DPV Diver

[PfcAJ]

I don't view swimming out as much of an option on anything deep and/or long. Gas and deco requirements become just preposterous.

Tow scooter is the move. Sometimes 1, sometimes 1 per person on the team. All depends on the depths and distances.

[nakatomi]

I think you're forgetting that you can take two scooters instead of one for dives where swimming out becomes impractical.

So are you suggesting that Frank doubles his old Gavin scooter and takes two of them to the back of JB or Ginnie, with not enough gas in his plan to swim out?

[victorzamora]

So are you suggesting that Frank doubles his old Gavin scooter and takes two of them to the back of JB or Ginnie, with not enough gas in his plan to swim out?

[LiteHedded]

So are you suggesting that Frank doubles his old Gavin scooter and takes two of them to the back of JB or Ginnie, with not enough gas in his plan to swim out?

at ginnie at least i would say it's easier to take the swimming gas instead of another scooter

[nakatomi]

at ginnie at least i would say it's easier to take the swimming gas instead of another scooter

And just for the record, of course I agree that it becomes impractical at some point to have an emergency plan based on a long swim. But, having said that, those dives are probably not done solo but in a team of preferably two (better three) divers with modern scooters, ample backups and good towing skills.

[bent]

at ginnie at least i would say it's easier to take the swimming gas instead of another scooter

Because it's not that deep?

[LiteHedded]

Because it's not that deep?

you'd have to work really hard to get any deco there. plus it doesn't really go anywhere and has that flow.
so weighing the PITA factor of dragging a second scooter vs maintaining swimming gas reserves, i would probably skip the tow scooter. get towed out if possible, swim if not

[midway]

Frank, maybe this example helps? ...

I could be mistaken but your example, although valid as a DPV dive plan (ignoring deco gas planning), has fallacies when drawing conclusions compared to the swimming case:

... using one stage and LP95's, getting to the stop light (4th T) which is at around 2300' or 2400' on thirds would about as far as I would expect to swim right now.

In essence, you are comparing apples and oranges. In the DPV case, you calculate max penetration and turn pressure based on gas volume remaining to swim out, with redundancy (you used 1.5). In the non-DPV case, you apply the standard 1/3 rule. In high flow JB for which you performed the estimates, to make the comparison meaningful you would want to calculate non-DPV turn pressure at the point where the remaining gas allows you to swim back, with the same redundancy (say 1.5) as in the DPV case. Otherwise, all that you're stating is that (i) you're being overly conservative in gas planning when you're swimming JB -- assuming your DPV planning is considered safe (I have no problems with it) -- (ii) or your DPV planning is unsafe relative to your safety standards when only swimming at JB. You can't have it both ways.

[nakatomi]

In essence, you are comparing apples and oranges. In the DPV case, you calculate max penetration and turn pressure based on gas volume remaining to swim out, with redundancy (you used 1.5). In the non-DPV case, you apply the standard 1/3 rule. In high flow JB for which you performed the estimates, to make the comparison meaningful you would want to calculate non-DPV turn pressure at the point where the remaining gas allows you to swim back, with the same redundancy (say 1.5) as in the DPV case. Otherwise, all that you're stating is that (i) you're being overly conservative in gas planning when you're swimming JB -- assuming your DPV planning is considered safe (I have no problems with it) -- (ii) or your DPV planning is unsafe relative to your safety standards when only swimming at JB. You can't have it both ways.

You are correct, it is comparing apples to oranges. Both dive plans are very different. DPV diving requires different planning than swim diving, which is why the class is so helpful.
And of course at first glance, the DPV emergency dive plan is not as "conservative" as the plan for the swim.
But don't forget, it already includes one catastrophic failure, a broken DPV.
So essentially you are planning for a full scooter failure from max penetration, plus reserved 50% more than you need to swim out, leaving room for other issues like siltouts, partial gas los, temporary lost line scenarios etc.
You would be surprised as to how many people plan their DPV dives much less conservative than I did in the example and still feel they are doing very safe DPV dives.

[floridabob]

I am afraid to say that none of the above examples necessitate much advanced planning. Its easy to swim out from the Hinkle on an 80. Same in JB on the aforementioned dives. Head out to over 5k feet and now you are thinking closer to actuality. Or 8k feet at 300'.

Be real: pretend youre at EN and want to run to the EOL up or down. Take a tow scooter. Have a bunch or reserves, too. Place bailout bottles. Plan something as deep but longer (think WKPP or Twin Dees) and youll need it all.

Remember, this started about "would you do it again, is it worth it, and why" rather than a look at me.

At Ginnie, I have used a back up scooter but it was when we went over 5k feet one way. I also had reserves for swimming. At Manatee we use a back up scooter per TM and have ample reserves for swimming out from 10k feet. In Twin Dees we have plenty of gas to swim and a scooter per TM and support divers.

Different dives. Different needs.

Bob