size would only give you 6 tonnes. That’s over double,” said the Captain Robson.
What is particularly important is the simplest and most cost effective access methods, which remain simply pushing the vessel hard against the boat landings. Mr Stewart described it as a matter of generating the maximum ‘stick’ between the boat fender and the landing tubes, damping out vessel motion as much as possible and allowing easy transfer for the technicians to the wind turbine. Mr Robson added: “It’s a case of rubber on metal. If we can do it at lower revs, and I am hoping I can push on at 50% power with this boat, then it gives us a lot of extra in reserve.”
Down below in the hulls of the catamaran is the tank area with 500 litres of fresh water and 5,800 litres of fuel. Aft of this, each hull holds an MTU 10V M72 engine that yields 1,250 bhp through ZF3000 gearboxes. A pair of Cummins Onan gensets provide the onboard electrical power, and both engines and auxiliaries are supported by battery packs: although there are ‘service’ and ‘starter’ banks, these can be cross linked to get the engines going if necessary.
Perhaps fittingly for a vessel of this calibre, the entire thing has a futurist feel. The engines are bright white, teamed with the silver insulation which covers the flame retardant wall coverings. Mr Robson explained “Along with the sensors and alarms there’s a camera here so the crew can see what’s happening below’’. Arguably however, the key safety device is the crew and their expertise and familiarity with these engines.
Located on the bridge you’ll find there’s Class A AIS, autopilot, SART, EPIRB and MOB location system, alongside a wealth of other features such as magnetic and GPS compasses, and radios that have been put together as a package by Boat Electrics. The two radar displays offer exemplary assistance in reduced visibility with electronic chart display. While these features are all relatively standard on a vessel of this class, some of the elements needed some optimization, which is hardly surprising when you consider how different the characteristics of the VLJ’s compared to anything that has gone before.
The deck saloon offers ample space comfortably accommodating 12 technicians, with Cleeman Nautic Star leather chairs arranged around four tables, allowing for the technicians to review plans in a social space which promotes productivity and team building. Alongside is galley, shower and washing space, as well as a laundry space.
The 21m2 forward deck space is equipped with a pressure washing system from Hercules, specialist equipment that can be used for cleaning down the towers T-pieces. It has the preparation for a hydraulic deck crane, as well as sporting a fuel transfer system and a Hercules hydraulic windlass. Towards the aft you’ll find another 20m2 space, with each deck having the sockets to lock in a 10ft container.
The quality of build and expertise in finish are something that cannot be ignored. The craft and integrity of the build team shines through, and teamed with its fantastic and unrivalled level of technology, Trearddur Bay truly deserves its title as world class.
Mr Robson reminds us, “Trearddur Bay does a 360 degree circle around a 250 metres radius, but does it without much loss of speed,” he said. “If you did this kind of hard lock turn with a conventional water jet, you’d usually find the jet gets deflected onto the nozzles with a resulting loss of thrust and momentum: the boat then just drops off the plane and will probably stop. This boat just keeps going.”
Trearddur Bay is a triumph for Aluminium Marine Consultants, speaking volumes for the integrity of their builds, and the fantastic workman ship that they offer, producing pioneering vessels that could change the face of an industry.