Maps

That's true. As a side note, remember that latitude/longitude has also changed with most coordinates having shifted by up to 200 metres. It's a minor point but potentially something to trip on if you're using it instead of grid references. At least now NZ's more consistent with the rest of the world, since the previous system created extra work for any international businesses or operators wanting to be compatible with NZ, and vice-versa. One way or another, all of these changes are supposed to make working with maps less complicated and more efficient, which should be good for everyone whether it's LINZ or general map users.

Geodatum 49 was apparently a very successful datum. You have to remember that we are on the opposite side of the planet from most of the world from everyone else so it is probable that any datum created for everyone else would have all the errors shoved in our direction. Also NZGD2000 is not the same as WGS84. It is identical for our purposes but there are differences. One thing I recall is that there is a factor built in for continental drift. This was not the case with Geodatum 49 and apparently there were significant errors is some parts of NZ. As for using lats and longs on 1:50,000 maps. I can only ever recall one instance in my tramping career of someone with an old Trimble GPS stringing dental floss from one edge of the map to the other to establish his position using lats and longs. That is the GOTCHA between the old and new maps, but it is hardly likely to be an issue with us mere mortals.

Absolutely, NZGD1949 made sense at the time, but it's also based on a flat(tish) plane model of New Zealand's part of the earth that was based on measurements between survey markers without really modelling the entire global context. And yeah, as a static datum it also never took into account that survey points move over time. Neither does WGS84, but as you pointed out and from what I've read, the NZGD2000 adaptation only becomes relevant if you care about accuracy of more than about half a metre. NZGD1949 also makes calculating heights of peaks complex too, because the NZGD1949 by itself doesn't model mean sea level nicely so there's a splattering of extra localised reference datums throughout NZ from which everything's calculated. Now I suddenly wonder if any elevations have officially changed with the switch to NZGD2000. I'll have to ask someone at LINZ when I get a chance. Does anyone know off-hand? I can certainly see why it makes sense to change things now. There's now a more global industry in mapping tools and methods, so it's useful to have everything operating on the same system. Better use of computers to do most (or all) of the mathematics, in a way that wasn't possible a few decades ago, also makes it easier to go this way.

You obviously know more about datums than I do. I had also heard that NZGD2000 was 3D datum but wasn't sure quite what that meant. When we walk past these trig stations on top of hills we have to realise that not long ago they were the only way for surveyors to connect from one valley to the other or to the rest of the country. There was no way to survey across the oceans. I have a mate who is a surveyor and he told me that occasionally he has had to look for pegs that are up to 100 years old. Despite what seems like primitive methods used back then to site pegs, there was nothing wrong with their accuracy. Usually he locates these old pegs exactly where they should be.

Only what I've read on the LINZ website in the last few months, unfortunately. I'm not speaking from any qualified experience. :) They have some quite detailed info there if you dig for it (including all the maths for how to convert between everything), but I don't think they've made it too obvious to find since I guess it'd distract from the main points they're trying to get through to people. ie. That the maps are changing!

As attempted in http://tramper.co.nz/?4875 - I've just printed 4 A3 colour prints, and at a total of $14 I like it. The contour lines are good enough, the image is quite vivd. Very happy. The idea then is to download the TIFFs and crop/join accordingly. NZTopoonline data is ok - but doesn't print nice.

I made a map of the Hollyford track from NZtopoonline it took several maps but it came out good

Has anyone heard of an official SAR line about printing maps for use while outdoors? LINZ now seems to be making it easier than ever for people to produce maps themselves, which is awesome, and I already know several people choosing to download and produce their own maps rather than going out to buy the pre-printed ones. I expect this is perfectly fine in most cases and far more convenient, especially for everyone who already knows what they need, but I've also wondered if it might increase the number of people using maps with bad scales, fuzzy detail, without proper grid references, and inconsistent production with paper and toner and so on. I'm sure I've heard SAR criticism in the past of people having these kinds of problems after they relied completely on self-produced maps.

I doubt SAR would have any sort of policy on self produced maps though I think you are expected to have adequate maps for the job. I guess that standard would be different for someone walking the Routeburn than for someone who was heading into the "great untrodden Ureweras". Mind you, when we used to tramp in the Olivine Wilderness in the early 1970s there were no topo maps. The only map we had was a line drawing of rivers and ridge lines that came out with the 1964 Alpine journal. But we did have Moirs Guide Book (aka the trampers bible or the gospel according to St Moir) But you do bring up a point. Electronic maps are useless if the batteries go flat, maps printed on an inkjet printer will turn to a blurred mush when exposed to 1 drop of rain. I saw one guy in the hills recently who had chopped up his maps into playing card sized bits and had laminated them. he just kept the relevant "cards" in his shirt pocket when tramping for easy access. Horses for courses I guess.

That poor hapless "ultralite" yank that tried to go the wrong way over Rabbit Pass a few years ago, was alleged to have inferior quality printed off maps. I think the coroner did a bit of a grumble about it.