Well, good questions.
I was thinking that we would shoot the bag, tie off the line and cut the reel loose. Ascend and then cut the smb off. Of course that leaves the line but we would pick that up later I presume. The gps would be carried in a waterproof box and pulled out at the surface to mark the spot.
The problem with knowing the direction and distance is that we don't really know where the boat is in this valley. We are planning to head out along one side of the valley and run search patterns from the side. Like out x minutes, turn 90 degrees for x minutes and then back. How do you extrapolate a straight line from a series of estimated zig zags in poor vis? My thinking is that you get a gps point and plot it on a map. Then you can draw a line and get a good bearing and distance which you can use to approximate trigger time.
Then you have the added bonus of numbers for when a buddy with a boat comes to visit.
Your Zodiac is pretty light and gas is cheap - wanna come out and help ping the bottom?
Hunter