Nasmith Director

aka Course Finder

The Nasmith Director is a simple angle-solver, using own course, target bearing, and angle on the target's bow. It's accuracy depends on the accuracy of the estimated AOB.

The Nasmith Director was invented by Martin E. Nasmith, of WW I fame. It was called a Course Finder by the U.S. Navy. I've never seen one - this is my own version which may or may not resemble Nasmith's.

Using the Director

It's really, really easy.

1. Align the index (at 0 degrees) on the middle wheel with your course on the outer wheel.
2. Align AOB on the inner wheel with the target bearing on the middle wheel.
3. Opposite the index (at 0 degrees) on the inner wheel, read off the target course on the outer wheel.

Making the Director

It's easy. Just print out the plan, cut it out, and mount the wheels through the center cross hairs on a pin or thumbtack. All the L pieces go on one side, and the C pieces go on the other. (The L side is a Whiz Wheel of my own design - described here.)

I mounted mine back-to-back with the Whiz Wheel on a piece of cardboard, but you don't have to. For an axle, I used two push pins, one of which I had "depinned" with a pair of pliers.

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