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Get A Grip!: 3-Blade vs 4-Blade Props

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On: Fri, Nov 27, 2015 at 2:16PM | By: Captain Ron Kowalyk

More Opinions from the Rock of Ages: never being one to avoid a “Barney”, here’s another opinion. With the Manatee Zones and other slow-speed no-wake areas, how do we best optimize the power on our skiffs? We want an optimum hole shot, for performance, safety, and economy. Power-to-weight ratios being taken into consideration, which prop is most appropriate on the shallow water flats?

Three-blade props generally provide higher overall speeds with greater RPM. If speed is the issue three props are the accepted configuration. Speeds can be increased with lower pitch as well, a typical characteristic of three-blade props. A 21-pitch prop will move through 21 inches of water every revolution. Every two inches of additional pitch will increase RPM. Smaller diameter props, similar tires on a car, need more turns to cover a distance. Every outboard is designed to operate at a preferred RPM range. Over-revving can be catastrophic for an outboard; check manufacturer's suggested limits.

Getting carried away here! Four-blade props grip more water per RPM than three-blade props, but they also can reduce optimum RPM ranges for different motors. Thus proper pitch designed into a four-blade prop should be carefully gauged. Most prop shops can estimate the optimum pitch to customize your prop and best address your hull, load, and draft requirements. Simple adjustments to best suit your millcan be made at most quality prop shops. Lugging your outboard with a sluggish pitch can be as detrimental as over-revving. Take care and review specs when buying or modifying your “wheel”

All this said, the general consensus is a balanced four-blade prop will best help you “get a grip” on the shallow water flats. More bite for your buck.

Capt. Ron Kowalyk: 239-267-9312


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