Kiwiprops™ are a unique cost effective feathering propeller design that eliminates gears, aligns the blades with the streamlines not the shaft, minimizes corrosion potential from the lightweight composite blades and offers users easy variable pitch adjustment.
It also offers users exception value.
Kiwiprops™ are now available as the result of a long and careful development program that was designed to bring new levels of performance and value to the sailor who wishes to retain the known benefits of a fixed three bladed propeller, for motoring and maneuverability, but at the same time minimise drag under all sailing conditions.
Traditionally feathering props have blades geared together, to ensure that they line up with the shaft when feathered. However the shaft rarely lines up with the water flow, thus increasing projected area and thus drag. With a typical inboard engine the shaft will be angled down at 10 to 15 degrees and with the hull sloping up at say 5 to 10 degrees, the shaft may be 15 to 25 degrees off the streamline of the water flow. This can cause auto-rotation and wear with the need for shaft locks. In addition there can be 5 to 10 degrees of leeway on the wind and surging sideways in big waves.
In the Kiwiprop™ designs - the individual blades are always free to "weather vane" in the actual water flow, to a minimum drag position.
This modern light weight three bladed feathering propeller has proved much smoother and quieter in operation than equivalent two bladed units and offers the additional benefits of variable pitch, is fully lubricated with minimal corrosion potential and offers full reverse thrust.
Kiwiprop K3 units has now been in production since 1995 with many thousand installed world wide on a huge range of vessels and drive trains.
The new K4 unit has been available since October 2011 with the same four composite blades on a larger Stainless Steel blade carrier and boss. This unit is designed for higher horsepower installations, and installations where for larger vessels, additional blade area is required, yet retains the same functionality and superior value proposition as the three bladed K3 unit. We now have well over 100 production status K4 units installed. Production status units are now available ex stock in various shaft sizes, rotations and mountings as shown on these web pages. We now have numerous sizing benchmarks for the popular installations but are also able to extrapolate from our existing units to allow sizing with confidence. Variable pitch always allows for fine tuning to optimise any particular installation. Power on the units installed varies between 28 hp on a slow speed Gardner Diesel to 85 hp on a number of various Perkins models. Saildrives up to 80 hp of various models have been installed.
Many of the design features of the K4 unit are identical to the K3 that now has over 40,000 propeller years of service. We are confident that identical features such as blade attachment and pitch adjustment will perform in the same reliable manner as in use on the well proven K3 unit.
The K2 ultra light weight folding unit with all composite blades and boss is in the final prototype testing stage. We have been refining this design and aiming for a very low weight - we are estimating a finished weight of 2.0 kg! - with a lower initial cost unit for small horsepower engines where a 3 bladed feathering unit will have a price disproportionate to the vessel. The initial 3D prints of these units have taken place and we are now continuing to refine the design for ease of assembly. Further updates will follow as testing is completed. Production economics are critical and we continue development in this area.