VESSEL REVIEW | Siabo – First of three new pilot boats for PNG Ports Corporation

Australian boatbuilder Norman R. Wright and Sons (NWS) has delivered a new pilot boat to Papua New Guinea port operator PNG Ports Corporation.

Siabo is the first in a series of three to be built by NWS for PNG Ports. It utilises a design that NWS said was originally optimised for harsh Australian conditions but has been modified to meet the specific needs of the customer.

In addition to performing pilot transfers, the boat will also be used as a port security and coastal patrol vessel. Its area of operations encompasses Port Moresby and nearby ports within the Caution Bay area.

PNG Ports expects Siabo and its sisters will fill a capability gap caused by the limited availability of vessels specifically suited to pilotage duties in PNG. The acquisition of the new pilot boats is being done in anticipation of growing demand for pilotage services as more and more cargo vessels sail and in and out of the country.

Siabo has an LOA of 14.8 metres, a moulded beam of 4.53 metres, a maximum draught of 1.17 metres, and a displacement of 17.4 tonnes at full load.

Durability and seaworthiness were the attributes specifically requested by the customer, as the boat and its sisters will be operated for long hours in all types of sea conditions. The resulting design thus placed considerable emphasis on safety.

"The boat features a unique extra-long waterline for optimum seakeeping and efficiency and a warped planing hull with deep tunnels for high propulsive efficiency," NWS told Baird Maritime. "Along with new construction techniques and hull design, these features result in a three-knot increase in maximum speed with 100 hp [74 kW] less power compared to our earlier models of pilot boats whilst retaining equivalent strength and improved seakeeping."

One of the newbuild's notable safety-enhancing features is its unique hull. NWS said that fitting Siabo with a wave-piercing bow – as is the norm with many other modern pilot boat designs – would have made the craft more susceptible to negative effects in following seas. The builder thus opted for a novel approach wherein a hull bottom from a larger boat was fitted onto a smaller deck length.

"This gives us the superior seakeeping and efficiency of a much larger boat with a smaller displacement," said NWS.

The company also decided to design the boat with a reduced centre of gravity to ensure enhanced stability when alongside ships.

The boat is of remarkably sturdy construction to guarantee improved load-carrying capability.

"We worked very closely with ATL Composites to integrate a unique composite construction combining resin-infused and -pressed FRP foam cored panels with DNV GL approval. Also, the hull bottom is designed and approved for a 3g loading."

NWS said that FRP was selected over aluminium, which was in use in the few other existing pilot boats in the PNG Ports fleet. This was because FRP offered a lighter weight and sturdier construction, which then translate into improved efficiency and lower maintenance requirements.

The cabin is fully customisable to offer a broad range of available layouts. The wheelhouse is completely isolated from the hull to minimise vibration and noise transfer and has five UES suspension seats and a custom settee that can sit four people. The main access below deck is also undercover and within reach of the aft cabin door and importantly within view of the coxswain.

"This way," said NWS, "the coxswain knows where people are on the vessel at all times."

The cabin also offers uninterrupted 360-degree visibility thanks to a forward-raked windscreen and roof-mounted windows that will allow the coxswain to keep the pilot in sight during the transfer. The windows are custom-made by G James.

For patrol duties, Siabo will be operated at reduced speeds, thereby ensuring it will have enough fuel for up to three full days of operation. An onboard settee and a fully-equipped galley with cooktop, refrigerator, and microwave can provide the crew with comfortable accommodations and an adequate food supply when far from port for extended periods.

Although the design is intended to accommodate a range of engine options, PNG Ports requested that the boat be powered by two Yanmar 6CXBM-GT diesels, each with an output of 294 kW at 2,500 rpm, partly for ease of servicing. The driveline is a conventional twin-screw shaft drive fitted into deep tunnels, resulting in significantly reduced vibration. The engines coupled with the deep tunnels and the warped planing hull enable the boat to cruise efficiently at patrol speeds and to also sprint to a top speed of just above 25 knots.

The engines are located forward under a large deck hatch. This will allow replacement to be carried out in 24 hours if required. Engine room access is from outside of the cabin to minimise noise transfer.

The electronics were supplied by Ultimate Marine Power, which Wright said worked closely with the client to ensure the most suitable package for the boat's area of operations. These include a radar with 48-nautical-mile range, AIS, and NAC-3 autopilot from Simrad, an Airmar depth sounder, and ICOM radios.

The vessel also boasts a wide array of deck equipment and other external features that make it well-suited for its dual roles of pilot transfer and coastal patrol. A custom fender provides good impact against ships' sides when boarding pilots while a Harken safety rail runs from the rear cabin door around the entire vessel to provide safety for pilots upon leaving the cabin.

The decks are the required clear widths and are 100 per cent unobstructed in compliance to AMSA Marine Orders covering coastal pilotage. There are no deck fittings or obstructions anywhere in the pilot traversing area to reduce the risk of trips, slips, or falls.

Siabo is also adequately equipped for emergencies.

"There is a man overboard retrieval ramp on the transom in case any crew member or passenger falls overboard. This allows them to be safely retrieved by one person utilising the aft control station, which has its own steering and throttle. There is also a life raft recessed into the forward engine hatch as well as a dedicated safety zone on the foredeck for pilots to hold with a bag storage area."

Although a highly capable and versatile craft, Siabo was nonetheless designed to be as simple as possible, particularly with regards to maintenance.

"The client wanted ease of maintenance due to the fact that some ports will have limited infrastructure for certain equipment and parts," NWS told Baird Maritime. "All engineering was thus designed to comply with NSCV standards."

The builder spent considerable time reviewing the latest materials and construction techniques that would help the company deliver a capable product that also boasted long-term durability.

"The only challenge was time. When we started the build it was right when the Covid-19 pandemic began and although we were lucky with downtime, it still had an effect. Otherwise, everything ran smoothly."

Further, as this was the first vessel built by NWS using resin-infused and -pressed FRP cored panels, the company claimed it faced "a steep learning curve" in applying the new materials and processes.

Despite these challenges, NWS took the opportunity to invest in a new construction method developed in collaboration with ATL Composites for the building of Siabo. The company credits this method with enabling it to build Siabo and other semi-custom boats in a more cost-effective way and in nearly the same time frame as a full production boat built in moulds. Since Wright does not make permanent moulds for its boats, this alternative approach enabled it to deliver within a rather short timeframe a capable vessel that it claimed was essentially designed and built entirely from scratch.

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