GPS Waypoint Information

[Needmorerum]

I know this has been spoken about so many times, what I am looking for is some websites that explain the difference between different waypoints. I have been given some waypoints from Ozi Explorer and they have 4 numbers in the final set.
My GPS (Lowrance LMS 350A) only takes 3 numbers in the final set. I followed the previous posts on this topic and, well, what can I say, I didn't really understand them.
Not sure where to go now, any help appreciated.

Corry

[Kerry]

So then to understand your actual problem need some examples of the format you've been given.

But based on the information above you should go back to the source (the person who supplied these in the first place)and ask 2 questions: What is the FORMAT and what is the DATUM. If that can't be provided then don't waste your time with them.

Cheers, Kerry.

[Heath]

First thing I would do, would be to ask the person who gave you the marks how come they only have 4 numbers in the final set.

Ozi has 3 modes for showing waypoints

xx.xxxxxx
xx.xx.xxx
xx.xx.xx.x

Download the free version of Ozi, pump your points into it in the format you were given the points, then change the way they are shown in Ozi using the configuration menu. It does all the conversion for you [smiley=2thumbsup.gif]

[Kerry]

Download the free version of Ozi, pump your points into it in the format you were given the points, then change the way they are shown in Ozi using the configuration menu. It does all the conversion for you.

Sure it will do the conversion BUT one still needs to know what the format is/was in the first place to put them back in as converting the unknown simply creates a bigger unknown.

Cheers, Kerry.

[isaac]

Corry, doesn't solve your issue but there is some easy to understand info on datums on these sites;

http://www.ga.gov.au/nmd/geodesy/datums/

http://www.amsa.gov.au/Shipping_Safety/Navigation_Safety/Positions_and_horizontal_datums_on_paper_and_elect ronic_charts/index.asp

[Needmorerum]

OK, first up, the format given was:
(those that live in CQ, close your eyes)

Lat: -23 51.0715 Long: 151 34.8890

My GPS is looking for xx°xx.xxx' and xxx°xx.xxx'

Jeff (Seafox), can you help with the Format and Datum?

I think I know why it was telling me to head further out to sea when I punched a waypoint into it the other day, I didn't think to change the N to an S, or the W to an E. I think this will then make it take me to the other side of the globe. Don't know if I would have had the fuel to get there. Thought I would be better off heading west again till I hit land. (One thing I like about me... always thinkin)

isaac, thanks for those sites, I will have a read and see what I can make out. I've got to do some work tonight, and with New Years tomorrow night, probably won't get a chance till Saturday, will let you know how I go with them.

Can anyone tell me if I can change the format with my GPS, with my handheld I can, but I can't find it through the menu system in the Lowrance. (If there is a Lowrance guru out there, is there a way of turning the main volume on and off as well, besides the volume up and down?)

Corry

[Kerry]

Based on the Longitude decimal value you could "assume" that format is Degrees Minutes & decimal minutes (to 1/10,000 of a minute 0.0001'), which is basically the same format of the 350A with the exception of it only being to 0.001' (1/1000 of a minute).

3 decimal minutes or 4 decimal minutes isn't of any concern as far as accuracy is concerned so basically round the minutes to 3 decimal places to be something like Lat: -23° 51.072' #Long: 151° 34.889'

The format of the 350A can not be changed.

The datum can not be determined from the coordinates themselves, so the person who provided the coordinates must be relied on to know (and tell you) what this is. To be usefull all coordinates MUST be tagged with the datum of the coordinates otherwise one is only guessing.

350A main volume is always on, either up or down, have you tried turning it all the way down to basically zero?

Cheers, Kerry.

[Needmorerum]

Thanks Kerry, just to ask another question, what does the datum do?

With the volume, I am trying to turn it on. I have it set to max but there is nothing coming out of it. I have heard that this is a common problem with the 350, apparently the speaker fails. Would this be something that can be repaired, or are these things sealed units that can't be opened for repair?

Again, your advice is appreciated.
Corry

[Kerry]

Corry, In simple terms a datum puts in the place the coordinates were actually meant to put you.

THIS DATUM LINK (http://www.cqnet.com.au/~user/aitken/gps_x/datum.htm) might explain the issue with datum's and THIS FORMAT LINK (http://www.cqnet.com.au/~user/aitken/gps_x/format.htm) some of the issues with formats?

Yes the 350A's are a sealed unit and as far as I'm aware Lowrance doesn't (won't) service them anymore? NOt that they ever serviced them in the first place as most units were simply replaced but these models were discontinued many years ago.

Cheers, Kerry.

[Barrymundi]

The speaker on mine stopped after a few years.

I repaired a cracked track on mine last year, pretty easy to pull apart.

Sealing is a problem, they are normally nitrogen filled.

I didnt bother, it is still working fine, actually it is for sale

Al