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Non Standard Shaft Tapers

We do not offer a facility to machine propeller bosses to individual customer specifications.

Our business model with all units machined in bulk to exact standard specifications does not allow for the substantial extra costs involved in fitting individual propellers to one off tapers / keyways and threads.

The customers measurements are often of very poor quality and will not deliver an adequate match of tapers. Even if measurement errors are made by the customer they will not generally accept the costs of a replacement unit as the previous unit is now worthless.

The process is difficult ( Not just the turning - but the internal key broaching ) and is most economically handled in bulk on the appropriate machine tool.

The customer expects it to be done for no additional payment.

Our recommended solution is therefore always the same:

Turning the shaft down to the next standard size is always quicker and cheaper !

Machining the outside of the shaft is much simpler than the inside of the propeller boss.

This way the customer gets a standard fitting and his shaft will then accept all propellers.

We believe the customer should pay for this - there is simply no reason why you would not adhere to the standards for shaft tapers that have been in place for over 100 years.

Alan Pollard in the UK does offer this machining service using blank bosses - but that is because most UK vessels do not have standard tapers. He also has access to the appropriate machine tools to undertake the required machining operations.

We can generally fit where only the shaft taper length is non standard - by modifying the nut to either extend further into the small end of the boss - or alternatively if the taper is too long - turning a recess into the end of the nut so it will fit over the shaft taper protruding past the rear face of the boss.

We can also offer some easily manufactured non standard threads - eg M16 x 2 which we use in other applications where that is all that is non standard.

Very early Beneteau's pre about 1992 used M16 x 2 threads prior to the advent of the current ISO standards instead of the 1.5 pitch now standard.

Taper ratios that are non standard - keyways that are non standard - we cannot accommodate.

Contact our UK agent directly if this service is required.