Looks like it to me. It's just much farther to the right on the graph


Rodney Myrvaagnes wrote:
In neither case does it get vertical, as an asymptote would.

1- an asymptote doesn't have to be vertical (or horizontal) on the graph

2- if the power/speed curve does not go vertical (or approach it very
very very closely) then you're saying that the boat can reach infinite
speed. This is impossible, nyet?


In the case of planing boats, the slope of the curve doesn't even
increase everywhere, buty goes over a hump at the onset of planing.

Depends on the boat. Some don't have much of a hump at all.

"Hump" is kind of a misnomer IMHO... what happens is that the boat's
power/speed curve trends increasingly upward as marginal power increases
faster than speed, then flattens out again as it starts planing. It's
not a hump, more of a plateau or shelf.


But ordinary medium-to-light-displacement sailboats zip right past
hull speed when the wind rises.

Do they reach infinite speed?

You're right about fast boats zipping right past hull speed like it's
not there... that's why I always say that "hull speed" is not a hard
limit... also you have to consider the speed-length ratio (or Froude
number if you prefer) is not the same for all boats. Two different boats
(say, a J-35 and an Island Packet 35) should not really have the same
"hull speed" even if their LWL is exactly the same.

The power/speed curve of all boats... power, sail, diplacement, planing,
mulithull, whatever... trends toward vertical as the speed increases.
For some boats it's way to the right, at impressively high speeds. But
it's there!

Fresh Breezes- Doug King

You are using "asymptote" in a metaphoric, rather than mathematical
sense.



On Tue, 31 Aug 2004 13:31:46 -0400, DSK wrote:

Looks like it to me. It's just much farther to the right on the graph


Rodney Myrvaagnes wrote:
In neither case does it get vertical, as an asymptote would.

1- an asymptote doesn't have to be vertical (or horizontal) on the graph

2- if the power/speed curve does not go vertical (or approach it very
very very closely) then you're saying that the boat can reach infinite
speed. This is impossible, nyet?


In the case of planing boats, the slope of the curve doesn't even
increase everywhere, buty goes over a hump at the onset of planing.

Depends on the boat. Some don't have much of a hump at all.

"Hump" is kind of a misnomer IMHO... what happens is that the boat's
power/speed curve trends increasingly upward as marginal power increases
faster than speed, then flattens out again as it starts planing. It's
not a hump, more of a plateau or shelf.


But ordinary medium-to-light-displacement sailboats zip right past
hull speed when the wind rises.

Do they reach infinite speed?

You're right about fast boats zipping right past hull speed like it's
not there... that's why I always say that "hull speed" is not a hard
limit... also you have to consider the speed-length ratio (or Froude
number if you prefer) is not the same for all boats. Two different boats
(say, a J-35 and an Island Packet 35) should not really have the same
"hull speed" even if their LWL is exactly the same.

The power/speed curve of all boats... power, sail, diplacement, planing,
mulithull, whatever... trends toward vertical as the speed increases.
For some boats it's way to the right, at impressively high speeds. But
it's there!

Fresh Breezes- Doug King


Rodney Myrvaagnes NYC J36 Gjo/a

"Religious wisdom is to wisdom as military music is to music."

I've really resisted jumping into this one, but....

I guess that if you consider VERY high speeds (approaching the speed of
light), it does go asymptotic. However, at anything significantly below
that, to suggest that there is some "brick wall" velocity that cannot be
surpassed no matter how much thrust is applied is just plain incorrect.

Now, the thrust required may not be achievable by any normal engineering
and forces on the hull may cause any it to disintegrate if built out of
any of the standard materials and methods. And even if you could build
it strong enough, stability and control problems will rear their ugly
heads when you start going fast enough. Afterall, if you could keep it
from pitch poling first, and pushed my Tayana fast enough, you'd get
seperation occuring with the water flow where my hull starts curving
back to the stern. Once the rudder is high and dry in this seperation
area, it'd be a might difficult to control.

So in the real world, I guess that there is a limit to how fast my
Tayana can go no matter how many JATO units you strap onto it. But it
is a pratical matter, not some theoretical "hull speed" value beyond
which the resistance somehow becomes infinite.

A quick thought experiment to show the point: Picture yourself speeding
along on glassy smooth water in a speed boat. You have a small model of
a displacement hull sailboat in your hand (only a few inches long).
Now, since the hull speed of this model is only a fraction of a knot, if
there were a hard and fast limit beyound which it is impossible to go,
then you could not reach over the side and drag this toy through the
water. It would wrench your arm off. If you had it somehow affixed to
the boat, it would stop the speed boat cold.

Can we find something else to agrue about now?



Rodney Myrvaagnes wrote:
You are using "asymptote" in a metaphoric, rather than mathematical
sense.



On Tue, 31 Aug 2004 13:31:46 -0400, DSK wrote:


Looks like it to me. It's just much farther to the right on the graph


Rodney Myrvaagnes wrote:

In neither case does it get vertical, as an asymptote would.

1- an asymptote doesn't have to be vertical (or horizontal) on the graph

2- if the power/speed curve does not go vertical (or approach it very
very very closely) then you're saying that the boat can reach infinite
speed. This is impossible, nyet?


In the case of planing boats, the slope of the curve doesn't even
increase everywhere, buty goes over a hump at the onset of planing.

Depends on the boat. Some don't have much of a hump at all.

"Hump" is kind of a misnomer IMHO... what happens is that the boat's
power/speed curve trends increasingly upward as marginal power increases
faster than speed, then flattens out again as it starts planing. It's
not a hump, more of a plateau or shelf.


But ordinary medium-to-light-displacement sailboats zip right past
hull speed when the wind rises.

Do they reach infinite speed?

You're right about fast boats zipping right past hull speed like it's
not there... that's why I always say that "hull speed" is not a hard
limit... also you have to consider the speed-length ratio (or Froude
number if you prefer) is not the same for all boats. Two different boats
(say, a J-35 and an Island Packet 35) should not really have the same
"hull speed" even if their LWL is exactly the same.

The power/speed curve of all boats... power, sail, diplacement, planing,
mulithull, whatever... trends toward vertical as the speed increases.
For some boats it's way to the right, at impressively high speeds. But
it's there!

Fresh Breezes- Doug King



Rodney Myrvaagnes NYC J36 Gjo/a

"Religious wisdom is to wisdom as military music is to music."

--
Dan Best - (707) 431-1662, Healdsburg, CA 95448
B-2/75 1977-1979
Tayana 37 #192, "Tricia Jean"
http://rangerbest.home.comcast.net/TriciaJean.JPG

Dan, don't confuse them with facts. they are their minds (such as their minds
are) made up.



I've really resisted jumping into this one, but....

I guess that if you consider VERY high speeds (approaching the speed of
light), it does go asymptotic. However, at anything significantly below
that, to suggest that there is some "brick wall" velocity that cannot be
surpassed no matter how much thrust is applied is just plain incorrect.

Now, the thrust required may not be achievable by any normal engineering
and forces on the hull may cause any it to disintegrate if built out of
any of the standard materials and methods. And even if you could build
it strong enough, stability and control problems will rear their ugly
heads when you start going fast enough. Afterall, if you could keep it
from pitch poling first, and pushed my Tayana fast enough, you'd get
seperation occuring with the water flow where my hull starts curving
back to the stern. Once the rudder is high and dry in this seperation
area, it'd be a might difficult to control.

So in the real world, I guess that there is a limit to how fast my
Tayana can go no matter how many JATO units you strap onto it. But it
is a pratical matter, not some theoretical "hull speed" value beyond
which the resistance somehow becomes infinite.

A quick thought experiment to show the point: Picture yourself speeding
along on glassy smooth water in a speed boat. You have a small model of
a displacement hull sailboat in your hand (only a few inches long).
Now, since the hull speed of this model is only a fraction of a knot, if
there were a hard and fast limit beyound which it is impossible to go,
then you could not reach over the side and drag this toy through the
water. It would wrench your arm off. If you had it somehow affixed to
the boat, it would stop the speed boat cold.

Can we find something else to agrue about now?



Rodney Myrvaagnes wrote:
You are using "asymptote" in a metaphoric, rather than mathematical
sense.



On Tue, 31 Aug 2004 13:31:46 -0400, DSK wrote:


Looks like it to me. It's just much farther to the right on the graph


Rodney Myrvaagnes wrote:

In neither case does it get vertical, as an asymptote would.

1- an asymptote doesn't have to be vertical (or horizontal) on the graph

2- if the power/speed curve does not go vertical (or approach it very
very very closely) then you're saying that the boat can reach infinite
speed. This is impossible, nyet?


In the case of planing boats, the slope of the curve doesn't even
increase everywhere, buty goes over a hump at the onset of planing.

Depends on the boat. Some don't have much of a hump at all.

"Hump" is kind of a misnomer IMHO... what happens is that the boat's
power/speed curve trends increasingly upward as marginal power increases
faster than speed, then flattens out again as it starts planing. It's
not a hump, more of a plateau or shelf.


But ordinary medium-to-light-displacement sailboats zip right past
hull speed when the wind rises.

Do they reach infinite speed?

You're right about fast boats zipping right past hull speed like it's
not there... that's why I always say that "hull speed" is not a hard
limit... also you have to consider the speed-length ratio (or Froude
number if you prefer) is not the same for all boats. Two different boats
(say, a J-35 and an Island Packet 35) should not really have the same
"hull speed" even if their LWL is exactly the same.

The power/speed curve of all boats... power, sail, diplacement, planing,
mulithull, whatever... trends toward vertical as the speed increases.
For some boats it's way to the right, at impressively high speeds. But
it's there!

Fresh Breezes- Doug King



Rodney Myrvaagnes NYC J36 Gjo/a

"Religious wisdom is to wisdom as military music is to music."

--
Dan Best - (707) 431-1662, Healdsburg, CA 95448
B-2/75 1977-1979
Tayana 37 #192, "Tricia Jean"
http://rangerbest.home.comcast.net/TriciaJean.JPG

On Tue, 31 Aug 2004 21:46:31 GMT, Dan Best wrote:

I've really resisted jumping into this one, but....



This weekend in Olympia, Washington State, is the Harbor Days
festival. During Harbor Days are the well-known tug boat races. As a
sailor, I understand bow waves, hull speeds, and displacement hulls.
It is a pretty good bet that the 70' tug will beat the 35' tug. I
think the longer tug could win with the engine just above an idle.

But it is really amazing to watch the bow wave dynamics in action.
A 30 foot tug with 600 horsepower can build a HUGE bow wave and still
not pass its hull speed. The waves generated in this race are far
greater than the waves from cargo ships that are 10 times as long and
1,000 times larger.

Skipper wrote:
On Tue, 31 Aug 2004 21:46:31 GMT, Dan Best wrote:

This weekend in Olympia, Washington State, is the Harbor Days
festival. During Harbor Days are the well-known tug boat races. As a
sailor, I understand bow waves, hull speeds, and displacement hulls.
It is a pretty good bet that the 70' tug will beat the 35' tug. I
think the longer tug could win with the engine just above an idle.

But it is really amazing to watch the bow wave dynamics in action.
A 30 foot tug with 600 horsepower can build a HUGE bow wave and still
not pass its hull speed. The waves generated in this race are far
greater than the waves from cargo ships that are 10 times as long and
1,000 times larger.


Boring to watch, after a very short while.

The spectacle of this thread, that is.

Just because a bulldozer is pushing a large pile of dirt does not
mean that it has failed to exceed hull speed.

Hull speed is only a theoretically derived number. It is a gauge of
relative numerical relationships; it is not something like the speed
of light, or even the speed of sound. It's kind of like saying hands
have 5 fingers, and figuring their average length. It is not a
limit, except perhaps to fuel efficiency calculations.

Does bring to mind the Hobie style catamaran planing concept,
though. It's kind of like squeezing a watermelon seed in snotty fingers.

We need to remember there are several different factors affecting
drag and dynamic forces at work in various hull types and speed
regimes. Fuel consumption in a sailboat is possible to imply, but
impossible to measure.

I prefer to ponder the "Stove pipe submarine" and it's wake, for a
starting point. It will lead us towards some interesting insights.

Submarines are theoretically detectable from orbit by wake analysis,
amid the chaos of wave noise. Well, it's not noise, folks, its only
chaotic because we cannot measure the causative forces in sufficient
detail, and that is all. If you examine bible message analysis, it
soon becomes obvious that you can find any message, in any language,
even looking for french in a chinese translation. It all depends on
generating the right key, and mowing enough grass, as we say in the
processor hall air conditioning department.

Anyway, if a submarine was constructed like a pipe with a narrowed
internal passage containing it's propellor, would it produce a wake,
especially with a hubless fan drive?

When you push against the water with a paddle, what is (are) the
forces contributing to the thrust reaction developed? An amount of
energy equivalent to the mass*velocity/ friction and delta vee of
the vessel must be left behind in the water. It's mechanism of
transformation must simply be rationalized.

See, at the front of the sp sub, there must be a declivity in the
water as large as the hill of water that would be left behind, and
turbulent water left behind in the wake, whether organized into
visible waves, as in a "normal" wake, or not, must non the less be
transformable into friction heating of the water. It is a question
of looking at the turbulence through the right filters, like
catching a boomer by it's straight lines on the surface / filter
amidst the chop. This is an example of energy being expressed purely
as information analysis, or a set of data passed through an
analytical filter, heating it. Time is the governing constant [?]
and computational capacity limits the keys. The sump pump in the
pare bit buffer must be cooled, or its conductors overheat.

The wake formation of the sp sub would seem to double it's "hull
speed" by removing the bulge in the middle of the vessel as it
pushes through the water, or in the case of the sp sub, as it sucks
itself along. Could that principle be applied to a surface piercing
vessel on plane, like a sea-doo?

Fuel for sailboats is free as the wind. Petroleum is fuel for
engine boats.

Whatever happened to the lye and aluminum refillable battery? could
it be said to be in a sense hypergolic, and using water as a catalyst?

Terry K

Rod and reel?

On Tue, 31 Aug 2004 17:01:57 -0400, Rodney Myrvaagnes
wrote:

You are using "asymptote" in a metaphoric, rather than mathematical
sense.

Hah, another bald statement of what's right and what's wrong:
let's go for some clarifications:

[lifted from a math site]

Definition of a horizontal asymptote: The line y = y0 is a "horizontal
asymptote" of f(x) if and only if f(x) approaches y0 as x approaches +
or - inf
Definition of a vertical asymptote: The line x = x0 is a "vertical
asymptote" of f(x) if and only if f(x) approaches + or - inf as x
approaches x0 from the left or from the right.

Definition of a slant asymptote: the line y = ax + b is a "slant
asymptote" of f(x) if and only if lim (x--+/-) f(x) = ax + b.
************************************************** *******************

Does this clarify your thoughts on what is and is not asymptotic?

:-)

Brian W

brian, obviously it did not clarify yours.

that is what happens when one expects a 10 second sound bite from CNN and/or
Google to bring universal enlightenment.



You are using "asymptote" in a metaphoric, rather than mathematical
sense.

Hah, another bald statement of what's right and what's wrong:
let's go for some clarifications:

[lifted from a math site]

Definition of a horizontal asymptote: The line y = y0 is a "horizontal
asymptote" of f(x) if and only if f(x) approaches y0 as x approaches +
or - inf
Definition of a vertical asymptote: The line x = x0 is a "vertical
asymptote" of f(x) if and only if f(x) approaches + or - inf as x
approaches x0 from the left or from the right.

Definition of a slant asymptote: the line y = ax + b is a "slant
asymptote" of f(x) if and only if lim (x--+/-) f(x) = ax + b.
************************************************* ********************

Does this clarify your thoughts on what is and is not asymptotic?

:-)

Brian W

On Tue, 31 Aug 2004 22:55:08 GMT, Brian Whatcott
wrote:

On Tue, 31 Aug 2004 17:01:57 -0400, Rodney Myrvaagnes
wrote:

You are using "asymptote" in a metaphoric, rather than mathematical
sense.

Hah, another bald statement of what's right and what's wrong:
let's go for some clarifications:

[lifted from a math site]

Definition of a horizontal asymptote: The line y = y0 is a "horizontal
asymptote" of f(x) if and only if f(x) approaches y0 as x approaches +
or - inf
Definition of a vertical asymptote: The line x = x0 is a "vertical
asymptote" of f(x) if and only if f(x) approaches + or - inf as x
approaches x0 from the left or from the right.

Definition of a slant asymptote: the line y = ax + b is a "slant
asymptote" of f(x) if and only if lim (x--+/-) f(x) = ax + b.
************************************************* ********************

Does this clarify your thoughts on what is and is not asymptotic?


No, because I already knew what it was.
:-)

Brian W


Rodney Myrvaagnes NYC J36 Gjo/a

"Religious wisdom is to wisdom as military music is to music."

Rodney Myrvaagnes wrote:
You are using "asymptote" in a metaphoric, rather than mathematical
sense.

Not at all.

Some realistic numbers, for example:

Let's say 1 horsepower (applied) will drive a given boat 4 knots.
2 horsepower will drive it 5.5 knots
3 horsepower will drive it 6.7
4 horsepower will drive it 7.5
6 horsepower will drive it 8.1
8 horsepower will drive it 8.5
12 horsepower will drive it 8.7
20 horsepower will drive it 8.8
50 horsepower will drive it 8.85

Now, is this a boat capable of planing? If yes, then we'll see an
increase in the amount increased speed for the next increase in
horsepower... then the trend will reappear.

Next thing you know, each increased bit of speed, down to hundredths of
knot increments, require many hundreds of horsepower to attain. Is this
asymptotic enough for you?

No?

Okay, let's keep going... we have hypothetically infinite horsepower
If we were adding millions of horsepower for each hundredth of a knot
increase in speed, is *that* asymptotic enough for you?

No?

How far do we continue this trend? We're inventing new universes to
contain the number of added horsepower for each increased femto-knot.

For the last umptysquintillion trillion horsepower we've added, we have
not seen a 1/8 knot increase.... Let me guess, you don't consider that
asymptotic?

I would, and so would most mathematicians & most yacht designers. YMMV

Fresh Breezes- Doug King