G'day,
On Wed, Mar 12, 2008 at 10:14 PM, Mark Stephens wrote:
> I've never been quite sure about the extra sailing loads argument as the rigging loads on a cat are taken by strips of uni in the top and bottom of the bulkheads, not a big deal.
There is about as much material in these strips as in the glass which
goes around the hull to support the harryproa mast. Other
comparisons are:
1) The cat has a substantial transverse bulkhead to keep the strips
apart and take the sheer loads, and a substantial compression post
under the mast, all of which needs to be very solidly glassed to the
very solid bridgedeck, hull and cabin roof. Some also have fore and
aft bulkheads to prevent the main beam buckling.
Harryproas have a single ring frame in the hull. Weighs less than 10
kgs glassed in.
2) The fore and aft loads on the cat are enormous and require the
hulls to be beefed up (either with extra material or bigger
dimensions), plus a forebeam, a seagull striker and a mainsheet
traveller with a large beam to support it. The forebeam then needs a
lot more hull height to keep it out of the waves. Not only heavy and
added windage, but it is in the extreme bow of the boat adding to the
pitching moment.
Harryproas have a simple stringer along the deck and the keel between
the beams. Maybe another 10 kgs.
3) Cats, especially those with the user unfriendly 3 stay rigs also
need considerable structure to support the chainplates. Minimum is a
decent thickness half bulkhead, solidly glassed to the hull and deck.
Harryproas don't.
4) The cat needs beefing up of the cabin top to take the headsail
track loads and the winches for the sheets.
Harryproas don't.
> Also weight isn't necessarily a big factor. Where a proa saves weight is in not having so much material as they don't have such an extensive fitout, and not so much solid bridgedeck and saloon. I think a proa built with the same accommodation and appointment as a cat will weigh about the same.
Weight is a huge factor. Blind Date has 2 doubles and a single berth
with space for 2 more single cabins , huge deck space, covered
cockpit, galley, large nav station and toilet. It weighs 2 and a bit
tonnes/tons in sailing trim. There are no catamarans with similar
usable space that are anywhere near this weight. Lower weight means
smaller motors, smaller rigs, higher speeds, lower build and
maintenance costs, less to paint, easier to haul out, etc etc.
The owner and I are working on tenders to build a 60' charter proa
optimised to take advantage of the proa and unstayed rig benefits.
The shell, bulkheads and beam materials are a touch under 2 tonnes
based on surface areas and laminates. This boat has 4 double cabins
(2 with island beds) each with a toilet and shower, a huge saloon and
covered deck space, plus enough cabin top to mount enough solar panels
to power the electric motors. Ready to charter it will weigh and
cost less than most 40' cats and outperform most 60 foot cats
according to the same spread sheet that accurately predicted Blind
Date's weight,.
>Where a proa gets it's performance is in the extra waterline length.
It's pretty pointless comparing proas with cats as they are such
different beasts fulfilling different rolls.
The harryproa role is cruising comfortably and safely for a given
price . Most cat owners would say the same. Harryproas do this
extremely well. Look at http://www.youtube.
Has anyone sailed on a cruising cat at 15 knots boatspeed in 15 knots
wind speed in such comfort with such low stress? Mark Giles, who has
test sailed a lot of cats (and one harryproa) for Multihull World
magazine hasn't. The cat fulfills this role comparatively poorly,
unless the comparison is with a mono.
Waterline length is part, but not all of the story. Other important
factors are:
The reduced drag from not having daggerboards and their slots.
Reduced weight and windage of superstructure that isn't compromised
for rigging loads and daggerbboards.
All the weight concentrated in the middle of the boat.
Higher righting moment for a given weight.
More efficient hull beam to length ratios.
Better rigs.
Superior hull forms (no rocker, high prismatic) which are not
compromised for tacking.
regards,
Rob
>
>
>
> Robert wrote:
>
>
>
> It is sad to hear but can understand. I thought the tension and
> cooperation were a good and productive coordination, but not always
> easy. It must be a little frustrating for Mark to have to design for
> all those extra sailing loads and subsequent weight, but the regular
> money and lack of dealing with sticky stuff would compensate.
> I may be interested in helping on the website but am not sure if I
> have the skills,
> Robert
>
> --- In harryproa@yahoogrou
> >
> > G'day,
> >
> > Mark and Michele have left harryproa. A more or less amicable split,
> > neither of us liked the way the others were doing things, so decided
> it was
> > time to move on. Mark is now designing and selling catamarans for
> Pacific
> > Multihulls, I remain designing and selling harryproas. I wish them both
> > well. Michele is removing their contact details from the web page and
> > closing the bank account, but all enquiries from now on should be
> sent to me
> > at harryproa@..
> >
> > The good news is that I am now free to pursue my main aim, which is
> to get
> > harryproas sailing and work on further simplifying the build technique,
> > where there is a lot happening. Anybody with incomplete plan sets
> should
> > let me know and i will get the missing pages to you as soon as
> possible. I
> > have almost completed the amateur built mast plans including a novel
> join so
> > they can be reliably built in two pieces and the new beam mounted rudder
> > plans are available for Elementarry. They will be available for the
> rest of
> > the designs as soon as testing them on Blind Date is complete, hopefully
> > early this northern summer.
> >
> > The bad news is that Michele is not updating the web page any more and
> > there is 8 months of progress to report. I am a bit busy getting
> > everything sorted out, including an excting, very light and cheap to
> build
> > 18m 4 cabin harry and a live aboard 20m version (which makes 6
> harrys over
> > 18m/60' currently under construction) so if anyone is interested in
> helping
> > out with the web page, please let me know.
> >
> > The other bad news is that with so much going on, I have not had
> time (or
> > money, bust ups are expensive in both) to get Solitarry completed. The
> > hulls and decks are sitting on the Gold Coast after the brand new, very
> > expensive, slightly overloaded ;-) trailer fell apart on the way up
> from
> > Coffs to Brisbane. Consequently, no Solo Transpac this year, but
> there is
> > another one in 2010, so that is the new target, with launching as
> soon as
> > possible. More on this as it happens.
> >
> > As Dan mentioned, there is an article by Mark Giles in the latest
> Multihull
> > World magazine on the launch and first sails of Blind Date. Gilesey was
> > suitably impressed. A smoother ride than a cat, his seasick prone
> wife now
> > wants one, very fast, serious contender in the cruising market,
> cheaper than
> > a 10m cat, all the benefits from the web page, etc. There is also an
> > article on Mark's first cat design and some interesting articles.
> Cost for
> > overseas is $Aus20 including air postage from info@... or ph
> > 61) 7 55938187. Easiest way to pay is by credit card.
> >
> > regards,
> >
> > Rob
> >
>
>
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