try Dave Gerr, for power required. He makes some dumb comments regarding theory
but his formulae are "close enough" to be more than useful for specific power
needed for specific speeds for "displacement" type boats. Double check with
your propeller vendor, and LISTEN to them, for they have some views that don't
necessarily map one to one with DG's thoughts.

btw, Bob Perry publicalycalled me "an asshole" (his words, several times) for
pointing out that a sine function does not EXPLODE at zero degrees (in fact it
does nothing at all at zero degrees), which of course means that tens of
millions of people across the country are -- by Bob's definition -- "assholes"
for knowing from sine functions.

Welcome back Jax.

We are looking forward your enlightening explanation of how to calculate
hull power requirements.

Mark Browne

Welcome back Jax.

Are you sure he didn't just call you an asshole because you are one?

I mean how do we know how much linkage to sine functions is really involved?

-W

"JAXAshby" wrote in message
...
btw, Bob Perry publicaly called me "an asshole" (his words, several times)
for
pointing out that a sine function does not EXPLODE at zero degrees (in
fact it
does nothing at all at zero degrees), which of course means that tens of
millions of people across the country are -- by Bob's definition --
"assholes"
for knowing from sine functions.

"JAXAshby" wrote in message
...
btw, Bob Perry publicaly called me "an asshole" (his words, several times)

===============================================

Bob is a very perceptive guy.

snickers softly

-W

"Wayne.B" wrote in message
...

"JAXAshby" wrote in message
...
btw, Bob Perry publicaly called me "an asshole" (his words, several
times)

===============================================

Bob is a very perceptive guy.

Welcome back Jax.

We are looking forward your enlightening explanation of how to calculate
hull power requirements.

Mark Browne

top posting corrected

"JAXAshby" wrote in message
...
try Dave Gerr, for power required. He makes some dumb comments regarding
theory
but his formulae are "close enough" to be more than useful for specific
power
needed for specific speeds for "displacement" type boats. Double check
with
your propeller vendor, and LISTEN to them, for they have some views that
don't
necessarily map one to one with DG's thoughts.

btw, Bob Perry publicalycalled me "an asshole" (his words, several times)
for
pointing out that a sine function does not EXPLODE at zero degrees (in
fact it
does nothing at all at zero degrees), which of course means that tens of
millions of people across the country are -- by Bob's definition --
"assholes"
for knowing from sine functions.


I did a little digging on the US navy training sites, as related to ship
design and propulsion.
I saw a fair amount on traverse wave systems, with analysis on wave-making
resistance as affected by beam to length ratio,
displacement, shape of hull, Froude number (ship length & speed), skin
resistance, laminar flow, and interaction between the drive system and the
hull. Most of it was fairly simple and easy to follow.

It would seem that the traverse wave system is the key to understanding
"hull speed".

The traverse waves travel at approximately the same speed as the ship
- At slow speeds, several crests exist along the ship length because the
wave lengths are smaller than the ship length
- As the ship increases speed, the length of the transverse wave increases
- As the wave length approaches the ship length, the wave making resistance
increases very rapidly
- When the transverse wave length equals the ship's length the vessel has
reached its HULL SPEED
It takes energy to produce waves, and as speed increases, the energy
required is a square function of velocity!
(Wave making resistance drastically increases above hull speed)


Here are my source links.
http://www.usna.edu/NAOE/courses/en2...efficients.ppt
http://www.usna.edu/NAOE/courses/en2...es/chap7_a.ppt
http://web.usna.navy.mil/~phmiller/en200/Chapter7.ppt
http://www.gidb.itu.edu.tr/staff/emi...cteristics.pdf
Some of these are long links - you may have to cut-n-paste to follow them.
The files are in PowerPoint or PDF format.
Most Military training material comes this way - sorry if you have trouble
reading it.
If you are on a Microsoft platform you can download free viewers (Search for
viewer) from Microsoft at:
http://office.microsoft.com/

Jax,
Help me out here; I seem to have missed the sine function thing.
Would you please elaborate?
Perhaps just a link to it and I will read up on it myself?

Mark Browne

JAXAshby wrote:

try Dave Gerr, for power required. He makes some dumb comments regarding theory
but his formulae are "close enough" to be more than useful for specific power

In other words, JAX has no clue how to figure out power/disp/speed demand curves,
but has looked at the pictures in Dave Gerr's book.


btw, Bob Perry publicalycalled me "an asshole" (his words, several times)

Let me congratulate him on his perspicacity.

for
pointing out that a sine function does not EXPLODE at zero degrees (in fact it
does nothing at all at zero degrees), which of course means that tens of
millions of people across the country are -- by Bob's definition -- "assholes"
for knowing from sine functions.

Well, since you don't know a sine function from an asymptote (BTW are you sure Bob
Perry didn't call you an "asymptote'?), you are on pretty safe grounds there. But
what does all this gibberish have to do with hull speed?

DSK

BTW are you sure Bob
Perry didn't call you an "asymptote'?

I can't imagine Perry would have a clew what the word meant.


But
what does all this gibberish have to do with hull speed?

DSK

weeeeeeeeeeeeeeeeell, dougies, if you gotta ask there seems no likelihood you
would understand the answer. You see, you have read the answer earlier in this
thread and you didn't even recognize it.

BTW are you sure Bob
Perry didn't call you an "asymptote'?

JAXAshby wrote:
I can't imagine Perry would have a clew what the word meant.

So, you don't know what it means either?

Actually, it has far more to do with hull speed than any "sine function."



But
what does all this gibberish have to do with hull speed?


weeeeeeeeeeeeeeeeell, dougies, if you gotta ask there seems no likelihood you
would understand the answer. You see, you have read the answer earlier in this
thread and you didn't even recognize it.

In other words, you still don't know.

Same old Jaxxie, same old BS. Some things never change.

DSK

So, you don't know what it means either?

it has no meaning in this context, though some semblence of meaning comes about
at higher orders of magnitude of hull speeds, say at 10,000x to 100,000x, or
1,000,000x hull speed.

Actually, it has far more to do with hull speed than any "sine function."

bull****, and your saying so clearly shows you don't understand the question.

In other words, you still don't know.

I said it before, and I'll say it again for you dougies, the sine function
quoted in the "theory" of hull speed does not EXPLODE at zero. In fact, it
does virtually nothing at all at hull speed, and even if true (which it isn't)
at 2x hull speed is just accounts for a 40% increase in hp required, while drag
accounts for an 800% increase in hp required.

I am sorry, dougies, if this confuses you so.

JAXAshby wrote:


I said it before, and I'll say it again for you dougies, the sine function
quoted in the "theory" of hull speed does not EXPLODE at zero. In fact, it
does virtually nothing at all at hull speed, and even if true (which it isn't)
at 2x hull speed is just accounts for a 40% increase in hp required, while drag
accounts for an 800% increase in hp required.

I am sorry, dougies, if this confuses you so.

It doesn't confuse me at all. But it's not as funny as I'd hoped.

Tell me, does this "sine function" quoted in the "theory" of hull speed have
anything to do with the concept that the hull makes waves and the "sine function"
also has something to do with waves?

As for the asymptote, the usually quoted hull speed is in fact an asymptote of the
combined resistance graphed against speed of a given hull. It has a lot more to do
with the "theory" of hull speed than any sine function.

But you don't want facts, do you Jax? They seem to make you uncomfortable.

DSK