Following a refit of its propulsion system, the trawler Jette Kristine has increased its bollard pull. The refit, carried out in Frederikshavn, Denmark, replaced the propulsion gear with a new propeller and nozzle.
Jette Kristine was given a bollard pull test prior to being taken out of the water. The result was pull of 19.1 tonnes. The test was repeated after a two-week refit on the PrimeServ slipway, with an impressive result of 23.6 tonnes – a 23.5% increase.
The team ensured that the test conditions were exactly the same both time, even as far to place the vessel in the same area in the harbour, with the same depth of water and the same draft and trim of Jette Kristine in order to make the test as fair and accurate as possible.
The new propulsion system is also a means to improve fuel efficiency and save costs. The potential to reduce more than 12% in fuel consumption is possible, as new propeller designs are more advanced than 10 years ago. The change in design means the blades are optimised to perform more efficiently.
Man Diesel upgrade solutions can be applied to not just trawlers, but also tugs, dredgers and offshore vessels. Bollard pull is important to the performance of all these working boats.
The upgrade can just be for the optimised propeller blades, or it can include the propeller nozzle as well. The recommended choice is for apply the optimised blade propeller alongside a newly designed nozzle, the Alpha High Thrust (AHT) nozzle.
This new nozzle has increased efficiency due to its design features, which include the double curved inner and outer nozzle profiles. The AHT was developed with advanced CFD tools to ensure optimal performance. They highlight the superior performance when compared to older 19A nozzles common in the marine industry.
Jette Kristine’s owner, Niels Arne Hounisen, based in Esbjerg, Denmark, took the vessel out for two fishing trips to evaluate the new propeller and nozzle in real life conditions.
As far as Hounisen was concerned, the new propulsion system lived up to the promise, delivering better towing power. He noted the difference between the old and the new propeller, stating that even though the old propeller was not outdated, the new MAN Diesel propeller gave him an extra 0.5 knots.
Other benefits were improved fishing gear control and vastly lower noise controls, which has made working (and living) conditions better for him and his crew.
However, the reduction in fuel consumption of more than 15% at trawling speed was the most important improvement Hounisen has seen.
