Register | Login
Attackpoint - performance and training tools for orienteering athletes

Discussion: I've been wondering what th...

in: CleverSky; CleverSky > 2020-01-12

Jan 16, 2020 9:58 PM # 
I've been wondering what the map scale is of the map I used. I know it says 1:7,500. But as printed by Staples, it fits nicely on an 8.5x11 piece of paper, though the printing isn't quite to the edge of the paper. There's a white border maybe 2 or 3 mm wide.

First check for me was the distance between north lines, which on my map I measure as 38 mm, which at 1:7,500 gives 285 meters between the lines, an unusual distance.

Any idea what it's supposed to be? Or whether my map printing inadvertently shrank or stretched the map.

I was just trying to add leg lengths to the AP splits and wasn't sure my map was 7500.

Assume Charlie will see this too. And maybe know the answer if things are different for Red and Green (other than advertised scale).
Jan 17, 2020 3:22 AM # 
My map measures 4 cm between north lines or 300 m @ 1:7500. Did you ask staples to print at actual size? Otherwise they will print to fit with a nice margin.
Jan 17, 2020 3:46 AM # 
Hey, what happened to my reply? Did I forget to click the button? (I typed it on my computer at work just before I left.) Well, maybe it will show up tomorrow, but the short answer is that my results were in agreement with what George said.
Jan 17, 2020 1:53 PM # 
I just printed out one at work. I don't have a metric ruler handy, but my oldskool ruler has the north lines at 1 9/16", which I'm converting as 39.7 mm, and that makes the north lines 300 m apart, which is plausible. I also measured from the north tip of East Lagoon to the circular driveway of the SE house, and that comes out to 6 7/8" => 175 mm => 1.31 km. Measuring the same distance on GoogleMaps gives me 1.32 km, close enough. So I'm calling it an accurate 1:7500, but it it possible that yours got shrunk a little in the printing process, and the paper can also change size a bit due to humidity fluctuations..
Jan 17, 2020 2:26 PM # 
George must be right -- I just asked them to print it. Just tried printing it here on my B&W printer. It was defaulting to 93% to make it fit. When I set it to 100%, I'm missing the edges, but the distance between the north lines is right on 40 mm.

Now, when I measure all the legs and multiply by 7,500, I get a course length of 4.9 km or just a little under, as opposed to 4.5 given. I thought the software for doing the clues automatically produced course distance, but maybe that's not the case?

It's not like this matters in the least. I do remember wondering before I went out what the map scale really was (based on the 38 mm between north lines on my printed version, but it never entered my mind while I was out there. (I don't think I pace-counted even once, and I think I use that skill way more than most.) Just curious. And, I suppose, if the course was a little longer, then we were all a little faster. :-)
Jan 17, 2020 3:19 PM # 
I suspect that the software didn't include the leg from the last control to #1 -- does that happen to be 400 meters? You'd have to have the same control listed as first and last for it to measure all the way around the loop.
Jan 17, 2020 3:32 PM # 
Bingo. Thanks!

Please login to add a message.