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


The following testimonials to our products and service are true to the original writer. They are not edited in any way beyond correcting the occasional spelling mistake and removing private addresses.

Dear Ben Hawke,

                            Nutmeg: Autostream propeller

Nutmeg is a SHE 36 designed as a cruiser/racer by Sparkman and Stevens and launched in 1977. A photograph of her is attached. Using the usual formula, Nutmeg has a theoretical hull speed of 7.6knots.

In the autumn of 2002 I decided to replace the old Volvo MD11D engine with the modern 30hp Lombardini LDW1003M. I needed a new propeller because the new engine was right handed, I chose the Gori 3 bladed folding unit. In sea trials and use, this propeller proved to be a really poor match for the engine-boat combination. The engine would not achieve full rpm and boat speed was worse than with the old 25hp Volvo. In addition, this propeller exhibited vicious prop walk in astern. After arguments with the manufacturer, I returned the propeller.

Having seen an advertisement for the Autostream propeller I decided to enquire. My email was promptly replied to and Seahawk recommended the 17inch 3 bladed Autostream. They also offered the Slipstream 2 bladed folding propeller. I went to see the propeller at the London Boat Show and was impressed by its sound engineering and the simple pitch adjustment arrangement. I was also pleased to see that I could adjust the reverse pitch separately from the ahead because as no marine gearbox has the same reduction ratio in both directions. I chose the feathering propeller because I could adjust the pitch to correct any mismatch between the engine, propeller and boat that might become apparent in sea trials. I was promised delivery for my new propeller in 3 weeks, and this was achieved. Steel Developments, the local agents, had set the forward and reverse pitches to the recommendations of Seahawk.

I chose a nearly flat calm day for the sea trials. Leaving the marina berth was straightforward; the prop walk in reverse was much reduced compared with the Gori. During the maximum speed trial, Nutmeg achieved 7.9knots at 3500 engine rpm. This means that the engine, boat, and propeller match is very close to optimum. At a cruising engine rpm of 2500, Nutmeg’s speed was just under 7knots. In ahead, no discernable prop walk was found. In reverse, prop walk is still there. During my year’s experience with the propeller, I have reduced the reverse pitch. Now I have excellent performance in reverse coupled with minimal prop walk. When, during the season, I have scrubbed Nutmeg’s bottom, the performance has always returned. In all respects, the performance of the Autostream 3 bladed feathering propeller is excellent and is “chalk and cheese” better than with the 3 bladed folding Gori propeller.  

Regards, Nick Humphris

<< Previous | < Go Back to Index > | Next>>