Sydney-Hobart won by multihull!!

Discussion in 'Multihulls' started by bad dog, Dec 26, 2009.

  1. bad dog
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    bad dog bad dog

    Now Chris and Doug - you boys can sort out your differences behind the boys toilets after school if you like, not here please...

    Chris - the photos back on p.4 are clearly tris. Langman's idea is IMHO a mono with bouyancy assistance, and I agree it would treacherous on a reach.

    The Mashford mono-cat is something like what I think I was possibly imagining, if that makes sense. As the "why" - you'd have to agree the idea is worth exploring, and hopefully they built a small cheap prototype before committing half a mill or more to this one. The extra beam aft has obvious accommodation benefit, plus would give heaps righting moment - a bigger lever!

    I wonder if there would be a lot of drag where the shape inverts from mono bow to cat stern - this surely adds wetted surface, and the shape itself can't help. But as I say - there may be advantages, is there a sailing report somewhere?

    And back to the point - would the CYCA let it enter the SH? (Assuming the hullform was fast enough to be competitive).
     
  2. oldsailor7
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    oldsailor7 Senior Member

    Neither Fish nor Fowl---and not the best of either. :eek:
     
  3. Bruce Woods
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    Bruce Woods Senior Member


    From memory (AYF blue book?) the test as to whether a boat is a mono-hull is too tack a piece of string to the gunnel and then pass the free end under the boat, pull it tight, and tack it to the gunnel opposite. The string should, basically, remain in contact with the hull all the way under if its a mono.

    One has to wonder how the early IOR boats with rating bumps passed this test however. This is probably why we don't see all boats with nice comfy hiking wings for the crews to relax on instead of sitting with some fitting jambed where the sun don't shine..

    or.......
    AYF Special Regulations,
    > Section 1.03 Definitions (page 131):
    > Monohull - Hull in which the hull depth in any
    > section does not decrease towards the centre-line. All
    > other boats are considered to be multihulls.
     
    Last edited: Jan 3, 2010
  4. bad dog
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    bad dog bad dog

    Odd test - no flared bows either then?!
     
  5. catsketcher
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    catsketcher Senior Member

    Its been done (sort of)

    The mono cat thing was done on Sydney Harbour in the late 70s. I remember being a little tacker and seeing this incredibly funny boat with a mast way back and a wishbone boom. It went really slowly. Last time we took Kankama to Sydney (2007) it was in Fivedock bay. If I go down again I can get a photo.

    Be very scared of sharp reverse curves in hulls. The back end of the mono piece is like the bum end of a Colin Archer or S and S 30. Not fast. The last time I saw something like that was on the stern of the Oasis 380 design. It had a bustle and was a bad investment for the owners of the moulds. It was designed to do 20 knots and did far fewer.

    I also see a hollow with no way of sucking air in - like channels on raceboards do. I hope no one puts their money into this without a 3rd scale model being made.
     
  6. bad dog
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    bad dog bad dog

    Yeah that's what I was looking at - the blind hollow. Got to be a problem surely? On the other hand, if you could get air in...

    I made a scale model of a force-fed hydroplane for a solar-powered boat - had skirt sides to keep the normal air out, and was force-fed air from a large-volume low pressure compressor. This was to 'float' the hull on a mass of air bubbles at low speed (which is all solar powered boats can do at this point in history), thus reducing drag without actually planing.

    In a sailing boat, without running a compressor (which is akin to the hydraulic pumps on a canter) the air would need to be fed naturally, possibly through two or more ducts of about 300Ø each from deck level? Would this even feed the void? What about the drag from the rising flat surface between the two hull-bumps? And what if - as in a stormy SH - you get lots of green water over the deck, drenching the ducts and losing the air-feed, would it momentarily slow down while the excess water dragged away and more air came in?

    Would it work anyway??? The 1/3 model sounds like a damn good idea!
     
  7. bad dog
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    bad dog bad dog

    ...should have said (of the hydroplane model) - skirt sides to keep the pressurised air IN, not the normal air OUT.
     
  8. Chris Ostlind

    Chris Ostlind Previous Member


    I'm too lazy to go look this up this morning, but back when Doug chose to first push this thing out onto these pages... there was a an accompanying set of quotes made by Julian as to the functional realities of the boat.

    Remembering this as best I can, Julian said that the boat would be pretty much impossible to sail and that he only drew it up like this because Langman insisted... or words to that effect.

    If it is, as you would prefer, a trimaran, then why in the world would one want to stick a draggy and god awful heavy appendage underneath the thing when the best weapon that a tri has is its light weight? If it is a tri, then why limit the beam provided righting moment with narrower ama placements? If it is a tri, why are the amas insufficient for the fairly robust size of the proposed rig?

    If one wishes to run with small amas and call this a trimaran, then I'd much rather see a decent crew of ex-Olympic sprinters who could make the run across the big platform as exceedlingly live ballast... and ditch the canting mess completely. That idea, at least, would gain access to the mainstream media for the obviously needed sponsors and their lust for big ju-ju PR.

    This boat, in all of its configurations, reminds me of how some folks like to design sailing craft by visiting the parts department of their local sailboat manufacturer to harvest all the fresh goodies within. It's kind of frustrating to see this particular boat because if it were me doing the "let's see how many techno-trinkets we can glue on to this thing" dance, this bad boy would have a gas turbine hover craft engine and perimeter skirting so it could fly on its own cushion of air. I mean, why stop with a pseudo tri/canter, when you can blow everyone's existing sailboat paradigm right out of the water? You'll pardon the pun, won't you?
     
  9. Doug Lord
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    Doug Lord Flight Ready

    ===================
    BD, here is a link to what Sean Langman says as to the "why" of his Maxi Skiff:
    http://www.sailinganarchy.com/innerview/2005/langman.htm
     

    Attached Files:

  10. Doug Lord
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    Doug Lord Flight Ready

    Pterodactyl

    And here is Julian Bethwaites rationale for his version of a "maxi skiff":
    http://www.sailinganarchy.com/fringe/2005/pteradactyl.htm
    -The concept was to include on-deck movable ballast-either lead or water.
    ---
    What wasn't known back then was what Julian says about it here. I asked him to comment on the Trapwing which he did in a PM that I'm publishing here with his permission. He reveals who was behind the Pterodactyl project:

    "A few years back these pages graced a thing called the Pterodactyl, it was a big double proa that Russel Coutts and Paul Cayard asked me to do as the ultimate circuit boat. Among other things its nice to see the OMR*go that route, but Russel was big on having 3 tonne of lead on tracks moving from side to side, inside the wing beams. I thought moving water through 200mm diameter pipes would be better, but the concept has merit. Your issue is that unless you have significant tip pods, then you will never be able to react quickly enough to keep the wings out of the water. Just cant do it! "
    *Ocean Multihull Rule: it is the predominant rating rule used in Asia (and
    Australia) it seems for handicap racing in this part of the world.(dl)
     

    Attached Files:

  11. Chris Ostlind

    Chris Ostlind Previous Member


    Pretty much any boat design can be seen to "Have Merit". It all depends on who is doing the looking. That's not a significant threshold for any design/build project. The real importance comes when it's time for someone to step up to the plate and open the cash register drawer. Clearly, the merit value is not so cool on that level, seeing as how the design still hasn't been built after all these years of being out there in the minds of ultra competitive designers, skippers and sponsors.

    If you stop looking at cherry picked phraseology for a moment, there is a more important comment within the overlying body of the Bethwaite's commentary... that being, that "...unless you have significant tip pods, then you will never be able to react quickly enough to keep the wings out of the water. Just cant do it!"

    No matter how much coolness one thinks is being generated with a funky collection of dismembered concepts, the bottom line is... is the darn thing workable in the real world of big water and wind. Clearly, on this objective issue, Bethwaite doesn't find it workable.

    By not having significant tip pods, as Julian calls them, the game is off. So, that leaves us with the obvious.... why not just recognize that the trimaran form, in its elegant manifestation with "significant tip pods", is a much, much better solution. It triumphs on several fronts over this potential design approach in that it's simpler to build (read less $), simpler to operate (read reduced crew size), has a long history of producing outrageously potent results and won't have a long honeymoon period where skippers and crews try like hell to get a handle on all the techno stuff that is bound to give them fits.
     
  12. oldsailor7
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    oldsailor7 Senior Member

    Quote:-"By not having significant tip pods, as Julian calls them, the game is off. So, that leaves us with the obvious.... why not just recognize that the trimaran form, in its elegant manifestation with "significant tip pods", is a much, much better solution. It triumphs on several fronts over this potential design approach in that it's simpler to build (read less $), simpler to operate (read reduced crew size), has a long history of producing outrageously potent results and won't have a long honeymoon period where skippers and crews try like hell to get a handle on all the techno stuff that is bound to give them fits". Quote.

    Well said Chris. :D
     
  13. Doug Lord
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    Doug Lord Flight Ready

    ===================================
    Well, thats one way to look at it but clearly Julian and Langman believe in the concept that includes "significant tip pods-so the game is on-not off!! And just as clearly both concepts offer things that neither tris or monohulls do. Both boats are designed to be self-righting while carrying more sail area than a conventional mono of the same weight could carry. Neither uses the buoyancy pods for sailing-just for emergency backup and as a place for crew and ballast. Boats like this equipped with just two hydrofoils could be faster than any current non-foiled monohull or multihull. These are potentially viable concepts for fast ocean racers.
    ----------------------

    Julian on Pterodactyl:

    "Effectively we were looking for an extreme racing machine, no preconceived limitations, no rules, no nothing.
    So you start with a skiff, it has advantages of a central hull which can
    stand fore stay tension, which is extremely important as this machine will never have apparent wind further aft then say 30 degrees and you
    start to grow the wings, at some stage ergonomics cut in, you simply
    can't move people fast enough to control the boat/balance, so you go to
    tip floats, and then as you go further and grow the tip floats, you
    finally end up with a cat or a tri in which case you are carrying extra
    hulls/weight for nothing.

    The happy optimum is some where in the middle, we did a lot of number crunching to end up with what we believe to be optimum wing width and pod size. The pods are big enough to sustain a severe aberration in the wind for about 10 secs plus big enough to carry sufficient water/lead (ballast) and house the crew to achieve sufficient rig loading so as we operate at the right CoL.Moving ballast, on 3 fronts, crew, possibly all but the skipper on wire more than for any other reason because they can move faster and its safer, probably 6 in number, water and lead, but not a canting keel,
    that is a joke on something like this, more on tracks under or in the
    wing beams and into the pods."
     
  14. Chris Ostlind

    Chris Ostlind Previous Member

    So, this fabulously "Game-On" boat is sailing where, just now?... and it's been in what significant ocean events in the last five years... where?

    No boat present is not Game-On, Mr. Lord.

    It is more like Game Never Happened.

    There's just as much of chance of my humorously suggested, turbine driven sailing hover craft to be produced, as there is for this aborted concept. They are equally viable as dreamscheme products.

    With the advent and apparent acceptance of engines aboard sailing craft, the next stop on the route is to virtually eliminate wetted surface drag through the power of the engine and totally shelve any need for lifting foils.

    Just dial-up the amount of lift required, point the thing in the direction you wish to go and get with the program. No surface issues with which to deal, no problem getting the boat back in the shed at the end of the racing day (you can simply drive the thing up the ramp and put it to bed behind closed doors) Multi-day races...? Just arrange for an in-flight refueling from a designated local helicopter service. Vector the bird in via SATNAV and a homing beacon and stick the gas prod out for a big gulp. Don't worry... they'll bill you, so there's not going to be a major hassle with whipping out the credit card while in the Southern Ocean somewhere.

    There'll be no foils to catch weeds, plastic bags, or semi-submerged objects... therefore a lot less vulnerable to stuff outside one's control. Of course, the bad boy is going to run well into the millions of dollars, even for a weekend can racing version, but hey, what's a few million among friends... ;-)
     

  15. CT 249
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    CT 249 Senior Member

    Re

    "And back to the point - would the CYCA let it enter the SH? (Assuming the hullform was fast enough to be competitive)."

    The Lake Macquarie Yacht Club let a 40'-ish boat with a similar hull shape race, inshore and (IIRC) offshore. It wasn't a total disaster, nor was it particularly fast. Last I heard it had been taken out of the water so it could be modified into a normal shape. So maybe the CYCA would allow the Monocat in.


    Re

    "Odd test - no flared bows either then?!"

    The YA definition doesn't stop hollow topsides or bows.


    Re

    "One has to wonder how the early IOR boats with rating bumps passed this test however. This is probably why we don't see all boats with nice comfy hiking wings for the crews to relax on instead of sitting with some fitting jambed where the sun don't shine.."

    I don't think any IOR bumps were deeper than the hull inboard of them.

    There have been monohulls with 'hiking wings for the crew' for years. They include the Skiff 38 (1988 vintage, I think, with two heads, wings, assy, fathead main, etc etc etc), the 35' Cassidy Wings, the 11m Elliott Sportscar, the 11m-ish Alcatraz in NZ, the Moore 30 and Kiwi 35 (1980s, USA) the UFO in Italy, and a bunch more.

    Many of these boats had significant problems with the lee wing slamming in a chop. They may also have had problems with self-righting. I think the Skiff 38 Afterburner was the only one that did Cat 2 racing. The wings didn't seem to bring the speed improvements people hoped and are not seem on new offshore boats much these days, if at all.

    Oh, and from experience on Afterburner I can assure you that there is just as much possibility of something sticking in your bum on a winged boat as on a conventional one! And before anyone says it, in my limited experience there are also racing multis that have the same problem, and having been through a bunch of ORMA 60s I wouldn't class them as exactly comfortable !:) Wonderful boats, though.



    BTW, as you probably know, the 'floating on bubbles' idea has been done before in dinghies (like the VJ Nu Hissy in the mid '70s IIRC), and is currently used in some F2 windsurfers. At least one F2 sailor had such a board with air pipes feeding bubbles under the hull back in '85. They have not shown any speed improvement. Whether it would work on a monocat may be a different matter.
     
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