KEY POINTS:
Every fisherman knows the frustration - the boat picks up a few knots and the fish-finder goes on the blink.
The problem could become a thing of the past thanks to two engineering students from the University of Auckland.
Maria Ogle and Luke Fowler have designed and built a transducer that works at 48 knots - the top speed for most recreational boats.
"When a boat is travelling at high speeds you obviously cannot fish, but it is useful to be able to see depths and follow shelves beneath you," said Ms Ogle.
Transducers are a key component on fish-finders. Attached to the stern of the boat, they send acoustic waves into the sea that measure depth and the presence of fish. That information is relayed to the on-board fish-finder screen.
But many lose their ability to detect depths and underwater objects at speeds above 30 knots.
The students discovered water vapours were forming underneath the transducer at high speeds, causing it to lose its signal. They designed a new elliptical-shaped device that improves the water flow and pressure on the transducer surface, allowing it to successfully transmit into the water.
The design also increased power efficiency by 21 per cent.
The product was developed in conjunction with Navico, the technology arm of Navman, and the final designs have been submitted to the company.
"We carried out full-scale testing on Navman's high-speed boat and proved it to work as predicted," Mr Fowler said.
Chris Hill, mechanical development manager at Navico, said transducer design was a problem for all manufacturers and fishermen.
It was exacerbated by higher-speed boats coming on to the market in the past few years.
"Everyone is looking at this and coming to the same agreement that there needs to be improvements," Mr Hill said. "Maria and Luke's findings very much match what we've been looking at and their design bolsters work we've been doing."
