I'm not sure about this. I had no luck of getting the right values for a Ranger class tanker. Also, seems like for many ships the right values come up on funnel height, not mast. And there is a problem with the UI, I was about to be rammed by a mad merchant and pressing the crash dive button I surfaced the boat

The depth unde keel and return 2 course icons are missing and it conflicts with the digital clock mod.. maybe you can move the icon on the tools panel.
Anyway, I'm happy that you released a standalone mod for this, not everybody use UI mods, so I hope this will get better. Thank you.