what datum to use on a gps

[oldboot]

2. You have now brought UTM into the confusion and this is not entirely correct with regard Australian Charts.

3. The majority of Australian Charts are Mercator and Transverse Mercator and generally Universal Traverse Mercator only used for the localized charts depending on coverage area and scale

4. I don't think it is appropriate to be talking in UTM & Zones with regard marine charts at all

If that is the case why are all my marine charts published by the QLD government clearly marked Projection "universal transverse mercator".
Frankly if we are talking about boating little else matters than the marine conventions.

All of these things are options when you look thru the set up menu on almost all gps units.
There is nothing confusing about the matter, all you need to do is look at what is written on the paper mapping resources commonly in use and make sure the set the options on your GPS to match.......In may cases these settings will not be set to suit local systems and conventions particularly if the item is mainly intended for the US.

Yes It all comes back to understanding, and the initial set up of a GPS is one of the most important things that needs to be understood.
And probaly the main reason we get posts here from people with weirdo marks on datums & references that do not match our local mapping conventions.

cheers

[SatNav]

1. UTM over small areas is not critical and even some AHO charts are also UTM but the mercator projection maintains rhumb lines etc as generally straight lines over large areas as it is projected from the equator where as the Transverse and Universal Transverse are projected from the longitude hence the term Transverse that being 90 degrees different to the standard mercator. UTM is restricted to only 6 degrees of longitude. Remember UTM is only a recent invention of the last 60 years.

2. Different options for different purposes and it's all about understanding not saying this IS what everybody uses as this is not what everybody uses.

3. The thing with many queries is that the references, datums, conventions do not match what people have been told or have come to expect or what some consider to be the norm as this can vary depending.

4. Yes it all comes back to understanding, very true.