Read Me First		How To	Do not work with your only saved version of this sheet, make a copy!
			Denotes a cell for user data input.
			Denotes a cell that has carried data forward from another area.
			Denotes a cell that has produced a result from a formula.
					Do NOT attempt to enter data anywhere except a green cell!
	This is a freeware product knocked up in my spare time. It is not meant to be a commercial product and
	so it is possible to get stupid answers by using bad data. While some attempt has been made to track this
	a small dose of common sense when using this sheet will work wonders!
	Numerical Conventions and Units used.
		This spreadsheet is exclusively based upon the Imperial system of measurement.
		This spreadsheet works internally to a high degree of precision, but input and displayed
		data is limited to a level of precision that is considered both meaningful and practical
		for the end user.
		A Metric to Imperial conversion utility is included.
	General Overview.
		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.
	Weird Results.
		There is an old saying in computers, Garbage In, Garbage Out. So check your data
		carefully, particularly if the results generated are off what you would expect.
		It is quite possible, even likely, that owners of production vessels will find that the results
		generated indicate a different set of figures to the actual specification of their vessel. This
		is due to the fact that the boat manufacturer has to juggle many other items in the equation,
		such as engine power versus accommodation volume, etceteras. This is even true of very expensive
		yachts, so do not assume that the results produced are wrong just because they do not match
		the original spec of your quarter of a million pound yacht!
		This sheet has been thoroughly checked against actual real world figures on a very wide sample
		of vessels (3 figure sample) and it produces excellent results. It does produce better data for true
		displacement hulls than any other form, but data produced for semi-displacement hulls is still
		extremely good. Data produced for planing hulls is good, but should be treated as an "expert
		guide" rather than a rule of law. Exotica such as surface propellers and hydrofoils are not
		modelled very well. Note that all hull types, even racing hydrofoils, fit the numbers well when
		off the plane and acting as displacement hulls.
	What this isn't.
		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.
		User are also asked to note that the bulk of the individual sheets are there merely for
		those that wish to see "under the bonnet". The data generated is used and collated
		into the same sheet as Data Input. So results are immediately presented next
		to input without the need to click through the whole spreadsheet.
	Some Notes.
		Many sailors worry about the drag of a "big" three bladed prop. This can be dramatically reduced
		if the prop and shaft are allowed to rotate freely in the wake. Check your gearbox design before
		doing this as it may result in damage. Fit a "de-coupler" if needed.
		Lower shaft RPM = higher prop pitch and less drag when sailing, but also = larger prop diameter
		when motoring. Large prop dia = efficient thrust = less effects of short seas or windage "braking"
		EVERY prop represents a trade-off somewhere in the equation, personally I would recommend a
		motor / gearbox / prop spec that will drive your hull at hull speed and create a reasonable bow wave
		with an "ideal" 33% DAR 3 blade prop. This will always get you off lee shores, tow, be economical etc.
		Use of any other configuration will restrict the maximum performance of your vessel when
		motoring. This could have serious safety repercussions in adverse conditions.
	Copyright and Distribution.
		This product is exclusive Copyright of Surfbaud 1998 / 1999 / 2000
		Surfbaud acknowledge copyright of Microsoft for Excel and Windows95, on which this
		spreadsheet was created.
		Surfbaud produce this work as freeware.
		Freeware may be freely distributed and copied, but NO CHARGE whatsoever may be made.
		Surfbaud EXPRESSLY PROHIBIT any and all alterations of whatever form of any part of this work.
		If you wish, you may examine the formulae contained, and re-use them in another product or
		application, but you must NOT copy and paste to do so. If you do reverse engineer this work
		to create an new and different work, Surfbaud would appreciate an acknowledgement.
		No responsobility is accepted for any loss or injury, financial or otherwise, arising out of use
		of this work. It is meant as a guide, not a bible.