Bill Tuthill wrote:
Paul Skoczylas wrote:
In a typical low head situation, PFDs won't save you--they'll just
make it easier to find your body (assuming it stays on). In this case,
it sounds like PFDs would have saved lives.

If a PFD provides enough flotation, wouldn't it be able to keep your head
above the water? I was surprised once that with drysuit, thick fleece,
and an Extrasport Hi-Float, I was able to breathe while trapped in a
hole.
I would have stayed in the hole if not for a throwbag, but I could
breathe.


I think it depends on a couple of things:
My experience with weirs is that if the water is too aireated, you
simply float just below the surface, due to lack of buoyancy. Also, if
the hydrolic below the weir is too strong, you get pulled below, despite
a PFD and wet-/dry-suit. You might come up every once in a while, but
since you stay under for quite a bit of time in between and since we
lack gills, that eventually means that you run out of air in between the
pop-ups.
:-(

A couple of years ago I had difficulties rescuing a friend of ours who
was getting recirculated, I remember that I was amazed at how long she
stayed under during each circulation, despite wearing a PFD.

--
Wilko van den Bergh wilkoa t)dse(d o tnl
Eindhoven The Netherlands Europe
---Look at the possibilities, don't worry about the limitations.---
http://kayaker.nl/

Wilko wrote:

A couple of years ago I had difficulties rescuing a friend of ours who
was getting recirculated, I remember that I was amazed at how long she
stayed under during each circulation, despite wearing a PFD.

In desperate circumstances, you're better off taking off the PFD and
diving down to follow the bottom current out of the backwash. Few
people who get in (low-head-dam) trouble have the knowledge or composure
to make that radical move, however.

Bob P wrote:

In desperate circumstances, you're better off taking off the PFD and
diving down to follow the bottom current out of the backwash. Few
people who get in (low-head-dam) trouble have the knowledge or composure
to make that radical move, however.

I've given that some thought. Over the years, this option seems to have
surfaced on RBP a couple of times. My main concern would be what happens
after you get out of the hydrolic, and what would happen if taking off
your PFD wouldn't get you out. I'm fairly ambiguous about whether or not
that would be a smart thing to do. It's the main reason why I have a PFD
with a front zipper though... so that I can quickly take it off if needed.


--
Wilko van den Bergh wilkoa t)dse(d o tnl
Eindhoven The Netherlands Europe
---Look at the possibilities, don't worry about the limitations.---
http://kayaker.nl/

"Wilko" wrote in message
...
Bob P wrote:

In desperate circumstances, you're better off taking off the PFD and
diving down to follow the bottom current out of the backwash. Few people
who get in (low-head-dam) trouble have the knowledge or composure to make
that radical move, however.

I've given that some thought. Over the years, this option seems to have
surfaced on RBP a couple of times. My main concern would be what happens
after you get out of the hydrolic, and what would happen if taking off
your PFD wouldn't get you out. I'm fairly ambiguous about whether or not
that would be a smart thing to do. It's the main reason why I have a PFD
with a front zipper though... so that I can quickly take it off if needed.

This boondoggle arises all the time.

As far as my experience goes, the old "take off your PFD and flush out the
bottom of the hole" strategy is an urban legend. Everyone knows the rule,
but afaik, no one knows anyone who has actually had to do it. Its in the
same legendary category as putting maggots in an open wound to stymie
gangrene from forming, or as using soldier ants as stitches to close a
wound, or to use a swiss army knife to cut an oar in half to extricate it
from your leg. Sounds good in theory, but in practice you are just never in
that exact type of situation, or else there are other complicating factors
that prevent it from really being a good strategy.

I think if you were actually trapped in a hole with sharp enough edges to
keep you in, you would be underwater and tossed around so much that you
would have no idea which way 'down' was, let alone how to crawl along the
bottom. Also, once you shed your pfd, the force of the water would almost
certainly prevent you from using the rocks along the bottom anyway, as you'd
be plastered down there at best, or slammed among them at worst. As Wilko
points out, even if it DID work, you'd then be downstream without a PFD,
pretty beat up and completely out of breath. Also, in the aerated water
behind the pourover, you would have less floatation than normal and would
have NO chance to catch a breath, so you'd be more likely to drown without a
pfd than with it on.

I think it'd be very interesting to hear some statistics about people who
have gone over low-head dams with and without PFDs, and get some statistics
of who actually has washed out vs who has drowned. I'd bet dollars to
doughnuts that the majority of people without PFDs drown, and the majority
of people with them flush out.

No, unless I hear some pretty definitive stories from folks who have had to
actually do this, and who can verify that their PFD remained in the hole
indefinately afterwards (in other words, it was a true keeper hole), I
choose to believe that this is a poorly thought out legendary old wives tale
that impressess newbies.

--riverman

riverman wrote:


I think if you were actually trapped in a hole with sharp enough edges to
keep you in, you would be underwater and tossed around so much that you
would have no idea which way 'down' was, let alone how to crawl along the
bottom.

That's correct. Spatial disorientation would be but one facet of the
experience that makes a low-head tailwater hydraulic a "drowning
machine". Visibility is bad to non-existent, bubbles go in all
directions, and the current is quite deceptive. I know a guy who went
diving in a similar current, looking for lost anchors. He did this and
several similar crazy things in his younger years, and is quite lucky to
have survived many of them. He's the only person I know who was in such
a current and lived to talk about it, he had SCUBA gear and advanced
training, he was quite impressed with the power of the hydraulic and
says he couldn't see how anyone without all the equipment could have
gotten out of it.

Our Dive/Rescue team had one of these hydraulics in our jurisdiction and
we used to really worry about a potential rescue or recovery there until
the Army Corps of Engineers solved our problem by rebuilding the
structure in question to eliminate the low-head dam.

riverman wrote:
"Wilko" wrote in message
...
Bob P wrote:
In desperate circumstances, you're better off taking off the PFD and
diving down to follow the bottom current out of the backwash. Few people
who get in (low-head-dam) trouble have the knowledge or composure to make
that radical move, however.
I've given that some thought. Over the years, this option seems to have
surfaced on RBP a couple of times. My main concern would be what happens
after you get out of the hydrolic, and what would happen if taking off
your PFD wouldn't get you out. I'm fairly ambiguous about whether or not
that would be a smart thing to do. It's the main reason why I have a PFD
with a front zipper though... so that I can quickly take it off if needed.

This boondoggle arises all the time.

As far as my experience goes, the old "take off your PFD and flush out the
bottom of the hole" strategy is an urban legend. Everyone knows the rule,
but afaik, no one knows anyone who has actually had to do it. Its in the
same legendary category as putting maggots in an open wound to stymie
gangrene from forming, ...

Actually, maggots are now occasionally used in hospitals to eat dead flesh.


I think if you were actually trapped in a hole with sharp enough edges to
keep you in, you would be underwater and tossed around so much that you
would have no idea which way 'down' was, let alone how to crawl along the
bottom. Also, once you shed your pfd, the force of the water would almost
certainly prevent you from using the rocks along the bottom anyway, as you'd
be plastered down there at best, or slammed among them at worst...

--riverman


As I said, it's a desperation measure. If you can keep your head above
water long enough for someone to rescue you, you're better off not
taking the chance.

However... If you look at the typical water flow of a low-head, the
water first goes down and along the bed, away from the lip of the dam
before it doubles back. It's the only path where the water takes you to
safety rather than holding you against the top flow. I've never use it,
and I certainly don't intend to experiment, but the logic is reasonable.

"Bob P" wrote in message
.net...
riverman wrote:
"Wilko" wrote in message
...
Bob P wrote:
In desperate circumstances, you're better off taking off the PFD and
diving down to follow the bottom current out of the backwash. Few
people who get in (low-head-dam) trouble have the knowledge or
composure to make that radical move, however.
I've given that some thought. Over the years, this option seems to have
surfaced on RBP a couple of times. My main concern would be what happens
after you get out of the hydrolic, and what would happen if taking off
your PFD wouldn't get you out. I'm fairly ambiguous about whether or not
that would be a smart thing to do. It's the main reason why I have a PFD
with a front zipper though... so that I can quickly take it off if
needed.

This boondoggle arises all the time.

As far as my experience goes, the old "take off your PFD and flush out
the bottom of the hole" strategy is an urban legend. Everyone knows the
rule, but afaik, no one knows anyone who has actually had to do it. Its
in the same legendary category as putting maggots in an open wound to
stymie gangrene from forming, ...

Actually, maggots are now occasionally used in hospitals to eat dead
flesh.


Yes, I know. But I was referring more to the 'Jungle Jim survival' scenario
that makes the Reader's Digest Drama in Real Life pages.



I think if you were actually trapped in a hole with sharp enough edges to
keep you in, you would be underwater and tossed around so much that you
would have no idea which way 'down' was, let alone how to crawl along the
bottom. Also, once you shed your pfd, the force of the water would almost
certainly prevent you from using the rocks along the bottom anyway, as
you'd be plastered down there at best, or slammed among them at worst...

--riverman

As I said, it's a desperation measure. If you can keep your head above
water long enough for someone to rescue you, you're better off not taking
the chance.

However... If you look at the typical water flow of a low-head, the water
first goes down and along the bed, away from the lip of the dam before it
doubles back.

Well, that's certainly the theory. In reality, the 'break line' where the
current splits surges around quite a bit (in all but the most surgically
designed dams), there are bursts and boils that erupt in various places, and
the bottom of the river is usually anything but regular. I think the
hydrodynamic model that we all look at is most accurate in man-made
spillways, with precise and consistent angles, concrete bottoms and very
clean riverbeds. And only somene with a death wish would be running
something like that: those are true killing machines. In the natural world,
there are always lots of little variations and 'irregularities' that affect
the model.

It's the only path where the water takes you to safety rather than holding
you against the top flow. I've never use it, and I certainly don't intend
to experiment, but the logic is reasonable.

Sure, if you assume that all the natural variations don't exist. All logic
is reasonable is you start with 'lets ignore any diversity to the model'.
Its like that old joke about the mathematician, the physicist and the
engineer betting on a horserace, and the mathematician says 'assume a
spherical horse'. :-)

--riverman

riverman wrote:
"Bob P"

It's the only path where the water takes you to safety rather than holding
you against the top flow. I've never use it, and I certainly don't intend
to experiment, but the logic is reasonable.

Sure, if you assume that all the natural variations don't exist. All logic
is reasonable is you start with 'lets ignore any diversity to the model'.
Its like that old joke about the mathematician, the physicist and the
engineer betting on a horserace, and the mathematician says 'assume a
spherical horse'. :-)

--riverman

So you wouldn't try the maneuver even if you knew you were going to
drown if you did nothing?

Here's a little story. It happened to me about 20 years ago.

We were paddling the Thurmond-to-Fayette section of the New River (WV)
at fairly low water.

About 2/3 of the way down there's an huge rock on river right (unknown
to me as The Undercut Rock). I had run the rapid a couple of times
before at high water and pillowed off the rock quite nicely. This time,
however, I came right up to the rock, broached and flipped upstream.
The boat was sucked down, down, down and finally lodged quite nicely
upside down with me in it. I popped my skirt, undid my thigh straps,
and tried to push myself out of the boat, but the water pressure kept me
pinned. Tried again, and again.

Hey! I'm going to die here! Time for a Desperation Move!

I reached above my head (actually down) and, (Holy Crap!) there was the
cockpit rim of another pinned boat below me. Somehow, I was then able
to pull myself out using the cockpit rim. I guess that the extra reach
was enough to get me all the way out of the boat.

I pushed off and was able to get into the current enough to get around
the rock. Come on Charlie Walbridge (pfd)!!! I reached the surface
just before I was about to take a nasty breath of water.

My boat came out 2 days later, when the water dropped even more.

So sometimes you do things, even if they have a low probability of success.

Wilko wrote:

Bob P wrote:
In desperate circumstances, you're better off taking off the PFD and
diving down to follow the bottom current out of the backwash. Few
people who get in (low-head-dam) trouble have the knowledge or composure
to make that radical move, however.

I've given that some thought. Over the years, this option seems to have
surfaced on RBP a couple of times. My main concern would be what happens
after you get out of the hydrolic, and what would happen if taking off
your PFD wouldn't get you out. I'm fairly ambiguous about whether or not
that would be a smart thing to do. It's the main reason why I have a PFD
with a front zipper though... so that I can quickly take it off if needed.

I suspect it's an urban legend. Perhaps all the swimmers found dead
without a PFD attempted to do it. Or their PFDs weren't tight enough.
Here's a story of somebody who did it and survived:

http://www.ptone.com/Kayak/RF/

Per Wilko:
It's the main reason why I have a PFD
with a front zipper though... so that I can quickly take it off if needed.

This thread is making me re-think my practice of tying that waist band on my
PFD...
--
PeteCresswell