THEORY of PROPELLER SLIP - Brian Rogers



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THEORY of PROPELLER SLIP.

Reference

Prop slip is a measure of how efficiently the boat is going through the water. Prop slip is not the same as propeller efficiency.

If the prop did not slip at all as it screws through the water, each rev theoretically propels the boat the forward a distance equal to the prop pitch. (a 15 inch pitch prop theoretically propels the boat 15 inches in one revolution). The propeller revolution rate is the engine rpm divided by the gear ratio. This propeller rpm times the prop pitch determines the theoretical distance that the boat should have moved in one minute, which can be converted to a theoretical boat speed in miles per hour.

Due to prop slip the boat is actually going slower than the theoretical speed. Normally on the nature of 10 to 20% slower at top speed, for fast boats.

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Brian Rogers Marine Engineering ABN: 74 710 480 215

brian@

Ph: - 61 7 3390 5306 Fax: - 61 7 3890 1176 Mob.:- 0413 771 090

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