@Jim Baldwin: You should read the info in Post #3 of this thread. Try it out and let us know if it works.
I downloaded this same manual four years ago and on page 55 it goes into detail on how to change from metric to standard. Could not do it. No standard selection.
I also let other folks that had Vypers have a go at it. They found the same thing. Apparently just a European model. No problem I dove it for three years without a hitch.
Finally gave up the ghost.