My last post I intended Robert not Mark on the marriage thng sorry.
Pitching come on its a 50' long right with Pc of .8 buoyancy almost
out to the ends from center. It won't start pitching untill your in
some 10 -15 foot rolling seas. Even then you can still get an angle
on it if the win is right. What about the roll or lateral pitching?
Todd
-- In harryproa@yahoogrou
wrote:
>
> G'day,
>
> Agree that half a degree of pitch is extraordinary at 15 knots for
a double
> ended boat with central rig.
>
> I'm not sure of the relationship between speed and drag (suspect
it is at
> least a square, possibly a cube), but a large portion of it is the
rudders,
> so can be reduced when reefed or off the wind by lifting the front
one.
>
> I guess the question of what lifts first can be calculated, but no
idea
> how. Has a lot to do with point of sail (offwind the stern will
lift first,
> beating, the ww hull will) and wave direction.
>
> regards,
>
> Rob
>
> On 8/9/07, Robert <cateran1949@
> >
> > a rough calculation gives less than half a degree pitch.
(working on
> > 2 inches up at the stern and 2 inches down at the bow gives 10cm
> > over 15m or 1 in 150) At 15 knots is extraordinary. Depending on
the
> > relationship between resistance and speed gives in the order of
only
> > a couple of degrees pitch at 25 knots.
> > How many deegrees before the stern leaves the water?
> > Is it possible to do the calculations of which goes first with
full
> > sail up, the stern leaves the water or the ww hull leaves the
> > water . I realise that you would have to have a much stiffer mast
> > for this to happen on Vis.
> > On the trans pac clearly you would be flying a hull first
> > Robert
> > --- In harryproa@yahoogrou
40yahoogroups.
> > Denney" <harryproa@>
> > wrote:
> > >
> > > G'day,
> > >
> > > Don't be fooled by the reverse sheer and the spray washing over
> > the bows.
> > > It is nowhere near it's limits, in fact, it has barely immersed
> > the bow past
> > > the waterline. Harrys have huge amounts of buoyancy in the
> > bows due to
> > > their prismatic coefficient (a measure of buoyancy
distribution)
> > of 0.8.
> > > Most cats are in the 0.6-0.65 range. With the rounded decks and
> > nothing to
> > > slow the boat (fore beam, trampoline, forestays, etc) it goes
> > through waves
> > > very easily.
> > >
> > > Not sure if you mean heel or pitch. Some of both are
inevitable.
> > As the
> > > lee hull waterline at the bow is just out of sight and at the
> > stern a couple
> > > of inches are showing, I would estimate a couple of degrees of
> > heel, and
> > > less of pitch. The absence of heel is confirmed by the angle of
> > the
> > > stainless lifeline against the horizon. Mark reckons it pitches
> > and heels
> > > less than any boat he has ever been on.
> > >
> > > The video is indeed sedate seas. Not much we could do about
> > that. In
> > > bigger seas, my experience with my boats is that they go
through
> > waves with
> > > no noticable effect (ie, you do not feel the boat slowing).
This
> > boat is
> > > bigger and heavier, may have even less effect. What is
noticable
> > on my
> > > boats, and to a lesser extent on Rare Bird, is that waves
hitting
> > the rudder
> > > cases do noticably slow the boat. Only happens at high speeds,
> > with large
> > > waves and is caused by the cases, rather than the brackets,
and it
> > has been
> > > addressed in later designs. It is evidenced by the creww
feeling
> > a small
> > > jerk each time it hits a large wave. As you can see by looking
at
> > the
> > > passengers, there is none of this.
> > >
> > > The rudder brackets have so far proven to be plenty strong
enough
> > to take
> > > the loads, including running aground at speed with the wooden
> > sheer pin
> > > replaced with a large steel bolt, causing case damage.
> > >
> > > In 25 knots with big seas? Time will tell, but on all my
> > prototypes, it has
> > > not been a problem. There are not many cruisers that sail
> > consistently and
> > > comfortably at 15 knots, much less higher speeds. Rare Bird has
> > punched
> > > through a wave that washed items off the boom (>10' off the
water)
> > while
> > > crossing the bar, with no ill effects.
> > >
> > > Great that you have advanced from "no good at all speeds"
to "good
> > at 15
> > > knots wind, 15 knots boat speed", and I appreciate your
ability to
> > accept
> > > evidence. I look forward to convincing you about the next step.
> > >
> > > regards,
> > >
> > > Rob
> > >
> > >
> > > On 8/9/07, Todd <bitme1234@> wrote:
> > > >
> > > > No I don't think a flared bow would be any better.It would be
> > worse.
> > > > The boat doesn't look to be sailing flat. It looks to me to
be
> > > > heeled 5 to 7 degrees maybe more in the video. To me the
leeward
> > > > hull just seems to shallow at the ends. In the 1 metre swell
the
> > bow
> > > > is punch through on a few all most buried. The video shows
pretty
> > > > sedate sea state and the boat looks all ready to be pushing
its
> > > > limits with the leeward hull low in the water. Along with the
> > > > appendage attachments. Load of rudders horizontally and
vertical
> > in
> > > > proper trim but what about at speed, 20knots being pounded
> > > > vertically hour after hour. In and out wave after wave?
> > > >
> > > > Good at 15 knot winds 15 knot boat speed but what at 20 to 25
> > knots
> > > > in lumper seas?
> > > >
> > > > Todd
> > > >
> > > > --- In harryproa@yahoogrou
40yahoogroups.
> > 40yahoogroups.
> > > > "Robert" <cateran1949@
> > > > wrote:
> > > > >
> > > > > The boat looks as though it is riding pretty flat to me .
With
> > 3m
> > > > > swell I am assuming the bow will simply punch into it and
> > gently
> > > > rise
> > > > > without any violent hobby horsing. The flat ride should
keep
> > the
> > > > sails
> > > > > working better than with violent motion of a flared bow
> > bouncing
> > > > off
> > > > > waves I can't think of any small boat that would not be
pretty
> > wet
> > > > in
> > > > > the same circumstances. The braces are designed to take the
> > loads
> > > > of
> > > > > the rudders. Shock loads from the braces hitting the top
of the
> > > > wave
> > > > > is nothing compared to loads from the rudders,
> > > > > Robert
> > > > > --- In harryproa@yahoogrou
40yahoogroups.
> > 40yahoogroups.
> > > > "Todd" <bitme1234@> wrote:
> > > > > >
> > > > > > --- In harryproa@yahoogrou
40yahoogroups.
> > 40yahoogroups.
> > > > "Todd" <bitme1234@> wrote:
> > > > > > >
> > > > > > > Hello Rob and folks, (sorry about that)
> > > > > > >
> > > > > > > Nice video, impressive. But;) Looks like 1 metre swell
> > > > possible in
> > > > > > > 15 knot winds for a boat speed of 15knots . Marshall
Island
> > > > Walap
> > > > > > > will do that. What about 25 knot winds in 3 metre
swell?
> > Looks
> > > > as
> > > > > > > throught the bow is pretty close to the edge in 15
knots.
> > As
> > > > far
> > > > > > as
> > > > > > > all out performance pushing the boat to the limits
what is
> > > > known?
> > > > > > >
> > > > > > > What about the braces for the weather boards, how much
> > abuse
> > > > will
> > > > > > > they handle being punched from underneath or swist from
> > > > changing
> > > > > > > angle of attacks in certain situations. The bottom
brace
> > seems
> > > > > > > really close to the water surface.
> > > > > > >
> > > > > > > Todd
> > > > > > >
> > > > > > > --- In harryproa@yahoogrou
40yahoogroups.
> > 40yahoogroups.
> > > > "Rob Denney" <harryproa@>
> > > > > > > wrote:
> > > > > > > >
> > > > > > > > G'day,
> > > > > > > >
> > > > > > > > My Harry did 15 in 15 with lousy sails, but not much
> > > > interior,
> > > > > > so
> > > > > > > probably
> > > > > > > > pretty similar. Blind Date will be faster than Rare
Bird
> > as
> > > > it
> > > > > > is
> > > > > > > lighter,
> > > > > > > > has less windage and a stiffer mast. Rare Bird's
sails
> > also
> > > > > > need
> > > > > > > some work,
> > > > > > > > it has not realised it's full potential yet.
> > > > > > > >
> > > > > > > > The only real difference in a Harry is whether you
have
> > the
> > > > > > > cockpit cover or
> > > > > > > > not. Bain has it and it works well. I prefer to feel
the
> > > > > > breeze,
> > > > > > > so the
> > > > > > > > solo boat will have a pram type fold up cloth cover
over
> > > > part of
> > > > > > > the cockpit
> > > > > > > > for keeping out of the rain and wind.
> > > > > > > >
> > > > > > > > regards,
> > > > > > > > Rob
> > > > > > > >
> > > > > > > >
> > > > > > > > On 8/8/07, George Kuck <chesapeake410@
> > > > > > > > >
> > > > > > > > > How will the 12m (40') Harry (built with the KSS
> > > > method)
> > > > > > > performance
> > > > > > > > > compare to Rare Earth or Blind Date ? Will it have
> > > > > > a "cruiser"
> > > > > > > or "sport"
> > > > > > > > > version option or be a compromise between the two ?
> > > > > > > > >
> > > > > > > > > George Kuck
> > > > > > > > > Chestertown, MD
> > > > > > > > >
> > > > > > > > > *Robert <cateran1949@
> > > > > > > > >
> > > > > > > > > It is pretty impressive for such a comfortable
boat.
> > Even
> > > > > > with
> > > > > > > the
> > > > > > > > > extra weight it is still pretty light compared to
most
> > > > > > > multihulls of
> > > > > > > > > similar length,
> > > > > > > > > \ Robert
> > > > > > > > >
> > > > > > > > > --- In harryproa@yahoogrou
40yahoogroups.
> > <harryproa%
> > 40yahoogroups.
> > > > > > > 40yahoogroups.
> > > > > > > > > Crawford <jmichael@> wrote:
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > Fifteen knots in fifteen knots of wind? In Rare
Bird?
> > > > Holy
> > > > > > > moly!
> > > > > > > > > >
> > > > > > > > > .
> > > > > > > > >
> > > > > > > > >
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