In article ,
says...
OK, Duncan. here's a little experiment you can do in your
bathtub.

1. Put an empty Coke bottle in the water. Observe how it floats.
2. Fill the Coke bottle 1/4 with water. Observe how it floats.
3. Fill the bottle 1/2 way. Observe how it floats
4. Fill it 3/4 full. Observe how it floats
5. Is the water in the coke bottle below the tub water surface?
6. Wash your butt last.

Scotty

a) What is the *point* of your experiement? - other than to only prove
my argument correct.

b) try this (your experiment pretty much, say 4) ...

So 3/4 full. Hold the bottle at the top and note the weight. Slowly
lower it into the water. Note the weight changing! ??? How can it be
getting lighter all by itself?

Note also the final level in the water. There is almost no difference
in the level of the water in the bottle and the level to which it has
sunk. (The difference being a result of the boyancy of the plastic).

ie, Ans to your Q5. the level of the water in the bottle is very
slightly higher than the water it is in.

PS: experiment not conducted, just using simple physics. Feel free to
do it and get back to me if I'm wrong.

--
Duncan
[Farr 7500 'Hi-Time' http://hitime.no-ip.info]

Whoa Davey
Here's a better idea.... jump in the water and see how much water you
displace. If you displace a lot ...as I suspect... you should still float
well enough to undertake the test due to the residue of hot air.

Now drink a quarter bottle of Lamb's Navy Overproof Rum and see where you
float... continue drinking and take readings at every quarter mark of the
bottle.

Get Back to Us on Water Ballast.... we'll inform the multi national sailing
franchises of your position that they're delusional and water ballast is
ineffective.
I'm certain someone would be willing to write a "definitive book" regarding
your findings.

CM

"Dave Doe" wrote in message
. nz...
In article ,
says...
OK, Duncan. here's a little experiment you can do in your
bathtub.

1. Put an empty Coke bottle in the water. Observe how it floats.
2. Fill the Coke bottle 1/4 with water. Observe how it floats.
3. Fill the bottle 1/2 way. Observe how it floats
4. Fill it 3/4 full. Observe how it floats
5. Is the water in the coke bottle below the tub water surface?
6. Wash your butt last.

Scotty

a) What is the *point* of your experiement? - other than to only prove
my argument correct.

b) try this (your experiment pretty much, say 4) ...

So 3/4 full. Hold the bottle at the top and note the weight. Slowly
lower it into the water. Note the weight changing! ??? How can it be
getting lighter all by itself?

Note also the final level in the water. There is almost no difference
in the level of the water in the bottle and the level to which it has
sunk. (The difference being a result of the boyancy of the plastic).

ie, Ans to your Q5. the level of the water in the bottle is very
slightly higher than the water it is in.

PS: experiment not conducted, just using simple physics. Feel free to
do it and get back to me if I'm wrong.

--
Duncan
[Farr 7500 'Hi-Time' http://hitime.no-ip.info]

In article %2Gwf.47038$km.7540@edtnps89,
says...
Whoa Davey
Here's a better idea.... jump in the water and see how much water you
displace. If you displace a lot ...as I suspect... you should still float
well enough to undertake the test due to the residue of hot air.

Now drink a quarter bottle of Lamb's Navy Overproof Rum and see where you
float... continue drinking and take readings at every quarter mark of the
bottle.

Get Back to Us on Water Ballast.... we'll inform the multi national sailing
franchises of your position that they're delusional and water ballast is
ineffective.
I'm certain someone would be willing to write a "definitive book" regarding
your findings.

LOL - I *love* the idea - mind if I make that a nice single malt scotch
though?

PS: the book was written many years ago now, some dude called Archimedes
IIRC - shame he's not still alive for Scotty to prove him wrong.


--
Duncan

"Dave Doe" wrote in message

LOL - I *love* the idea - mind if I make that a nice single malt scotch
though?

Single Malt is a worthy choice

PS: the book was written many years ago now, some dude called Archimedes
IIRC - shame he's not still alive for Scotty to prove him wrong.

Yeah... I believe something about the buoyant force on the solid object is
equal to the weight of the fluid displaced . So... are you saying that 50
gallons of water in your bilge won't lower your waterline??? Good Grief
that means I can store unlimited supplies of rum onboard.

CM

"Dave Doe" wrote in message
. nz...
In article ,
says...
OK, Duncan. here's a little experiment you can do in your
bathtub.

1. Put an empty Coke bottle in the water. Observe how it
floats.
2. Fill the Coke bottle 1/4 with water. Observe how it
floats.
3. Fill the bottle 1/2 way. Observe how it floats
4. Fill it 3/4 full. Observe how it floats
5. Is the water in the coke bottle below the tub water
surface?
6. Wash your butt last.

Scotty

a) What is the *point* of your experiement? - other than to
only prove
my argument correct.


To prove to you that water BELOW the water line can still act as
ballast.
Also , to wash some of the stink off of you.



Scotty

In article ,
says...

"Dave Doe" wrote in message
. nz...
In article ,
says...
OK, Duncan. here's a little experiment you can do in your
bathtub.

1. Put an empty Coke bottle in the water. Observe how it
floats.
2. Fill the Coke bottle 1/4 with water. Observe how it
floats.
3. Fill the bottle 1/2 way. Observe how it floats
4. Fill it 3/4 full. Observe how it floats
5. Is the water in the coke bottle below the tub water
surface?
6. Wash your butt last.

Scotty

a) What is the *point* of your experiement? - other than to
only prove
my argument correct.


To prove to you that water BELOW the water line can still act as
ballast.

Indeed it can and I have not questioned that, only it's effectiveness as
not just ballast, which I have stated provides a positive stability
factor - but I question its effectiveness when used as a righting
moment. And further posed the question:

How much water ballast (approx litres) does it take to equal say
200lbs of lead hanging 6' down (on say a swing keel)?

To make it easier, how about we metricate it all for ease of
calculation:

Assume Standard Temp & Pressure (STP)
How much fresh water (density: 1000kg/m3) does it take to equal 500kg of
lead (density: 7140kg/m3) hanging 2m down with the boat at 45deg? Water
ballast tank at 1m wide and the boat is in fresh water (also at STP).

Feel free to use other figures, I've adjusted from my original, using
hopefully more "average" figures and rounded to make calcs easier.

So how much water?

And... looking at say a Mac, they say they have 1150lbs of water
ballast, that's about 520kg.

You change the figures if you think mine are unrealistic - I'd just like
to see the comparision.

PS: only got to sail against a Mac 26M once out in Lytellton; my boat's
just under 25' - the Mac is 26'. We thrashed it. (They might be quite
competative in light air; 5knts or below). My boat's 23? years old, the
Mac is less than 1. It's longer.

--
Duncan

"Dave Doe" wrote in message
. nz...
In article ,
says...

"Dave Doe" wrote in message
. nz...
In article ,
says...
OK, Duncan. here's a little experiment you can do in your
bathtub.

1. Put an empty Coke bottle in the water. Observe how it
floats.
2. Fill the Coke bottle 1/4 with water. Observe how it
floats.
3. Fill the bottle 1/2 way. Observe how it floats
4. Fill it 3/4 full. Observe how it floats
5. Is the water in the coke bottle below the tub water
surface?
6. Wash your butt last.

Scotty

a) What is the *point* of your experiement? - other than to
only prove
my argument correct.


To prove to you that water BELOW the water line can still act as
ballast.

Indeed it can and I have not questioned that, only it's effectiveness as
not just ballast, which I have stated provides a positive stability
factor - but I question its effectiveness when used as a righting
moment. And further posed the question:

How much water ballast (approx litres) does it take to equal say
200lbs of lead hanging 6' down (on say a swing keel)?

To make it easier, how about we metricate it all for ease of
calculation:

Assume Standard Temp & Pressure (STP)
How much fresh water (density: 1000kg/m3) does it take to equal 500kg of
lead (density: 7140kg/m3) hanging 2m down with the boat at 45deg? Water
ballast tank at 1m wide and the boat is in fresh water (also at STP).

Feel free to use other figures, I've adjusted from my original, using
hopefully more "average" figures and rounded to make calcs easier.

So how much water?

And... looking at say a Mac, they say they have 1150lbs of water
ballast, that's about 520kg.

You change the figures if you think mine are unrealistic - I'd just like
to see the comparision.

PS: only got to sail against a Mac 26M once out in Lytellton; my boat's
just under 25' - the Mac is 26'. We thrashed it. (They might be quite
competative in light air; 5knts or below). My boat's 23? years old, the
Mac is less than 1. It's longer.

--
Duncan

My understanding is that the Macs have an optimal window of between 7-10
kts.wind, they will hardly move in light air. Tiny rig and sailplan. Have
seen a rating for the old 26X at 226, IIRC, but I'm willing to bet that it's
very tough to sail anywhere near it's rating. Anecdotal, but I was sailing
back to the marina one day, playing with the a-sail, and I passed an x that
didn't appear to be moving, my knotmeter was reading 3-4 kts, maybe around 5
kts.of wind.

John Cairns

Dave Doe wrote:
a) What is the *point* of your experiement? - other than to only prove
my argument correct.


Dave, since your argument is not correct, it would be pretty
hard to prove.

Are you saying that the water ballast inside a boat hull
does not affect it's stability? That the water ballast
"weighs nothing" until it is above the waterline?

If that were true, the boat's waterline would be the same
when the ballast tank was empty as when it is full.

Does the boat's displacement increase when the ballast tank
is filled? If so, then the the water ballast "weighs"
something, regardless of where it is relative to the waterline.

If the unit conter of gravity is below what the boat's
Center of Gravity would be without the ballast, then it
increases the boat's stability, regardless of whether the
tank is above or below the waterline.

b) try this (your experiment pretty much, say 4) ...

So 3/4 full. Hold the bottle at the top and note the weight. Slowly
lower it into the water. Note the weight changing! ??? How can it be
getting lighter all by itself?


Try this experiment.

Float an empty bottle. Mark where the waterline is.

Now fill it however full you want, 1/4 or 3/4 or whatever.

Does the bottle sink any deeper into the water?

No?

Then it "weighs" more, the water inside the bottle must be
weighing it down.



PS: experiment not conducted, just using simple physics. Feel free to
do it and get back to me if I'm wrong.


Yep, it's just simple physics. But a number of people have
tried to proclaim that water ballast can't possibly work
because "water doesn't weigh anything in water." But it
obviously *does* work, and the physics (when considered
correctly) show why.

Fresh Breezes- Doug King

I guess all those big ships with water ballast tanks are just
pretending.

Scotty


"DSK" wrote in message
. ..
Dave Doe wrote:
a) What is the *point* of your experiement? - other than to
only prove
my argument correct.


Dave, since your argument is not correct, it would be pretty
hard to prove.

Are you saying that the water ballast inside a boat hull
does not affect it's stability? That the water ballast
"weighs nothing" until it is above the waterline?

If that were true, the boat's waterline would be the same
when the ballast tank was empty as when it is full.

Does the boat's displacement increase when the ballast tank
is filled? If so, then the the water ballast "weighs"
something, regardless of where it is relative to the waterline.

If the unit conter of gravity is below what the boat's
Center of Gravity would be without the ballast, then it
increases the boat's stability, regardless of whether the
tank is above or below the waterline.

b) try this (your experiment pretty much, say 4) ...

So 3/4 full. Hold the bottle at the top and note the weight.
Slowly
lower it into the water. Note the weight changing! ??? How
can it be
getting lighter all by itself?


Try this experiment.

Float an empty bottle. Mark where the waterline is.

Now fill it however full you want, 1/4 or 3/4 or whatever.

Does the bottle sink any deeper into the water?

No?

Then it "weighs" more, the water inside the bottle must be
weighing it down.



PS: experiment not conducted, just using simple physics.
Feel free to
do it and get back to me if I'm wrong.


Yep, it's just simple physics. But a number of people have
tried to proclaim that water ballast can't possibly work
because "water doesn't weigh anything in water." But it
obviously *does* work, and the physics (when considered
correctly) show why.

Fresh Breezes- Doug King

Scotty wrote:

I guess all those big ships with water ballast tanks are just
pretending.


Of course they are. It's just a scam to irritate the
enviro-whackoes.

The Navy is in on the joke, too...
http://p2library.nfesc.navy.mil/P2_O...book/11_9.html

Notice that ship stability takes a back seat to needling
those tree-hugging pinheads: (quote from the above web site)
"Ships with water compensating fuel systems (WCFS) are not
allowed to discharge compensating ballast water overboard in
some navy ports. Navy ship destroyers (e.g., Spruance and
Kidd class) and cruisers (Ticonderoga class) are designed
with WCFS to enhance ship stability."

DSK