Notes and Errata page.

Users are asked to note very well that this site is intended as a guide for those who are not expert in propeller specification, so out of necessity a simple approach has been taken that “dumbs down” the subject a little. Please do not e-mail me to tell me that my definitions of Wake Factor (for example) are too simplistic or wrong, as I am trying to explain a technical definition in such a way that anyone who has watched water swirling around their hand in the bath can understand.

Users are also asked to note that there is an issue of practical accuracy, the spreadsheet rounds calculations, as there is no point in determining that you ideal propeller has a diameter of 14.1254 inches and a pitch of 6.9524 inches. This is because they come in 1 inch increments, so the spreadsheet rounds these figures down to a useful level of accuracy and tells you to fit a 14 x 7 propeller.

I have decided not to include a message board on this site, I would recommend that you use your local sailing newsgroup for this purpose... uk.rec.sailing in my case.

I have also not posted any links from this site to any propeller manufacturers, because I do not wish to influence anyone when all you need to do is go to a search engine and type in “marine propeller manufacturer”. So this site does not plug any particular manufacturer or product. The purpose of the site is to arm you with enough knowledge and understanding to be able to take a decisive role in vendor and propeller selection.

The example vessel used for this site is (was) in fact a real boat, and it was vastly overpowered, simply because when she was being built there was no competition when it came to choosing between a new “marine” diesel and a second hand ex taxi BMC 2.2 and Borg Warner. The Heat exhanger was new from Bowmans and the shaft and sterngear came (again second hand) from an ex P&O lifeboat.

If you note any errors, or have any suggestions or criticisms please e-mail me with details.