It is, of course, though many ignorant people will claim they read it in a
book, so it HAS to be true.

[the above to _try_ to instill *some* talk of boats on this silly ass ng]

Too late, Jax....
This NG has been taken over by limp-dicked lame-ass off topic posters that
have no life. I suggest finding a specific owners' group and hanging out
there.
It is sad that there is no moderation on this board. It USED to be a pretty
good source of information.



"JAXAshby" wrote in message
...
It is, of course, though many ignorant people will claim they read it in a
book, so it HAS to be true.

[the above to _try_ to instill *some* talk of boats on this silly ass ng]

Then why is the effect both predictable and
consistent?

When the results of an experiment conducted a million times are identical in
all regards, at what point can one draw a conclusion without being guilty of
voo doo science?

You could make a case that, under unique conditions, a vessel in displacement
mode
will attain speeds (in knots) greater than (sq rt of waterline expressed in
feet) X 1.3. You can make an accurate case that the multiplier for specific
hulls may vary between 1.2 and 1.4.

What cannot be argued is that beyond the calculated hull speed a vessel meets
the resistance of the bow wave, and must start climbing that wave (leave
displacement mode) in order to increase speed.

Exceptions prove the rule. If I observed that it is possible to have a rain
squall pass 20 yards away and stay perfectly dry, that would neither establish
that such a lucky break is a common occurence or that water isn't wet. :-)

Then why is the effect both predictable and
consistent?

it isn't. Most recreational sailboats made in the last 40 years will exceed
"hull speed" without any heavy lifting, and Hobie cats will go 3x "hull speed"
or more.

Some would argue that those hulls are planing, though plainly that is not the
case.

btw, mathematically the extra effort needed "to climb the bow wave" is zero at
"hull speed" and still doesn't amount to all that much at 2x "hull speed".

the THEORY is not theory at all, but oft repeated hearsay.

When the results of an experiment conducted a million times are identical in
all regards, at what point can one draw a conclusion without being guilty of
voo doo science?

You could make a case that, under unique conditions, a vessel in displacement
mode
will attain speeds (in knots) greater than (sq rt of waterline expressed in
feet) X 1.3. You can make an accurate case that the multiplier for specific
hulls may vary between 1.2 and 1.4.

What cannot be argued is that beyond the calculated hull speed a vessel meets
the resistance of the bow wave, and must start climbing that wave (leave
displacement mode) in order to increase speed.

Exceptions prove the rule. If I observed that it is possible to have a rain
squall pass 20 yards away and stay perfectly dry, that would neither
establish
that such a lucky break is a common occurence or that water isn't wet. :-)

it isn't. Most recreational sailboats made in the last 40 years will exceed
"hull speed" without any heavy lifting, and Hobie cats will go 3x "hull
speed"
or more.

Hobie "cat". The hull speed equation is intended to apply to monohulls in
displacement mode.


The arguable point is really the definition of displacement mode, not the
veracity of the hull speed theorem. IMO, a Hobie Cat is on plane....(hell,
sometimes airborne)..when it is making better than hull speed.

On 10 Apr 2004 17:22:35 GMT, (Gould 0738) wrote:

it isn't. Most recreational sailboats made in the last 40 years will exceed
"hull speed" without any heavy lifting, and Hobie cats will go 3x "hull
speed"
or more.

Hobie "cat". The hull speed equation is intended to apply to monohulls in
displacement mode.


The arguable point is really the definition of displacement mode, not the
veracity of the hull speed theorem. IMO, a Hobie Cat is on plane....(hell,
sometimes airborne)..when it is making better than hull speed.

A hobie cat doesn't plane. But it does break the hull speed "rule"
because that only applies to L/W ratios of around 3 or less. Hobie cats
are like in the 15-20 area.

Steve

But it does break the hull speed "rule"

hull speed is a not a "rule" but rather an explanation that assumes both that a
boat *must* go over a wave rather than through it AND that boat speed is
governed by the speed of unconstrained water waves of infinite fetch.

IMO, a Hobie Cat is on plane....(hell,
sometimes airborne)..when it is making better than hull speed.

Hobies have DEEP Vee hulls, not possible to plane.

IMO, a Hobie Cat is on plane....(hell,
sometimes airborne)..when it is making better than hull speed.

Hobies have DEEP Vee hulls, not possible to plane.


Normally laden, all but a few inches of that
"Deep Vee" is above the waterline.

What's the effective draft of a Hobie Cat, in inches?

One could make a case that the boat is always, (effectively) on plane at least
as easily as a case that it cannot plane at all.

http://www.hobiecat.com/sailing/index.html

The exceptions prove the rule, as always.

The arguable point is really the definition of displacement mode, not the
veracity of the hull speed theorem.

displacement means displacement, as in not rising above the natural float point
of the hull due to impact of water against the hull due to motion.