Nomad Willy
Guru
On Willy I have an 18" Michigan "MP" prop driven w a 40hp engine w 2.57-1 reduction. Of the 40hp I usually use about 18 to cruise at 6.15 knots. I'm slightly over propped but one inch pitch reduction would make me under propped.
Ideally I like to be just a tad under propped like about 50rpm. The prop is under loaded at 18hp so I'm think'in that reducing parasitic drag by taking off a bit of the prop edges or edge will gain the rpm I need, reduce the P drag and avoid using too much power to turn the blades through the water. Always a danger w large low pitched props w too much blade area for the power.
One could make an accurate line on the blades on each of the 3 blades, grind off to the lines and dress the edges appropriately. If I took some extra effort while trimming balance should not be affected. So would save a trip to the prop shop.
Could take it all off on one or the other side or the same amount off both. I'm leaning toward all off the trailing edge.
What think all?
Ideally I like to be just a tad under propped like about 50rpm. The prop is under loaded at 18hp so I'm think'in that reducing parasitic drag by taking off a bit of the prop edges or edge will gain the rpm I need, reduce the P drag and avoid using too much power to turn the blades through the water. Always a danger w large low pitched props w too much blade area for the power.
One could make an accurate line on the blades on each of the 3 blades, grind off to the lines and dress the edges appropriately. If I took some extra effort while trimming balance should not be affected. So would save a trip to the prop shop.
Could take it all off on one or the other side or the same amount off both. I'm leaning toward all off the trailing edge.
What think all?
