Best known for their modern Autoprop feathering and Varifold folding propellers, Bruntons have been designing and manufacturing propellers and sterngear for all types and sizes of vessels for over 100 years.
Autoprop - Automatic Variable Pitch Propellers
Whatever your type of cruising yacht, mono or multihull, heavy or light displacement, you will find fitting an Autoprop greatly enhances the performance of your vessel under power and sail. Better performance means faster passage times and more satisfying sailing for both skipper and crew.
Autoprop automatically adopts the most efficient pitch setting taking into account the driving force of the sails. The result is increased speed at lower engine revs, giving longer range and more comfortable cruising. Fuel saving Autoprop is the only propeller which automatically varies its pitch depending on operating conditions, thus maintaining maximum efficiency at all times. Higher speeds and greater range are the result.
With the blades in the feathered position, drag compared with a fixed three blade prop is reduced by up to 85%. The two blade version provides even bigger reductions. These huge savings can equate to a knot or more in added boat speed when sailing.
Varifold Folding Propeller
The complete range of Varifolds has a model for cruiser racing and racing yachts of every size. Varifold brings reductions in noise and vibration and excellent performance under engine, both ahead and astern, the result of the propeller's 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.
A 4 blade version has successfully been fitted to a boat with a 750hp engine. 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.
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.