Also known as a Portland Course Plotter, this was an amazing find at £2.50. Captain Gueret’s invention has been on the market for fifty-five years, now, and it still useful for navigators in 2024. The concept is simple in practice, but incredible in design.
The idea is that you have a rule that sits between two points, facing North, with the 360 degree protractor allowing to point it in specific directions. It is all done by pointing the rule to North on the chart’s North, thus allowing for accurate, analogue, navigation.
It’s a little sad that Gueret didn’t patent the idea, allowing for other companies to take the design for their own, but he’s still credited as its inventor, and that is enough to at least give clarity to where the thread of creativity came from. I love navigatory tools and used to sail, so this was a great pick up, for what is otherwise priced at £15, as a used article. Not a bad purchase, even as a draughtsman tool, I am happy with it. Now, where should we go to, next?
