The brief for newbuilds Mercury Clipper and Jupiter Clipper was for less weight and more energy efficiency. Passenger Ship Technology went to check their progress at Wight Shipyard and to find out more
At first glance, MBNA Thames Clippers’ new catamarans – named Mercury Clipper and Jupiter Clipper – are the same design and construction as their Hunt class sister vessels delivered two years ago.
But scrape the surface, and differences in terms of weight and energy efficiency become apparent.
MBNA Thames Clippers chief executive Sean Collins said that the new boats were likely to end up 2.5-3 tonnes lighter than the sister vessels which were delivered by Incat in 2015. Mercury Clipper and Jupiter Clipper, due to be delivered at time of writing in July, are being built by the UK’s Wight Shipyard Co for operation on the River Thames in London.
Mr Collins said: “The aviation techniques that are being applied enable weight reduction. Non-structural areas have been riveted instead of being welded which has also led to a reduction in the thickness of the plate required on the superstructure area of the vessels. This is crucial to reduce power and emissions and achieve the speed that we need. We constantly fight against those competing priorities from a safety, durability and maintenance perspective.”
Wight Shipyard Co senior technical advisor Roy Whitewood explained: “The weight saving is about a lot of little things.”
He gave, as an example, the fact that the catamarans are glued together in some places rather than welded – in the structure under the windows, for instance. “We took the glueing technique from the aviation and hovercraft industries. We can use thinner, lighter material in the parts that do not need to be welded.” Indeed, the aluminium used where glueing is applied is only 2mm to 3mm thick.
Another technique that contributed to the weight saving was the use of carbon fibre shafts rather than steel drive shafts for the engines and jets. This not only saves weight but also cuts down on noise and vibration, as not as many bearings need to be used.
Furthermore, the use of vinyl rather than paint to coat the hull saves weight. Paint weighs more than vinyl and at least four coatings of it are needed, as opposed to one coating of vinyl. This solution was also used in the earlier Hunt class vessels. Vinyl has other advantages, too. It is quick to use and replace as it can be peeled off and stuck on, and it is good for production as no fumes are emitted.
Alongside weight – and indeed linked to it – energy efficiency is very important. Mr Collins highlighted, as an example, the energy efficiency of the first Hunt class vessels. While the agreed contract speed was 25 knots at 90 per cent FCI (fuel consumption index), they achieved 27.5 at 80 per cent. “This shows what a good hullform these vessels have. They are a first in class on which we plan to expand with our naval architects, One2three in Australia.
“The brief to the designer was that the vessels would need to be extremely shallow draughted and at the very least have the same – ideally better – wash characteristics as our existing fleet. This is to enable them to operate in the shallow waters of our route to the west of London while producing minimal wash.”
The new vessels will also boost energy efficiency by operating bilge pumping equipment and auxiliary pumping equipment under direct current (DC) from the main engines, as opposed to through the generators. “We have got to have the generators because of the HSC Code [IMO’s International Code of Safety for High-Speed Craft], but we only use one generator at any one time. Using DC means that there is a lower power specification for the generator.” While the previous Hunt class vessels also use DC, Mr Collins said: “We have gone a step further with these current vessels.”
In terms of layout and design, Mr Collins said that “aesthetically there is very little difference” between the two sets of ferries. The only, minor, differences are that the layout of the back decks has been rearranged to accommodate more bicycles, because of considerable demand to take these on board. The seat specification has been changed, as well – from a seating capacity of 150 persons on the first Hunt class vessels to 172 on the newbuildings.
“We have included more seats to meet commuter demand on route RB6 [from Putney to Canary Wharf] as well as greater off-peak custom with tourists,” said Mr Collins. Jupiter Clipper and Mercury Clipper will be serving Battersea Power Station on the south bank of the Thames, which is being redeveloped.
When it comes to propulsion, two Rolls Royce Kamewa 40A3 waterjets have been fitted to the vessels. Mr Collins said: “Low wash is very important and is a significant contribution to enabling us to operate in the low water conditions. The waterjets also offer good manoeuvrability and assist with access in and out of the difficult locations of some piers.”
Scania engines are used on Jupiter Clipper and Mercury Clipper, as well as on the previous Hunt class vessels and on Thames Clippers ferries Star Clipper, Storm Clipper and Sky Clipper. Each newbuild is equipped with two Scania DI16 072M marine diesel engines, rated at 625kW (850hp) at 2,100 rpm. These are an efficient combination when it comes to combatting vibration. The engines meet all environmental regulations and have minimum sulphur emissions. They are also 2-3 per cent more efficient than other, similar engines.
Silver foil protection that has A60 fire rating has been used in the enginerooms, which means that a fire can take hold for 60 minutes without it melting.
Summing up the advantages of using a local shipyard as opposed to one in Australia, where the previous Hunt class vessels were built, Wight Shipyard’s chief executive Peter Morton said: “The relationship with the end user is a lot better. It means that Thames Clippers’ in-house staff, such as its engineers, are involved in the building. This means that when they take delivery of their ferries the snagging surveys have already been done. There are a lot of advantages to building locally.” These include the specific skills, such as its welding expertise, that Wight Shipyard is able to offer thanks to its location (see Wight Shipyard's winning welding techniques).
HSC Code: adding weight to Thames Clippers’ newbuilds
MBNA Thames Clippers’ first Hunt class vessels have been designed to comply with the International Code of Safety for High-Speed Craft (HSC Code) Category A with MCA (Maritime & Coastguard Agency) Equivalences appropriate to operation solely in UK Category C waters. This aspect makes the ferries stand out – they are the first of Thames Clippers’ fleet to be built to the HSC Code and a rarity among high speed river vessels. Most vessels of this type are not built to the HSC Code, which tends to be used for ocean high speed ferries. It is something that chief executive Sean Collins has questioned, as he does not believe that river craft need to satisfy all the requirements that ocean high speed ferries need to meet.
One of the HSC Code requirements that added weight to all the Hunt class vessels was the need to have 100 per cent redundancy in liferafts. The catamarans are double-bottomed, too, as a result of HSC Code requirements – again, something not normally seen on a river boat. High speed ferries are typically double-bottomed if they sail the oceans, so that they will be protected if they hit objects such as containers. It was challenging fitting the double bottoms on the Thames Clippers catamarans in terms of size and available.
Wight Shipyard’s winning welding techniques
A particular benefit of using Wight Shipyard Co is its expertise in welding. MBNA Thames Clippers chief executive Sean Collins said some of the welding techniques used are “the best I have ever seen.”
Wight Shipyard has shown innovation in its use of machinery to build the operator’s latest vessels. It has built a bespoke machine to create any compound curvature that is needed, such as round bilge hull plates. This speeds up the process as it means everything is manufactured on site.
One reason that Wight Shipyard’s welding is so good is the heritage of local industry. The yard’s chief executive, Peter Morton, told Passenger Ship Technology: “Both the aircraft industry and the hovercraft industry have had a strong presence on the Isle of Wight, which means that there is a history of welding here. If you have good training and a good standard around you, then the whole standard rises. I would put our welding up against anyone. The feedback we get from naval architects and others is that our welding is better than virtually anywhere else.”
Hunt class: main suppliers
Scania (Great Britain) | DI16 072M engines with ZF 2000 gear boxes |
Rolls-Royce | twin Kamewa S40-3/CA waterjets |
Aalco | aluminium, stainless steel, plastics |
G James Glass & Aluminium | aluminium extrusions |
Beta Marine | marine diesel generator set 42kW, 400V 3-phase |
Beurteaux | seating (tourist passenger and crew) |
Hercules Hydraulics | foredeck winch |
Ceiling Works | ceiling systems |
PSP Logistics | freight handlers |
SEC Marine | electrical and lighting outfitting |
Greenham Regis | main navigation communications equipment |
Furuno DRS4D-NXT solid state digital radar scanner | |
Sailor 6222 VHF DSC Class A transceiver | |
Furuno PG-700 fluxgate compass | |
Furuno GP-170 GPS | |
Fireboy-Xintex | fire detection and FM200 fire suppression |
Exalto | windscreen wipers |
Ixus Distribution | Fujitsu air conditioning system |
Survitec Group | lifesaving and safety equipment |
Seaglaze Marine Windows | windows and doors to pattern |
Grapefruit Graphics | vinyl wrapping |
i-Line Counters | saloon coffee bar |
Main statistics
Length 35.37m
Length waterline 32.45m
Beam 8.30m
Hull depth, moulded 2.15m
Load draught 1m
Passengers 172
Crew 3
Class Lloyd’s Register
Sean Collins, MBNA Thames Clippers: snapshot CV
Sean Collins has been at the helm of MBNA Thames Clippers since the inception of the business in 1999. At that time it operated one boat with a capacity of just 62 that served three piers and employed two crew. Today, Thames Clippers has an annual turnover of over £20 million (US$25.7 million), and employs almost 340 people. The business operates 19 vessels. Mr Collins began his career aged 16 in 1984 when he was apprenticed to the Company of Watermen and Lightermen. During his career on the River Thames, Mr Collins has worked as a captain on passenger vessels and tug boats.
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