DirtRider:
I just got my padi basic open water and advanced open water done back to back but noticed something funny on some compasses that the instructor couldn't answer. There was a person in my class who was a private pilot and asked why his compass had printed 270 degrees at East instead of 90 degrees. What is the deal? I imagine that perhaps this compass is supposed to be used differently than the other kind...might have something to do with the lubber line....
I have never seen one like that before so I am curious.
Your instructor needs to refresh his navigation skills and knowledge...
Look at the site again you referenced.... "Dual-reading display with side viewing window"
I grew up surveying and it seems simple, but here's a quick lesson. Looking at the top of the compass, you use the N,S,E,W as reference to see what general direction your traveling. (bearing) as north, northeast, northwest, south, southeast, southwest. Bearings are expressed in degrees from north or south, i.e 0-90 NE, SE, SW, NE. Note your azimuth 0-360, (the angle measured from north, eastward along the horizon) grows 0-90 in the northeast quadrant, 90-180 in the southeast quadrant, 180-270 in the southwest quadrant, and 270 -360 in the northwest quadrant. Those numbers printed lower on the compass are viewed through the site window when pointing the lubber line in your direction of travel for a more accurate heading.
So, next time you go for a dive, orientate your self to the shore line, i.e. "I'll be heading north east from the shore, now point your lubber line out to a marker or bouy, and read your azimuth (should be between 0-90, close to 45), figure your way back by adding or subtracting 180, here it would be 45+180=225 or southwest!
So if you're on the "East" end of your compass, and you look through the site window, you're headed west, or 270 Az. Make sense?
Like my wife says, it's easier to show than tell, but that's a general explaination of the numbers printed on that type of compass. Dive safe
tony
