Sylpha, sorry did not get to you awhile ago, first of all, take and old spg down to 8 fathoms, pull you knife out and cut the hose right off. you will have time to get to the surface, as you said you have saved in this case. also if this were to happen kink the hose and it will slow considerably.
Diving doubles for the dive is when you plan to spend some bottom time.
slamfire you want to learn, I like it. Ok you dive 72 Cf, you go down to 130 with a casual ascent(sorry all my tanks are filled to 3500, lp and hp tanks) anyways, say I take 4 min getting there, I look and see 3100 ta 3200 left, I swim around for awhile at 2600 ta 2700 I slowly ascend and do a multilevel dive, at two thousand I make my way back towards the boat, at 1300 I do my safety, release my anchor and ascend up anchor line.
Slamfire, do a dive, and just look at psi, you have redundant if you feel at safety you need to look and see if you blew any deco obligations. and I have dive watches , computers, analyzers. But for a spearfishing dive, I am out to spear fish, and just do a dive, I just want to do a dive.
Any thing past 190' and I call 200' a 190', I will use a computer or timing device or both. Knowing the navy tables is a great bit of knowledge to know in this way of diving. You can do the decos even if you are not sure you need to, why not, yea it is boring on a wreck or pinnacle dive on a anchor line, or shootin a bag.
And stoo thanks, I would have missed this, you of all should know, diving wrecks in the great lakes, my gosh tobermory. If known max depth on wreck, or a look at depth sounder. You know your planned dive, wrecks are only so tall, then scoot up the ascent line and do decos, stay awhile longer on each stop, and last stop, deploy gas to a point you know you have accomplished that deco.
You have to know what you breathe in an amount of CF in a certain tank, then practice the dives leaving 1000 left once to the surface.
YOU WILL PICK UP ON YOUR OWN OF THINGS THAT WILL HELP YOU TO BE COMFORTABLE DIVING THIS WAY.
My diving also consist of know compass, and I have no bc on my last 50 hours of diving. I go through ell grass, and thick kelp to get down to the cabezon, mind you I hang on to an inflatabe with anchor line (no Anchor) and use only a plastic backpack, but thats a whole nother game.