Siabo delivering beyond expectations for Norman R. Wright & Sons

Norman R. Wright & Sons are famous for building quality boats over the last 110 years that deliver on their design promise. A pair of Yanmar 6CXBM-GT engines in their latest pilot boat design has exceeded those expectations – and more! Story by Mark Timmerman.

In yet another first for Yanmar Marine, Norman R. Wright & Sons’ brilliant new XLW Class Pilot Boats being built for the PNG Ports Corporation of Papua New Guinea are using the proven propulsion power of Yanmar 6CXBM-GT engines.

The first of these state-of-the-art vessels, named Siabo, represents a significant advance in pilot boat design and seakeeping – utilising the XLW’s composite construction techniques that include a unique combination of resin-infused and pressed GRP cored panels. Recent testing off the Queensland coast is proving their design with superb results in performance, stability and efficiency with the 6CXBM-GT’s onboard.

Norman R. Wright & Sons Managing Director Tony Riek spoke with Power Equipment about the company’s new 14.2 metre pilot boat design and Yanmar engines;

“With 110 years of boat building experience, and having built literally dozens of pilot boats, you could say we understand what pilots and coxswains need in these applications,” said Tony.

“Based on hull form work we’ve done for a long time, the XLW represents the latest improvements and a heap of time we’ve put into the overall structure.”

Tony is referring to design improvements such as the XLW’s lower centre of gravity and impressive new warped planing hull. A wheelhouse built as a separate component and attached via isolated rubber mounting blocks also makes for a kinder operating environment for those onboard.

The lower centre of gravity was achieved with close attention paid to positioning key components of the vessel lower inside the hull, including the Yanmars, fuel tanks, water tanks and batteries.

At only 17.4 tonnes fully loaded however, (that’s with 2,400litres of fuel, 300litres of water and nine crew onboard), weight savings have been helped by the comparatively light weight of the 6CXB’s, (at 856kg dry weight), and their slim overall dimensions.

“The fact that the Yanmars are a small package and light weight works well with this design – they really do seem to do everything needed in this application,” Tony says.

“This boat also has a longer waterline, the equivalent of a 15+ metre boat really which increases performance,” explained Tony.

Simple, easy to maintain engines

PNG Ports Corporation wanted Yanmars powering their new pilot boats, citing local support and good local acceptance for the brand as factors in this choice.

Other fleet operators, (especially those in remote territories), have had good results with the Yanmar 6CXB and like the uncomplicated design and low cost of ownership benefits that the 7.413 litre displacement Yanmar 6CXB series offers.

“They also wanted a simple engine that is easy to maintain and repair if necessary,” explained Tony.

The 6CXB series of engines, designed specifically as a marine engine, incorporate ease of maintenance features such as a 500-hour service interval, easy-to-replace spin-on type oil filters and large inspection windows on the side of the block that allow in-situ replacement of pistons if ever necessary.

Like the entire Yanmar range, they’re built tough and incorporate improvements over previous generation components like larger piston pins and bushes, an improved fuel injection pump along with an increased capacity sea water pump and intercooler.

Yanmar even offer a high-capacity front PTO across their commercial marine engine range which is unlike many of their automotive based engine competitors.

Don’t be fooled however – this engine delivers far and beyond its PTO, easy-servicing and inspection benefits.

The “M” rated 6CXBM-GT Yanmar model going into the XLW Pilot Boats delivers a medium duty rating (applications up to 3000hrs per year) of 294kW @ 2500rpm of propulsion with alternative ratings of 341kW and 374kW @ 2700rpm available for applications with less annual utilization.

“This boat is using around one-third less fuel than any other pilot boat we’ve designed…”

Under load these engines deliver in spades with heaps of torque-rise in reserve, offering the advantage of minimal speed reduction against sudden load changes.

That makes for handy control capabilities when skippers are needing to position safely alongside big ships both at anchor and underway in pilotage transfers.

They can also be matched against a wide range of propeller variants, making them a favourite across multiple commercial applications. Propellers on the Siabo are a four-bladed design with 27.5 X 28.5 X 4 dimensions.

The 6CXBM-GT delivers its torque peak not far above 1500rpm, yet delivers superb power and efficiency performance right up to its full rated speed.

At WOT, Siabo delivered a consistent 25 knots in official sea trials and has hit around 25.8 knots according to Tony.

“Based on our calculations for this new design, we had a pretty good idea of how the boat would perform,” Tony says, “but with the Yanmars it is doing better than we predicted.”

Using around 76 litres per hour (combined) at 18 knots, Tony says fuel consumption is proving to be a shining standout bonus from the Yanmars.

“This boat is using around one-third less fuel than any other pilot boat we’ve designed,” Tony says.

“Of course good hull design and weight are factors in this, but the Yanmars are also delivering great economy.”

“That’s going to be very pleasing to a client like the PNG Ports Corporation, because such operators are always looking to improve efficiencies and reduce costs where possible.”

So impressed with Norman R. Wright & Sons’ new XLW and Yanmar combination, PNG Ports Corporation ordered another two!