03 - Scale Determinations

Before starting to fabricate any part of the model, it was necessary to determine the actual scale of the model I had acquired. There was no indication of scale on the packaging, so I used the measurements given by Jenson in his book for key aspects of the full-size Bluenose II and then calculated various scale dimensions for different scale ratios. It became apparent that not all dimensions of the model were consistent with a single scale ratio. The chart below shows my findings:

Comparison chart of full size, model and theoretical dimensions. 

(Used to determine model scale ratio.)

The yellow column records the full-size measurement (from Jenson) and the red column details the corresponding measurements from the model. The next four columns are the theoretical scale measurements for the following ratios: 1:40, 1:44, 1:48 and 1:60. While no single ratio matched the model dimensions exactly, the scale ratio of 1:44 (green column) came closest, and that is what I have chosen for this model. Not a usual scale as far as I can determine but I'm sure no one will notice!

With this ratio established, I undertook to generate a spreadsheet to allow for easy determination of scale dimensions without the need to perform individual calculations each time I wanted to make a measurement. Here is the chart that I'm using - a real time saver. The chart is divided into two parts: the upper portion provides scale conversion for full-size measurements in inches from 1" to 60", and the lower portion provides conversion for full-size measurements in feet from 6' to 97'. Thus, any full-size dimension up to 102 feet (by combining data from both portions of the chart) can quickly be converted to a scale dimension in inches. Other than overall length of the boat, this will accommodate every possible measurement that will be encountered when modeling the Bluenose II.

Scale conversion chart for scale ratio of 1 to 44.

Another scale requirement is the need to ascertain the correct size of ropes used in the standing and running rigging. Since the sizes of wire and cable of the appropriate dimensions for this model are usually differentiated by "gauge" number, it was also necessary to develop a scale conversion chart for this purpose. (Wire, manila and polypropylene ropes used on the Bluenose II range in diameter from 3/4 to 3-1/4 inches.) With information sourced on the Internet, felt this chart afforded the best display of the required information:

Wire gauge chart. 

Note that the actual dimensions of the diameter of model-size rope and twine will be in the order of 0.018 to 0.074 inches, or 26 to 15 gauge.

Next post, I will document my use of this information to fabricate my first model components - rigging blocks to replace the round "bobins" on the original model.

But not until I'm back from Florida...