G'day,
Sorry for the delay on this, I accidentally trashed it. The numbers
in ()are imperial for the windward hull on rapscallions boat, those in
[] are yours for your near enough same length leeward hull
Ww hull loa 7m (23') [24']
wetted surface 4.5 (48 sq') [47]
displacement 455 kgs (1,000 lbs) [795]
Prismatic .755 [.783]
draft: (.2m 8") [?]
waterline beam .537 (21") [6"]
b/l 1:13 [1:13]
20% more displacement, 2% more wetted surface, narrower hull. Yours
must be very deep draft. Add on another 10 sq' for a rudder foil on
mine. In reality, the lee hull on this boat is 40' long and it has
530 sq' of sail, with pretty similar all up weight to yours.
Next is the Imperial numbers for this hull scaled down to your length
and displacement with your square harry numbers in ( ). Your length
to width ratio is wrong. 8" waterline beam, 16' long is 24:1, not
12:1. This makes it a very deep hull, so I have presumed it should be
16" wide to get the 12:1 ratio. The hull I get by this scaling is far
from what it would be if I designed it from scratch. The more ideal
numbers are in [ ], although I would never design a 16' windward hull
to carry 900 pounds.
Ww hull loa 16' (16') [16']
wetted surface 40 (46) [38]
displacement 888 (882) [889]
Prismatic .77 (.764) [.758]
draft:12" (?) [10]
waterline beam 17" (16") [20]
b/l 11 (12) [9.6]
As you can see, the wetted surface is lower, but the l/b ratio is
unacceptably low. I would not have such a high payload on such a short
hull as it will either be too wide or too deep. I would make it 20'
long, or remove some weight.
If I was you, I would also do the numbers for the lee hull carrying
all the weight, ie with the hull flying. This is also handy to get
the amount of freeboard at the bow in this situation.
Hope this is not too confusing. It is difficult to get accurate
comparisons when our basic hull shapes are so different. Any imperial
numbers that look wrong, probably are. It is a while since I used
this system.
Raps, the square reference is the section shape of the hull . Neither
his hulls nor the harry's plane, (insufficient flat area in harry's,
insufficient area aft in both) they just keep going faster until
friction equals drive. All else being equal, as harrys have less
wetted surface, they should perform better in low winds and have a
higher top speed. However, if Todd can steer his without a rudder and
without reducing the optimum drive from his rig, then the wetted
surfaces are more equal, so the above won't apply. Because the harry
rudder foil should be more efficient than his hull side at reducing
leeway, I would expect the harry to point higher. However, Todd gets
some pretty good upwind angles, so this may be wrong as well.
Any questions, let me know.
regards,
Rob
On Mon, May 26, 2008 at 4:07 AM, tsstproa <bitme1234@yahoo.
>
>
> On your surface area numbers for trailor sailor. I was scratching
> my head thinking the 15 sqft was the wetted area and the 163 sqft
> was the total. Going geez how does he do it? But realized 15sqm
> total area.
>
> What is the wetted surface area for what waterline/displacem
> both hulls.
>
> 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
>
> --- In harryproa@yahoogrou
> <captian_rapscallio
>>
>> --- In harryproa@yahoogrou
>> <captian_rapscallio
>> >
>> >
>> Is it possible to use the carbon tow on the hulls?
>>
>>
>> > I also like the idea of using the KSS method. Can't wait to see
> more
>> > of the design!
>> >
>> >
>> >
>> >
>> >
>> >
>> > --- In harryproa@yahoogrou
> wrote:
>> > >
>> > > G'day,
>> > >
>> > > Could have made it bigger, but cost goes up and speed goes
> down.
>> > > Could not have made it big enough to get around the bunks and
> still
>> > > have both hulls at the same height on the trailer which is
> essential
>> > > with telescoping beams. Middle of the night access to and
> from the
>> > > bunk for the inside sleeper wil probably be through a hatch in
> the
>> > > roof.
>> > >
>> > > The beams are each in two pieces, which telescope together, on
>> > > rollers. Rollers are what makes telescoping viable and is one
> of the
>> > > reasons alloy beam telescoping doesn't work well. The
> rollers are
>> > > simply made from delrin tube and fibreglass shafts and
> brackets. They
>> > > add a bit to the build time, but as the beams are box section,
> they
>> > > can be assembled and tested before they are glued together.
> As the
>> > > rollers don't take any sailing loads, precision alignment is
> not
>> > > required. Pictures and an explanation when I have finished the
>> > > drawing.
>> > >
>> > > regards,
>> > >
>> > > Rob
>> > >
>> > > On Fri, May 23, 2008 at 12:19 AM, Robert <cateran1949@
>> > > > -I don't feel there has been enough made of the possible
> width fro
>> > > > accommodation. I only see about 2m width of hulls all up. I
>> reckon you
>> > > > have enough width left over for access to the bunks from
> inside the
>> > > > hull, though it would mean extra windage. I do like the
> weight,
>> > > > Robert
>> > > >
>> > > > -- In harryproa@yahoogrou
> <harryproa@> wrote:
>> > > >>
>> > > >> G'day,
>> > > >>
>> > > >> Just posted the weights and materials spreadsheet to
> the "Trailer
>> > > >> sailor,see post 3348" file.
>> > > >>
>> > > >> As you can see, the weight (415 kgs/913 lbs) is less than I
>> > estimated,
>> > > >> giving an empty Bruce number of 1.9, which is much more
>> respectable.
>> > > >>
>> > > >> Anything that looks like a mistake probably is, so please
> let me
>> > know.
>> > > >>
>> > > >> Still cleaning up the drawing, and seeing if the whole
> thing can be
>> > > >> made from partially glassed flat panels, which will make it
> much
>> > > >> quicker to build and eliminate a lot of fillets and tabbing.
>> > > >>
>> > > >> regards,
>> > > >>
>> > > >> Rob
>> > > >>
>> > > >> On Thu, May 22, 2008 at 9:23 AM, Rob Denney <harryproa@>
> wrote:
>> > > >> > G'day,
>> > > >> > There are a number of ways to add to the bruce number. A
> longer
>> > mast
>> > > >> > is one, although this is harder to erect/remove and
> trailer.
>> If you
>> > > >> > leave the mast building until after the hulls and beams
> are
>> > built, you
>> > > >> > will be an expert in telescoping structures and could go
> with a
>> > > >> > 15m/50' luff which telescopes to 8m/27'. Better in the
> light, and
>> > > >> > heavy and quicker to erect/remove. This would give you
> sail
>> area of
>> > > >> > 41.5 sq m/456 sq' plus 6 sqm/64 sq' of mast . Total 47.5
> sq
>> > m/510 sq'
>> > > >> > and assuming we saved enough weight to keep it the same,
> a Bruce
>> > > >> > number empty of 2.2, and loaded of 1.77 which is
> definitely
>> record
>> > > >> > breaking material.
>> > > >> >
>> > > >> > Plans cost is the same as the 12m harry, $Aus3,000, which
> all
>> > goes to
>> > > >> > the engineer. The plans will show you how to build
> everything
>> > except
>> > > >> > the sails. You will get a 10% rebate from anyone who buys
> a
>> set of
>> > > >> > plans between now and when the next one after yours hits
> the
>> water.
>> > > >> > After that, if anyone buys one because of you or your
> boat,
>> you get
>> > > >> > the 10%. Payment is 50% now, 50% when the plans are
> complete.
>> This
>> > > >> > keeps me enthusiastic during the boring part of the design
>> process,
>> > > >> > although there should not be much of that with this boat.
> It also
>> > > >> > allows me to improve the plans based on feedback from
> other boats
>> > > >> > without having to draw everything twice. I will send you
> bank
>> > > >> > details and some other stuff offlist.
>> > > >> >
>> > > >> > I will do some more work on the drawings and have some
> more exact
>> > > >> > numbers tonight, including the materials costs. Could
>> probably ship
>> > > >> > the Polycore direct from China so it would not be any more
>> > expensive
>> > > >> > than buying it here.
>> > > >> >
>> > > >> > A racing hull is a good idea, but really only for day
>> sailing. The
>> > > >> > hull drawn would be pretty much as small as any sane
> person
>> > would want
>> > > >> > to sail on the Great Lakes in. Plus, weight in the ww
> hull is
>> > not the
>> > > >> > big deal it is on cats and tris. It would be a pity to be
>> freezing
>> > > >> > your butt off on/in a minimal hull that had to have water
> added
>> > to it
>> > > >> > to get enough righting moment.
>> > > >> >
>> > > >> > See you for the Chi/Mac next year!
>> > > >> >
>> > > >> > Regards,
>> > > >> >
>> > > >> > Rob
>> > > >> >
>> > > >> > On Thu, May 22, 2008 at 12:16 AM, captian_rapscallion
>> > > >> > <captian_rapscallio
>> > > >> >>
>> > > >> >> I really like the concept! I would build using your
> carbon fiber
>> > > >> >> approach, with the hope I add a bit to the bruce number.
> I
>> > > > believe the
>> > > >> >> limit on the type II trailer is 2500 lbs. Perhaps we
> should
>> > discuss
>> > > >> >> the plan details offline?
>> > > >> >>
>> > > >> >> Also, do you have a rough cost of the build? I was
> thinking
>> > polycore,
>> > > >> >> or nidacore - polycore is better and cheaper but the
> shipping
>> > might
>> > > >> >> not make it cost effective.
>> > > >> >>
>> > > >> >> And as for crewing in the Chi Mac, if you actually show
> up,
>> > I'll crew
>> > > >> >> and you can skipper!
>> > > >> >>
>> > > >> >> And if I have any money left over maybe I can build
> a "racing"
>> > wwhull
>> > > >> >> just for the mac and key west. I was budgeting for a 31'
> KH
>> > trimaran,
>> > > >> >> and it was going to be very a tough build cash - wise.
> This
>> > boat is
>> > > >> >> closer to what I'm looking for (easier to launch,
> cheaper and
>> > easier
>> > > >> >> to build, easier to sail and should be a fun ride!)
>> > > >> >>
>> > > >> >> Eventually, I would like to get a bigger boat in a warmer
>> > climate and
>> > > >> >> cruise, and a proa is perfect for that, so this will be
> a good
>> > middle
>> > > >> >> step in the right direction.
>> > > >> >>
>> > > >> >> --- In harryproa@yahoogrou
> <harryproa@>
>> > wrote:
>> > > >> >>>
>> > > >> >>> G'day,
>> > > >> >>>
>> > > >> >>>
>> > > >> >>>
>> > > >> >>> On Wed, May 21, 2008 at 12:03 AM, captian_rapscallion
>> > > >> >>> <captian_rapscallio
>> > > >> >>> > Basically,
>> > > >> >>> >
>> > > >> >>> > I was thinking of a proa designed to be the ultimate
> trailer
>> > > > sailor/
>> > > >> >>> > racer cruiser. Although the boat will probably be
> kept in a
>> > slip,
>> > > >> >>> > (meant for a monohull) I really like the idea of a
> true
>> trailer
>> > > >> >>> > sailor, meaning a sail boat that can be launched
> almost as
>> > > > easily as a
>> > > >> >>> > fishing boat. I think the Rio Hondo 40 is a good
> example of
>> > such a
>> > > >> >>> > boat. (it's a bit big, but I like his line of
> thinking.
>> > > >> >>>
>> > > >> >>> Think we can do a lot better than the Rio Hondo (11
> knots
>> > > > reaching or
>> > > >> >>> running in 16 knots of breeze). Launching will be harder
>> than the
>> > > >> >>> fishing boat as the mast has to be raised and the beams
>> > sorted, but
>> > > >> >>> both can be done quickly if designed for it.
>> > > >> >>>
>> > > >> >>> My ideal would
>> > > >> >>> > be capable of being pulled by an ordinary car. I was
> also
>> > > > hoping it
>> > > >> >>> > would telescope to about 8'6" for the trailer and the
> mast(s)
>> > > > would be
>> > > >> >>> > easily set up by one person quickly.
>> > > >> >>>
>> > > >> >>> 8' 6" is possible, the mast will take a couple of
> minutes
>> to lift
>> > > >> >>> (with a gin pole alongside the mast) and insert. Quicker
>> than any
>> > > >> >>> stayed mast to erect. The telescoping is also very
> quick, if
>> > it is
>> > > >> >>> set up properly. Makes the building of the beams a
> little more
>> > > >> >>> complicated, but all the tight fitting pieces use other
>> parts as
>> > > >> >>> moulds and it is possible to dry run everything before
> final
>> > > > assembly,
>> > > >> >>> so it is easy enough to build.
>> > > >> >>>
>> > > >> >>> I'm willing to give up a bit of
>> > > >> >>> > performance for ease of setup and tear down. I live 5
> to 6
>> > > > miles from
>> > > >> >>> > the launch ramp. I really don't have a maximum trailer
>> length,
>> > > > just a
>> > > >> >>> > weight limit (type II trailer hitch. Nothing weird to
> report
>> > > > about the
>> > > >> >>> > ramp.
>> > > >> >>>
>> > > >> >>> Should not need to give up any performance. I doubt
> there is
>> > 20 kgs
>> > > >> >>> extra in the telescoping.
>> > > >> >>>
>> > > >> >>> Solitarry is 15m/50' and weighs three quarters of a ton
>> ready to
>> > > > race.
>> > > >> >>> Be pretty awful to tow, though, so let's say 12m/40'.
> What
>> is the
>> > > >> >>> weight limit on a type 11 hitch?
>> > > >> >>>
>> > > >> >>> Trailerable width of 2.5m (8'3"), marina width of
> 3.6m/12' and
>> > > > sailing
>> > > >> >>> width of 6m/10' is easy enough with single telescoping
> beams.
>> > > >> >>> Leeward hull length 12m/40', windward hull length 7m/24'
>> > > >> >>> Weight of the shell (hulls, beams, rudders, rig) will be
>> > about 550
>> > > >> >>> kgs/1210 lbs. For the sake of discussion, I have
> allowed 400
>> > kgs/880
>> > > >> >>> lbs of payload in the windward hull. It is easy enough
> to
>> > tweak the
>> > > >> >>> windward hull and or the beam overall for more or less
>> weight or
>> > > > sail
>> > > >> >>> area. All up weight 950 kgs/2,090 lbs
>> > > >> >>>
>> > > >> >>> Sail area 26 sq m (main) plus 4 sq m of unstayed wing
> mast,
>> > (12m/40'
>> > > >> >>> long overall) =30 sq m/323 sq'.
>> > > >> >>>
>> > > >> >>> Bruce number fully loaded 1.4 Bruce number empty 1.7.
> Not a
>> > record
>> > > >> >>> breaker, but there would not be many trailer sailors
> that
>> will be
>> > > >> >>> faster. .
>> > > >> >>> Hull flying wind speed empty, 5 knots, Full 15 knots
>> (actually a
>> > > >> >>> fair bit more than this as the mast bends to spill the
> wind).
>> > > >> >>>
>> > > >> >>> Layout as per the rough rendering in the Files section.
>> Finished
>> > > >> >>> boat would have radiussed corners on all panel joins,
> windows,
>> > > >> >>> hatches, a lot more detail, etc. I will get onto this
> when I
>> > get a
>> > > >> >>> bit of time, or someone wants to buy one.
>> > > >> >>> >
>> > > >> >>> > Accommodation: I was hoping for standing headroom and
> a fully
>> > > > enclosed
>> > > >> >>> > head, a very modest galley, sitting headroom for the
> bunks is
>> > > > ok. I
>> > > >> >>> > was just hoping for some more permanent than a pop
> top. The
>> > > > two week
>> > > >> >>> > trips would be once a year for 2 people. I'm currently
>> > doing such
>> > > >> >>> > trips with a laser 28. The boat would be located on
> Lake
>> > > > Michigan, and
>> > > >> >>> > will hopefully race there, (CHI MAC would be nice) I
> would
>> > > > also like
>> > > >> >>> > to take it to Florida for the Occasional Key West
> Race is
>> > > > possible.
>> > > >> >>> > Lake Michigan is cold and can get pretty rough, so it
>> would be
>> > > > nice to
>> > > >> >>> > have a seat out of the cold in addition to the cockpit
>> > seating if
>> > > >> >>> > possible. I live in the fresh water surfing capital
> of the
>> > > > world to
>> > > >> >>> > give you an idea of how rough.
>> > > >> >>>
>> > > >> >>> Can do a cover over the cockpit easily enough, which
> will
>> > keep the
>> > > >> >>> wind and awater off, but I would make it folding (pram
> hood
>> > style),
>> > > >> >>> just in case you ever do get a sunny day ;-) Crew/wife
> can
>> > sit/lie
>> > > >> >>> on the bed down stairs if it is really nasty. Close
> enough to
>> > > > talk to
>> > > >> >>> the driver, but dry and warm. The galley space is the
> opposite
>> > > > end to
>> > > >> >>> the bunk. Lots of it, but not much is really usable.
> Probably
>> > put a
>> > > >> >>> divider across it with a hatch in the roof for access
> from
>> > > > outside and
>> > > >> >>> use it for storing batteries, fuel, fenders etc. The
> enclosed
>> > > > head is
>> > > >> >>> easy enough, but does not quite have standing headroom.
> The
>> door
>> > > >> >>> and walls are not shown on the layout drawing.
>> > > >> >>> >
>> > > >> >>> > Gear weight for the trips would hopefully be minimal.
> I
>> > would be
>> > > >> >>> > stopping at Marinas in the evening for water and
> possibly
>> > fuel. I
>> > > >> >>> > would think 100 lbs of food and gear would be more
> than
>> > > > enough, and 2
>> > > >> >>> > people at 150 lbs each. I like the idea of an
> electric motor
>> > > > instead
>> > > >> >>> > of a gas one, simply because I have always fought an
> exhaust
>> > > > leak on
>> > > >> >>> > my laser 28. It would be nice to not have to worry
> about
>> that.
>> > > >> >>>
>> > > >> >>> The Torqueedo electric motor may do the trick, as would
> a 5
>> > hp (or
>> > > >> >>> less) outboard.
>> > > >> >>> >
>> > > >> >>> > As far as performance goes, I am hoping for a fast
> boat. I'm
>> > > > willing
>> > > >> >>> > to give up some speed to gain convenience, but it
> will spend
>> > > > most of
>> > > >> >>> > it's life racing. I simply want a comfortable ride
> while
>> > > > racing, you
>> > > >> >>> > know, for the wife :)
>> > > >> >>>
>> > > >> >>> Most of the comfort can be removed/replaced if you want
> to race
>> > > >> >>> seriously. Although, as it is all righting moment, it
> is less
>> > of a
>> > > >> >>> big deal to leave it there than it is on a cat. If you
> do the
>> > > > Chi Mac
>> > > >> >>> in it, I want to crew!
>> > > >> >>>
>> > > >> >>> Comments, suggestions, criticisms welcome.
>> > > >> >>>
>> > > >> >>> regards,
>> > > >> >>>
>> > > >> >>> Rob
>> > > >> >>> > --- In harryproa@yahoogrou
>> <harryproa@>
>> > > > wrote:
>> > > >> >>> >>
>> > > >> >>> >> G'day,
>> > > >> >>> >>
>> > > >> >>> >> Sure can. I would use the same basic methodology as
> I am
>> > > > using on the
>> > > >> >>> >> telescoping mast on Solitarry.
>> > > >> >>> >>
>> > > >> >>> >> Harrigami was complicated as I thought the mast and
>> ballestron
>> > > >> >> had to be
>> > > >> >>> >> raised and lowered with the boat on it's side. There
> are
>> > easier
>> > > >> >>> > ways. The
>> > > >> >>> >> 12m/40' cat 'W' that I built a few years ago had a
> beam
>> which
>> > > > varied
>> > > >> >>> > from
>> > > >> >>> >> 4m/13' to 7.5m/25' and could be expanded/contracted
> by one
>> > > > person.
>> > > >> >>> >>
>> > > >> >>> >> I need to know a little bit more about exactly what
> your
>> > > >> >>> > requirements are,
>> > > >> >>> >> maybe email me off list (or on list if you want
> everybody
>> > to add
>> > > >> >> their
>> > > >> >>> >> sixpence worth) and we can discuss it.
>> > > >> >>> >>
>> > > >> >>> >> The questions are:
>> > > >> >>> >>
>> > > >> >>> >> Maximum trailerable length? This will be longer if
> it is a
>> > once a
>> > > >> >>> > year trip
>> > > >> >>> >> from home to the slip, and shorter if you want to
> use it
>> as a
>> > > > trailer
>> > > >> >>> >> sailor.
>> > > >> >>> >> "Traditional slip" width?
>> > > >> >>> >> How often will you be trailering it?
>> > > >> >>> >> Are there any launching/retrievin
> peculiartities?
>> > > >> >>> >> How much gear you need for two weeks? Either a list,
> or a
>> > > > best guess
>> > > >> >>> > of the
>> > > >> >>> >> weight will do for preliminary drawings.
>> > > >> >>> >> How much comfort do you need. ie, is a two burner
> cooker,
>> > sitting
>> > > >> >>> > headroom
>> > > >> >>> >> in the bunk, comfortable cockpit seats enough, or do
> you
>> need
>> > > >> >> more than
>> > > >> >>> >> this?
>> > > >> >>> >> Motor requirements?
>> > > >> >>> >> Electrical requirements?
>> > > >> >>> >> What is your sailing area? More importantly, how
> sunny and
>> > > > how cold
>> > > >> >>> > is it
>> > > >> >>> >> likely to be?
>> > > >> >>> >> Any thing else that may be of interest.
>> > > >> >>> >>
>> > > >> >>> >> regards,
>> > > >> >>> >>
>> > > >> >>> >> Rob
>> > > >> >>> >>
>> > > >> >>> >>
>> > > >> >>> >>
>> > > >> >>> >>
>> > > >> >>> >> I also like the Seabattical design, not so much
> because of
>> > it's
>> > > >> >>> > looks, which
>> > > >> >>> >> are way down the list of characteristics I like about
>> > boats, but
>> > > >> >>> > because it
>> > > >> >>> >> fulfills it's requirements so well. The first of
> these was
>> > > > low cost
>> > > >> >>> > (very
>> > > >> >>> >> high on the characteristics list).
>> > > >> >>> >>
>> > > >> >>> >> On Tue, May 20, 2008 at 10:51 AM,
> captian_rapscallion <
>> > > >> >>> >> captian_rapscallion
>> > > >> >>> >>
>> > > >> >>> >> >
>> > > >> >>> >> >
>> > > >> >>> >> > I like the elementary design, and the harrygami
> design.
>> > I was
>> > > >> >>> >> > wondering if a design that had a cabin with
> standing head
>> > > > room and
>> > > >> >>> >> > accommodation for a two week trip for a couple
> would be
>> > > >> >> possible in a
>> > > >> >>> >> > proa designed to "fold" using a sliding mechanism
> that
>> would
>> > > >> >> allow the
>> > > >> >>> >> > proa to be moored in a traditional slip and be
> trailered
>> > > > easily.
>> > > >> >>> >> >
>> > > >> >>> >> > I also really like the seabattical design.
>> > > >> >>> >> >
>> > > >> >>> >> >
>> > > >> >>> >> >
>> > > >> >>> >>
>> > > >> >>> >
>> > > >> >>> >
>> > > >> >>>
>> > > >> >>
>> > > >> >>
>> > > >> >
>> > > >>
>> > > >
>> > > >
>> > >
>> >
>>
>
>
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