TAIL SHAFT


Standardization is very used at the industry in benefit of users and manufacturers to assure 100% compatible products. For example we can buy a CD fabricated by one manufacturer and play it in a CD player fabricated by a different manufacturer. We know that the CD will work thanks to standardization. All manufacturers of music equipments follow the same standard rules, sizes, protocols etc.

From the desktop of

Edgar Reyes

Propeller manufacturing is the same. If we have a standard tail shaft we would not have any problem to install a propeller in our boat. The standard that rules manufacturing of tail shafts and bore of propellers is SAE-J755.


SAE-J755 defines the shaft taper that must coincide with the propeller’s taper. For example the norm shows that the taper for tail shafts up to 5 1/2" diameter must be 3/4 inches per feet (1/16 (0.0625) inches per inch).


Next figure can help us to understand the standard taper concept with a 5" diameter tail shaft.




Taper is calculated using this formula:





Where:    DM = Large Diameter
               dm = small diameter
                 L = Length


For example tail shaft:




As we can see taper is 0.0625 according standard SAE-J755. So you can inform your propeller manufacturer that you need a propeller for a standard 5" tail shaft and you can be sure that you will install it without any problem.


If you need more information about this subject, contact us and we will be glad to help you.

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