Author Topic: Best way to determine true north  (Read 935 times)

0 Members and 1 Guest are viewing this topic.

Offline tweatherman

  • Forecaster
  • *****
  • Posts: 519
Best way to determine true north
« on: April 26, 2022, 07:09:08 PM »
Just curious what some of the members here use for exact reference for true north when setting up a wind vane? GPS app or other mapping software?

Thanks,
tweatherman

Offline CW2274

  • Forecaster
  • *****
  • Posts: 6361
    • Conditions @ CW2274 West Tucson-Painted Hills Ranch
Re: Best way to determine true north
« Reply #1 on: April 26, 2022, 07:41:53 PM »
Old school here. Polaris.

Offline havtrail

  • Senior Contributor
  • ****
  • Posts: 192
    • Haverford Weather Station
Re: Best way to determine true north
« Reply #2 on: April 26, 2022, 07:50:24 PM »
I use a magnetic compass and the declination factor in degrees for my area. I sight from in front of the vane using the compass and degree offset, to a distant reference point (tree, etc).

Rich K.
Onset HOBO RX2102 Cellular
https://www.havtrail.com/weather/
NEWA https://newa.cornell.edu Haverford, PA

Offline Bashy

  • brecklandweather.com/pws2021
  • Forecaster
  • *****
  • Posts: 1395
  • brecklandweather.com/index.php
    • Breckland Weather
Re: Best way to determine true north
« Reply #3 on: April 26, 2022, 08:05:28 PM »
I just use a Silva compass to align my anny, if i didnt have that to hand then i would use my phone as its too much of a faff to wait for   a clear night and use the stars :)
Kind regards
Bashy

Offline Randall Kayfes

  • Weather - Photography - Astronomy - Computer Admin
  • Forecaster
  • *****
  • Posts: 1937
    • Arizona Kaymann
Re: Best way to determine true north
« Reply #4 on: April 26, 2022, 08:06:23 PM »
Actually, a combo of CW2274 and Riches is pretty good solution. I would not want to be up fiddling with my anemometer at night but if you can put yourself directly in between Polaris the north star and your anemometer, then like Rich says pick out an object in the distance. Go to work in the daytime to pick out that object and sight your anemometer. Also getting a magnetic compass to ignore any metal in your anemometer pole is not fun on ladders or roofs. Polaris also gets rid of any question of nearby metal objects screwing up your compass as well (metal fences, declination etc.)



Offline CW2274

  • Forecaster
  • *****
  • Posts: 6361
    • Conditions @ CW2274 West Tucson-Painted Hills Ranch
Re: Best way to determine true north
« Reply #5 on: April 26, 2022, 08:11:37 PM »
Actually, a combo of CW2274 and Riches is pretty good solution. I would not want to be up fiddling with my anemometer at night but if you can put yourself directly in between Polaris the north star and your anemometer, then like Rich says pick out an object in the distance.
This can come in handy as well.

https://www.timeanddate.com/astronomy/measuring-the-sky-by-hand.html

Offline CW2274

  • Forecaster
  • *****
  • Posts: 6361
    • Conditions @ CW2274 West Tucson-Painted Hills Ranch
Re: Best way to determine true north
« Reply #6 on: April 26, 2022, 08:24:27 PM »
I would not want to be up fiddling with my anemometer at night
Don't forget, you always can adjust the vane's offset in the console after getting your ciphering done if necessary.

Offline Bashy

  • brecklandweather.com/pws2021
  • Forecaster
  • *****
  • Posts: 1395
  • brecklandweather.com/index.php
    • Breckland Weather
Re: Best way to determine true north
« Reply #7 on: April 26, 2022, 11:49:09 PM »
Actually, a combo of CW2274 and Riches is pretty good solution. I would not want to be up fiddling with my anemometer at night but if you can put yourself directly in between Polaris the north star and your anemometer, then like Rich says pick out an object in the distance. Go to work in the daytime to pick out that object and sight your anemometer. Also getting a magnetic compass to ignore any metal in your anemometer pole is not fun on ladders or roofs. Polaris also gets rid of any question of nearby metal objects screwing up your compass as well (metal fences, declination etc.)

I learnt a long time back, actually pretty much from day 1 with my 1st mast and thats to hold the compass at arms length away from any possible source of interference, i also find it a lot easier to adjust the second to last segment of the mast prior to tightening up the guylines. I check the bearing standing directly below the anny with my back to the mast holding the compass out, now, I do know there is no interference from the mast itself as thats aluminium but even the phone can play a apart or screwdrivers in my pocket etc, also, you do not have to have the compass right next to the anny even working at height, so interference should never be your enemy.

I also fly drones as a hobby, nothing much worse for them as magnetic inteference, take off over some hidden rebar in concrete and youre on for a world of hurt, so its pretty much in my blood now and i dont mean the iron lol

Why would you need a combination bearing if you already have the compass?
« Last Edit: April 26, 2022, 11:51:29 PM by Bashy »
Kind regards
Bashy

 

anything