Welcome to the Introduction page.

Please note very carefully, that this entire site is based upon the Imperial convention of measurement, so all data is required in Pounds, Feet, BHP, and so on.

Ideally you will download the Propking spreadsheet from the Spreadsheet page and work through the calculations and examples contained in the site in real time. To do this you need to have installed Microsoft Excel.

If you do not have Excel you can still do all the calculations using pen and paper but you will miss all the “fun” of changing a particular criterion and seeing the ramifications displayed instantly alongside it.

Propellers have long been a “black art” as far as the average sailor is concerned, and there are lots of valid reasons for this, not least of which is the fact that unlike the car tyre on the road not only is the propeller “invisible” but it works in a liquid medium. Add in factors such as hull shapes, all the different engine and gearbox possibilities, varying density of sea water, and it soon becomes clear that specifying a propeller is something that takes 20 years of practice at “guesstimating” the right answer.

In actual fact this is not the case, anyone with basic arithmetic skills can do their own CALCULATION with no experience or guesswork at all required. The purpose of this site is to show you how to do this calculation, and how to do it right, first time, every time.

If you work your way through the site methodically, or go straight to a specific area that you do not understand, all will be made clear, but please bear in mind that you need to be conversant with all the aspects and areas of the site and see them as an integrated whole before you can safely apply the resulting answers to the process of selecting a propeller.

If you have any comments or suggestions, please feel free to get in touch.