Seahawk - Feathering Propellers Seahawk - Folding Propellers
Home Feathering Props Folding Props VariProp Propellers Propeller Estimation Testimonials Zinc Anodes & Parts SAE Shaft Tapers Dealers Contact us
Choosing a Propeller Instructions & Old Models Trobuble shooting Dimensions Pitch estimation Common Questions Glossary/Materials The Autostream story About Seahawk Warranty Form


By Julian Barrett

I am what you may call a ‘self-taught engineer’ and in my younger days was keenly interested in aeroplanes and racing cars. My interest later turned to sailing and in particular to cruising sailing. At that time I owned an H28 (circa 1960-1970 with a mighty 28hp two-cylinder, two-stroke engine, driving a three bladed, cloverleaf style fixed pitch propeller. It was okay in calm water, but to beat into any adverse sea it was one step forward and one step back.

In those days propellers were pretty crude affairs. What was good for propulsion was bad for sailing, and although there were folding propellers, then, their reliability was questionable. I used to think of those large, beautiful aircraft propellers with controllable pitch and feathering capability and, in principle, how it would suit a sailing craft.

It was in 1972 during a sleepless night that I thought of the idea of what is now the Autostream propeller. However my idea was not the first of its kind. There was a very similar propeller displayed in a London museum dated 1898 and also a patent application dated 1923 so any thought I had of a patent was doomed.

I decided to go ahead and make one to see if my theory worked in practice. I made a test tank consisting of two intersecting drums four feet in diameter, which made a sort of figure eight shape, and the propeller was driven by a one-horse power reversing electric motor. I soon found out that the blade cross section had to be symmetrical, and that automotive lubricant was useless. After some trial and tribulation it worked fairly well, and it was interesting that when the propeller was feathered the swirling water would take some minutes to stop, but if the propeller was stopped in reverse, and did not feather, the water became very turbulent and stopped in a few seconds.

My next step was to get it onto a boat, and a friend of mine was brave enough to let me fit it to his yacht ‘Sea Mist’. It worked very well indeed, and never let him down during its years of service. I made two more of that design and they too were successful.

However although they worked very well they were large ugly lumps of things, and those who were interested suggested two blades instead of the three would be more popular.

The first two bladed propeller I made was also rather lumpy to look at. The first three I made were all fitted to boats and all worked well. I was now determined to design a propeller that had a visual appeal to yachties and the result was the present day two blader. The first was made in 1976 and was put on retail sale in 1977.

A company called ‘Preventative Maintenance Engineers’ took on the sales side, and then after about a year Terry Ryanč, until Wayne acquired the ‘Prop Shop’. A great relief it was for me when WayneČ took over the production of Autostream. What started out for me as proving my idea and a future hobby developed into a demanding one-man business. Counting the early propellers I made close on two hundred altogether.

The early propellers were made in a workshop belonging to a friend who had an electrical business. He let me use it so long as my work didn’t interfere with his, and I paid a nominal fee to cover costs of power etc. Later I equipped my garage with all the requirements necessary for production, which continued until Wayne came on the scene.

Wayne and I got on well together, and over the years we theorised and experimented and designed propellers to suit the market. Now Seahawk is producing the stainless steel series, precision investment cast and the best of its type in the world.

1 – Terry Ryan sold the Melbourne based ‘Prop Shop’ to Wayne Hawke in 1972. Terry went to Australia’s Gold Coast and developed the successful ‘Prop Scan’ Propeller measuring system.
2 – Wayne Hawke still runs the ‘Original Prop Shop’ repair business under the parent company ‘Seahawk Pty Ltd’. Seahawk has since grown to be one of the world’s biggest manufacturers of propellers for sailboats and is also one of only a few specialists’ in this area.

The photos above show the original 3-blade Barrett Autostream Propeller as produced by Julian Barrett. Seahawk still occasionally sees these in for service, even though they are well over 20 years old, a testament to Julian’s workmanship and design.

These early props had twisted blades and were manufactured in either right or left-handed configuration. Julian knew a Peter Joubert, who at the time was a Professor of Fluid Mechanics at Melbourne University, both a keen yachty and boat designer. Peter had designed his own variable pitch propeller that used flat blades. After some discussions on the advantages or lower drag and simpler construction, versus a negligible loss of efficiency, Julian changed his design to a flat blade. This flat blade has been improved upon over the years to become the current very thin and blade with large area at the tip and small area at the base.