Propulsion and bollard pull calculation spreadsheet
Year: 1998 Language: english Author: Surfbaud Genre: Convention (rules) Format: XLS Quality: Unknown Pages count: multiple Description: The calculation of propeller data can soon become an immensely complex task. The user will understand that winter waters near the outflow of a large river will be denser than summer waters in the med. Add in hull fouling over the season, sea state, hull profiles and coatings, and it can soon be seen that there is no nice mathematical solution to be had. Due to these variables propeller selection has always been a bit of a black art, in that it is practically impossible for the average sailor to determine whether his vessel is fitted with the ideal prop. Even a prop that just absorbs full motor power may well be less than ideal, as there is more than one pitch/diameter/area/profile that will absorb any given amount of power. The object of this spreadsheet is to allow the user to enter a few items of readily obtainable data, data which is of a concrete nature, such as waterline length, and for the spreadsheet to do all the complex calculations and produce a set of simple figures which the user can then comprehend easily and use as a shopping list spec. By the nature of the medium, the results produced will indicate a "best match" solution. Bear in mind that there is no unique solution, as every change in each variable such as water salinity (density) will alter the ideal prop spec. Only high budget powerboat racers have the luxury of selecting from 10 or 20 different props according to the conditions at the time of the race. This sheet does not attempt to be a learning resource, there are enough textbooks already out there on the subject, so you won't be gaining enlightenment through the use of this sheet. What you will be doing is inputting a few figures and getting good answers. Very useful when planning the re-engine project in the winter evenings, or impressing the Commodore of the local yacht club, or just maximising fuel economy and "oomph" from your existing set-up.
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Propulsion and bollard pull calculation spreadsheet
Language: english
Author: Surfbaud
Genre: Convention (rules)
Format: XLS
Quality: Unknown
Pages count: multiple
Description: The calculation of propeller data can soon become an immensely complex task. The user
will understand that winter waters near the outflow of a large river will be denser
than summer waters in the med. Add in hull fouling over the season, sea state, hull profiles and
coatings, and it can soon be seen that there is no nice mathematical solution to be had.
Due to these variables propeller selection has always been a bit of a black art, in
that it is practically impossible for the average sailor to determine whether his
vessel is fitted with the ideal prop. Even a prop that just absorbs full motor power may well
be less than ideal, as there is more than one pitch/diameter/area/profile that will absorb any
given amount of power.
The object of this spreadsheet is to allow the user to enter a few items of readily obtainable
data, data which is of a concrete nature, such as waterline length, and for the spreadsheet
to do all the complex calculations and produce a set of simple figures which the user
can then comprehend easily and use as a shopping list spec.
By the nature of the medium, the results produced will indicate a "best match" solution.
Bear in mind that there is no unique solution, as every change in each variable such as
water salinity (density) will alter the ideal prop spec. Only high budget powerboat racers
have the luxury of selecting from 10 or 20 different props according to the conditions at
the time of the race.
This sheet does not attempt to be a learning resource, there are enough textbooks
already out there on the subject, so you won't be gaining enlightenment through the use
of this sheet. What you will be doing is inputting a few figures and getting good answers.
Very useful when planning the re-engine project in the winter evenings, or impressing the
Commodore of the local yacht club, or just maximising fuel economy and "oomph" from your
existing set-up.
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bollard pull calculation1.xls
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