Morgan O says:

It actually depends on the size of the rig and the momentum. The rig can be
undersized!!! ...and then it's the momentum that doesn't matter!

Morgan, for someone who professes to know little about the subject, I can only
say that you are accurate - you know little.

Since you don't know his boat, you can't say for shure ..and that's why I
didn't.

When you have designed boats that have raced around the world, and come home
with their rigs intact, then come back and tell me I'm wrong. Until then,
either buy the book I recommended to you, and read up on the subject, or be
quiet and stop giving out potentially dangerous information with no knowledge
of the subject.

Steve
Stephen C. Baker - Yacht Designer
http://members.aol.com/SailDesign/pr...cbweb/home.htm

On 23 Oct 2004 16:01:42 GMT, Stephen Baker wrote:

you know little.

I don't like people to give faulty advice anyhow. I just liked to give a
hint to PeterM.A about that.

...but I will not fall to your standards of attacking...

....explained this way...

If you have a rig in solid concrete, which would matter the most to the rig?
A) wind speed?
B) the momentum of the solid concrete?

take care... hope you understand something new now!



Morgan O.

Morgan says:

If you have a rig in solid concrete, which would matter the most to the rig?
A) wind speed?
B) the momentum of the solid concrete?


If you had a boat with infinite righting moment, it would be dry land, not a
boat. Not an apple, just another orange...

..but I will not fall to your standards of attacking...

not attacking, Morgan, just quoting you at the beginning of this series of
threads.

Steve "plonk!"

On Sat, 23 Oct 2004 16:58:02 GMT, Morgan Ohlson
wrote:

On 23 Oct 2004 16:01:42 GMT, Stephen Baker wrote:

you know little.

I don't like people to give faulty advice anyhow. I just liked to give a
hint to PeterM.A about that.

..but I will not fall to your standards of attacking...

...explained this way...

If you have a rig in solid concrete, which would matter the most to the rig?
A) wind speed?
B) the momentum of the solid concrete?

take care... hope you understand something new now!



Morgan O.

You are absolutely right. If the rig were mounted in concrete the
important force would result from wind velocity and sail area.

However -- we are discussing a rig installed on a BOAT and the
important force is righting moment.

i.e., in the case you are discussing the mast is fixed and therefore
the effective area of the sail is constant. In the case of a spar
mounted on a movable base, i.e., a boat, the spar moves and therefore
the effective area of the sail changes with changes in wind velocity,
thus the important figure is the force opposing the spar movement, the
righting moment.

Most people who have any knowledge of boats understand this fact
instinctively.




Cheers,

Bruce
(k4556atinetdotcodotth)

On Sun, 24 Oct 2004 07:13:04 +0700, Egis/CORE wrote:

On Sat, 23 Oct 2004 16:58:02 GMT, Morgan Ohlson
wrote:

On 23 Oct 2004 16:01:42 GMT, Stephen Baker wrote:

you know little.

I don't like people to give faulty advice anyhow. I just liked to give a
hint to PeterM.A about that.

..but I will not fall to your standards of attacking...

...explained this way...

If you have a rig in solid concrete, which would matter the most to the rig?
A) wind speed?
B) the momentum of the solid concrete?

take care... hope you understand something new now!



Morgan O.

You are absolutely right. If the rig were mounted in concrete the
important force would result from wind velocity and sail area.

However -- we are discussing a rig installed on a BOAT and the
important force is righting moment.

i.e., in the case you are discussing the mast is fixed and therefore
the effective area of the sail is constant. In the case of a spar
mounted on a movable base, i.e., a boat, the spar moves and therefore
the effective area of the sail changes with changes in wind velocity,
thus the important figure is the force opposing the spar movement, the
righting moment.

Most people who have any knowledge of boats understand this fact
instinctively.

1'st... I undertand exactly what you are saying...

But tech /nature doesn't stop there. There is more to it. Especially that
part comes into account in this case, a 2 hull vessell.

You are stuck in what sometimes goes under the label "psychic prisons".


Morgan O.

On Sun, 24 Oct 2004 11:20:44 GMT, Morgan Ohlson
wrote:

On Sun, 24 Oct 2004 07:13:04 +0700, Egis/CORE wrote:

On Sat, 23 Oct 2004 16:58:02 GMT, Morgan Ohlson
wrote:

On 23 Oct 2004 16:01:42 GMT, Stephen Baker wrote:

you know little.

I don't like people to give faulty advice anyhow. I just liked to give a
hint to PeterM.A about that.

..but I will not fall to your standards of attacking...

...explained this way...

If you have a rig in solid concrete, which would matter the most to the rig?
A) wind speed?
B) the momentum of the solid concrete?

take care... hope you understand something new now!



Morgan O.

You are absolutely right. If the rig were mounted in concrete the
important force would result from wind velocity and sail area.

However -- we are discussing a rig installed on a BOAT and the
important force is righting moment.

i.e., in the case you are discussing the mast is fixed and therefore
the effective area of the sail is constant. In the case of a spar
mounted on a movable base, i.e., a boat, the spar moves and therefore
the effective area of the sail changes with changes in wind velocity,
thus the important figure is the force opposing the spar movement, the
righting moment.

Most people who have any knowledge of boats understand this fact
instinctively.

1'st... I undertand exactly what you are saying...

But tech /nature doesn't stop there. There is more to it. Especially that
part comes into account in this case, a 2 hull vessell.

You are stuck in what sometimes goes under the label "psychic prisons".


Morgan O.


Sorry old buddy but whether the boat has one hull or many the
calculation is the same since the force is the same - the force
necessary to heel the vessel, or to phrase it another way, the force
the vessel exerts in attempting to stay upright. the Righting Moment,
in other words.

Certainly the force necessary to heel a multi-hull is higher then that
necessary to heel a mono-hull but that doesn't change the fact that
the force applied to the mast is exactly the same in each case -- the
force necessary to heel the vessel against the opposing force of the
vessel trying to remain upright -- the Righting Moment.

To stay in the real world, if you approach a mast manufacturer with
the intent of designing a mast you will be asked for the righting
moment, usually RM30, i.e., Righting Moment at 30 degrees. If you
approach a marine engineer/boat designer for information regarding the
strength of a mast you will be asked for the RM30.

In short, no matter what you think, the rest of the world firmly
believes that the strength of a mast is directly dependent on the
forces opposing it, i.e., the force the vessel can exert against the
mast, the righting moment in other words.

Now it appears that either (1) you are wrong; or, (2) the rest of the
world is wrong. Take your pick.





Cheers,

Bruce
(k4556atinetdotcodotth)

Egis/CORE ) writes:

Sorry old buddy but whether the boat has one hull or many the
calculation is the same since the force is the same - the force
necessary to heel the vessel, or to phrase it another way, the force
the vessel exerts in attempting to stay upright. the Righting Moment,
in other words.

why hasn't anyone simply stated Newton's law?
for every force acting on a body at rest there is an equal and opposite force.
whether you measure the acting force or the reacting force they are equal.
in many cases, like the heeling of a boat, it's easier to calcualte the
reacting force that it is to calculate the acting force.
--
------------------------------------------------------------------------------
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homepage: www.ncf.ca/~ag384/top.htm
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On Sun, 24 Oct 2004 20:20:53 +0700, Egis/CORE wrote:

On Sun, 24 Oct 2004 11:20:44 GMT, Morgan Ohlson
wrote:

On Sun, 24 Oct 2004 07:13:04 +0700, Egis/CORE wrote:

On Sat, 23 Oct 2004 16:58:02 GMT, Morgan Ohlson
wrote:

On 23 Oct 2004 16:01:42 GMT, Stephen Baker wrote:

you know little.

I don't like people to give faulty advice anyhow. I just liked to give a
hint to PeterM.A about that.

..but I will not fall to your standards of attacking...

...explained this way...

If you have a rig in solid concrete, which would matter the most to the rig?
A) wind speed?
B) the momentum of the solid concrete?

take care... hope you understand something new now!



Morgan O.

You are absolutely right. If the rig were mounted in concrete the
important force would result from wind velocity and sail area.

However -- we are discussing a rig installed on a BOAT and the
important force is righting moment.

i.e., in the case you are discussing the mast is fixed and therefore
the effective area of the sail is constant. In the case of a spar
mounted on a movable base, i.e., a boat, the spar moves and therefore
the effective area of the sail changes with changes in wind velocity,
thus the important figure is the force opposing the spar movement, the
righting moment.

Most people who have any knowledge of boats understand this fact
instinctively.

1'st... I undertand exactly what you are saying...

But tech /nature doesn't stop there. There is more to it. Especially that
part comes into account in this case, a 2 hull vessell.

You are stuck in what sometimes goes under the label "psychic prisons".


Morgan O.


Sorry old buddy but whether the boat has one hull or many the
calculation is the same since the force is the same - the force
necessary to heel the vessel, or to phrase it another way, the force
the vessel exerts in attempting to stay upright. the Righting Moment,
in other words.

Perhaps ordinary engineering isn't good enough for boat historians.

Think...
Inert mass
Roll resistans
Non capsizeing vessells
Heavy ghusts

....and you get quite different scenarios.

It's quite alright to use old rules of thumb... but know their limits!


Morgan O.

Morgan O says:

Non capsizeing vessells

No such thing ;-)

Some boats will always right themselves, but there is NO boat that is
"non-capsizing".

Steve

On Sun, 24 Oct 2004 20:20:53 +0700, Egis/CORE
vaguely proposed a theory
.......and in reply I say!:

remove ns from my header address to reply via email

The day I give an RM30 about a catamaran is the day I get
worried....G

To stay in the real world, if you approach a mast manufacturer with
the intent of designing a mast you will be asked for the righting
moment, usually RM30, i.e., Righting Moment at 30 degrees. If you
approach a marine engineer/boat designer for information regarding the
strength of a mast you will be asked for the RM30.

************************************************** ***
Have you noticed that people always run from what
they _need_ toward what they want?????