Dolphin inspired propeller alternative is just a fluke

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A Swedish company called Dolprop Industries has developed propulsion technology for small vessels that is based on the way that the tail flukes of whales and dolphins work.

The fluke is made from a plastic that offers limited flexibility and it is shaped to replicate a dolphin’s tail

The inventors claim it will eliminate cavitation and offer better efficiency than conventional propellers.

The Dolprop operates in some respects like a pumping hydrofoil with the foil able to move up and down under power. An earlier version that was installed at the bow of a boat was the basis of a wave-powered boat but whilst it worked there was no acceptance for wider applications. Inventor of the Dolprop Thomas Jemt claims that his Dolprop offers a better solution. “Dolprop’s target is to mimic the bottlenose dolphin motion pattern that provides phenomenal performance. The Fluke Technology proves to be both energy efficient, quiet, safe and practical.”

The fluke is made from a plastic that offers limited flexibility and it is shaped to replicate a dolphin’s tail. The drive system is designed to allow this Fluke to move up and down thus replicate the movement of a fish tail and this generates propulsive thrust. The challenge is to create a drive system that can turn rotary motion into the required vertical motion to power the flexible fin.

The solution from Dolprop is to use an electric motor in the hub of the unit and the company has been funded by private equity plus 1 million SEK from the Vinnova Research and Grow programme. This will allow Dolprop to develop a number of prototypes based around the concept of a low powered outboard motor. The outboard motor concept would incorporate steering and could be fully turned for reverse but if the system develops into a propulsion system for larger commercial vessels then steering may have to be achieved using bow and stern thrusters.

Jemt claims that the Dolprop would offer much higher efficiency than a conventional propeller and would be less likely to be fouled and harm marine life. Whilst the Fluke Technology has potential to provide an alternative and more efficient propulsion system for small craft operating in calm waters and the outboard motor version may offer this, translating this new propulsion concept into a commercially viable system will require major work particularly in the activation of the drive system and the construction of the fluke.

By Dag Pike