Wonder no longer: soda cans and plastic soda bottles are favorites for
stress testing in engineering schools. Either of these modern marvels
can take high multiples of the pressure rise noted when going from
coldest Antarctic to hottest Oklahoma. It wouldn't do to deprive the
American public of its taste for gassy soda, or to have explosions en
route.

Brian W

On 23 Dec 2003 11:15:31 -0400, Gregg Germain
wrote:

One has to wonder what happens to the bottles if you put them in
during a chilly spring day, and then the seasons change and it's a 95
degree Summer day.

Or vice versa....if you put them in on a hot day, what happens in
September or October. Do the bottles crush some? Does that imact
flotation?


--- Gregg
"Improvise, adapt, overcome."

Smithsonian Center for Astrophysics
Phone: (617) 496-1558

On Tue, 23 Dec 2003 21:20:55 +0000, Dave Cannell
wrote something
.......and in reply I say!:

Isn't that just the kinks popping out from when it contracted in the
first place?

If I have an empty bottle in the back seat over a winter's night I can
hear it cracking as the car heats up and the air inside expands.

Pirate_Dave

************************************************** ** sorry
remove ns from my header address to reply via email

I was frightened by the idea of a conspiracy that was
causing it all.
But then I was terrified that maybe there was no plan,
really. Is this unpleasant mess all a mistake?

If someone was worried about it, but wanted removable flotation, then why
not pour 2-part urethane flotation foam into the plastic pop bottles? Just
trim the ooze, screw on the cap, and I think it would last just about
forever underwater. Needs to be poked through a deck plate and the deck
plate needs to be good enough quality to stay closed under impact.

Brian

--
My boat project: http://www.advantagecomposites.com/tongass


"Brian Whatcott" wrote in message
...
Wonder no longer: soda cans and plastic soda bottles are favorites for
stress testing in engineering schools. Either of these modern marvels
can take high multiples of the pressure rise noted when going from
coldest Antarctic to hottest Oklahoma. It wouldn't do to deprive the
American public of its taste for gassy soda, or to have explosions en
route.

Brian W

On 23 Dec 2003 11:15:31 -0400, Gregg Germain
wrote:

One has to wonder what happens to the bottles if you put them in
during a chilly spring day, and then the seasons change and it's a 95
degree Summer day.

Or vice versa....if you put them in on a hot day, what happens in
September or October. Do the bottles crush some? Does that imact
flotation?


--- Gregg
"Improvise, adapt, overcome."

Smithsonian Center for Astrophysics
Phone: (617) 496-1558

Tailgunner wrote:
: Bear with me for a second.

: I have been hearing about people using ping pong balls for floatation.
: However, I can't find anyone who has actually done it.

: It makes sense in that it will allow water to flow and not trap water in
: the bilge. They should last a while and certainly easy to install.

: Anyone have any first hand knowledge of doing this?

There was a magazine article a few years back something to the effect of
"Klepper, the NATO Kayak". In that article they mention using mesh bags
filled with ping-pong balls for floation because it cannot be deflated by
a single shot.

For our scout kayaks, we used plastic milk jugs.

--
John Nelson
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Dave Cannell wrote:

Try taking a plastic down to 100' under water then filling it with air
from your regulator and closing the cap. It certainly does 'puff up'
when you return it to the surface. BTW - So does a diver if they forget
to exhale on the way up 8-(


On our deep sumbmersible they frequently take items down and shrink them. 16oz Styrofoam
cups become doll sized. Of course we're talking DEEP submersible.

--
Tailgunner

Yup...

In article , Old Nick wrote:
On Tue, 23 Dec 2003 21:20:55 +0000, Dave Cannell
wrote something
......and in reply I say!:

Isn't that just the kinks popping out from when it contracted in the
first place?

If I have an empty bottle in the back seat over a winter's night I can
hear it cracking as the car heats up and the air inside expands.

Pirate_Dave

************************************************** ** sorry
remove ns from my header address to reply via email

I was frightened by the idea of a conspiracy that was
causing it all.
But then I was terrified that maybe there was no plan,
really. Is this unpleasant mess all a mistake?

Okay, I just spoke to my boss who has a PhD in Physics. Don't ask.

Using Charles Law which states that under conditions of constant pressure and quantity,
there is a direct relationship between the volume and absolute temperature for an ideal
gas.

Supposing a 20C or 36F degree temp range.
273 (absolute temp, zero scale) + 20 = 293.
20/293 = .068
That means there is 6% change.

Plastic soda bottles can certainly handle 6% expansion and contraction.

--
Tailgunner
http://boat.nbrigham.com/

Tailgunner wrote:

Jim Conlin wrote:

At a dime each, it's cost over $100/ft^3. How about plastic beverage
bottles?


I found a place that sells a gross at $20 ($0.07 each). Not much better. I
thought about bottles (free). But the deck would have to be removed to install
them. Next year I am thinking of replacing the deck so maybe. They are
certainly not flammable even with the caps epoxied on.

Put a pinch of baking soda and a drop of vinegar inside each
bottle, and tighten the cap. No need to glue the lids. The co2
generated by the chemicals will pressurise the bottle so it
doesn't lose bouyancy with cold temperatures and submersion.

The pop bottles will take a lot of pressure, they are designed to
avoid the danger of exploding glass pop bottles, remember those?
One little ding and kabloowie, hot pop all over, along with glass
shards.

Yes, the gas inside plastic pop bottles shrinks when cold,
reducing their floatation.

Terry K


Tailgunner wrote:

Bear with me for a second.

I have been hearing about people using ping pong balls for floatation.
However, I can't find anyone who has actually done it.

It makes sense in that it will allow water to flow and not trap water in
the bilge. They should last a while and certainly easy to install.

Anyone have any first hand knowledge of doing this?

--
Tailgunner
BS#232

--
Tailgunner
BS#232

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SofDevCo

WaIIy ) writes:
On 23 Dec 2003 22:53:46 GMT, (William R. Watt)
wrote:

I poured foam peanuts into the floatation chambers and bunged
the holes with corks. I would not recommend it for areas that could be
continuously wet.

How did you get the peanuts out the next year through little cork holes?

They were big corks, but I never took them out as the canoe was home based
while I owned it.

BTW the previous owner had sprayed Day-Glo paint on the inside so he could
spot it under the water in the spring. In case anyone ever wants to try it.
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"Matt/Meribeth Pedersen" ) writes:

... So sorry, it's not enough to make a loud noise, just
the small crackly ones.

any idea how many freeze-thaw cycles those pop bottles can go through
before the plastic creases and splits open? do they get brittle at low
temperatures? just wondering as I don't drink soda pop and boats go
through several freeze-thaw cycles over the winter and spring in this area.
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