Kiwiprops™

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K4 - Performances

The following article by Nigel Calder - a well known and highly respected yachting correspondent is required reading for a very detailed understanding of  relative propeller performance in larger sized vessels with more powerful engines typical of  K4 installations.

It was published in Australian Yachting in May / June 2011 and was undertaken prior to the release of the K4 unit which is  not included in the test results.  What it does show how similar are all the units tested with maximum motoring speed of all units within the range of  8.3 ~ 8.9 knots.

The vessel used for all these extensive tests is a MALO 46' of 14,100 Kg lightship displacement with a waterline length of 11.89 m that was fitted with a Volvo D2-75 rated 72 hp @ 3000  on a shaft drive with a 2.74:1 reduction leading to much slower shaft speeds than with the Saildrive version which has a 2.20:1 redn fitted and consequently significantly higher shaft speeds.

The large reduction gear fitted - coupled with the relatively low 3000 max rpm of this engine allows for larger than usual propeller diameters and consequently improved performance and efficiencies over what could be expected in a similar saildrive installation.

Australian Yachting article:   http://www.mysailing.com.au/news/folding-prop-gear-test 

Detailed test results:            http://www.mysailing.com.au/files/dmfile/FOLDINGPROPS%2Epdf    

NB: The above  article may no longer  be avilable after some years.