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A propeller
with variable pitch and replaceable blades is this spring’s big innovation
- and not only in Sweden.
By LASSE GENBERG
Once
again, Sweden is at the leading edge in propeller technology. A recent
Swedish invention patented all over the world is a composite propeller
with replaceable blades, which can be adjusted to five different pitches.
It will facilitate the handling of propellers throughout the distribution
chain, all the way to the consumer. Let’s examine the new propeller from
the boat-owner’s perspective.
The boat-owner is five times more likely to find the right propeller, i.e.
one with the correct pitch, than when buying a conventional propeller. One
of the five pitches will undoubtedly be the right one. The propeller has a
range of five inches and 200 rotations/inch.
Being able to adjust the pitch according to the boat’s load is a useful
attribute, although not one necessarily required on a daily basis.
An indisputable advantage, however, is that retailers can now keep a
constant stock of propellers in the correct size. The new propeller comes
in four different sizes, covering the entire spectrum from 30-140 hp. This
means saying goodbye to those long, sunny days of waiting.
A further advantage is that even the smallest retailers in the tiniest
locations can afford to keep a full range of propellers in stock. The
propeller is available from Olds Engineering
Replacing the blades couldn’t be easier. Undo the bolts, remove the
damaged blade and attach the new one - you can’t go wrong. Adjusting the
pitch is equally foolproof. Loosen the bolts by 3-4 turns, then raise or
lower them. All the blades move simultaneously - that’s the patented
feature.
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Going aground inevitably damages a propeller blade or two. The blades on
the new propeller are easily replaceable, their cost varying according to
the model size. The new propeller, christened ProPulse, costs the same as
a standard propeller, approximately 2,000 SEK. This makes the cost of each
blade around 350 SEK.
Many people are doubtful about composite as a choice of material. But
composite, like steel, comes in both high and low quality varieties. The
composite used for ProPulse was developed by Sicomp of Piteå, owned by the
Swedish government and the Luleå University of Technology, and considered
a European leader in this field. The propeller is manufactured by
Formelprodukter of Boden. Tests have proved ProPulse to be stronger than
standard aluminium propellers in every respect, although the overall
winner was stainless steel.
Creating a variable pitch propeller is no mean challenge. Experts insisted
that this feature would cause the propeller to lose too much in
efficiency.
Anders Samuelsson of Piteå, the son of Erik Samuelsson, designer and
constructor of the Orrskär motorboats, chose to swim against the tide, and
succeeded in making the pitch adjustable by five inches, while getting all
the blades to move in co-ordination, at exactly the same pitch. Following
two years of tests, patent applications, market surveys and pursuing
manufacturers and distributors, ProPulse will be ready for the market this
spring. |
