FrankF
Guest
Izzy,
I calculated some worst case scenarios for you. (Just to try and dissuade you from making the 30cf mistake.)
You are doing a recreational dive to 130 fsw. You limit yourself to swimming 5 minutes away from the anchor line knowing that this is an NDL dive. You look down at your gauge and you are at your turn point, you make your turn and, for whatever reason, your reg freeflows uncontrollably. You've been separated from you buddy (or chose not to dive with one). You are pretty freaked out and you scramble and switch to your pony system (if it is backmounted lets just hope you remembered to turn it on--again another argument). You are freaked out but know you have to get back to the anchor line. A five minute swim. Your sacr creeps up to 1.0 cf/min/ata with all the frenzy. With this sacr you eat up 24.7 cf on your swim back to the anchor line. You see the mighty anchor line and it settles you so your sacr drops to .6 as you make your ascent. With an avg ascent dept of 75 ft. and an ascent time of 3 mins (give or take the 10 feet) you eat up another 5.9 cf. To do a 5 min safety stop at 20 fsw will cost you another 4.8 cf. 24.7 + 5.9 + 4.8 = 35.4 cf.
Planning dives is all about worst case scenarios. In this one your short a few cubes. Get the 40.
I calculated some worst case scenarios for you. (Just to try and dissuade you from making the 30cf mistake.)
You are doing a recreational dive to 130 fsw. You limit yourself to swimming 5 minutes away from the anchor line knowing that this is an NDL dive. You look down at your gauge and you are at your turn point, you make your turn and, for whatever reason, your reg freeflows uncontrollably. You've been separated from you buddy (or chose not to dive with one). You are pretty freaked out and you scramble and switch to your pony system (if it is backmounted lets just hope you remembered to turn it on--again another argument). You are freaked out but know you have to get back to the anchor line. A five minute swim. Your sacr creeps up to 1.0 cf/min/ata with all the frenzy. With this sacr you eat up 24.7 cf on your swim back to the anchor line. You see the mighty anchor line and it settles you so your sacr drops to .6 as you make your ascent. With an avg ascent dept of 75 ft. and an ascent time of 3 mins (give or take the 10 feet) you eat up another 5.9 cf. To do a 5 min safety stop at 20 fsw will cost you another 4.8 cf. 24.7 + 5.9 + 4.8 = 35.4 cf.
Planning dives is all about worst case scenarios. In this one your short a few cubes. Get the 40.