Measurement of Hub Dimensions
(For Early Wooden Propellers)
Hub Dimensions Chart
The measurement of the dimensions of the wooden hub is sometimes the only way to confirm the engine for which a particular propeller was designed. They must be correlated with the specific metal hub assembly designed for that propeller.  Once the measurements are taken, refer to this chart for specific engine applications. 
Note that these dimensions actually refer to the metal hub assembly, and the wooden hub will have a larger diameter than that listed in the chart.  Once the number of bolt holes is known, many hubs can be determined by just B, C and F alone, so focus primarily on these 3 measurements..

A - Center bore of counterbore segment (rarely used)
B - Center bore diameter
C - Bolt hole circle.  Note that this is the diameter of the circle on which the bolt hole centers rest. ( It is the  same as the measurement from the edge of one bolt hole directly across to the same edge of the opposite bolt hole.)
D - Diameter of hub.  This is the diameter of the metal hub, and the wooden hub diameter is usually larger than this.
E - Number of bolt holes
F - Bolt hole diameter
G - Hub thickness, or height..  In this case the wooden hub thickness should be close to the measurement on the chart, but will change slightly with moisture content..
H - Not applicable to wooden hub.
(Another list of hub dimensions for modern propellers can be found at theSensenich web site.)