GPS DATUM

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Tackleberry
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GPS DATUM

Post by Tackleberry » Wed Sep 28, 2016 1:21 am

ok every one what datum do you use on your gps
"When the people fear the Govn't, that is Tyrany, when the Govn't fear the people, that is Liberty"

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re-tyred
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Re: GPS DATUM

Post by re-tyred » Wed Sep 28, 2016 5:06 am

WGS 84 . Is the one most charts are drawn to. If you use the Australian 66 datum you will be approx 120 mtrs different for the same numbers. The thing that gets most people is not the datum but the format of the LL.
Degrees . minutes and decimal minutes is the most common. Degrees minutes and seconds and degrees decimal degrees are sometimes used. ,
EG 38.75000 degrees is 38deg 45.000 minutes
There's nothing . . . absolutely nothing . . . half so much worth doing as simply messing around in boats.
Kenneth Grahame, The Wind in the Willows (River Rat to Mole)

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Re: GPS DATUM

Post by re-tyred » Wed Sep 28, 2016 5:24 am

Minutes max is 59 same for seconds but decimal is 99.
So 45 minutes is 0.75 of a degree. 45 seconds is 0.75 of a minute. So 38 d 45.75 minutes is 38.45.45 in D M S.
Most GPS can change in the setup without altering the marks position.
There's nothing . . . absolutely nothing . . . half so much worth doing as simply messing around in boats.
Kenneth Grahame, The Wind in the Willows (River Rat to Mole)

skronkman
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Re: GPS DATUM

Post by skronkman » Wed Sep 28, 2016 6:24 am

WGS84 all the way. I personally haven't seen a chart for Australia in anything other datum. And what retired said about syntax is also important, it's not hard to convert between the formats but I've seen a few different ones that could be traps for young players.

Degrees^minutes'seconds"
Degrees^minutes.decimal
Degrees.decimal

I prefer the first buts it handy to know how to convert between them and recognise the difference. It's also handy to know that 1 nautical mile (1.8km) is 1 minute of latitude and 1 second is 30 meters.

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Re: GPS DATUM

Post by Mappo » Wed Sep 28, 2016 6:32 am

I use GDA94 in decimel format.

Cheers,

Mappo.

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Re: GPS DATUM

Post by re-tyred » Wed Sep 28, 2016 7:16 am

GDA94 is basically the same as WGS 84
There's nothing . . . absolutely nothing . . . half so much worth doing as simply messing around in boats.
Kenneth Grahame, The Wind in the Willows (River Rat to Mole)

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