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Taper Charts and How to measure propeller taper boresUsing digital or vernier callipers ;- Measure the small end to the taper bore - nut end I.D. (inside diameter) Measure the keyway width and height. Measure the overhang distance at the nut end (draw) with the propeller tightened on the taper properly. Check if old prop fits the taper without rocking and check the amount of draw or overhang is enough. Record any markings on the hub, the propeller Rotation, Diameter, Pitch, Number of blades etc Right hand propellers rotate clockwise when viewed from astern facing forward and are more common. Left hand propeller rotates counter clockwise when viewed astern facing forward. Twin screw vessels often use contra-rotating propellers with the left hand prop usually fitted on the port shaft. Tapers in common use are; 1 in 10, 1 in 12, and the 1 in 16. Special purpose tapers are used for ski boats and high performance including Morse and Menkins. Propeller tapers are sometimes not machined to any standard or are inaccurate, presenting challenges. Therefore, if replacing the shaft and propeller, it is wise to follow the Taper Standards for access to a wide range of replacements propellers. S.A.E. Specification J755 1 in 16 taper is 3/4" inch to the foot and the angle centre line is 1 degree 47' minutes 23" seconds. S.A.E. Specification J755 (unit: inches)
NON-STANDARD SHAFT TAPERS Please measure carefully and fill in this section for dimensions from the shaft and/or the section for dimensions from your existing propeller
A: Thread Diameter
B: Taper Small end Diameter C: Keyway Width D: Shaft Diameter E: Taper Length F: Thread Length G:Thread Pitch Are measurements inches or mm ?
AND/OR EXISTING PROPELLER HUB DETAILS
A: Taper Length
B: Keyway Width C: Taper Small end Diameter D: Taper Large End Diameter Are measurements inches or mm ?
PROPELLER CLEARANCE IS IMPORTANT PLEASE DO A SKETCH WITH MEASUREMENTS IF CLEARANCE IS A CONCERN.
A: Tip of shaft to nearest obstruction
B: Centre of shaft to Hull C: Hub or blade to rudder D: Hub or blade to stern post, skeg or bearing Are measurements inches or mm ?
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Propeller Pages -
78-80 North Street, PO Box 3030 Pallas St. Post Office,
Maryborough Qld. 4650, Australia. Phone: + 61 7 41 231085 Fax: +61 7 4123 3590 E-mail: propellerpages@olds.com.au |
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The most widely followed dimensions for propeller tapers is the internationally accepted standard S.A.E.
taper dimensions which is 1 in 16 up to and including 5 1/2" diameter. Above 5 1/2" diameter the S.A.E. taper is 1 in 12. This standard is incorporated in the American Boat and Yacht Council (A.B.Y.C.) rules which are commonly used in Australia. All dimensions for S.A.E. taper standards are based on the SMALL end of the taper so that propellers with different hub lengths will fit the same shaft diameter and have the nut face in the same position on the shaft.
This ensures inter-changeability. (Different hub lengths will have different inside diameters at the large end of the taper bore.)
