Don't take a DPV where you haven't swam before ?

[chimie007]

This is a poll for folks that have used a DPV. I'm curious to hear your personal experience and not an opinion which can be discussed in a thread.

Recent discussion have brought the following advice "Don't take a DPV where you haven't swam before". Some have said it was good advice. Some have said that it might be too hard/complicated/impossible to swim there. Some have have said that the important was to be able to swim back (smaller gas requirement in high flow system to swim in than out), carry a backup scooter, etc.

While everyone has an opinion on it, the question is what did YOU do on your first dive to the Henkel (or similar distance in a high flow system, 3000'). Did you swim or scooter ?


:)

[billybones519]

... I'm curious to hear your personal experience and not an opinion

While everyone has an opinion on it, the question is what did YOU do on your first dive to the Henkel (or similar distance in a high flow system, 3000'). Did you swim or scooter ?

:)

Scooter. It would never occur to me to swim back to the Henkel.

[EGIB]

This is a poll for folks that have used a DPV. I'm curious to hear your personal experience and not an opinion which can be discussed in a thread.

Recent discussion have brought the following advice "Don't take a DPV where you haven't swam before". Some have said it was good advice. Some have said that it might be too hard/complicated/impossible to swim there. Some have have said that the important was to be able to swim back (smaller gas requirement in high flow system to swim in than out), carry a backup scooter, etc.

While everyone has an opinion on it, the question is what did YOU do on your first dive to the Henkel (or similar distance in a high flow system, 3000'). Did you swim or scooter ?


:)


I was planning on swimming it first, but then I scootered.

That was not my first scooter dive in Ginnie though...I first went to Double Domes (I had swam there before), then I went to the Insulation Rooms, then I went to the loop past the insulation rooms, then the Bear Room, then the Henkle. All in all I did about 25 dives (not all scootering but a lot of them were) from the time I first scootered to the time I went to the Henkle. I gradually got familiar with the gold line passages and jumps farther into the system before I all out went to the Henkle. I actually ended up going there on the scooter before I was planning to but I was ready I think.

Since then I have gone farther on a DPV than I have swam in other systems, using very conservative gas planning. I have also had gas leaks, multiple gas leaks, regulator failures, been towed on a scooter quite a few times, seen a rock fall on my friend, and had an incident where I nearly killed my instructor in DPV class (not actually, he just choked a little). All things that would have scared the crap out of me even after my full cave training, but now are just little things you have to deal with during the dive...actually some of them were so funny I almost drowned because I was laughing too hard.

I just think it is important to plan on having enough gas to swim out, carry gas in multiple bottles, and be confident in your own ability to get yourself out when the sh*t hits the fan.

[jpdiver]

My first dive and everyone thereafter to the Hinkel was with a DPV. The same goes for Jackson Blue ( Banana room etc). I always take enough bailout gas so that I can swim out in case of scooter failure.

I can see the point of " don't DPV where you haven't swam before" in systems that are more restrictive and siltier. I did many swimming dives in Telford ( Ardvark room) etc. before I scootered.

[Slüdge]

As JB is my "home base," I can describe my experience there better than at Ginnie.

When I got my first cave scooter, I stressed to my buddy that I wanted to obey the "swim then scooter" rule. As I had swam to within a few feet of the third T, we scootered to there, clipped off the scooters, and swam to the Trash Room. The next dive, we scootered to the Trash Room and swam to stage rock. Next, we scootered to Stage Rock and swam several hundred feet beyond it.

Then it got tricky. There's nowhere good to leave a scooter in the next thousand feet or so. So I bent the "swim then scooter" rule. I would scooter to a hundred feet past my previous max. It took me ten dives to go from p2,500' to p3,500'. Which is pretty much the limit for a Tekna or Mako.

[FW]

I think you may be missing the point of the recommendation. The idea is not to buy a scooter, and make the Henkel your first scooter dive. You need to work up to something like that, so you have some idea of how long it takes to swim out of a place, vs scooter out.

FWIW, I scootered to the Henkel first, but my first scooter dive was in 1981. I also had staged about 3/4 of the way there before I scootered it.

[FW]

Russell has the right idea for progression. Scooter to the farthest place you have dived a system, then swim. Then you can add that to your farthest "swim" dive for the next scooter dive.

[Jay]

OK, since we are being honest, my third dive after full cave cert was a scooter/stage at JB. I did swim JB as far as I could the dive before though.
My 4th dive was the mile at Peacock.
I swam about as far as I could in ginnie up a lot of lines before I scootered to the henkle.

And the first time I scootered in Cow...... j/k. :smt064

Yeah, do it Russells way.

[rjack]

Russell has the right idea for progression. Scooter to the farthest place you have dived a system, then swim. Then you can add that to your farthest "swim" dive for the next scooter dive.


Caveat: I don't scooter in caves. I have gotten my butt kicked on OW scooter dives. Being left with dying batteries along a cliff a long way from an exit...(long story).

So with that in mind:
On the one hand this swim then scooter guideline makes sense. Know your limits and all that jazz.

On the other hand at some point its impossible to swim (out) anymore. You'll be towing backup scoots, diving only stages, dropping safeties, whatever. That point probably varies with flow and other day to day variables.

I am posing this as a question not trying to troll here...

If you choose the swim then scooter path, are you substituting experience for proper, training, pre-planning, towing, multiple bottles, and other skills? Maybe not bringing along redundancy when you should - cause one day in the past you were able to swim out of something?

E.g. Scooter back 3,000ft, clip it off, then swim another 500ft. Now you thumb it and return to a flooded scooter. Has this swim-before-scooter approach really prepared you for this circumstance? You might never have swam out from this point with this little gas before. If you had not done the swimming workup dives and had swimming in the back of your mind as a backup plan, would you have been more likely to bring a backup scooter?

I'm curious about where to balance these issues.
Richard

[Tegg]

I wonder how far the WKPP guys would have explored by now if they followed this "rule"? :smt102

[aainslie]

and had an incident where I nearly killed my instructor in DPV class (not actually, he just choked a little). All things that would have scared the crap out of me even after my full cave training, but now are just little things you have to deal with during the dive...actually some of them were so funny I almost drowned because I was laughing too hard.


yeah - Rich told me about how the only thing more disturbing than having his mouthpiece come off his reg (leaving him breathing water) was how funny you found it!! :)


Caveat: I don't scooter in caves. I have gotten my butt kicked on OW scooter dives. Being left with dying batteries along a cliff a long way from an exit...(long story).

So with that in mind:
On the one hand this swim then scooter guideline makes sense. Know your limits and all that jazz.

On the other hand at some point its impossible to swim (out) anymore. You'll be towing backup scoots, diving only stages, dropping safeties, whatever. That point probably varies with flow and other day to day variables.

I am posing this as a question not trying to troll here...

If you choose the swim then scooter path, are you substituting experience for proper, training, pre-planning, towing, multiple bottles, and other skills? Maybe not bringing along redundancy when you should - cause one day in the past you were able to swim out of something?

E.g. Scooter back 3,000ft, clip it off, then swim another 500ft. Now you thumb it and return to a flooded scooter. Has this swim-before-scooter approach really prepared you for this circumstance? You might never have swam out from this point with this little gas before. If you had not done the swimming workup dives and had swimming in the back of your mind as a backup plan, would you have been more likely to bring a backup scooter?

I'm curious about where to balance these issues.
Richard

Yes, yes, yes. I am 100% with Richard.

It often worries me how frequently we replace careful thought with "rules of thumb". I think that swimming to the Henkle is damn good practice, and I recommend it to anyone who is serious about cave diving. But it does little to improve your scootering skills.

To survive a scooter death/flood, you need to have careful gas planning, or a buddy who you are comfortable won't lose you and disappear into the cave after your scooter dies. Preferably both. This means, once more, understanding that thirds is not a solution.

Frankly I think that the way this is taught is pretty poor. For any serious penetration, I recommend that you sit down with Excel and do some serious "what if" planning. A hint - using a scooter, in some ways, turns a cave into a syphon if you work on the assumption that it works on the way in and fails at the worst point. Hence, once you have estimates of your swim speed, the scooter's speed and the flow rate in the cave you're diving, you can use the spreadsheet that I posted around Christmas to plan safely. Enter "Speed" as your swim speed, plus (scooter-swim)/2, not the scooter speed, and add (scooter-swim)/2 to the flow rate as well. Flow rate should be entered in the sheet as negative in a spring like Ginnie, or positive in a syphon.. For example, let's say you're scootering Ginnie - and that your swim speed is 50 fpm, your scooter speed is 100 fpm and the flow rate is 20 fpm (all these are made up as I think it's important for each person to verify their own speeds). Then enter "speed" as 50+ (100-50)/2 or 75 and "flow" as -20+(100-50)/2 or + 5 as the flow rate. See - your scooter has just turned Ginnie into a syphon! How scary is that? Allowing for a bare exit, and allowing for the possibility that you will have an OOA AND a scooter failure on one dive (remember, scooters fail often - did you REALLY finish charging it last night?), you should turn at a rounded pressure of 2600 PSI in tanks at 3600 PSI. That's actually not too bad. Thirds would not cut it, sixths is too conservative. I'd probably plan a turn at 2800 on this dive.

Once more - swimming with a scooter is equivalent to INCREASING your swim speed by (sscooter-swim)/2, and INCREASING the flow (where a syphon is positive, a spring negative) by the same amount. To get some intuition of why this is true, add in the numbers for a situation where your scooter runs at exactly the same speed as the flow in that cave and see what happens.

The link for my spreadsheet is at http://www.andrewainslie.com/spreadsheets/downstream%20calcs%20Murphy.xls - and I am not going to explain my algebra for why you should add (scooter-swim)/2 to both the flow rate and the swim speed as I'd like someone independent (hey Doron, are you there?) to once more verify my math.

Seriously, if you want to do big dives solo with a scooter, you need to do some spreadsheet work, and to have reasonable measures of your swim, scooter and flow speeds in the cave you're penetrating. This stuff is too serious to be using silly rules of thumb that don't work.

Or what the hell. Swim it, and use that overconfidence to think you're OK now.

Frankly I'm done with swimming. I'll happily go do Manatee waaaaay past where I could ever swim... when I find someone to do it with :)

[Line Squirrel]

Andrew - just curious, where do you get your flow rates from? I truly am curious and not trying to stir the pot.

[chimie007]

The link for my spreadsheet is at http://www.andrewainslie.com/spreadsheets/downstream%20calcs%20Murphy.xls - and I am not going to explain my algebra for why you should add (scooter-swim)/2 to both the flow rate and the swim speed as I'd like someone independent (hey Doron, are you there?) to once more verify my math.


Andrew doing math again :roll:

While it can calculated, isn't it just easier to actually do the swim back and record gas consumption (which is an option here compared to other cases where it might not be that easy like a siphon for example). I did that on my first dive to the Henkle. Now, I know what I need to swim back from there. It's not a rule of thumb or calculation but a number that I know worked and will work (knock on wood) for similar flow system. I did have a rough idea of gas requirements ahead of time based on other swim dives there.

Mike...what's that thing on your back ;)

[aainslie]

Hey Mike,

I covered this last time. Take a piece of cave of known length, say from the sign to Stage Rock. Swim there and record how long that took - then swim out and record that too. So - you need time at start, at the rock and when you get back to the sign. Put these in my spreadsheet in the "speed calcs" section - it'll spit out your swim speed and the average flow rate.

Repeat using your scooter. This time it'll spit out scooter and flow rates. Use the more conservative of the two flow rates it spits out.

As a quick example - stage rock is at 1800 ft. if it takes you 50 mins to swim there, and 25 to swim out, that would give a swim speed of 54 fpm, and a flow rate of -18 fpm.

Raphael, the problem is, at some point you're going to be scootering where you can't swim. Then what?? I think it helps to use the math. It's really not that hard especially since I've written the spreadsheet :)

[Line Squirrel]

Mike...what's that thing on your back ;)

Hey, the thing just followed me home...Mom!! Can I keep it?

[FW]

I wonder how far the WKPP guys would have explored by now if they followed this "rule"? :smt102
If you follow their rules of redudnancy, you won't go wrong. They take spare scooters, stash spare gas, etc.

[Kelly Jessop]

I wonder how far the WKPP guys would have explored by now if they followed this "rule"? :smt102
A little different when you have stage depots placed at increments through out the cave,back up scooters,and a support team. Losing a scooter is an incovenience,not an emergency.

[FW]

Frankly I'm done with swimming. I'll happily go do Manatee waaaaay past where I could ever swim... when I find someone to do it with :)
I agree with you! I had my battery die about a mile into Manatee. Trouble was, my buddies were already out of sight. I calcuated I could just about swim to Friedman's, but would't have gas for deco. Luckily, they missed me, and stopped to wait.

Long solo, scooter dives are pretty dangerous, even if you bring a spare scooter, and gas.

[Kelly Jessop]

I personally believe in progressive penetration for cave diving. When I made it to the Heinkel,I had swam every leg already.

[MengTze]

Swam it first, figured it was too frikin' exhausting......bought a scooter. First scooter dive (after class), got stuck in the lips. That is why it is bigger now.........I confess:smt102

[ARY]

We swam it even that i knew it was a bad idea and we already had scooters at that time. And still think it is kinda stupid to risk getting a hypercapnia back 3000' for what? To find that you scooter twice faster than walk? To find that i need 120 cuft to swim out from there? It is not worse it. But i appreciate the help of kind friends Reggie and Max who placed bottles for us at Roller Coaster. It saved us a setup dive. We did 32% but at the far end i was sorry i didn't fill it 21/35.

[saturation]

We swam it even that i knew it was a bad idea and we already had scooters at that time. And still think it is kinda stupid to risk getting a hypercapnia back 3000' for what? To find that you scooter twice faster than walk? To find that i need 120 cuft to swim out from there? It is not worse it. But i appreciate the help of kind friends Reggie and Max who placed bottles for us at Roller Coaster. It saved us a setup dive. We did 32% but at the far end i was sorry i didn't fill it 21/35.

I wrote a reply to your buddy, Tom, about the attempt. If you risk getting hypercapnia, running out of gas, cramping, etc., its likely one is working too hard to get there.

There is no rush to get there, but the penalty will be deco. Scooters will outswim swimmers anyday, so speed is not the issue, but to figure a procedure to do it safely without it.

[saturation]

Seriously, if you want to do big dives solo with a scooter, you need to do some spreadsheet work, and to have reasonable measures of your swim, scooter and flow speeds in the cave you're penetrating. This stuff is too serious to be using silly rules of thumb that don't work.

Or what the hell. Swim it, and use that overconfidence to think you're OK now.

Frankly I'm done with swimming. I'll happily go do Manatee waaaaay past where I could ever swim... when I find someone to do it with :)

HI Andrew,

And this is exactly what we did. On a single scooter each, and knowing our real gas consumption rates, we planned push into Manatee, and got to about 3500' or so, not sure because the distance markings are a bit unclear, but at least beyond the well casing with Larry Green's name on it. We also spent some scooter time looking for a room we didn't find, but the gist was I had planned for a scooter failure on the return, and that I would swim the remaining distance out based on our gas consumption. My scooter stopped outbound just before Friedman's sink, so it was just a 1000' or so to be towed. But the confidence to do that all scooter dive, and we plan for more later, was given to us by being able to swim to the Henkel, safely.

Which brings us to the issue of swimming. After a year of scootering, I noticed I no longer had the same ability to swim as well as I did before the scooter. It did not help my gas consumption rate and I was more prone to cramps in far easier dives. So, after my last cave trip in November, I have stopped using the scooter except as needed, and returned to much more swimming.

[Line Squirrel]

Which brings us to the issue of swimming. After a year of scootering, I noticed I no longer had the same ability to swim as well as I did before the scooter. It did not help my gas consumption rate and I was more prone to cramps in far easier dives. So, after my last cave trip in November, I have stopped using the scooter except as needed, and returned to much more swimming.

Back in my o/w days I did a ton of Aggressor Liveaboards, 2-3 annually. One boat, The Bay Islands Aggressor had scooters for rent. The captain of the boat used one on everydive he made...he was also the ummm, heaviest captain by far out of all of them :yawinkle:

[rjack]

If you follow their rules of redudnancy, you won't go wrong. They take spare scooters, stash spare gas, etc.

I guess that's what I was getting at. Up to a point swimming out is fine (call it "A"). From then on its increasingly risky depending on the day. And then there's a point where swimming out is just not gonna happen (call that "B").

I see some of these swimming workup efforts as an effort to understand the gray zone between A and B. Fair enough. But when you scooter in, then drop the scooter and swim, when do you know if you've swam across "B"?

Rather than keep pushing, getting closer to "B" on any given day, I <think> I would prefer to just start planning like you are going beyond "B" way earlier. Like shortly after "A". Skip the whole progressively try out the grey zone dealio.

I'm still a huge advocate for progressive penetration, just not with swimming in your back pocket much beyond "A". Cause I don't ever want a "hail mary" kinda dive coming back from just short of "B" with 50psi remaining.

[aainslie]

Which brings us to the issue of swimming. After a year of scootering, I noticed I no longer had the same ability to swim as well as I did before the scooter. It did not help my gas consumption rate and I was more prone to cramps in far easier dives. So, after my last cave trip in November, I have stopped using the scooter except as needed, and returned to much more swimming.



I definitely agree with this one. I rarely do a pure scooter dive, but I do like using it to get to places that might be hard to reach otherwise. A healthy swim after dropping the scooter is a lot of fun and good for the SAC in the long run.

[MengTze]

....A healthy swim after dropping the scooter is a lot of fun and good for the SAC in the long run.

You could take up running for that.........:smt079

[Cindy]

I swam it per the suggestion of my past cave diving instructor. His stand still is that no one should scotter anyplace you haven't swam first. I don't always follow that rule but I can see the value in what he was saying. James Hurley and I did a set up for the dive with two stages. I almost over did it. James could swim like a fish! When we turned I had 2/3 of my backgas left. Out of curiousity I swam out on back gas, picking up my stages but not using them. I still had about 500 psi left in my backgas. It was reassuring and a good lesson on sac rate, breathing, safety and swim techniques. Cindy

[Rubis]

I scootered it the first time, but there are plenty of other caves that I swam first.
I guess YMMV.
If you just got your scooter cert, it is better to get accustomed to scootering first, learn the cave by swimming, how much gas is needed, etc etc ...
One thing that needs to be said about caves with flow, is that if you swim it first, you will learn how to stay out of the flow. Then when you scooter, you follow the same path and you earn valuable minutes.
On the other hand, if you have already experience with cave diving and scootering, you will be able to stay out of the flow as well and you know how much gas you need anyways.
So you don't really need to swim it first (Plus for big dives, you build in some level of redundancy, extra gas, back-up scooters, etc ...)

I guess the advice "swim it first" applies well to the people that just got their scooter card.

I would love to swim it now, especially if I had plenty of time to spend down in cave country. I would love to get to the point of swimming to the Hinkle in less than 45 minutes, with a set of double 85s, and not even reaching thirds.
That probably would improve my skills quite a bit :D

When I got my scooter I wanted to scooter all the time. Now that I dive CCR and time is not an issue, I really enjoy swimming in a cave, taking my time and poking around.

[MengTze]

...... I would love to get to the point of swimming to the Hinkle in less than 45 minutes, with a set of double 85s, and not even reaching thirds.
That probably would improve my skills quite a bit :D..

I think we know a guy who probably could......(and has). Say hello for me will you?

[amphipod06]

Now that I dive CCR and time is not an issue, I really enjoy swimming in a cave, taking my time and poking around.

On the other hand, scootering on the CCR is soooo cool, and quiet except for the hum of the motor....

Yeah, I scootered to the Henkel, but I had been swimming Ginnie for a while before that and carried extra stages etc....just in case.

Like someone I know says, 3 things to know about your scooter:

1. Know your burn time
2. Know your burn time and
3. Know your burn time

It has saved me a lot of grief to know this and I plan scooter dives accordingly, these days we have a tow scooter, just in case....

Dive safe,

Celia

[Slüdge]

On the other hand, scootering on the CCR is soooo cool, and quiet except for the hum of the motor....

Yes, but the way I skip breathe, it's pretty much the same thing.:smt102

[runawaylobster]

Hi Raph,

everyone is different therefore it's hard to agree with such a statement.

by the way haven't swam before is bad grammar, it should be

haven't swum before...

;)

LL