The E-6B was more created than invented by Phillip Dalton in the early 1930s. It was initially called "The Dalton Dead reckoning Computer" . The exact derivation of E6B is not known but the E-6B has become the generic name for a vast number of similar devices, which include a circular slide rule and a sliding wind angle ground speed plotter. The Dalton E-6B was developed from a large shipboard device for handheld use aboard aircraft. My first E-6B, which is still in the family, is from WWII and made of solid brass with enameled engraving. A quality piece. Plastic E-6Bs became common later in the war. Aluminum and cardboard came later as the E-6B became obsolete with the advent of electronic E6Bs.

E-6B
Dalton invented several flight computers before the design that we all know so well, but they were NOT derived from a shipboard device. (A much earlier - 1917 - very popular flight computer was, however, so it's easy for people to think all F/Cs came from marine usage. Some of the navigation principles are the same, of course.)

His "Model J" was first bought in quantity by the US Army Air Corps in very early 1940, I believe, and it was given the designation of a navigation device "E" along with the "-6B". Even though there was an "E-6A" made, a very real possiblity is that the "6B" was arbitrarily settled on because that was the British/Canadian/ Australian prefix for aerial navigation devices. (e.g "6B/245" for one example RAF flight computer)