A barge can save quite a bit of fuel if it has an extra sharp propeller rim. It is this advantage, among others, that has made van Jooren Scheepsschroeven, a Dordrecht-based company, such a success in recent years.
The interview on AD.nl features John Vermeulen, the inventor of a special grinding method that resulted in the Green Screw Edge. By grinding an extra sharp edge, the propeller has less resistance when spinning in the water. As a result, fewer propeller revolutions per minute are needed for the same heiferousness. This saves litres of fuel. Moreover, the propeller makes much less noise.
Up to seven per cent less fuel
At Jooren Scheepsschroeven, the company John runs with his wife and brother-in-law, they calculated that an average inland vessel, depending on the shape of the vessel, with an extra-sharp propeller edge, saves between three and seven per cent of fuel per month.
In the AD, John tells how he made the discovery by chance. He has been working in the family business for 30 years and while grinding, he was reminded of a conversation he had earlier with a skipper. In it, they discussed whether there would be advantages in sharpening the edge of the propeller. Purely by feel, Vermeulen dragged an extra sharp edge on the blade. The skipper who tested it was enthusiastic, particularly because it was much quieter in the house on board. After that, Vermeulen found more skippers willing to be test subjects.
Smoother through the water
After a while, the sharper propeller was subjected to a really serious test, at Dynamic Maritime Test Facility at the Sustainability Factory in Dordrecht. in a tube full of water, they ran a 'normal' propeller at full speed and then the propeller that had been machined by Vermeulen. This showed that the sharp propeller moved more smoothly through the water. "I think it has to do with top and bottom pressure," Vermeulen told AD.nl. "By sharpening the edge further, the flow on the water is changed in a positive way. So that produces less noise and ensures that the ship needs less fuel to still move forward." Additional tests in Spain confirmed the benefits of the Green Screw Edge, after which Jooren Scheepsschroeven applied for a grant for the innovation. A new product was thus born. "We grind the edge purely by sight," says Vermeulen, "but I carefully examine every screw that goes out the door. Quality control is very important."
The company will continue to roll out the innovation and deploy it more widely in the coming period.
Source: AD.co.uk - Photos: YouTube Jooren.
