Charles Perdue
Well-Known Member
- Joined
- Oct 8, 2005
- Messages
- 2,177
Ok guys, with the help of some boating friends, the instructions that I wrote for Mr. Bill McGraws Speedmaster Prop Pitch Gauge have been found and are ready to be posted.
The second part of the article that I wrote for Mr. Bill about how to do the procedure called "Blade Mapping" cannot be found at this time. Basicly it consist of making an expanded drawing, on graph paper, of one of the blades of the prop that you are working on. Assign a unit of measurement to the grids for the drawing on the graph paper. For instance, I used a tenth of an inch on the prop blade itself so that expanding or contracting the measurements is kept very simple. Plot the corresponding points of the grid for the blade drawing onto the prop blade itself using the grid pattern. An example of this is say you use the tenth of an inch unit of measurement on the prop, then you can expand this measurement to say 5 tenths between the grid points on the graph paper. This will make the drawing much larger and easier to work with.
After you have your points marked on the prop blade, carefully take a pitch reading of each of these points and write them on the corresponding points of your prop blade drawing on the graph paper. After you have plotted all of your measurements, you have a very precise reference with dimensions of that prop blade. You can then match the other blade(s) to these dimensions or if you happen to damage the prop you can go back and duplicate it very accurately. This sounds much more difficult than it actually is.
This is not something that you would want to do to every prop in your box. But if you found that magic prop that works very well on your boat then you would certainly want to be able to duplicate it. This procedure is just another tool.
Enjoy,
Charles
Instructions for prop pitch gauge (1).pdf
The second part of the article that I wrote for Mr. Bill about how to do the procedure called "Blade Mapping" cannot be found at this time. Basicly it consist of making an expanded drawing, on graph paper, of one of the blades of the prop that you are working on. Assign a unit of measurement to the grids for the drawing on the graph paper. For instance, I used a tenth of an inch on the prop blade itself so that expanding or contracting the measurements is kept very simple. Plot the corresponding points of the grid for the blade drawing onto the prop blade itself using the grid pattern. An example of this is say you use the tenth of an inch unit of measurement on the prop, then you can expand this measurement to say 5 tenths between the grid points on the graph paper. This will make the drawing much larger and easier to work with.
After you have your points marked on the prop blade, carefully take a pitch reading of each of these points and write them on the corresponding points of your prop blade drawing on the graph paper. After you have plotted all of your measurements, you have a very precise reference with dimensions of that prop blade. You can then match the other blade(s) to these dimensions or if you happen to damage the prop you can go back and duplicate it very accurately. This sounds much more difficult than it actually is.
This is not something that you would want to do to every prop in your box. But if you found that magic prop that works very well on your boat then you would certainly want to be able to duplicate it. This procedure is just another tool.
Enjoy,
Charles
Instructions for prop pitch gauge (1).pdf
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