[Alpha Von Burg]

When I reach my patrol area I would try and stay submerged for as long as I can and suface when CO2 levels hit 50%. I usually set a schedual to when I surface, being some time after sun set and sometime before sun set.

Being submerged as its advantage, such as hydrophone scan which has better "visual" range, most of the time and reduces any chance of being spotted first.

And to conserve battery life I just stay at slow speed.

Hope this help...