So far I have been working with reference to True North. As an alternative how could I switch to UTM Grid or at least display the grid lines please?

Hi Mark,

Switching from Geographic to UTM is as simple as clicking on the UTM icon next to Geographic icon in the Calculate tab... This said, if you have done some Plan drawings while using Geographic "projection", you won't see them anymore when zooming onto your displayed data. There are not gone, but all your Plan drawings will found around X=0, Y=0 as the cave ref point in Geographic "projection" is X=0, Y=0... far away from your cave ref point in UTM coordinates.
To bring your drawings to the correct UTM location, first under Drawings tab, enable the Grid display. You should now see the UTM grid and coordinates under the Elements tab. Zoom out until you have both X=0,Y=0 (where your Geographic drawings live) and your cave data displayed in the UTM projection on the same screen. Select all the drawing elements at once and drag them toward the UTM cave ref point. Zoom in and drag them again, closer to your data.... Do it again and again, until you can drag them to overlay nicely your survey data.

This would be the same "issue" if you decide to switch the depth ref Entrance/Sea level.

Thanks, I tried that out and it works OK. Some lack of fidelity on colour fill though. Also I had to rotate the drawing elements slightly to fit the survey skeleton using keys fn - alt- mouse wheel.
Cheers, Mark T.

Great news.
You're right I forgot about the rotation. One of the differences between Geographic and UTM is that the vertical axis is the true north using Geographic mode vs grid north using UTM mode. The exact rotation from true north to UTM grid north is found in the Cave data frame (bottow left) in the box Meridian, but I think the rotation tool as steps of 1 degree. So you might have to adjust parts of your drawings after dragging them back in there new location.

Thanks again. By trial and error I discovered that smaller rotation increments are possible using keys:
bigger increments ctrl - alt - mouse wheel.
smaller incrments fn - alt - mouse wheel.
REgards, Mark T.