Actually meant to post only 2 place precision. Yes is only accurate to 1
decimal place.
Bill

"JAXAshby" wrote in message
...
3.21 x 3.21 != 10.3041 is only accurate to 10.30.

correct me if I am wrong, but as I remember it 3.21 x 3.21 is only
accurate to
one decimal because the factors are accurate to only 1 place. I am pretty
sure
of that but it has been a while since I worried about "precision" and
"double
precision" numbers.

On 18 Jan 2004 18:36:14 GMT, (JAXAshby) wrote:

3.21 x 3.21 != 10.3041 is only accurate to 10.30.

correct me if I am wrong, but as I remember it 3.21 x 3.21 is only accurate to
one decimal because the factors are accurate to only 1 place. I am pretty sure
of that but it has been a while since I worried about "precision" and "double
precision" numbers.

Correct.

Later,

Tom
S. Woodstock, CT
----------
"My rod and my reel - they comfort me."

St. Pete, 12 Lb. Test

On Sun, 18 Jan 2004 11:57:33 +0000, Wayne. wrote:

On Sun, 18 Jan 2004 08:54:44 -0800, "Lloyd Sumpter" wrote:

"Far Cove" Catalina 36 - hull speed 7.5kn, has seen 10

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

Lloyd, what is your water line length (LWL) ?

30 ft - with a "fudge factor" of 1.35 gives hull speed of 7.4 knots. Easy to see
5, she will do 6 on a 10-knot breeze, 7 is a good reach, 7.5 is reaching on 15
knots, 8 is close-reaching on 25 knots or so...

Lloyd

On Sun, 18 Jan 2004 11:53:25 -0500, Wayne.B
wrote:

The concepts being wrestled with here are "precision" and "accuracy".

Precision implies repeatable results to some number of decimal places
plus or minus an uncertainty factor.

That is true.

Accuracy implies the correct answer in absolute terms.

Accuracy is related to how good (accurate) the data set is. For
example, "accurate within 3 meters" is not an absolute - it could
be dead on, or three meters off. Now if the phrase stated "accurate
to within 2.987654321 =/- .0000000001 meters" - that is precise - you
will always know that you will be within 2.987654321 +/- .0000000001
meters of any mark rather than somewhere within the accuracy range of
0 to 3 meters.

Now I have a headache.

Later,

Tom
S. Woodstock, CT
----------
"My rod and my reel - they comfort me."

St. Pete, 12 Lb. Test

On 18 Jan 2004 13:17:34 GMT, (JAXAshby) wrote:

also wrong, but what the hey it is simple and complete.

Where exactly is it wrong?

among other things, there is no reason whatsoever that a boat MUST go over top
of a wave rather then through it, and a sin function does NOT explode at zero
degrees.

Really?

I can think of a thousand reasons why a boat MUST go over a wave,
however I can only think of one reason why a boat MUST go through a
wave and that is if it is heavier than water and is capable of passing
through a wave.

Later,

Tom
S. Woodstock, CT
----------
"My rod and my reel - they comfort me."

St. Pete, 12 Lb. Test

snip
The concepts being wrestled with here are "precision" and "accuracy".

Precision implies repeatable results to some number of decimal places
plus or minus an uncertainty factor.

That is true.

Accuracy implies the correct answer in absolute terms.

Accuracy is related to how good (accurate) the data set is. For
example, "accurate within 3 meters" is not an absolute - it could
be dead on, or three meters off. Now if the phrase stated "accurate
to within 2.987654321 =/- .0000000001 meters" - that is precise - you
will always know that you will be within 2.987654321 +/- .0000000001
meters of any mark rather than somewhere within the accuracy range of
0 to 3 meters.

snip
I work with precision measuring devices and find that these are slippery
concepts for most people. The shoddy day-to-day usage and close relationship
between the two words does not make things any easier.
See:
http://www.ieee-uffc.org/freqcontrol...g/vigaccur.htm
for a nice intuitive explanation of the difference between accuracy and
precision.

Mark Browne

I can think of a thousand reasons why a boat MUST go over a wave,

nah.

however I can only think of one reason why a boat MUST go through a
wave and that is if it is heavier than water and is capable of passing
through a wave.

all boats pass through waves to some greater or lesser extent. Just stand at
the bow and watch, or watch a Hobie cat go by (a displacement if there ever was
such a thing)

besides, the sine function claimed to support "theorectical hull speed" does
not hardly EXPLODE at zero degrees. In fact, it is zero at zero. In fact,
even at 2x hull speed it -- if it were accurate and it is not -- would only
account for about a 40% increase in needed hp, while doubling the speed would
required 800% more hp just to overcome drag.

"JAXAshby" wrote in message
...
and will only add
that it is theoretical

it is not even theoretical. It is and always was just scientific sounding
gibberish.

Welcome back Jax.

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

Mark Browne

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

On Sat, 17 Jan 2004 22:20:54 GMT, "Calif Bill"
wrote:


"Joe Parsons" wrote in message
.. .
[HAIRSPLITTING=ON]

On Sat, 17 Jan 2004 19:57:18 GMT, Short Wave Sportfishing
wrote:

A nautical mile is also, precisely, 6,076.12 feet.

That's not precise--that's rounded to two decimals.

A nautical mile is, by definition, precisely 1,852 meters, as mentioned
above.

That converts to 6,076.11549 feet (which still is not precise!).

[HAIRSPLITTING=OFF]

I look at it this way - if I can get within four feet of something, I
can holler at it. :)

Now THAT is practical navigation!


Joe Parsons


Difference between an engineer and a mathematician.

Voluptuous Dallas Cheer leader is standing nekid on the goal line.
The engineer and math nerd are on the other line. Told that the first one
to her gets her. Only restriction is can move only 1/2 the distance to the
goal in any one move. Math nerd says 'won't even start, is an infinite
series and will never get there.'. Engineer is moving and states, 7 moves
and I am close enough for any thing I want to do.

Joe, you a math minor in a business major?
Bill

Neither. I'm a writer.