5 Gallon Pail, Back Inflation & Aluminum, G-O Diving

As someone recently pointed out, you can estimate the amount of weight
required for drysuit underwear by packing the suit in a bucket and
translating the volume at 8 pounds per gallon. I did just that and wore two
full sets of underwear on the 123 minute Sunday dive in 46 degree water.

The first set of underwear is Thermolite and Polartec. It filled the five
gallon plastic container. That indicated forty pounds were required. The
next underwear is Polartec and appeared to be about two gallons. Total then
is 56#. That's a lot of lead. I borrowed a couple sixes and had a couple
8's and a couple 5's. I packed an 8 and a 6 in each of the Dive Rite
pockets, put one 5 in my right leg pocket of the dry suit and zipped the
other 5 inside the dry suit on the opposite side. I sank like a rock even
with all the underwear.

G-O diving is short for grossly over-weighted diving. That's where you sink
fast enough to break two ear drums on the descent and two legs hitting the
bottom.

To offset weight air is added. When you are G-O diving the volume of air
change is significantly more with relatively minor changes in depth. Go up
and little and you start to rise because the air has expanded greater than
"normal." Go down a little and you find yourself kissing the bottom. It's
harder to control your buoyancy. I added air to become neutral, adjusted to
the situation, and took off for the other end of the lake.

Two hours and three minutes later I surfaced quite warm and comfortable
except for my right hand and forearm. My dry glove was leaking when I
entered the water. If it hadn't been for that I would have been toasty warm
and dry. I ended up carrying the spear gun and flag reel in my left hand
and that hand wasn't even cold. Visibility was perfect - best I'd ever seen
it. I could have stayed in another hour based on my air supply but my right
hand was too cold. I knew the glove was shot too because I pinched it
pulling the bands of a speargun on a previous dive.

Back inflation is nothing to mess with if your not experienced. It can push
you forward big time with an aluminum cylinder and weight in the front -
like the Dive Rite pouches. The bigger the bladder and more weight involved
the more you will be pushed face down. Remember to keep your regulator in
your mouth if it happens to you.

The five gallon pail to estimate weight required is a good idea. Plenty of
insulation is a super idea. (The warm water weenies are drooling now.)

ben bradlee wrote:
> As someone recently pointed out, you can estimate the amount of weight
> required for drysuit underwear by packing the suit in a bucket and
> translating the volume at 8 pounds per gallon. I did just that and wore two
> full sets of underwear on the 123 minute Sunday dive in 46 degree water.

Hi Ben!

Good report! I'm glad it wasn't a boat dive over deep water! (Or was
it?) 8^)

Hopefully, when you say "packing" the suit, it means that you actually
compressed the underwear down after stuffing it into the bucket, thus
reducing its volume about 1/3, depending on the compressibility of the
material.

> The first set of underwear is Thermolite and Polartec. It filled the five
> gallon plastic container. That indicated forty pounds were required. The
> next underwear is Polartec and appeared to be about two gallons. Total then
> is 56#. That's a lot of lead. I borrowed a couple sixes and had a couple
> 8's and a couple 5's. I packed an 8 and a 6 in each of the Dive Rite
> pockets, put one 5 in my right leg pocket of the dry suit and zipped the
> other 5 inside the dry suit on the opposite side. I sank like a rock even
> with all the underwear.

Yes, that is a lot of lead.

Did you close your exhaust vent down a bit to retain air more easily?

> G-O diving is short for grossly over-weighted diving. That's where you sink
> fast enough to break two ear drums on the descent and two legs hitting the
> bottom.

Now you're scarin' me...

Kinda nice being able to walk on the bottom without a hardhat, though,
right? Surf surge be damned! 8^)

When I described this method of estimating a starting point for
weighting, I was hoping to convey the need for in-water fine-tuning (or
gross-tuning, in this case). Shallow water shore entry is good for
this. Was it a boat dive?

I'm curious, did you get into the water and then shed some weights to
determine the _minimum_ needed to get to neutral with the full tank?
Then you could adjust the weighting for any expected change in tank
buoyancy when empty.

> To offset weight air is added. When you are G-O diving the volume of air
> change is significantly more with relatively minor changes in depth. Go up
> and little and you start to rise because the air has expanded greater than
> "normal." Go down a little and you find yourself kissing the bottom. It's
> harder to control your buoyancy. I added air to become neutral, adjusted to
> the situation, and took off for the other end of the lake.

You've found one of the major drawbacks to being overweighted in a
drysuit. Another is the increased wasted air because of larger amounts
of air used to adjust when changing depths quite often. Another is an
out-of-control buoyant ascent because your exhaust valve can't vent
quickly enough.

More insulation means more air, so these problems go with it.
Overweighting just increases the problem.

I accept those drawbacks, since my typical 5-lb overweighting gives me
significantly more warmth. It's not hard to manage and it's not to the
point of causing any air-shifting problems. My air consumption is
higher. Steel 120.

By the way, did you notice any air-shifting problems, such as might
affect your trim?

> Two hours and three minutes later I surfaced quite warm and comfortable
> except for my right hand and forearm. My dry glove was leaking when I
> entered the water. If it hadn't been for that I would have been toasty warm
> and dry. I ended up carrying the spear gun and flag reel in my left hand
> and that hand wasn't even cold. Visibility was perfect - best I'd ever seen
> it. I could have stayed in another hour based on my air supply but my right
> hand was too cold. I knew the glove was shot too because I pinched it
> pulling the bands of a speargun on a previous dive.

Beautiful! Warm is wonderful, isn't it?

Two hours in 46 degree water is super. You'll find ice-diving a lot of
fun now, perhaps without needing much more thermal protection than you
just used.

Chest pads may be a help. The pressing of the water on my chest when
horizontal tends to make that area of insulation less effective, so I
loft it up with more layers.

I might even try some kidney pads sometime, but I've usually got a good
layer of air on that upper surface, so it's not often a cold spot.

Now I'm curious to hear how much you were actually overweighted. When
the tank was near empty and 4 lbs buoyant, did you still feel grossly
overweighted? Any idea how much? Did you test it by removing weights?

If you're an average-sized guy, I'm going to guess you might have gone
with 45 lbs, judging from your description of your "Pipin" descent.


> Back inflation is nothing to mess with if your not experienced. It can push
> you forward big time with an aluminum cylinder and weight in the front -
> like the Dive Rite pouches. The bigger the bladder and more weight involved
> the more you will be pushed face down. Remember to keep your regulator in
> your mouth if it happens to you.
>
> The five gallon pail to estimate weight required is a good idea. Plenty of
> insulation is a super idea. (The warm water weenies are drooling now.)

Seriously, thanks for the report. I'd like to hear more about the dive.
Was it a boat dive? Saltwater? Max depth? Anchor line? Less tendency to
cramp since you were warmer?

Regards,

Dave C

PURE TALC: Source, supplier of unscented, oil-free, USP grade PURE
TALC, ideal for use on drysuit latex seals. If interested, please see
my talc offerings on eBay (eBay ID: dave4868). Thank you!

"Dave C" <dcalderbank@top.monad.net> wrote in message
news:1162261904.643977.43930@f16g2000cwb.googlegro ups.com...
>
(snip)>
> Chest pads may be a help. The pressing of the water on my chest when
> horizontal

Eh?

(snip)

chilly wrote:
> "Dave C" <dcalderbank@top.monad.net> wrote in message
> news:1162261904.643977.43930@f16g2000cwb.googlegro ups.com...
> >
> (snip)>
> > Chest pads may be a help. The pressing of the water on my chest when
> > horizontal
>
> Eh?
>
> (snip)

(Louder) Chest pads may be a help. The pressing of the water on my
chest when horizontal tend to make that area of insulation less
effective, so I loft it up with more layers.

Can you hear me now? 8^)

The lowest areas (depending on position) get the compression from
water, compacting the insulation there, but upper areas don't get
compacted because the migrated air has allowed the insulation to retain
full loft.

Have you noticed which areas get cold when diving in real cold water?
Like 3 or 4 degrees C?

I lay some fleece material over my chest which retains enough loft even
when compacted. It's warmer.

Works nicely without adding unnecessary undergarment elsewhere, like
using a vest instead of a jacket.

Dave C

PURE TALC: Source, supplier of unscented, oil-free, USP grade PURE
TALC, ideal for use on drysuit latex seals. If interested, please see
my talc offerings on eBay (eBay ID: dave4868). Thank you!

ben bradlee wrote:
> As someone recently pointed out, you can estimate the amount of weight
> required for drysuit underwear by packing the suit in a bucket and
> translating the volume at 8 pounds per gallon.

My impression was that this method was suggested to estimate relative
changes in bouyancy from changes in thermies...ie, along the lines of
'if thermie set#2 was 2 gallons larger than the normal set, then use
16lbs as a starting point'.


> The first set of underwear is Thermolite and Polartec. It filled the five
> gallon plastic container. That indicated forty pounds were required. The
> next underwear is Polartec and appeared to be about two gallons. Total then
> is 56#. That's a lot of lead... I sank like a rock even
> with all the underwear.

How many pounds do you figure you were overweighted by?


-hh

"-hh" <recscuba_google@huntzinger.com> wrote in message
news:1162290936.368329.281040@m73g2000cwd.googlegr oups.com...
>
> How many pounds do you figure you were overweighted by?

I don't know. I think I could have taken 10# off without a problem. Next
time I go, that's what I'll try. I'm sure I'm going to keep diving with
more insulation, so now it's just to fine tune what I know can be done.

ben bradlee wrote:
> "Dave C" <dcalderbank@top.monad.net> wrote in message
> news:1162261904.643977.43930@f16g2000cwb.googlegro ups.com...
> >
> >
> > Hopefully, when you say "packing" the suit, it means that you actually
> > compressed the underwear down after stuffing it into the bucket, thus
> > reducing its volume about 1/3, depending on the compressibility of the
> > material.
>
> That's right. It didn't really compress much even with quite a bit of
> pressure. I suspect that wearing the underwear and being compressed by
> surrounding water is more efficient for compression.

Ben, I agree, I think that's what happens. Each fold of the material
adds space that wouldn't be there when worn. It's not too bad with
fleece, but it's significant with nylon fabric lined undergarments with
heavier seams. The error of this procedure increases quite a bit with
larger, stiffer garments.

> >
> > Did you close your exhaust vent down a bit to retain air more easily?
>
> Yes. I'm cautious when doing this but I made several adjustments while
> staring at the sand.

8^0 You really were pinned by the overweighting! Good thing it wasn't
a silt bottom! Our grey-brown jello would have swallowed you up!

> > I'm curious, did you get into the water and then shed some weights to
> > determine the _minimum_ needed to get to neutral with the full tank?
>
> No. No adjustments no testing. I knew as long as I could stay down with
> all the insulation I could manage the buoyancy. If it had been too bad I
> would have canned the dive right at the start.

Smart.

> > By the way, did you notice any air-shifting problems, such as might
> > affect your trim?
>
> No. The underwear sucked up the air. It wasn't bubbled anyplace that I
> could tell. Sometimes the air will balloon in the shoulders or elsewhere.
> I do not recall any ballooning or air shifting.

Doesn't sound any worse than the inch of air I might have above my
shoulders when vertical. When it starts forcing its way out of one's
neck seal, it's certainly time to reduce weight. ;^)

> > Beautiful! Warm is wonderful, isn't it?
>
> Sure beats cold.
>
> > Seriously, thanks for the report. I'd like to hear more about the dive.
> > Was it a boat dive? Saltwater? Max depth? Anchor line? Less tendency to
> > cramp since you were warmer?
>
> It was a shore dive in fresh water. I entered at public access and swam
> over the weeds before venting the bladder air and kissing the sand. That's
> in about 12 feet of water. I adjusted the exhaust valve, washed the inside
> of my mask, and descended to 25 feet. At 25 feet I adjusted trim by again
> adjusting the exhaust valve a couple more times. At this point I was
> looking for rough fish and ready to go. I stayed above the thermocline
> looking for fish. Maximum depth was 33 feet. Most of the dive was spent
> between 25 and 30 feet but I did spend about 20 minutes at 20 feet. I
> didn't find anything I could shoot. I did pick up a drivers license and
> passed on a lure with a nice hook set because I didn't have anyplace except
> my dry suit pocket to store it.

That's my kind of dive! Finding treasure and hunting!

What do you shoot, carp?

I'm sure I get laughed at for bringing so much gear with me, but I tuck
a little plastic pencil box under a bungie on my weight belt for
fragile or sharp items.

> I swam constantly, got leg cramps, saw a boat, cash register, computer, and
> some interesting bottom structure. According to the computer I had an hour
> worth of air left when I surfaced. Cramping was the reason I got out. I
> don't usually swim that much but usually get cramps after an hour. On this
> dive it was almost two hours before I started to get cramps. I attribute
> cramping to position as much as cold, but don't really know the reason.
> Buoyancy was still very negative but don't know by how much. My weight
> selection for the dive did not lend itself to adjustment. The 8# and 6#
> were in the weight pouches while one 5 was in the dry suit pocket and the
> other zipped in the suit. If I had wanted to adjust weight I would have
> used 2's and 3's and put them someplace else.

Excellent air consumption, I must say!

The cramping sounds about like my pattern. Worse on the second dive,
too.

Did your computer give that 1-hour estimate of air based on the depth
at the surface and breathing rate? An hour at a shallow depth might
only require 20 cubic feet of air, but how much was actually left in
the tank?

Two hours in chilly water, finning all the time is super.

> All in all it was a really good dive. Completing a dive with both sets of
> underwear on makes it a success. Two times before I tried both sets of
> underwear without success. The weighting made the difference. I only tried
> it again because of your post.
>
> A few times I've found stuff on the bottom that I've hauled back. One item
> was a 29 pound, cast, scissors anchor with 100 feet of line. (Nearly
> drowned lifting that up on a pier.) Another item was a foldable, aluminum,
> boat ladder. When you find things like these you get to practice buoyancy
> swimming them to the surface.

I've always been leery of using my own buoyancy to suspend a heavy
object, for the obvious reasons.

Here's where another of my unusual gear comes in handy; I always dive
with a tuna ball (round 18" float) to which I attach my flag line. The
flag itself is on a 2-foot tether to the ball. That has made it easy to
bring back anchors up to 60 lbs, not to mention downrigger balls and
even a like-new mountain bike once. This tuna ball rig is the same we
use to support a bag of scallops just off the bottom. It's also the
reason I made a Lexan line handle- the plastic ones would fold over on
themselves when the heavy item was attached to the clip.

I also bring along a 100-lb lift bag to send bigger stuff to the
surface, tethered to my flag line, but don't want to routinely do that
because of the risk of it coming down on me during the dive.

Thanks for sharing the interesting details of your dive.

Dave C

PURE TALC: Source, supplier of unscented, oil-free, USP grade PURE
TALC, ideal for use on drysuit latex seals. If interested, please see
my talc offerings on eBay (eBay ID: dave4868). Thank you!
http://myworld.ebay.com/dave4868

"Dave C" <dcalderbank@top.monad.net> wrote in message
news:1162290894.285233.204790@b28g2000cwb.googlegr oups.com...
>
> chilly wrote:
> > "Dave C" <dcalderbank@top.monad.net> wrote in message
> > news:1162261904.643977.43930@f16g2000cwb.googlegro ups.com...
> > >
> > (snip)>
> > > Chest pads may be a help. The pressing of the water on my chest when
> > > horizontal
> >
> > Eh?
> >
> > (snip)
>
> (Louder) Chest pads may be a help. The pressing of the water on my
> chest when horizontal tend to make that area of insulation less
> effective, so I loft it up with more layers.
>
> Can you hear me now? 8^)

Eh? The water presses more on your chest than anywhere else on your body?

> The lowest areas (depending on position) get the compression from
> water, compacting the insulation there, but upper areas don't get
> compacted because the migrated air has allowed the insulation to retain
> full loft.
>
> Have you noticed which areas get cold when diving in real cold water?
> Like 3 or 4 degrees C?

Every part of me was cold! I couldn't even tell I had my reg in my mouth
other than I was still breathing. I got water in my mask and my contact
lenses froze up.

I'm thinking that water pressing sensation you are getting is ice.

>
> I lay some fleece material over my chest which retains enough loft even
> when compacted. It's warmer.
>
> Works nicely without adding unnecessary undergarment elsewhere, like
> using a vest instead of a jacket.
>
> Dave C
>
> PURE TALC: Source, supplier of unscented, oil-free, USP grade PURE
> TALC, ideal for use on drysuit latex seals. If interested, please see
> my talc offerings on eBay (eBay ID: dave4868). Thank you!
>

chilly wrote:
> "Dave C" <dcalderbank@top.monad.net> wrote in message
> news:1162290894.285233.204790@b28g2000cwb.googlegr oups.com...
> >
> > chilly wrote:
> > > "Dave C" <dcalderbank@top.monad.net> wrote in message
> > > news:1162261904.643977.43930@f16g2000cwb.googlegro ups.com...
> > > >
> > > (snip)>
> > > > Chest pads may be a help. The pressing of the water on my chest when
> > > > horizontal
> > >
> > > Eh?
> > >
> > > (snip)
> >
> > (Louder) Chest pads may be a help. The pressing of the water on my
> > chest when horizontal tend to make that area of insulation less
> > effective, so I loft it up with more layers.
> >
> > Can you hear me now? 8^)
>
> Eh? The water presses more on your chest than anywhere else on your body?

Poor description on my part. This is the mechanical compressing of the
suit material because the air has migrated out of the lower areas, I
assume because of the slight pressure difference at the slightly deeper
depth.

Less loft (air) makes it colder there, meaning the chest and other
frontal areas, when horizontal in a prone position.

Do I have the physics right?

> > The lowest areas (depending on position) get the compression from
> > water, compacting the insulation there, but upper areas don't get
> > compacted because the migrated air has allowed the insulation to retain
> > full loft.
> >
> > Have you noticed which areas get cold when diving in real cold water?
> > Like 3 or 4 degrees C?


> Every part of me was cold! I couldn't even tell I had my reg in my mouth
> other than I was still breathing. I got water in my mask and my contact
> lenses froze up.

8^)

> I'm thinking that water pressing sensation you are getting is ice.

That's only when I invert and crawl along the bottom of the ice for a
goof!

Dave C

In article <Lg03h.2198$hr3.98@newsfe08.lga>, jcassara@optonline.net
says...
> Your safety or deco stop will be at 10 feet or deeper the water pressure
> will compress the suit and undies enough to off set the swing in steel
> tanks.

I guess it depends on the type of drysuit and underwear - the
trilam/polartec I use doesn't compress enough to be noticable. I also
like to be heavy enough at the end so I can put some extra gas in the
suit for warmth on deco.