SUBSIM: The Web's #1 BBS for all submarine and naval simulations since 1997 
04192019, 12:06 PM  #1 
Neptune's daughter
Join Date: Apr 2007
Posts: 293
Downloads: 149
Uploads: 0

Clever Maths people  I need your help!
This site:
http://46.101.125.20:8080 If you click on WIZARD it describes a Function / Equation that you need to enter to create a nomogram. I'm trying to put together a PDF of a High resolution manoeuvring board in metric, and I need a nomograph for Minutes (0200) to Metres / Kilometres (0  200?) then to Knots. I'm fine with circles and triangles but equations like this and trying to create one that fits the requirement, I have no idea how to do that. Can anyone please help? Thanks 
04192019, 03:49 PM  #2 
Silent Hunter

Seems like template #2 is the most similar to your Speed=Distance/Time. Where the third variable would need to be defined as function 1/z. But I let it generate with default settings (just to see it works) for 7 minutes now and nothing comes out. So I suspect it (or the back end) is buggy.
That's sad, as you found a nice gem in the interwebs with this one.
__________________
Steam profile: https://steamcommunity.com/profiles/76561198032774177/ My site downloads: https://ricojansen.nl/downloads Last edited by Pisces; 04192019 at 04:00 PM. 
04192019, 04:05 PM  #3 
Silent Hunter

Yeah, 20 minutes later still nothing. Loosing the little bit of faith I had left in it just being slow. And I'm usually patient enough. Did you get any result?
There is a Windows installation procedure to let it run on your PC: http://pynomo.org/wiki/index.php/Installation I don't have the time to try it now. Maybe one day later I will try it. Supposedly you should be able to copy the script from the website to a text file and save it with .py extension.
__________________
Steam profile: https://steamcommunity.com/profiles/76561198032774177/ My site downloads: https://ricojansen.nl/downloads 
04202019, 01:19 AM  #4 
Navigator

Caveat: I'm no math wiz.
One Yard is 0.9144 meters  so you can pretty much use the yard scale on the existing MB as an estimation of meters (or kilometers) traveled in a given time period. But, I did manage to modify the nomogram to make it slightly more accurate when using meters/kilometers. Try it out and let me know what you think:
__________________
If you have a question about celestial navigation ... ask me! 
04202019, 03:40 AM  #5 
Seaman
Join Date: Jan 2013
Location: Hong Kong
Posts: 37
Downloads: 65
Uploads: 2

Looks great. I guess you just streched the range scale to 1.09361 times the length of the original scale?

04202019, 04:16 AM  #6 
Navigator

Thank you.
Actually, I tried scaling it based on the proportions  but that didn't seem to work so well. What I ended up doing was compressing*/repositioning it until various precalculated results [mostly] matched up. I must admit, though, that I'm not entirely sure that I got it just right. That's why I'd be very interested in anyone's test results. *Counter intuitively, the distance scale needs to be compressed rather than stretched.
__________________
If you have a question about celestial navigation ... ask me! 
04202019, 05:28 AM  #7  
Neptune's daughter
Join Date: Apr 2007
Posts: 293
Downloads: 149
Uploads: 0

Quote:
Thank you SO much! That's fantastic! 

04202019, 05:59 AM  #8 
Silent Hunter

Nathaniel B: The scale compression (or expansion) should not have been needed. An order of 10 on each scale should have the same difference in pixel coordinates. Only a horizontal shift of the distance scale would be needed to turn the yards into meters.
By how much? Draw a vertical line between the same mark on the time and speed scale. This crosses at a specific distance. Calculate what this should become: i.e. 10 kts in 10 minutes = 3086.67 meters. (=10min *10kts * 1852m/60 min) Measure the pixel distance (on the original scan) between 3000m and 30000m. Then the offset of the 3000m mark w.r.t. the 10kts and 10 minutes marks = ( log_10(3086.666)log_10(3000) )*pixeldistance. The 3000m mark would come left of the vertical line so shift in the appropriate direction.
__________________
Steam profile: https://steamcommunity.com/profiles/76561198032774177/ My site downloads: https://ricojansen.nl/downloads Last edited by Pisces; 04202019 at 06:14 AM. 
04202019, 06:13 AM  #9 
Navigator

Interesting, thanks! I'm glad to receive any input that might make it more accurate. I'll mess around with it more when I have time to test more examples.
__________________
If you have a question about celestial navigation ... ask me! 
04202019, 06:16 AM  #10 
Silent Hunter

I corrected my formula above, I placed the difference of logarithms between brackets.
__________________
Steam profile: https://steamcommunity.com/profiles/76561198032774177/ My site downloads: https://ricojansen.nl/downloads 
Thread Tools  
Display Modes  

