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Brunton's Propellers Ltd

Oakwood Business Park Stephenson Road West, CO15 4TL Clacton on Sea, Essex
United Kingdom of Great Britain and Northern Ireland
Telephone +44 1255 420005
Fax +44 1255 427775

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Our range of products

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Our products

Product category: Propellers


The Autoprop feathering propeller for cruising sailing yachts, displacement motor vessels, and hybrid and purely electrically driven craft with engines to 350hp

Autoprop’s unique design and superb build quality make it the first choice feathering propeller among cruising yachtsmen the world over, with drag reduction when sailing by at least 85%, and a unique ability to change pitch automatically to suit prevailing wind and sea conditions when motoring or motor sailing. Auto pitching, auto feathering, the same thrust in astern as ahead, less prop-walk in astern, a brand new version for hybrid and purely electrically driven vessels, and a recently developed ability to produce very efficient and economic propulsion for purely diesel powered displacement motor boats are more than reason enough.

Autoprop is a unique propeller which has been praised by yachting writers around the world. Whatever type of cruising sailing yacht you may own, mono or multihull, or displacement motor vessel, leisure or commercial. If you need more information don’t hesitate to contact us.

In the world of leisure yachting our leading brands; the Autoprop feathering propeller and the Varifold folding propeller are acknowledged as world leaders in sailing boat propulsion. Our fixed bladed propellers for motor yachts, commercial and naval craft, are designed and manufactured to the same exacting standards in order to provide outstanding performance.

You can see from the image Autoprop in drive mode. When reversing the blades swing through 180 degrees and produce the same thrust as in forwards. When sailing the blades feather automatically, reducing drag by up to 85%

The feathered image on the right shows how, when sailing, Autoprop reduces drag by up to 85% compared with a three blade fixed propeller; with the two blade propeller the reduction can be even greater.

This drag reduction can equate to as much as one additional knot in sailing speed.
With other feathering and fixed pitch propellers performance under engine is a compromise. No such compromise exists with Autoprop, her blades admittedly rather an odd shape, are the result of a huge investment in design time and testing. The Autoprop blades, unlike those of conventional propellers, maximise the thrust delivered whatever rpm the yachts engine is running at.
Autoprop automatically varies its pitch depending on the conditions. Put simply, as the wind or sea conditions vary so does the blade pitch of your Autoprop. The less pressure the Autoprop feels on its blades the more pitch is applied and vice versa.

The result is maximum efficiency whatever the conditions, with increased speeds at lower engine revs and lower fuel consumption and emissions.
In reverse the Autoprop blades swing through 180 degrees and present exactly the same blade shape as they do ahead.

The result, the same excellent thrust, with greater stopping power and less prop walk.
Likewise in adverse weather conditions, the vessel’s speed will be reduced because of the adverse weather such as high winds and choppy sea conditions. The Autoprop senses the load acting upon it and reduces the pitch angle allowing the engine to to run to a higher maximum rpm.

Much like travelling up a hill in your car, you need a lower gear ratio to allow the engine to run faster and produce more power.
This unique feature of the Autoprop, enables the full power of the engine to be used in situations such as towing, or in emergencies. With conventional propellers because the pitch is too coarse at very low speeds, the engine cannot achieve its full revolutions and therefore full thrust is not achievable.

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Product category: Propellers



When it was launched nearly thirty years ago the designers of the Autoprop could not possibly have realised how important their unique design was to become. Thousands of cruising yachtsmen around the world sail faster and motor further and more economically using Autoprops.

With this history and its unique abilities it is not surprising that a new version of the Autoprop called the Autoprop Eco*Star has been developed to propel the rapidly growing number of hybrid and purely electrically driven craft, both motor and sail, which are being launched around the world. Its development has been the work of a formidable team of expert naval architects, engineers and scientists from Bruntons, sister company Stone Marine Propulsion, and the world renowned Insean Research institute in Italy who provided invaluable assistance in evaluating and testing the propellers characteristics, mathematical modelling and optimisation.

Benefits of the Autoprop Eco*Star 
  • It’s already acknowledged that Autoprops are highly efficient because of their ability to auto pitch depending on engine speed and weather and sea conditions; an ability that provides optimum thrust at all times. But with purely solar or with hybrid power the list of advantages provided by the new Autoprop Eco*Star Propeller is further extended
  • Electric motors, unlike diesels, provide a constant torque from zero to maximum rpm. Only the Autoprop Eco*Star Propeller, using its auto pitching ability, can match its own efficiency curve with that of the electric motor. The result, a considerable improvement in the economy deliveries available compared with other propellers. Put simply, more boat speed but using much less energy.
  • On sailing yachts, when speed is not an issue but increasing battery energy is, the Autoprop Eco*Star Propeller can be allowed to turn in the vessels wake and the drive motor automatically becomes a generator recharging the batteries. Up to 1Kw of power can be regenerated in this way.
  • Displacement motor vessels of many types which are powered by diesel, hybrid or purely electric propulsion systems can also greatly benefit from fitting an Autoprop Eco*Star. The fixed pitch propeller fitted to most of these craft will only be operating at its most efficient at or near maximum revs. Autoprop Eco*Star maintains exactly the right pitch whatever the engine revolutions ensuring the propeller produces significantly more thrust at lower propeller shaft speeds. The result; higher speeds at lower revs and better fuel efficiency
  • All the original Autoprop benefits are still available with the Autoprop Eco*Star Propeller. Backing down is much more efficient thanks to the propeller blades being the same optimum shape in astern as they are ahead.
  • Drag when sailing with the Autoprop Eco*Star Propeller’s blades feathered is reduced by up to 85%, providing speed increases of up to one knot.
  • For existing vessels the Autoprop Eco*Star Propeller is ‘retrofitable’. It comes already assembled to fit on an existing shaft or saildrive leg. It is silent in operation and optimises its pitch fully automatically. In short it provides the most environmentally responsible and efficient propulsion for any vessel powered by hybrid or solar systems.

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Product category: Propellers



Varifold – the folding propeller for larger cruising yachts, cruiser racers and purely racing yachts of all sizes with engines from 10 to 1000hp.

Varifold folding propellers have taken the market by storm. Regularly fitted by such notable yacht building names as Baltic, Swan, Wally, Moody and Oyster, the complete range of Varifolds has a model for cruiser racing and racing yachts of every size. Varifold is revolutionary in design and brings a revolution to the yachts they are fitted to. Radical reductions in noise and vibration and excellent performance under engine, both ahead and astern, are the result of the propellers unique design. Varifolds have proper helical pitch distribution, including pitch reduction towards the blade tip. This pitch reduction ‘unloads’ the blade tips and, combined with the skewed blades, greatly reduces noisy pressure pulses against a yachts hull. While some other folding propellers have a helical pitch shape, few have proper sections or pitch distribution. None, put all these requirements into a complete package, except Varifold.
So advanced is Varifolds design that a 4 blade version has successfully been fitted to a yacht with a 750hp engine, we believe that would have been an impossible task for any other folding propeller. Each Varifold, whatever its size, is built to the same extremely high specification from a nickel-aluminium-bronze alloy which guarantees great strength and high corrosion protection. Cruiser racing and racing yachts can now get the best of both worlds; a folding propeller that combines low drag when sailing, with efficient and quiet power when motoring. Oh, and by the way – Varifolds open in reverse, and not just sometimes!

From 10hp to 1000hp there is a Varifold propeller for your yacht, whether it is a small cruiser racer that does more cruising than racing, or an out an out racer that just needs a propeller to get back into port.

Our two, three and four blade versions are designed to produce excellent thrust when motoring with exceptionally low noise and vibration levels, and when folded for sailing, to reduce drag to a minimum.

Many well-known yacht manufacturer’s now fit Varifold as standard and the list of yachts re-propped with a Varifold to solve existing problems grows longer.

Even to the untutored eye close examination of a Varifold says excellent design and build quality. Hardly surprising when you realise that Bruntons Propellers are far from just being a supplier of propellers to builders and owners of leisure craft. The company designs and supplies propellers of the most advanced design to navies and commercial shipbuilders around the world and our in house designers, engineers and Naval Architects who work on those projects also bring their undoubted expertise to Varifold and our other leisure propellers.

Design of course is only one part of the process; a brilliant design is nothing unless matched by the highest quality build materials and construction processes. Our state of the art CNC manufacturing plant allows us to ensure that Varifolds highly advanced design features, like the special low pitch at the blade tips, which contributes so much to the excellent low noise and vibration characteristics of the propeller, can actually be manufactured and accurately reproduced on every blade.

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Product category: Propellers


Bruntons SigmaDrive is a brand new 21st Century solution that is already an award winner and provides effective anti-noise and anti-vibration solutions of the highest order.

What makes SigmaDrives different is their ability to resist propeller thrust when installed as a standalone coupling, directly from the shaft to the output flange on the engine’s transmission. It reduces and even eliminates vibrations that originate from an imperfect alignment between the propeller shaft and the engine, compensating for up to 3 degrees in all directions. This system can also be installed using thrust bearings so that the engine can be placed utilising the space available ergonomically.

SigmaDrives are designed to fit virtually all boats from yachts to workboats, canal narrow boats to military vessels; in fact pretty much any powered vessel with engines up to 1300hp. They are extremely easy to fit, requiring no modifications to the craft, which can usually be equipped with the drive unit whilst still in the water. Together with its anti-noise and vibration abilities having a SigmaDrive on your vessel also ensure that seals and bearings are always perfectly aligned, reducing wear and guaranteeing a longer trouble-free life for all associated components.

Why does a SigmaDrive work so well? Because SigmaDrive is a constant velocity joint which allows the propeller shaft to rotate without transmitting the engines movements and vibrations. Other attempts at solving these solutions rely on rubber couplings or Carden units.

The SigmaDrive requires none of these, is compact and easy to fit, usually without slipping the vessel or requiring modifications to the shaft line. It’ s a premium product manufactured from a special bronze alloy that is maintenance free and its internal components are hard wearing and long lived.
Looking at the image you can see the usual method of connecting an engine with a propeller. The three fixed points, consisting of the propeller mount, the mechanical seal and the engine / gearbox, are individually or collectively capable of creating the two potential causes of noise and vibration. Firstly, any imperfect alignment of the three points can create vibration and noise. Secondly those vibrations and the associated noise are then transmitted directly through to the hull of the vessel and thence throughout the boat.
The simple solution is to fit a SigmaDrive coupling in the place of the standard one. The whole system from gearbox to propeller instantly becomes much more flexible, with the coupling able to correct imperfect co-axial alignment between the prop shaft and the gearbox of as much as 8 degrees. As can be seen in this second image with the SigmaDrive in place the reduction in the rigidity of the whole propulsion system means that the engine vibrations are significantly reduced or eliminated completely, and the prop-shaft can rotate naturally with no vibrations or noise to transmit to the hull.

This product is for conventionally driven vessels. The system uses a constant velocity joint to self-align the shaft. Thrust taken up on the engine from the propeller invariably changes the angle of the shaft line, particularly when the engine uses soft rubber mounts. Using a single SigmaDrive replacement coupling will ensure the shaft is correctly aligned at all times, especially under high load. The result, reductions in many cases of around 50% in noise and vibration.

The SD standalone unit that resists the propeller thrust compensating for up to 3 degrees in all directions.

SD 55, 100, 150, 225 and 300

This system incorporates a thrust bearing to isolate the propellers’ thrust to the engine. It uses a combination of three SD units built together. Two of which are incorporated in the thrust bearing and another coupled to the transmission with an intermediate shaft.

STS Sigma Thurst System STS 550, STS 1000, STS 1500, STS 2250, STS 3000

D-Sigma is a replacement Cardan drive also coupled to a pair of constant velocity joints and can replace existing Cardan shaft for Water jet Drives and Pod Drive propulsion systems.

D Sigma D 55, D 100, D 150, D 250 and D 300


The SD unit is a standalone unit that resists the propeller thrust compensating for up to 3 degrees in all directions and fits all makes of V drive transmissions.

V Drive SDV 55, SDV 100 SDV 150, SDV 225 and SDV 300

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Product category: Propellers


Bruntons Propellers, throughout its history has never been a ‘me too’ company. Every product designed and manufactured by us is the result of extensive research, development and testing with the resulting equipment being either a substantial improvement on currently available products, or completely unique in its field.
  • Without a doubt the greatest innovation that awaits a user of the Bruntons CPP system is its ability to monitor required vessel speed and load, weather conditions and sea state, and then automatically set the correct propeller pitch to keep the required speed whilst maintaining maximum fuel efficiency. The system has different pitch control modes which allow the operator to select the one most relevant to the required operating requirements for example maximum power or, as described earlier, maximum fuel efficiency.
  • The highly advanced computerised monitoring system can be used on hybrid powered vessels, not just for propulsion efficiency, but also for battery use optimisation and monitoring and will ensure that the system is optimising regeneration of electricity as well as usage.
  • Our Naval Architects and Engineers having considered the current limitations of CPP propeller design have produced a system that overcomes two major problems associated with this type of propulsion; excessive blade wear and high spindle loads. Excessive blade wear will be dramatically reduced with the inclusion of a new blade retention system.
  • Every propeller will be manufactured to the highest standard required for the use the vessel will be put to culminating in ISO class 1 with class ‘S’ pitch tolerances for the craft with the most exacting requirements.
  • Every propeller will be custom designed for the vessel it is propelling to further improve performance and reduce cavitation. 
  • Pitch distribution across the propeller blades will be carefully designed to provide pitch reduction towards the blade tips. This will create ‘tip unloading’ a feature which reduces propeller pressure pulses against the hull.
  • Rake and skew of every system will be custom designed to maximise clearance from the hull, strut and rudder.
  • The hub will be faired into the aft strut bossing to create smooth water flow into the root sections.
  • The system will be capable of fully feathering its propeller blades making it ideal for sailing vessels looking to minimise drag and resulting speed loss while sailing. The system will be capable of fully feathering its propeller blades making it ideal for sailing vessels looking to minimise drag and resulting speed loss while sailing.
  • On twin-screw motor vessels, when operating requirements allow it, one propeller can be fully feathered providing significant improvements in fuel economy whilst steaming under one engine. 

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Product category: Propellers


At Bruntons we are very well known for the exceptionally high quality of the propellers that we produce, whatever the type of vessel they are intended for. Using many years of experience, and manufacturing processes that exceed the most exacting international standards and classification society requirements our designers, metallurgists and naval architects produce propellers, with or without complete sterngear packages, which are second to none.

Each propeller we produce is designed to ensure that it performs at maximum efficiency, providing the vessel to which it is fitted with the best performance, not just in speed but also fuel consumption and emissions; all this performance to be provided with the lowest possible noise and vibration.

Depending on the application many of Bruntons propellers are manufactured using alloys developed by the company’s own metallurgists. The alloys Nikalium and Superston where developed for propellers requiring maximum strength and corrosion resistance; a high tensile manganese bronze alloy is available for less demanding applications, and propellers are also produced from a choice of several grades of stainless steel selected according to the customers’ requirements.

Whatever type of vessel you own you can rely on Bruntons to provide a highly efficient, superbly designed and constructed propeller and sterngear package for it.

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Product category: Propellers


Most of the propellers that we design are specifically for the vessel for which they are intended but with naval vessels, and often superyachts, the requirement for a custom design is paramount.
We design and manufacture propellers for naval vessels that are designed for various different uses, from mine hunters to high speed patrol craft. In all cases it is very important that apart from producing the required performance the vessel should have the lowest possible noise ‘signature’.

Superyachts, with regard to propeller design, share several similarities with naval vessels: they are usually highly advanced in both their overall design and construction materials. We often find that the actual design of the vessel can make the installation of a conventional propulsion system difficult or even impossible. In situations like these our experience and specialist knowledge enables us to work very closely with the vessels designers and builders to develop exactly the right propulsion solution for that vessel.

Suffice to say, if you have designed a propeller for a nuclear submarine, which we have, then there is very little which is going to defeat you!

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Product category: Propellers


A propeller that continues to rotate when a vessel is sailing can be major problem. It is most likely to affect yachts fitted with a hydraulic gearbox. To solve this problem we developed the Autolock.

As its name suggests Autolock is a shaft braking system for yachts fitted with hydraulic gearboxes. Its operation is totally automatic, springs apply the brake when the engine is turned off and the brake is automatically released by gearbox oil pressure as soon as the engine is started.

If you are looking for a reliable way to enable your feathering or folding propeller to do its job when you start sailing and want the added benefits of reduced gearbox wear, reduced prop drag and the elimination of the sounds of a prop shaft turning and intruding on your sailing, then the Autolock is your solution

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Product category: Propellers


Retractable, replaceable anode system.

Most boat owners know the damage caused by electro-chemical reaction when metal parts are immersed in salt water without suitable protection – if they don’t, they soon will! No protection can cause very expensive and potentially dangerous damage, and often in a very short space of time.

IONGUARD really is a major step forward in the protection of any boat from the effects of stray electrical currents.
Today’s sacrificial anodes have changed little since they were first invented in 1824 by Sir Humphrey Davey and the whole business of protecting a boat from damage is still, to a large extent, a hit and miss affair. The problem is not the anodes themselves, but the extent to which they erode in a normal season and the difficulty of monitoring the speed of erosion. It’s an expensive business to haul out a boat just to check the condition of its anodes and not much cheaper to hire a diver to check them for you. Until now, many owners, realising that the cost of not checking could be much greater, have had to spend the money!

These problems are in the past however, and the solution is Bruntons IonGuard. This clever device is capable of protecting smaller vessels all on its own, but for owners of larger boats it provides the opportunity to monitor the rate of attrition of the vessels other anodes without haul outs or divers, and this is only one of many benefits.
  • IonGuards own anode is easily replaced while your vessel is afloat. Replacement is as simple as unscrewing the old anode and screwing on the new.
  • Racing yachts can have their anode retracted in seconds, reducing drag. It might not sound much, but with every second counting, the cleaner the bottom of a racing yacht the better!
  • Different anodes are often required for salt and fresh water use, a fact that many owners may not be aware of. With IonGuard, the type of anode can be changed in seconds, ensuring the boat is getting the best protection possible.
  • Whatever type or size of boat, IonGuard allows owners to monitor their corrosion protection. This gives the confidence that comes with knowing that expensive metal parts of the yacht are fully protected, and saves the cost of unnecessary haul outs.
  • IonGuards can be purchased with a range of different skin fittings and anode materials, which means an IonGuard is available for any craft, whatever its construction material, or its area of operation.
  • IonGuards benefits are applicable to both power and sail vessels of all types.

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About us

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Whatever type of vessel you require a propeller for you can be sure that Bruntons have the solution – not just any solution but exactly the right one.

Why? Because Bruntons are the one company in the world that designs and manufactures just about every type of propeller in regular use today. We have no reason to try and get you to settle for second best because we will have the perfect answer.