AUTOPROP - Automatically variable pitch

AUTOPROP

The AUTOPROP:

The AUTOPROP's distinguishing feature is that each blade revolves 360°; this is what makes the AUTOPROP outstanding in that it automatically sets the optimum and most effective pitch for every craft speed. It is available as a 2 or 3-blade propeller, in sizes 13" to 35" for a power range of 6 to 294 kW.

Yacht with Autoprop

The manufacturer og the AUTOPROP is Brunton's Propellers Ltd., England. The compangny is not only famous worldwide for the AUTOPROP, but also, in particular, for its production of the approved S-class propellers for fast coastguard boats and luxury yachts.

SPW is an official distributor for the AUTOPROP.

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Design, development and quality

Autoprop

Design and development:
The development of the Autoprop was a result of our long-standing experience of manufacturing customised propellers. Our close cooperation with member companies of the "Langham Industry Group" and the affiliated research institute "Marine" has ensured that the AUTOPROP represents the absolute best in propeller construction. What's more, the AUTOPROP is produced using state-of-the-art CNC manufacturing processes.

Quality and material:

The Autoprop is made in accordance with ISO 9000. Before dispatch, each Autoprop is subjected to a test run in a test tank so as to guarantee its efficiency and proper functioning. For production, only high-quality, certified nickel aluminium bronze and stainless steel are used, which guarantees strength and corrosion resistance. The blades are made of "SUPERSTON", which is approx. 40% harder and stronger than conventional propeller materials. "SUPERSTON" was specially developed for the propellers of icebreakers.

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How does the propeller work?

Forward position

Autoprop forward position
In forward gear, the propeller automatically turns the blades to the correct pitch. One advantage of the increased propeller efficiency is the reduction in fuel consumption.

Feathered position

Autoprop feathered position
Under sail, the propeller turns the blades to the feathered position, which produces approx. 85% less drag than a 3-blade fixed-pitch propeller.

Reverse position

Autoprop reverse position
The AUTOPROP also automatically turns its blades to the reverse position, thus generating the same degree of thrust in both reverse and forward gear.
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Models and descriptions:

APS (AUTOPROP Saildrive):

APS (AUTOPROP Saildrive):
  • Diameter from 330mm to 460mm or 13'' to 18''
  • Available compatible with all saildrive manufacturers, such as Volvo, Bukh and Yanmar
  • The rubber-cushioned hub absorbs the shock of gear shifting and protects the saildrive
  • Stainless steel ball bearings
  • Anode is standard

H5:

Autoprop H5
  • Diameter from 380 to 510mm or 15" to 20"
  • For shaft diameter 20 to 30mm or 7/8" to 11/2"
  • For engines up to 75kW/100hp
  • Stainless steel ball bearings
  • Anode is standard

H6, H9 and H62:

Autoprop H6, H9 and H62
  • Diameter from 470 to 990mm or 19" to 35"
  • For shaft diameter from 35 to 75mm
  • For engines up to 292kW/400hp
  • Stainless steel ball bearings
  • Anode as standard

H20:

Autoprop H20
  • Diameter from 330 to 430mm or 13" to 17"
  • For saildrives and shafts
  • For engines up to 37kW/50hp
  • Stainless steel ball bearings
  • Anode as standard

Comparisons

Thrust comparison:

Autoprop - thrust comparison
The Autoprop produces more thrust than any other propeller designed for the same engine output. The fact that the Autoprop automatically sets the optimum pitch means you get more speed, increased range and lower fuel consumption.

Drag comparison:

Autoprop - drag comparison
As the graphic clearly shows, the drag is up to 85% less than with a fixed-pitch 3-blade propeller and up to 60% less than with a fixed-pitch 2-blade propeller. The gain in speed (at the same rpm) is approx. 1 kn at least if you fit an Autoprop instead of a fixed-pitch propeller.
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Performance, advantages, installation and maintenance

Motor sailing:

Boat with Autoprop
The Autoprop regulates the pitch according to the existing forward thrust or that generated by the sail. The result is high speed at very low rpms.

Economy - saving on fuel:

The Autoprop always works at the optimum pitch. The motor is not overloaded and in dangerous situations maximum thrust is available. This generally leads to a fuel saving of 10% - 30% (compared to conventional folding and feathering propellers). Your range is increased, it is better for the environment and you save money.

Thrust:

Even a 3-blade fixed-pitch propeller cannot generate the thrust of an Autoprop (see Yacht Test 5/97). The blades always automatically select the optimum pitch.

Reverse thrust and manoeuvrability:

In marinas it is often very narrow. That's why with Autoprop you get the the same thrust forwards and backwards (at the same gear ratio in forward/reverse gear). Since there is as much flow against the blades forwards as backwards, the full power of the Autoprop is released after only a 1/2 shaft revolution.

Installation:

Installation is very simple. The Autoprop fits directly onto your present shaft or saildrive and need only be inserted onto it and fixed in place.

Maintenance:

Autoprop installation
Routine maintenance is carried out every time underwater paint is reapplied. For this, we recommend you spray off the Autoprop with a high-pressure washer and freshwater. It goes without saying that depending on the build-up of salt the anode may need to be replaced. In older models with water-lubricated ball bearings, these ball bearings should be adjusted. In newer models with grease-lubricated ball bearings, it is necessary to grease all 3 blades with special grease. For this we recommend the high-quality grease EP/SAL, which you can purchase from us.

Please also follow the instructions in the operating manual (vent screw must be screwed off). If you wish to remove the propeller from the shaft we recommend a special puller.

Wear and tear:

Of course this page would be incomplete if we didn't mention the subject of wear and tear; Autoprop shines here, too. There is no toothing, gears or attachment points. The water-lubricated ball bearings should be replaced every 1000 hours; the grease-lubricated ones every 2000 hours.
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