Propeller Diameter (ideal)				How To
		Formula
			D= ( 632.7 x ( shaft HP exp 0.2 ) ) / ( RPM exp 0.6 )
		18	Ideal Minimum prop diameter for hull
		16	Maximum prop diameter permissible.				<-- See Min Prop Dia sheet
		42	SHP
		2000	RPM
		14	Theoretical ideal prop diameter (inches).
			This is for a "standard" 3 blade prop with 33% Disc Area Ratio,
	This "standard" configuration is the ideal form of propeller. Use of propellers with a greater Disc Area Ratio
	or a greater number of blades is recommended only for special applications such as fishery. The use of props
	with lower DAR and/or two blades is recommended only for special applications such as racing sailboats.
	These special applications should consider the use of alternatives to the rigid propeller, such as variable
	pitch or folding or ducted designs.
	The more a prop deviates from "standard" configuration, the greater the trade off in lost performance at one end
	of the curve to boost performance in the other. A low drag sailing prop will not have sufficient area to generate large
	thrust. A large area towing prop will have a high drag when sailing. A high thrust prop is not a high speed prop.