6.5 to 7.5 metre performance/cruise multihulls

Discussion in 'Multihulls' started by Gary Baigent, Feb 27, 2015.

  1. Gary Baigent
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    Gary Baigent Senior Member

    I couldn't do anything without adhesive tape!
    You are right to question the double foil configuration - because I don't know if it will work. Well, it will work, but will it work well? However there have been a few designs with trianglular type foils, that is frontal view, like Williwaw and Icarus foilers, also this really interesting design Spitfire (although looking a little sluggish _ but check the third sailing image) with very clever foil (and rig designs) - also the local Auckland Knaggs foiler from a few decades ago - and there are many other examples. My thoughts are that my (separate) double set up will have less drag. But won't be as strong as the connected foil designs. As said, will find out. Trusting carbon to save my bacon.
    I don't hike out on Sid; the lee foil set on the square beam/length platform does all the work, windward foil flies clear of water surface.
     

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  2. sigurd
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    sigurd Pompuous Pangolin

    I think your angles are more like the uppermost drawing (fig. 1a), is that right?

    So then the 'rungs' will lose lift when the the leeway increases due to reduced strut span when flying higher.

    And then, flying even higher, the top rung will breach, hopefully letting the bottom one stay at a decent depth.

    Ladders have been used in several different ways, some motor craft had superventilated bottom rungs and subcavitating upper rungs. The upper ones would be in the air at speed.
    I could see the opposite being used as well, a superventilated surface runner top rung limiting the depth of the subcavitating bottom rung.

    Could inward pointing J also work on Frogs? (fig 2a)

    The ? foil in fig 2b is just a more hightech version of the F's: weaker, but no junctions with their drags and pressure peaks. Also the bottom corner has continuous lift over it, unlike the F where the pressures are reversed over the corner.
     

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  3. Gary Baigent
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    Gary Baigent Senior Member

    This is the port foil position while under sail power. The shed wall, so to speak, is the minimalist float positon; it slopes outward a few degrees on the Frog so that under power and heeling, the float approaches the vertical.
    At rest the upper foil position will be sloping downwards a few degrees. I didn't want uptip here because I want it to clear water surface in one movement, lift and then when clear, no drag - whereas the lower immersed and main foil will have uptip (for practical reason of boat drying out on the hard - no damage to foil tips). I've learned this the hard way. Also Frog has a main hull dagger: I'm not relying on the near vertical sections of the lifting foils to counter leeway. This is same setup on Sid. Which works okay.
    Frog's out-facing foils are to maintain the widest beam measurement when foiling whereas in-facing create less overall platform beam and therefore less stability.
    Also for trailering, the 6.5 metre beam Frog, with the beam rotated fore and aft, the out facing foils and floats will not foul the main hull bow and stern. To have in-facing foils would require a 7 or more metre beam - which I thought kind of impractical ... being a sensible and practical person?
    You have to remember the Frog project is not AC stuff with cranes, full wings and million dollar deep and adjustable carbon foils etc - but a somewhat crazy little boat that can be trailered and also sit on a beach.
     

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  4. sigurd
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    sigurd Pompuous Pangolin

    Thanks for the pic and explanation, I understand better now.
    You do get to rest the boat on the knuckle of the foil. What every other half V foil (ref. your pics post #301) gets to do is to taper the board so that the chord reduces as the span leaves the water, reducing profile drag. But yours has an increasing or constant average chord as it lifts.

    Illustration shows that with the same horizontal foils, if you move the strut to the outside, the beam is the same and the aka is the same length and the RM is the same, but you get the strut out of the water and main foil can taper like I mentioned. So I don't get what you mean in the quote. But sure enough, fig 3a can't rest on the knuckle. Sonic tube?
     

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  5. Gary Baigent
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    Gary Baigent Senior Member

    You're right, almost, because in Frog's case the out facing foil strut/board is angled at say a few degrees (when platform is heeled and under sail power). However my point about the reduced beam, if carrying in facing V type foils, is incorrect, or not of importance on a wide beamed platform anyway. Sure the out-facers have a longer lever arm - but you're talking only small distance, hardly important. So I was wrong to say that - because I went into some mistaken and forgetful trance thinking of my old Groucho 45 degree foil setup. Old age? If they angle 45 inwards, like Hydroptere, then that definitely makes a difference to platform beam when foiling.
    The chord doesn't change on Frog's foils until reaching the tip areas - but the thickness does taper from root to tip.
     
  6. Gary Baigent
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    Gary Baigent Senior Member

    Crude mockup of Frog's float? and foil. The float will have built up foam/glass at base, shallow half moon shape tapering to fit around the foil. I'll also use foam/glass to shape curves to the end of beam/float junction; float will be spread wider at this point to fair into lower beam section.
     

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  7. Gary Baigent
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    Gary Baigent Senior Member

    https://www.facebook.com/racetoalaska/
    Some radical and very practical thought and design going into the second running of this "semi-lunatic fringe" race.
    Actually it is not the above tongue-in-cheek derogatory comment because the R2AK has caught a very large number of maritime peoples' imagination - similar to the Everglades Challenge and other like events appearing now.
    Is this the new direction of yachting ... because it certainly is a hot topic at moment.
    My Frog would fit in there perfectly? Fast sailer. Easy to row. Very comfortable? Just joking.
     

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  8. buzzman
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    buzzman Senior Member

    LOL... yeah Frog or Sid would be great for R2AK.

    I think the first race last year was won by a Farrier 27 from memory, so it's hardly surprising that lots of custom tris abound, as they are small enough and light enough to row or scull and beamy enough to carry large rigs that can better utilise whatever wind is on offer.

    The Salish Sea is renowned for calms and motor-sailing, which is impossible under the R2AK rules banning engines, so an alternate form of propulsion is required.

    Trick for tris is using oars, with amas getting in the way.

    So unless you can fold the amas in you need super-long oars or some sort of mad cranking system using levers to operate outboard-ama oars.

    The yuloh is quite popular I believe, like a scull off the stern.

    The R2AK, like the Everglades Challenge, is an interesting concept but is, at the end of the day, "just another race", with an emphasis on winning rather than 'participating' so as always in every form of human endeavour, the 'race to win' will eventually triumph over whatever spirit of challenge was originally invoked as justification.

    Participants need to go back later and smell the pines, look at the wildflowers, drop anchor in a few of the dozens of wilderness coves, and commune with the nature they 'whizzed' past in their drive to be 'first over the line'.

    Winning isn't everything and, far too often, it is 'money talks' that determines the outcome, vis Oracle's 11th hour total rebuild in the last AC, trumping the previously 'innovative' Kiwis.

    GB's low-cost self-builds epitomise the 'innovation approach' vs the 'throw money at it' approach, so, yeah, I'd like to see one of Gary's boats in the R2AK.

    Might be interesting.....wink, wink....
     
  9. Gary Baigent
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    Gary Baigent Senior Member

    Not so sure, Buzz, that the emphasis is on winning in R2AK and EC, seems to me the competitors are there really for fun/challenge. Of course being first in would be fine motivation too. But I'm sure they all enjoy the smell of the pines too.
    I'm reasonably a dab hand using a yuloh off the stern but I think this method would not be fast enough in these races. However well designed sweeps would work well with my single beam designs, nothing in the way to tangle your oar strokes.
    I'm actually glad the extended MOB/ORMA? tri couldn't make it; like bringing a sniper's rifle to shoot a roosting chook? Their second choice replacement looks lethal enough however - and more in keeping with the spirit of the race.
     
  10. Corley
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    Corley epoxy coated

    The winner of the inaugural R2AK was Elsie Piddock a F25C trimaran, second place was Mail Order Bride a F85sr trimaran.
     
  11. buzzman
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    buzzman Senior Member

    Thanks Corley, I was too lazy to look it up! Farriers 1st and 2nd.

    GB - I concur. The R2AK like the EvCH is a lot more about non-powered, non-invasive "challenge" than the win at all cost extravaganzas like S2H or AC, but....

    ....the human competition gene will eventually kick in and ruin it like it has every other form of 'sport', where "winning" is the ONLY goal.

    It's one of the reasons F1 and V8s are so boring these days, because in order to enable a degree of 'level-playing field competition' it's necessary to over-regulate the crap out of it. Common tyres, common engines, I mean WTF..??

    And it's why football has become so controversy filled, with salary cap breaches etc, and doping of other sports stars like Armstrong, the entire Russian athletics team, etc etc..

    Especially for the so-called "professional sports" it is WAY more about the money and the "business" than it is about mere participation, or personal challenge.

    Even kids' weekend sporting games are now rife with 'win at all costs' ********, and aggro parents on the sidelines yelling abuse at kids who are, let's face, not professionals and are only trying to do their best....

    Rant over.

    I understand the 'competitive gene' and accept that it drives innovation and moves us forward, but I (and lots of academic researchers) question whether the same thing can't be achieved (or even improved) through 'co-operative' means rather than competitive.

    Competitive means 'money' - and monopolising results....

    Co-operative tends not to generate profits, or they're 'shared' rather than 'monopolised', so it all comes back to greed in the end, I guess.

    One of the most interesting outcomes of the proliferation of the internet has been the notion of 'free sharing' where people, like GB, share their skills and technical know-how (and experiments) for free with other interested parties.

    This is also true of electronics and automotive forums and so on....with the 'gurus' giving of their expertise and time for no reward other than satisfaction of being able to assist.

    Which *DOES* tend to indicate that the 'natural' human function is, in fact, "sharing", rather than "competing".

    So can we blame 'money' or 'capitalism' for the rest.....??

    LOL
     
  12. santacruz58
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    santacruz58 Senior Member

    I think the biggest difference between us and the rest of the ape family is that we like to teach each other. To me that means giving. But I think that even if the human race becomes more giving we will always be competitive. Most times that means competing against yourself. Gary is always trying to improve on his designs or competing against himself.
    Just my 2 cents.
    nelson
     
  13. buzzman
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    buzzman Senior Member

    sc58 - I agree. As I said previously I fel it is inherent in our base nature to want to learn, to teach - to share knowledge.

    And history shows that when we do so, collectively, we can achieve extraordinarily well.

    The co-operative research and development that took place during WWII is a fine example of how much we can advance society as a whole when we work together, rather than against each other.

    But it too often seems that this 'spirit of co-operation' only 'works' when we are faced with a common enemy - an external enemy.

    The problem these days is that all those previous achievements have left us in the situation where we are, ourselves, the 'enemy', nowadays.

    I recently re-read an intriguing article likening humanity to a parasitic organism - defined as one that continues to reproduce and produce waste exponentially until it eventually kills its 'host'.

    The example used was a bacterium that eventually kills cows, or sheep, or whatever, but then drops its eggs to the ground where they are then ingested by the next unwitting victim.

    The problem for humanity is that we have only the one 'host' that we know of, and we are slowly but surely killing it. Destroying ecosystems, poisoning rivers, polluting the oceans, wiping out other species at an extraordinary rate, and so on.

    Much of this destruction is driven by 'competition' - competition for scarcer and scarcer resources.

    And when competition aligns with 'money' - money wins over the environment most of the time.

    I'm not saying I have a 'magic wand solution' [oh, that I did...!!] but it occurs to me that it is seemingly *irrational* for us to continue to act 'competitively' when it is so demonstrably not in our best interestrs, and when acting co-operatively would be som much better for us and our 'host'.

    Having said *that*, I agree that it's a double-edged sword. As sc58 points out, it is often competition against ourselves - eg: athletes; or competition among ourselves seeking to improve perormance eg: Gary's boats - that drives innovations that are beneficial.

    The competition to find cures for diseases is one in which this argument doesn't necessarily hold - as it would be much better if we acted co-operatively and 'shared' whatever profits are eventually generated.

    But on the other hand, it is the desire to achieve profits (especially to satisfy shareholders returns on investments) that drives so much of the competion in industry today.

    It's a dliemma, I agree, but my point was to raise awareness that we need tobe constantly on our guard to ensure that the 'win at all costs' mentality does not continue to spoil so many of our othewise pleasurable endeavours.

    Sailing, for example.

    :)
     
  14. sigurd
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    sigurd Pompuous Pangolin

    Hi Gary, so there is a sort of little planing surface at the bottom of the foil trunk/float/ wingtip thing?
     

  15. Gary Baigent
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    Gary Baigent Senior Member

    It will be a combination of these two rough sketches but with vertical leading and trailing edges to the float? I'll take a couple of photographs tomorrow after fairing and laminating glass and carbon over foam.
     

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