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Old 10-17-2012
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Re: Any PSC37s with 4-blade Variprops out there?

I am not sure what the presets were when the Vari-Prop factory set it up for us. I do know that the order was as follows:

DF-1 07
VariProp DF-107 hub 4-blade RH 18"x14"x12" for 1" SAE shaft
Pacific Seacraft 37
LWL 27'g"r displacgment 16,200 lbs. Yanmar4JH2-E 51hp @3600, 2.62:'1 reduction, RH rotation, 1" A22 shaft

The concern was whether the 1" prop shaft was made of Aquamet 22 vs 316 stainless. It turns out it was the higher quality Aquamet 22 and the Prop being speced as a 4 blade would work. Rick Steadman came to our boat and did the measuring to determine the appropriate size and configuration. This is what he reported:

According to the computer for a vessel of 16,200+ lbs. with 51hp the shaft size should be 1-1/8” if standard 316 stainless steel. A 1” shaft should be the higher strength Aquamet 22 alloy or equivalent. 316 stainless and A22 visually are the same so I do not know how we’d determine if your shaft is the higher strength material or not without documentation from Pacific Seacraft or a metallurgical test.

Observations:
The shaft presently has ¼” more length beyond the end of the bearing than is specified by ABYC standard. I measure 1-3/4” between the end of the bearing and the start of the taper. ABYC calls for 1.5 X shaft diameter as the maximum. If you are to fit the VariProp I recommend shortening the shaft to meet the current ABYC standard.

The shaft and aperture configuration has sufficient opening for the length of the VariProp when installed however since the opening is not enlarged by swinging the rudder to the side I think that for installation of the propeller either the shaft will have to be moved forward and then inserted into the propeller once the propeller is in the aperture or the propeller will need to be disassembled and reassembled on the shaft.

This doesn't answer your question on pitch but the Variprop people did the figuring for me and I decided to not second guess their calculations.

Curtis Smith

s/v Cilantro
PSC 37 yawl
#334
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