Don't want to discourage you but I found that the "maps" feature of my Sol to be the least useful and stopped using it. Firstly the resolution means that you are limited to very large thick lines and large shapes. Anything fine, small or complex gets lost in the resolution. I tried doing a simple map of one of the wreck sites that I dive often. I drew it in a simple drawing package and uploaded to the Sol. I tried several versions. If I made it big and simple, it was not useful underwater. If I made it detailed and complex, the detail was lost in the resolution.
On the other hand, I have found the ability to load text messages very useful. I have programmed about 15 simple messages, a few related to diving (e.g. let's turn around and go back) but most related to video shooting with a model.
Some examples are:
"Stop, wait here 15 seconds, then follow me",
"Swim over my head",
"Look at this thing that I am pointing at",
"Please don't smile or wave at the camera".
I use these to give instructions to people who volunteer to model for my underwater videos. Works well. Just scroll to the message and show it to them. Beats waving your arms around like a crazy man...
But, please let us know if you do have a successful experience with drawing maps for the Sol.
Do you now the resolution of the screen?