...is pretty easy if you keep an eye on your bottom time. You know you'll turn at near 1/2 your gas and ascend some on the return. Say you go out at 70 ft. for 25 mins. and turn at 1500psi. Turn and up to 35 ft. for 20-23 minutes and ease up to safety stop depth, as you approach 50 minutes, you should be real close to the starting point. I usually find a bottom feature on the decent at 15-20 fsw. that I can locate on the safety stop and have a back azmuith to the dock so I can burn some more air from the safety stop to the dock, making that last 15 ft a real slow ascent hugging the sand.
Worst case if you can't find your point, just surface after your safety and get a bearing to the dock. You'll be within a minute or two and you can go back to 15 ft and ease in to the dock!
Take a look at the soft corals as you desend and you can see if there is any current, as you know' begin in to the current and you'll have plenty gas for your return leg as you are shallower and swimming with the current.
Porta Marie has a nice double reef system with a sand flat about 40-70fsw where an old pontoon frame sits on the bottom, nice for orientation. There's a cut in the second reef to the south east and that portion (further south/ east) gets pretty deep, the north/ west has nice shallows, see if you can find the seahorses on the first reef.
Worst case if you can't find your point, just surface after your safety and get a bearing to the dock. You'll be within a minute or two and you can go back to 15 ft and ease in to the dock!
Take a look at the soft corals as you desend and you can see if there is any current, as you know' begin in to the current and you'll have plenty gas for your return leg as you are shallower and swimming with the current.
Porta Marie has a nice double reef system with a sand flat about 40-70fsw where an old pontoon frame sits on the bottom, nice for orientation. There's a cut in the second reef to the south east and that portion (further south/ east) gets pretty deep, the north/ west has nice shallows, see if you can find the seahorses on the first reef.