wreck in the bay

[snappa]

hi all
i am chasing the wreck "neilston" i think thats the spelling. ???
does anyone know and could you give me the gps marks
for the wreck.
a trip out if you can remember.
snappa

[Lucky_Phill]

153.20.020 27.11.147 NILSON capt nilson (WGS 84 )

[snappa]

lucky phil
thanks for the gps marks for the nilson
what is wgs 84 mean
many thanks again
by the way have you any wrecks on the outside of moreton
i heard that there is plently of trawler wrecks and one i am keen on to find is about 12 ks east of cape moreton
snappa

[Kerry]

lucky phil

thanks for the gps marks for the nilson
what is wgs 84 mean

Well I find that rather a worry asking for "GPS marks" and not knowing what WGS84 means .

Cheers, Kerry.

[Big_Kev]

LOL
Yeah thats a good one Kerry.
Cheers Kev.

[grey_inflatable]

ha mate why u want to know wrecks for.
is it for diving or fishing,if it is diving there many in the bay sounds cool
c u

[xxxxhornet]

G'day Snappa - mate I had to look in my manual - it means World Geodetic System 1984.

Got me stuffed either what importance it has though so that makes two of us.........
I believe its to do with what part of the world you are operating the gps in.

cheers

[Kerry]

G'day Snappa - mate I had to look in my manual - it means World Geodetic System 1984.

Got me stuffed either what importance it has though so that makes two of us.........
I believe its to do with what part of the world you are operating the gps in.

NO it's really got all to do with finding what you are actually expecting to be looking for. The same part of the world can have several different datums, just like we have in Australia along with the confusion that they cause.

Basically the same coordinates used with the wrong datum (and WGS84 & GDA94 & AGD66 & AGD84 & WGS72 etc are all datums) will be a DIFFERENT physical point on the ground. The difference between AGD and WGS84 is around the 200 metre mark.

Cheers, Kerry.

[webby]

It amazes me that people using gps systems, dont know what datum they have setup in their gps's.
Would hate to be following them on a night jointy if their using their gps for navigational purposes.
It would be like missing the beacon by 400m and finding yourself high and dry on some rocky outcrop.
regards

[sharkbait]

Not everyone knows everything like some of you seem to think you do, why don't you just explain what it means. Its more than likely their gps is set to wgs 84 anyway.

[banshee]

Okay,something that Ive thought about but never found the answer to,if I enter a mark from AGD84(example) into my unit while it is in this datum,then change back to WGS84 does the mark transfer accurately?Likewise if I change format,enter a mark then change back to the format I prefer to use, does this mark I have just entered also transfer over accurately?

[SteveCan]

Hi Banshee -

No - when you change the datum - the numbers of a waypoint will not convert over, they stay exactly as you entered them. the only difference is that as Kerry said earlier, those co-ordiantes will refer to a spot on the ground somewhere else

WGS84 is very much the standard - Kerry could give you the technical expanation why I guess, and my GPS came with that set as default. I have never had reason to change from WGS84 as all of the points I have are in the same format. When giving or receiving GPS marks to anyone the Datum should be specified or those points cannot be trusted...

Cheers
Steve.

[peterbo3]

Evening Banshee,
I may be wrong but I believe that modern Charts using a Datum other than WGS 84 will have a correction for Lat & Long (in Notes at the bottom of the Chart)to enable co-ords plotted on these charts to be adjusted so that a true WGS 84 location can be accurately plotted on them. This adjustment is similar to Magnetic Variation but applies to a position as opposed to a compass bearing. Conversely, a position on an old chart should be able to be converted to WGS 84 & hence an accurate GPS fix obtained in real time whilst at sea..

[Kerry]

.... Its more than likely their gps is set to wgs 84 anyway.

Is it now ??? but shouldn't users know what their unit is set to instead of making assumptions.

"Explain it", I can try. The following is a simplistic view of why there is a difference and the link outlines what it can mean in the real world. Any questions, feel free



http://www.cqnet.com.au/~user/aitken/gps/datum.htm

Cheers, Kerry.

[Kerry]

Okay,something that Ive thought about but never found the answer to,if I enter a mark from AGD84(example) into my unit while it is in this datum,then change back to WGS84 does the mark transfer accurately?

Most GPS receivers do BUT there's some that don't (didn't) and the best way to check (without knowing the make/model of your GPS) is to actually try it. "Some" very popular units in the early days DID NOT and is another possible reason why many of the marks kicking around today are rather suspect.

The change won't appear to be much in Lat/Long but the change will be enough to notice.

Likewise if I change format,enter a mark then change back to the format I prefer to use, does this mark I have just entered also transfer over accurately?

Haven't seen a unit that won't do this with regards formats.

However the biggest problem with formats is the umteen ratty ways that many are published/printed these days. Indiscrimate use of decimal points and the total lack of identifiers can contribute to bigger errors than even exists with datums. So simple to eliminate format issues and fail to see why publishers can't do it right in the place.

http://www.cqnet.com.au/~user/aitken/gps/format.htm

Cheers, Kerry.