-T o me it makes sense on a skinny boat with little or no rocker to
make the bows just go under as the stern just comes up. After that,
you are rapidly increasing your resistance. Therefore I work on taking
the total displacement when the bhorizontal boat is just wetting the
top of its bows and then use half that weight as the maximum of the
total boat displacement.
Robert
-- In harryproa@yahoogrou
>
> I was merely showing you my wetted surface areas. I don't see where
> I left anything out. Now if you wanted my hull outline and shape in
> which I achieve my figures for wetted area. Instead of
> misrepresenting my hull form from your misunderstanding of what was
> given is who's fault.
>
>
> My 24' square harry I'm getting a total area of 156sqft total skin
> area and wetted area of 47sqft at a depth of 6'' for a displacement
> of 795lbs at a prismatic coefficient of .783 17/1 length to width
> ratio. Same 24' hull @ a 3''depth at displacment of 382 lbs for a
> wetted surface area of 35sqft. with a pricmatic coefficient of 784.
>
> Leaving a 3''depth margine for waterline displacment From lightest
> load to heaveist load is hardly designing light and sailing heavy on
> a 24' hull length.
>
> Now on having enough buoyancy in bows to carry sufficient sail area
> and how high to carry it is where I'm at now. I get 3,839lb if you
> were to load it evenly submerging it to the tops of bows which are
> 24''high from keel. 24'' back from bow, bulkhead #2 keel width 8'',
> sheer width 13.5'', height from keel 28.35''. I'm going to build the
> model to get a better idea and use the easy rig with 180sq'' sail
> rig that I have already for a comparison.
>
> Any idea with demensions given to determine estimate of bow buoyancy
> pressed. Would it be half of total, 1,919 lbs thats not taking into
> account for the radius from 24'' bow height to 36'' rise to middle
> of hull and the fact the the hull increases in width the higher you
> get to sheer . Middle of hull bulk head #12 keel width 15'', sheer
> width 30'', height from keel 36''
>
> Todd
>
>
> --- In harryproa@yahoogrou
> wrote:
> >
> > G'day,
> > On Fri, May 30, 2008 at 10:56 PM, tsstproa <bitme1234@> wrote:
> > > Wow above the waterline doesn't alter anything are you serious?
> > > One thing I learned from you that you stress is windage on
> hulls!!!
> >
> > It obviously alters the sailing, but not the below water
> > characteristics, which is what the rest of the numbers were about.
> > You need more than just height and width to determine whether the
> > height at the bow, beams and mast is sufficient.
>
>
> > >
> > > Knowing 36''height at center of reverse sheer seems high for a
> 16'
> > > wwh. 30'' sheer height at center on 24'lwh with reverse sheer
> might
> > > increase it to 36''
> > >
> > > You think the 3,ooo + lbs displacement on 24' lwh submerged to
> the
> > > tops of its bows 24'' will be enough reserve buoyancy for descent
> > > sail carry capacity?
> >
> > No idea, depends on rig height, crew weight and location, beam
> overall
> > and shape of the hull above the waterline at the bow.I would need
> at
> > least a lines drawing and a rig picture to form an opinion.
> > >
> > > I just wanted to compare your 24 WWH with My flat bottom 24 LWH
> > > wetted surface are to see how much difference the wetted areas
> would
> > > be. That is all. I gave you all the numbers except waterline beam
> > > width so I think that was the confusion.
> > >
> > > As far as weight of boat and weight carried by boat. I figured
> plan
> > > for the worst (heaviest) or extra load on sundays in the bay with
> > > family and friends and build for the (lightest)
> > > possible with materials used. You have a cushion between the two
> to
> > > get it right for most any load/weight within reason.
> >
> > Building light and sailing heavy seems to be the wrong way round
> to me.
> >
> > regards,
> >
> > Rob
> > >
> > > Todd
> > >
> > > --- In harryproa@yahoogrou
> > > wrote:
> > >>
> > >> G'day,
> > >
> > >>
> > >> On Wed, May 28, 2008 at 1:32 PM, tsstproa <bitme1234@> wrote:
> > >> >
> > >> >
> > >> > Rob I didn't give waterline beams widths, sheer widths, or
> height
> > >> > from keel to sheer.
> > >>
> > >> Above the waterline doesn't alter anything, but the waterline
> > > length
> > >> is critical for comparison.
> > >> >
> > >> snip
> > >> >
> > >> > I just wanted your numbers of your boats wetted surface area.
> > > What is the wetted surface area for what waterline/displacem
> on
> > >> > both hulls.
> > >>
> > >> For the trailer sailor in the files section, the wetted surface
> for
> > >> the ww hull at 450 kgs/990 lbs is 4.4sq m/46 sq', beam
> 485mm/19".
> > > The
> > >> lee hull at 300 kgs/660 pounds is 4.sq m/51 sq', waterline beam
> 370
> > >> mm/14.6"and at 750kgs/1,650 (hull flying) is 7.5 sq m/81
> > >> sq',waterline beam 440mm/17.3" . Prismatics are .8 The
> > > advantages
> > >> of short fat hulls in light air, where friction from wetted
> > > surface is
> > >> important is obvious.
> > >> >
> > >> >
> > >> > My 24' square harry I'm getting a total area of 156sqft and
> > > wetted
> > >> > area of 47sqft at 6''waterline for a displacement of 795lbs
> at a
> > >> > prismatic coefficient of .783 17/1 length to width ratio
> > >> >
> > >> > 16' wwh with out cabin , 129sqft 46sqft wetted area at a
> > >> > 8''waterline with a displacement of 882lb prismatic
> > > coefficient .764
> > >> > 12/1 length to width ratio.
> > >> >
> > >> > total displacment 1,675lbs total weight of boat 800lbs. 800lbs
> > > crew
> > >> > and gear, 250-300sqft sail area.
> > >> >
> > >> > Todd
> > >> >
> > >>
> > >
> > >
> >
>
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