Just one trip up that I know of...
There are a couple of anchoring apps out there. I installed them both on my phone
, picked the one I liked.
Then tried to load on my iPad
one (no 3G/GPS) iTunes would not let me load that app and kept erroring "This app needs a GPS
." of course I had an external gps
I worked with the developer who was very responsive but we could not solve this. I still suspect it was something to do with when he loaded the app to iTunes he must have filled out some sort of "system requirements" screen
or something, which he swears he didn't.
Anyway - make sure you allow for non-3g/gps tablets that use an external gps.
I am sure you have considered this but you have to allow for offset and swing and it has to be dead simple. You should be able to "mark" the anchor
position when you drop or manually enter the offset if the crew did not mark it while anchoring.