"IanM" wrote

You *are* missed.

Well, thank you. OK, I'll throw something into the pot. Here's a first
draft of something I may come back to later. A discussion along the same
lines got started here quite a while ago and disolved into the usual flame
war. I brought it up over at the high class bar where I hang out now and
another RBC refugee complained that I never finished my explanation here and
was I going to leave them hanging over there as well? It's winter and there
are only so many hours a day I can work on my boat so I whipped this up:

http://www.rogerlongboats.com/Stability.htm

Sorry, Virginia, buoyancy is imaginary.

--
Roger Long

On Sat, 21 Feb 2009 17:15:04 -0500, "Roger Long"
wrote:

"IanM" wrote

You *are* missed.

Well, thank you. OK, I'll throw something into the pot. Here's a first
draft of something I may come back to later. A discussion along the same
lines got started here quite a while ago and disolved into the usual flame
war. I brought it up over at the high class bar where I hang out now and
another RBC refugee complained that I never finished my explanation here and
was I going to leave them hanging over there as well? It's winter and there
are only so many hours a day I can work on my boat so I whipped this up:

http://www.rogerlongboats.com/Stability.htm

Sorry, Virginia, buoyancy is imaginary.

Roger, welcome back, your expertise is missed.

We once had a discussion about anti-roll tanks and how to design them.
Some where in that discussion or in a stability discussion, the
subject of roll period came up, ie, the time for a complete roll, over
and back. My recollection is that I estimated the roll period for
our GB49 trawler to be about 3 seconds, and that some discussion
ensued about whether or not that was impossibly fast. I have since
then taken more recent measurements and come up with a more accurate
figure by averaging a number of rolls. It came out to about 3.2
seconds, quite close to my original estimate. Perhaps you could
comment on the implications of that as it relates to stability.

The GB49 is a ballasted, full length keel, semi-displacement trawler
with hard chines, a displacement of about 70,000 lbs and a draft of 5
1/2 ft.

On Sat, 21 Feb 2009 17:15:04 -0500, "Roger Long"
wrote:

"IanM" wrote

You *are* missed.

Well, thank you. OK, I'll throw something into the pot. Here's a first
draft of something I may come back to later. A discussion along the same
lines got started here quite a while ago and disolved into the usual flame
war. I brought it up over at the high class bar where I hang out now and
another RBC refugee complained that I never finished my explanation here and
was I going to leave them hanging over there as well? It's winter and there
are only so many hours a day I can work on my boat so I whipped this up:

http://www.rogerlongboats.com/Stability.htm

Sorry, Virginia, buoyancy is imaginary.

Rather a long drawn out exercise in semantics, isn't it? All to prove
that, a beautiful, buoyant ball bounding over the wine-dark sea,
isn't.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

"Wayne.B" wrote
I have since then taken more recent measurements and come up with a more
accurate
figure by averaging a number of rolls. It came out to about 3.2
seconds, quite close to my original estimate.

Is that a complete roll, all the way from one side, over to the other, and
then back again to the starting point?

--
Roger Long

Roger Long wrote:
.... Here's a first
draft of something I may come back to later. A discussion along the same
lines got started here quite a while ago and dissolved into the usual flame
war. I brought it up over at the high class bar where I hang out now and
another RBC refugee complained that I never finished my explanation here and
was I going to leave them hanging over there as well? It's winter and there
are only so many hours a day I can work on my boat so I whipped this up:

http://www.rogerlongboats.com/Stability.htm

Sorry, Virginia, buoyancy is imaginary.

--
Roger Long



I enjoyed that piece. You probably make too much of your
"buoyancy is imaginary" thesis, but you use the same criteria for
buoyancy as everyone else, so what harm is that?
I enjoyed the railing against the Coastguard.
That's what it is to be American, after all.
A healthy disrespect for the folks who try to keep us safe(?)

:-)

Regards

BrianW

"Brian Whatcott" wrote

I enjoyed the railing against the Coastguard.
That's what it is to be American, after all.
A healthy disrespect for the folks who try to keep us safe(?)


Don't confuse the inspections branch of the CG with the people who go out in
boats and aircraft to keep us safe. The latter deserve enormous respect.
For that matter, it isn't the fault of the people now in the inspections
branch that they are stuck enforcing regulations poorly written decades ago.

--
Roger Long

On Sun, 22 Feb 2009 08:19:02 +0700, Bruce in Bangkok
wrote:

On Sat, 21 Feb 2009 17:15:04 -0500, "Roger Long"
wrote:

"IanM" wrote

You *are* missed.

Well, thank you. OK, I'll throw something into the pot. Here's a first
draft of something I may come back to later. A discussion along the same
lines got started here quite a while ago and disolved into the usual flame
war. I brought it up over at the high class bar where I hang out now and
another RBC refugee complained that I never finished my explanation here and
was I going to leave them hanging over there as well? It's winter and there
are only so many hours a day I can work on my boat so I whipped this up:

http://www.rogerlongboats.com/Stability.htm

Sorry, Virginia, buoyancy is imaginary.

Rather a long drawn out exercise in semantics, isn't it? All to prove
that, a beautiful, buoyant ball bounding over the wine-dark sea,
isn't.

For me it's more than that. The best explanation of why a boat floats
that I've seen, and a straightforward explanation of what affects boat
stability. Of course I'm not an engineer, and do get a bit befuddled
when the going gets a bit heavy.
I did glean that Wayne's boat rolls quickly due to a lengthy GM, and
that it's not necessarily a bad thing.
Have to go back and reread to figure out what the hell GM is.

--Vic

"Brian Whatcott" wrote in message
...
Roger Long wrote:
.... Here's a first
draft of something I may come back to later. A discussion along the same
lines got started here quite a while ago and dissolved into the usual
flame war. I brought it up over at the high class bar where I hang out
now and another RBC refugee complained that I never finished my
explanation here and was I going to leave them hanging over there as
well? It's winter and there are only so many hours a day I can work on
my boat so I whipped this up:

http://www.rogerlongboats.com/Stability.htm

Sorry, Virginia, buoyancy is imaginary.

--
Roger Long

I enjoyed that piece. You probably make too much of your
"buoyancy is imaginary" thesis, but you use the same criteria for buoyancy
as everyone else, so what harm is that?
I enjoyed the railing against the Coastguard.
That's what it is to be American, after all.
A healthy disrespect for the folks who try to keep us safe(?)

:-)

Regards

BrianW


Whatever floats your boat, right?

--
"j" ganz @@
www.sailnow.com

On Sat, 21 Feb 2009 21:05:59 -0500, "Roger Long"
wrote:

"Wayne.B" wrote
I have since then taken more recent measurements and come up with a more
accurate
figure by averaging a number of rolls. It came out to about 3.2
seconds, quite close to my original estimate.

Is that a complete roll, all the way from one side, over to the other, and
then back again to the starting point?

Yes, one complete roll.

On Sat, 21 Feb 2009 20:23:27 -0600, Vic Smith
wrote:

On Sun, 22 Feb 2009 08:19:02 +0700, Bruce in Bangkok
wrote:

On Sat, 21 Feb 2009 17:15:04 -0500, "Roger Long"
wrote:

"IanM" wrote

You *are* missed.

Well, thank you. OK, I'll throw something into the pot. Here's a first
draft of something I may come back to later. A discussion along the same
lines got started here quite a while ago and disolved into the usual flame
war. I brought it up over at the high class bar where I hang out now and
another RBC refugee complained that I never finished my explanation here and
was I going to leave them hanging over there as well? It's winter and there
are only so many hours a day I can work on my boat so I whipped this up:

http://www.rogerlongboats.com/Stability.htm

Sorry, Virginia, buoyancy is imaginary.

Rather a long drawn out exercise in semantics, isn't it? All to prove
that, a beautiful, buoyant ball bounding over the wine-dark sea,
isn't.

For me it's more than that. The best explanation of why a boat floats
that I've seen, and a straightforward explanation of what affects boat
stability. Of course I'm not an engineer, and do get a bit befuddled
when the going gets a bit heavy.
I did glean that Wayne's boat rolls quickly due to a lengthy GM, and
that it's not necessarily a bad thing.
Have to go back and reread to figure out what the hell GM is.

--Vic

Given that the dictionary gives one definition of buoyancy as:

2. (Physics) The upward pressure exerted upon a floating body
by a fluid, which is equal to the weight of the body;
hence, also, the weight of a floating body, as measured by
the volume of fluid displaced.
[1913 Webster]

It seems that the writer has gone the long way round to prove an
already accepted meaning for the word.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)