Croker Oars, Flutes and Innovation

Isaiah Harrison winning US Rowing Youth Nationals using RANDALLfoils

I was driving out of Sydney with a pair of sculls strapped to the roof of my car, singing along to the radio. I had shared my hydrofoil blade discovery with Howard Croker, founder of Croker Oars, and his son and business owner Darren. I had discovered that applying a hydrofoil to the top edge of the blade greatly improved blade stability and boat speed. The Crokers were kind enough to invite me up to their rural property on the Manning River, to show me their oar factory and to entertain my enthusiasm for blade design.

Playing on the radio was the song “We come from the land Down Under” by Men at Work, Australia’s much-celebrated but unofficial National Anthem. (if you don’t know it … follow this link https://youtu.be/XfR9iY5y94s). It is a song that has also become synonymous with Australian copyright law after it was pointed out on a tv game show, that the flute solo is a direct copy of the children’s classic “Kookaburra sits in the old gum tree” (further interest … https://youtu.be/OTR0awcvVN4). A judge awarded the copyright owners of the children’s song 5% of all royalties.
Australia has a history of creative innovations, but we have learnt some hard lessons and I was to discover that the Croker’s have had their fair share. Having a creative concept or an insight into a potential innovation is perhaps the smallest component of what it takes to be successful and there are many dangers, even an innocent flute riff can cost millions.

The most famous Australian innovation was the winged keel on the yacht Australia II, winning the America’s Cup in 1983. Such was the national significance of the design that it changed Australia’s understanding of its place in the world and any new Australian innovation is declared “the next Winged Keel!” Yet the design came at a huge cost to the designer Ben Lexcen who had to fight hard to get it adopted by the Australian crew, gain official certification and survive sustained legal challenges from the competition. The crew members of Australia II were reluctant to use the keel after it returned from the Netherlands following tank testing when it didn’t handle and feel like a ‘normal boat’. In the era of foiling America’s Cup AC75’s the purpose of the winged keel seems self-explanatory but at the time the concept and on-water performance were entirely unfamiliar to the crew. Not only did the keel provide greater lift, but also stability and lightning-fast manoeuvres. What did the crew expect of the new design? The primary purpose of any design innovation is to create improved performance and not the consistency of feeling. It was the principal investor, entrepreneur Alan Bond, who believed in both the designer and design and insisted that the keel be used. History is now written.

The link between the famous keel and my hydrofoil rowing oar was all too real for me and I hoped that the Croker’s would also recognise it and together we would write a new chapter in Australian sporting history! Up in Taree, I unwrapped my oars and laid my foil prototypes out on a table. I saw Howard and Darren look at each other and roll their eyes.

Howard explained that the rowing oar already is a “foil” but more complex than any other (footnote: ‘foil’ defined as a surface set against the natural flow of a liquid to create lift). The rowing blade is a far more complex foil than a sail, propeller or wing as these only have to work in one fluid and in one direction. Whereas a rowing blade operates in two different fluids moving in multiple directions. The blade needs to operate efficiently in both air and water and any inefficiency in one will upset the performance in both. It is easy enough to visualise the blade going in and out of the water at the Catch and Release. It is difficult to visualise what is going on with the water during the stroke, and impossible for a computer to model.

Howard went on to say, at the Catch, the water is moving in across the blade as the oar is moving out and away from the boat. At perpendicular, the water is beginning to change direction toward the Release where it moves out and away from the blade. The water needs to be able to flow across the surface of the blade freely to enable the full efficiency of the blade to come into effect. Not understanding this complicated flow of liquids has seen the development of the Vortex Strip – intended to provide ‘grip’ and encourage water to ‘stick’ to the back face of the blade – it is the very opposite of what Howard understands water needs to do.

Darren commented on my prototype blades and acknowledged that the top edge of the blade has long been identified as having possible performance potential. In the ’90s, they were involved in a costly design project with the Sydney University Computer Science department who had claimed to have mathematically modelled a rowing blade. Based on this model the team had scientifically designed a new blade with a revolutionary ‘top edge’ to capture the flow of water over the top of the blade. Croker Oars had invested time and money in this joint venture to create this revolutionary design. Darren showed me the blade and said that while it might have been good in a computer simulation, it simply could not be rowed. The design turned out to be completely unsuitable for rowing. This blade had a large top curve or wave formation, much like a contemporary kayak paddle. The blade and the top edge wave could be buried at the Catch but would jam in at the finish as it couldn’t be released from the water. They spent hours seeking to make the waveform work by shaving it down millimetre by millimetre until it would release. The only way it wouldn’t jam was to remove the waveform completely. The project was abandoned.

I am extremely grateful to the Croker’s for sharing their research with me and for their work in conclusively showing how the top of the blade should NOT be formed. The Randall foil offers a new solution to unlocking the potential of the top edge, but understandably the Croker’s declined to revisit this work. The Croker’s and I both identified the performance potential of the top edge of the rowing blade, we have sung the same songbook, though the Randall foil has a completely different flute solo.

Note: The Randall foil is designed on the principle of the hydrofoil and not like the Sydney University waveform blade.

About The Author

Ian Randall

See author's posts