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Hi Jason
By having a circular aerofoil section the prop creates a positive pressure at the inside narrow end of the kort
and a negative pressure on the outside rear of the kort , the resultant pressure difference causes a lateral force to be
applied to the kort which in turn is transmitted to the hull through the kort pintle on steerable or through the kort fixings
on non steerable korts. This aerofoil section is quite different to an aeroplane section where an upwards force is generated.
Full size korts increase the thrust on the ships hull up to 30% at very low ship speed and above 12 to 15 knots the kort
nozzle drag negates the extra thrust, so korts are mostly used on tugs, trawlers, etc.When kort props go astern they have
a distinct dis-advantage of generating an opposite and negative thrust, and that`s why korts that can turn through 360 degrees have props
that only go ahead for max thrust on ASD tractor tugs
Hope it makes sense,and yes I would use an aerofoil section.
regards pompy boy
