NavList:

Hello Tony

You wrote:

"One thing still is not yet clear - the scale to use as an intercept distance can not be placed on the protractor directly - because that scale depends on the latitude. Do you do an extra calculation - to convert the T|A miles into the millimeters on the protractor's (DIY) scale?

Could you please elaborate on that a bit more?"

The scale comes from whatever is your favourite plotting sheet, initially as a cut and stick operation. No calculations or other brain work needed.

Looking at the original post and its 'Capella 3' Towards 040' photograph, expand it up and look carefully and you will see small pieces of paper scale, stuck on the underside of the working edge of the plotter with scotch tape. They are cut with scissors from the central meridian of a another printout of Frank's UPS. The system can be worked with just the paper scale cut outs, if you wish. For a Douglas protractor scheme, cut out a longer piece of scale and stick it along the 'side' of the straight edge. The Marker pen scales are optional,  once you've worked up a geometry that suits your usual practice. Any arbitrary scale can be used, as you wish.

Good plotting

Michael