Project Details
We completed an extensive engine room renewal and general refurbishment on the 34.8-metre Newlyn-based St Georges beam trawler in December 2017.
This was our second vessel overhaul as part of an ongoing programme of improvements to the fleet of 12 beam trawlers owned by W Stevenson & Sons Ltd. One of their objectives was to improve performance, including fuel consumption and more effective towing, among their boats. Several months earlier, in July 2017, we completed an upgrade of Stevenson’s Trevessa IV PZ 193.
We began our work on the vessel, originally built in 1974, by reviewing its existing performance, including the stern gear arrangement (propeller size and nozzle type) against its underwater hull shape. Based on this, we designed a new propeller and propulsion nozzle and worked out the gearbox reduction ratio best suited to the vessel’s new engine.
We removed a section of the vessel’s deck and hull plating on the portside of the engine room to take out the original Deutz SBV6M545 main engine, which had been re-rated to 750kw a number of years ago, and its Kuypers gearbox. We then fitted the new centreline machinery package consisting of a Caterpillar 32A main engine, a Reintjes WGF 675 11.818:1 reduction gearbox, a new tail shaft, seals and 2750mm five-blade propeller and high efficiency nozzle.
We selected this particular main engine because it is electronically controlled for optimised fuel efficiency, with a Wide Operating Speed Range (WOSR) for a flat power curve, enabling it to deliver full power when running at between 1600 and 1800 rpm, so that the large propeller can turn slowly for maximum propulsion efficiency. We also fitted a new Mitsubishi 6D24TC auxiliary engine to drive the electric winch motor.
We had to modify the underside of the keel with additional ballast totaling 12 tonnes of steel bar section, as well as adding six tonnes of concrete-topped steel bar to the end of the engine room, to compensate for the heavier weight of the new components. We lengthened the rudder to suit the larger stern components.
We completed an extensive amount of work which was not in the original plan without impacting on the initial deadline, in order to ensure the boat would pass its re-certification with flying colours. This included replacing the wheelhouse windows, cleaning and preparing its fuel tanks for ultrasonic testing, replacing the engine room access door, re-plating a section of the crow’s nest, renewing several bulwark rail pins and replacing two sections of hull where a thickness survey carried out while it was in dry dock showed evidence of thinning.
As a result of the upgrade, the vessel is achieving an average top speed of 11.5 knots and when steaming at 9 knots from 1200 rpm, uses 74 litres of fuel per hour, compared to between 70 and 80 litres when towing at around 4 knots with the main engine running at 1000-1100rpm.
This is the second project I have managed involving Parkol Marine (the first being the Trevessa IV), and again it was a delight to work with them. They are always prepared to go the extra mile and do everything they can to support the client’s needs. The scope of works was once again delivered on time and on budget.
Marine Surveyor & Consultant Peter Fenna, of MetOcean Ltd.