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Continuous Measurements – The PropScanTM Propeller Measurement System

 

 

 

 

 

 

 

 

 

 

thus guaranteeing efficient and accurate work while avoiding over-working the metal.

Data from the initial scan of a propeller exposes the problem areas.  After repairing or upgrading the propeller the customer is presented with scans showing both the initial and final state of the propeller, as seen below.   The owner thus has an exact record of the work done (and the reasons for the work) as well as his ISO Class Certification.  

 

Computer Driven  

The measurement system is linked to a computer which analyses the data from the scanning unit, and presents our technicians with graphical screens which guide them while they “move metal” to either repair damage, or remanufacture and tune the propeller to a higher ISO class. The tuning or repair process involves several iterations between metal movement and measurement,

 

PropScanTM is the world leader in computer-aided analysis of marine propellers.  The system gives us a 3-D view in great detail of the surfaces of a propeller and calculates the propeller's conformity with ISO accuracy standards and its design. In addition, the PropScan certification program offers our technicians training in the techniques of propeller repair and reconditioning.  There are today 70 PropScan workshops worldwide dedicated to propeller repair, tuning, and sales. Worldwide, more marine propellers are repaired or tuned every day using the PropScan system than with any other.

PropTech measures propeller pitch to better than 0.1% using the techniques defined in the ISO standards.  Pitch is measured at hundreds of points over the entire surface of each blade, and then compared to the manufacturer’s specification at 4 local segments per section, at 4 or more radii per blade to attain class I or class S certification.  The mean pitch of each blade is compared to the other blades on the same propeller.  The pitch of the propeller as a whole is then compared to the target pitch.  Finally, the pitch of both the left and right propellers off the same boat are adjusted to be within ISO Class I or Class S tolerances.

 

                                                                               

 

  
Blade Section  Pitch After PropTech Service
Blade Section  Pitch Before PropTech Service

                 

                                               

 

 

This graphic represents section pitch, that is, pitch averaged along a line of constant radius. The left graphic illustrates the poor pitch distribution of an ISO class 3 propeller, while the right graphic illustrates the same propeller after being tuned to an ISO class S prop. Each cluster of four column graphs represents the pitch of each of four blades (green is blade 1, blue is blade 2, etc.) at a particular radius from the rotational axis of the propeller. Here, the first cluster represents pitch at radius 0.6, the second cluster at radius 0.7, and so on. The small column cluster represents the blade pitch (averaged over the entire surface of each blade), while the deep blue column represents the total propeller pitch, which is also displayed numerically in the upper LH quadrant of the graphic (in this case, in inches). The tolerance band is shown in dashed yellow lines. Within each cluster, the pitch of each blade must lie within the tolerance band. Before service, this propeller vibrated badly.

Additionally, each propeller’s data is stored in the PropTech database.  This allows us to quickly rebuild a propeller returned in a damaged state, or to affect a performance change in the future.