On the PC version I open and before syncing dives I click log > plan dive. I then set the start time to whatever I'd like. If I do a second dive it will automatically add a 1 hr si. You can change the si to be whatever you like, it's just based off the end time of your 1st planned dive (+1hr).How do you add a second dive to the Subsurface planner? I didn't think it supported a second dive.
Only PC (and I'm sure Mac), not available on app (at least not android).
I love Subsurface.. I wish the app could plan dives back to back. Hope that helps.