Lyra – Dutch Pilotage Tender Born Under a Lucky Star at Barkmeijer Shipyards

On 5 July 2013, Barkmeijer hosted a double celebration with the naming ceremony of the High Speed Tender Lyra and the launching of the Pilot Station Vessel (PSV) Procyon. Pilot Tender Lyra is the third of a series of five Pilot Tenders currently being built for the ‘Nederlandse Loodswezen’ (Dutch Pilotage) by Barkmeijer Shipyards.

This tender is an Aquila 2-Class (or L-Class) vessel with a deep V planing hull of 22.9 metres in length and a beam of 6.8 metres. Boasting a top speed of over 28 knots and a crew of three, she has seating in the wheelhouse for up to twelve pilots at any one time. These three tenders of the improved Aquila-class have an aluminium hull and are water jet driven. The other two tenders will be steel hulled, but otherwise the design is quite similar. An important difference, however, is that later are equipped with (conventional) propellers instead of water jets, making the vessels suitable for light ice conditions.

Whilst the PSVs are named after stars, Lyra and the other tenders are named after constellations. The Procyon and the Lyra are part of a major fleet renewal at the Dutch Pilotage, to replace vessels at the end of their life.

Barkmeijer Shipyards

”A ship has to be practical, durable and efficient, at sea and in port”; this straightforward maxim has been adopted as a standard by the leading Barkmeijer Shipyards. Barkmeijer has been a leading Dutch shipbuilder for some 165 years. They are specialists in customisation down to the smallest detail and have a fine track record in the construction of bulk carriers, dredgers, tankers of all types, fishing vessels and container ships. Barkmeijer pride themselves on their ability to produce a customised vessel to satisfy any client requirements, as they believe that nothing is impossible until proved otherwise.

Among the large range of ships being built, are also PS Vs and Pilot Tenders. Initially Barkmeijer signed a contract with the Dutch Pilotage to deliver three such PSVs. The success of this was confirmed when Barkmeijer were awarded a second order for five tenders. The building of the tenders is done in close collaboration with No Limit Ships in Groningen. No less than 25 local subcontractors from the Dutch provinces of Friesland, Groningen and Drenthe were involved in the development of these vessels, thus providing a strong benefit to the northern Dutch shipbuilding industry.

Improved Aquila Class – aluminium hull with water jet

As stated above, Barkmeijer is building two versions of the tenders, a steel and an aluminium hull version, both however with an aluminium wheelhouse. The three jet driven aluminium tenders are the successors for the Discovery-class currently in use, which will be replaced after about 16 years of service. In 2010, the Dutch Pilotage had three Aquila-class ships built in the United States. This ‘long-distance’ collaboration, however, did not always quite meet the expectations and this experience drove them back to the Dutch craftsmanship of Barkmeijer. Together with a few Dutch partners, Barkmeijer developed the Aquila 2-class, also known as the L-class. Lynx was the first tender in this class, followed by Lyra and Lacerta, to be delivered in 2014.

Two Hamilton water jets, delivery AMW, each driven by a Caterpillar C32 ACERT engine of 969 kW, propel the aluminium vessel. The water jet pushes a large volume of water behind the vessel, thrusting the vessel forward. This is done by means of a tunnel inside the hull which houses an impeller. Steering is achieved by controlling the nozzle from which the water exits. By placing a deflector in this jet stream, it is possible to reverse or hold the boat stationary. A reversing reduction gearbox has been installed between the engine and water jet. This enables

Practical, durable and efficient

back-flushing when rope, plastic or other floating debris is imbibed into the jet pump.

This propulsion system makes the tender very manoeuvrable and even moving sideways is possible. The emergency stopping distance of the 56 ton vessel, at full speed, is no more than one ships length, whilst the turning circle is approximately 40 metres. When stationary obviously it can turn in its own length.

So far, the principle of the first Aquila-series appears to be quite similar to the Mark 2. In terms of changes, between the original Aquila-class to the upgraded L-class, there are quite a few though. To be specific, in total more than 100 items have been changed, of which a few of the most significant will be listed below. To start with the classification society: the tenders have been placed under Bureau Veritas (BV) instead of American Bureau of Shipping (ABS). The air-conditioning systems are different and have an increased cooling capacity to create better climate conditions. The electrical systems, both AC and DC, have been redesigned, especially in respect of the requests for the Dutch Pilotage for more redundancy. The construction of the interior carpentry and finishing has been rethought and improved to obtain more strength (= less vibration) and a higher level of ergonomics. Also a new Poly Marine fendering system has been applied, which will be described below.

The Soottech installations have been deleted and replaced by a new exhaust system, thus resulting in more space and accessibility in the engine room. As icing on the cake the new tender produces considerably less noise, due to the application of improved fire insulation and sound proofing materials, in combination with the modified wet exhaust silencers.

However sophisticated as this vessel might be, the design is not suitable for sailing all areas of the North Sea, especially in colder conditions. The reason is that the cooling systems of the water jets and engines can be blocked by floating ice or in worst case freeze. Hence the desire for an alternative tender configuration.

Development of the Hercules/Hydra-Class – steel hull with propeller

Almost simultaneously with the new Aquila-Class a similar steel hulled sister was developed to allow operations in light ice conditions. The design of this steel tender is similar to that of its new aluminium counterpart with one important difference, this tender is equipped with propellers instead of water jets.

This steel tender has a system in which a large part of the hot cooling water, produced by the engine, is reused to melt the sucked in ice. In the sea inlet box the hot water is mixed with ice water and the resulting warmer water goes back into the engine.

The five-bladed 950 millimetre propellers, developed and delivered by Sip Marine from Drunen in the Netherlands, are optimised to perform at relatively high speed in water with floating light ice. They are additionally strengthened to crush the encountered ice and the Developed Area Ratio was increased to 140% to obtain optimal thrust with a given pitch, whilst at the same time restricting cavitation. To match the performance and strength of the propellers, the propeller shafts are larger in diameter. The propeller shafts are driven by the main engines through ZF 3050 reversible reduction gearboxes with trawling valves. Both tender types employ the same Caterpillar C32 ACERT main engines. To provide additional redundancy, the rudders have two separate steering systems, each with their own two dedicated hydraulic pumps.

An ‘ice belt’ has been created by increasing the thickness of the shell plating to 16 millimetres around the waterline. Elsewhere plating was limited to six millimetres, to keep the weight of  the vessel at an acceptable value. The steel hull has tunnels in way of the propellers.

Other ice modifications include the deck, which is fitted with an electric heating system from the stern all the way to the bow. The handrails, crucial for the pilot’s safety, are also heated, as are the three front and the two most forward side windows. This tender configuration has Bureau Veritas ‘ICE’-class notation

Lyra/Aquila 2-Class – Meeting the demands

The functional requirements ‘sufficient power’ and ‘a high level of redundancy’ were at the top of the wish list of the Dutch pilotage. The third place requirement was ease of maintenance, accessibility and serviceability. The combination of Hamilton water jets and Caterpillar engines met the requirements for sufficient power, in other words ‘thrust’ and ‘speed’. This combination provides great manoeuvrability; even better than the steel/propeller version.

A high level of redundancy, in combination with the thrust/speed/manoeuvrability requirements, is indispensable in emergencies. When the crew have to abort any manoeuvre in close vicinity of vessels and start an emergency breakout procedure to prevent collision and clear the area, they have to be able to rely on the vessel. Even a single point failure condition, resulting in the unavailability of one drive-line or generator should not impair the tender’s capability to initiate emergency breakout procedures. To provide that level of redundancy, all engine, propulsion, generator and most electric equipment is duplicated, resulting in an impressive length of 6.5 kilometres of installed cable. Wolfard & Wessels Werktuigbouw was responsible for co-designing and installation of all technical spaces.

To provide easy maintenance, accessibility and serviceability the tender is fitted with many access hatches to relatively spacious technical spaces. The wheelhouse, in fact, is built as an easily removable separate module and bolted to the deck on eight flexible mounts. The joint between hull and the superstructure is sealed with a flexible silicon seal. All connections between wheelhouse and hull are via the junction box, fitted to the part of the hull protruding into the forward section of the wheelhouse. This assembly method also reduces noise and vibration transfer.

Lyra/Aquila 2-Class – Exterior design features

One of the most eye-catching exterior details is the fendering. The strong, energy absorbing fenders are supplied by Poly Marine Service.

Steel versus aluminium – water jet versus propeller

The material was carefully considered given the operational requirements of the tender, constantly going alongside larger vessels. The fenders are fitted between two longitudinal triangular aluminium profiles by means of stainless steel pins. All aspects were carefully considered to facilitate easy replacement.

Fitted to the transom is a hydraulically powered aluminium rescue platform for man overboard recovery. In the event of ‘pilot overboard’ (this will always happen near the bow) the tender backs-up and the person is guided to the stern with the aid of a rescue hook, then assisted into the net and rolled on board hydraulically.

Handrails (instead of railings on the side of the deck) and a safety traveller system are fitted to the side of the wheelhouse, all the way around protruding onto the fore deck on one side and ending near the entrance of the accommodation on the other. This way safe transfer of pilots to vessels is provided. The travellers run on a 360-degree symmetrical four-point-star-shaped rail, specially developed by/for the Dutch Pilotage.

The bollards on deck are angled inward to prevent damage occurring when the tenders are rolling in the swell of the North Sea. For all exterior lights, Barkmeijer chose LED-systems, thus reducing the energy consumption and heat developed. Mechanical ventilation inlets in the sides of the wheelhouse are Spraybest louvres with mist eliminators on the inside. These are developed specifically to withstand the amount of green water to be expected on these types of vessels and still have a low air intake speed.

Lyra/Aquila 2-Class – Interior design features

The wheelhouse is fitted with all state-of-the-art nautical, navigation and communication equipment. Communication with and ‘tracking’ of the pilots not on board is also well provided and all pilots are ‘armed’ with a personal life beacon.

The engine room layout is relatively unchanged, compared to the first Aquila’s, however by applying other and better equipment (and omitting certain components that became superfluous) more space could be gained. An additional advantage of leaving all components in almost the same spot, was that the well-balanced centre of gravity was maintained. The main engines are, as stated above Caterpillar C32 ACERT 2 DITTA with heavy-duty power output of 969 bkW at 2,100 rpm. The two diesel engine driven generator sets are Northern Lights, providing 400/230V three phase 50Hz AC at 1,500 rpm with a continuous output of 32 ekW to provide power for air conditioning, heating and domestic facilities.

The shaft between the engine and the impeller flange is a hollow carbon shaft; this presented Barkmeijer with an interesting challenge as it passes through a watertight bulkhead. While class obviously focused on a watertight seal around the shaft in way of the bulkhead, the potential leakage through the hollow shaft could not be ignored and a plug had to be inserted inside the shaft.

A wet exhaust system has been adopted for the main engines and generators sets. The seawater cooling flow of the respective engines cools the exhaust system. Cooling water is injected into the Halyard synthetic exhaust silencer and discharged, with the exhaust gasses, through the vessels hull just above the waterline. The machinery spaces are protected with a Novec fighting system, which is manually operated from the steering position.

Both tender types are again an extreme good example of Dutch craftsmanship by Barkmeijer and a wide range of Dutch partners. The deployment of these vessels improves port accessibility and the Dutch Pilotage will thus make an important contribution to the success of the Dutch seaports.

Tom Oomkens & Andrew Rudgley