GF42 trimaran design

Discussion in 'Multihulls' started by Corley, Jul 27, 2013.

  1. Corley
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    Corley epoxy coated

  2. Doug Lord
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    Doug Lord Flight Ready

    Gf42

    Damn good looking boat! Interesting the renderings seem to show curved ama foils except the one below that sorta looks like t-foils in the ama. Wonder which it will be?

    click,then expand to see the T-foils-
     

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  3. redreuben
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    redreuben redreuben

    I love way the chines(?) in the sides have been used to create flare and interior volume.
    I have been visualising something similar for a pure cruiser in the 18-30 range, a slimmer sexier Horstman or smaller Cirrostratus type boat.
     
  4. redreuben
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    redreuben redreuben

    That should have been 28-30' range.
     
  5. Corley
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    Corley epoxy coated

    It's an interesting aesthetic that's for sure. I like the way they are carrying the bulk into the chine as well. The benefit should be increased volume at a more useful level than a conventional flared type main hull.
     
  6. redreuben
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    redreuben redreuben

    Exacary ! Would love to see a cross section !
     
  7. Corley
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    Corley epoxy coated

    Greg mentioned that he is doing the tooling for a lot of the smaller interior parts on his own CNC mill at home and supplying the tooling to Westerly Marine for construction. Pretty amazing what can be done with rapid prototyping these days. Half float mold at Kreysler & Associates.
     

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  8. oceancruiser

    oceancruiser Previous Member

    I would be worried re the chine so low to the water line height and being aft The widest form section and probably the berth section. Slapping an vibrations would be horrendous 16 knts plus.
    Have you sailed on a Chris White Tri with the Chine in the main hull bow section. Could not use head at 14 knts plus and unable to sleep with the vibrations and one needed to be strapped in if you did not want to land on the floor sole from being vibrated there. Aft had no chine and comfortable, no noise, little vibrations, able to sleep in berths non strapped.

    3 berths for a 42 footer. Hmmm?

    OC.
     
  9. Blackburn
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    Blackburn Senior Member

    3 berths means I suppose that on overnight races, you are limited to having a crew of 12 on board...

    6 wonderfully slim women, and their mates.

    :cool:
     
  10. catsketcher
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    catsketcher Senior Member

    Tris can't cut it as cruisers

    RedReuben

    The reason designers don't design modern cruising tris is because there is not much point. A cruising boat by definition has to have a fair bit of room, have a comfortable motion, take a fair bit of cruising weight and be a great boat at anchor - where most time is spent.

    On every one of the above points a tri will score worse than a cat. High end speed is not required and even counter productive on a cruising boat so the extra speed of a tri like this will never be utilised in most cruising situations. The high volume floats will pound in a seaway, this will be exacerbated by the extreme beam. The lack of privacy for the crew may exacerbate friction caused by the flopping at anchor and under sail.

    I was the most one eyed tri fan until I drew a cat for myself (I got a cat designer to design it) and have never regretted it. I sailed two trips to the reef on my Twiggy which was great boat but in reality a lousy cruiser. We go much faster on Kankama now.

    Strangely I would urge anyone thinking of BUYING a multi to seriously look at tris. If you are a singlehander or a couple the low price of secondhand tris allows many people to get into flat sailing and other multihull advantages at a realistic price. If Kankama burnt down I would probably buy a Searuner in the states and sail it home - or get a nice Cirro and put a permanent dodger on it - I wouldn't buy a cat for just my wife and me but I would for a family.

    So for anyone thinking of building a cruising tri (Except a trailerable tri which works very well) you are going to get a boat with less resale, payload, interior room and crew amenity that won't go any faster cruising anyway. Tris are great boats and I love them but there are good reasons why they appeal mainly to afficianados who love sailing - for this I would urge the Cirro or a Newick style float section anyway - high volume circular section floats will drive the crew nuts on a long cruise.

    All this from a guy who was greatly offended when a close friend said I should consider a cat.

    PS - as to the use of chines - I hope the builders are good. As a builder I shudder at the thought of having a distinct and sharp line detailing how well I built the edge of a panel. Always round edges if at all possible as it allows you to have far looser tolerances in building - not that you need to be at all off to have a sharp line become wavy - round the edges and save many hours - there will be no difference in use.

    The other problem with having an assymetric waterplane as dictated by the flare down back is that any change in mainhull displacement will cause a change in trim. I am very wary of these types of shapes as if the builder can't get the boat to weigh EXACTLY what the designer says, or if the owner adds some weight, then the boat will go bow down if loaded. It is always easier and safer to make the waterplane roughly symmetrical above the waterline for about 300mm so that you don't get these problems.

    So this could be a good boat for a good building firm but could be rough for the amateur.

    cheers

    Phil
     
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  11. Corley
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    Corley epoxy coated

    Well I think it's horses for courses Greg is after some serious performance out of this boat and it only needs to be comfortable not spacious. Peter Aschenbrenner describes his cruising ORMA60 Paradox as "a luxury boat where the luxury is speed" nothing wrong with that as a SoR.

    The main hull halves are to be built using female cnc molds If everything is done properly and I have no doubt it will be the result should be about as perfectly symmetrical as a boat can be.
     
  12. oceancruiser

    oceancruiser Previous Member

    catsketcher

    Senior Member

    I disagree with you as well. Sail all three types Monohull Cats and Tris. Speed is every thing more so with a cruising yacht. Allows you more time cruising instead of being in port consumming wine, dinning and telling boating stories while waiting for the weather to change for slow boat sailing. If you have speed you arrive at your destination quicker and earlier thus reducing the time being exposed to foul, or sudenly forming storms and cyclones on the high seas because you can sail faster, speed wise, than what they are advancing [ Bad weather ]or sail around it / them.

    "The high volume floats will pound in a seaway, this will be exacerbated by the extreme beam." The same can be said re Catamarans but even more so. If you have speed and modern access to weather information you will probably never or should never experience the situation you are trying to convince people except when racing.

    Re Modern cruiser/ racing Trimarans having poor resale value. Hmmm. But todate and for years there have been any. So how do you figure poor resale value. There is no data or examples to base such a argument.

    Speed also allows you to go sailing in the Cyclone season because you can sail considerably faster than cyclones tracking speeds.

    http://multihullblog.com/wp-content/uploads/model79WIDEUPPSP1.jpg



    OC
     
  13. catsketcher
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    catsketcher Senior Member

    Gday Ocean

    From the start let me restate - I love tris - as sailing boats. If you love your sailing then a tri will be a good boat. If you like sailing along the coast in a boat that really gives you some sensory input back a tri is a great boat. But a tri will never be as good as a cat at anchor and won't be much (if at all) faster than an equivalent cat.

    I anchored and lived on my Twiggy for about 1000 nights so I know what I talk about when I talk about float slamming and extreme beam. A slight chop sets the boat jiggling which then gives the rig a shake and if the chop gets more then you can get quite severe float slamming and no one gets a good sleep. On the approx 1000 nights on the cat I have had no similar situation as the cat hulls don't come in and out of the water. So I don't like round bottom floats on cruisers - Newick or the Cirro are good. Read the bit in Chris White's book on float shape. Read what Newick says - he is a great designer and won't design floats without lots of rocker because of seakindliness considerations. (Look for an interview in MW about 18 months ago on Newick)

    As to speed - I am always worried about designers going for potential speed versus achievable speed. I raced and cruised a real speedster but she was hard on my family so I slowed down - she gave us a rough time in a seaway. On the cruiser orientated cat I go faster because she is smoother through the water. I cruise faster on the boat with less potential because she is so much smoother than the speedster I had - more speed from a slower boat. Think difference between a Porsche and Landcruiser on a dirt road. You go faster in the Landcruiser.

    That is probably why I don't really get excited by a design like this - sure it has way out shapes and looks fast but it will be expensive, small inside, have little payload and be hard to live in at anchor. As Corley says - Horses for courses - but having ridden this horse I would be more interested in a tri more like the Eldin designs that get room, good accomodation, more veed floats and ease of construction into a tri package.

    I don't get excited by many cat designs either, it seems to me that many designers draw stylish boats but never have to build or afford them themselves. I am sure if they had to then boats would be designed far more cleverly as they would try to get the same design facets in a much more build and cost friendly package.

    cheers

    Phil
     
  14. oceancruiser

    oceancruiser Previous Member

    Goodmorning Catsketcher,


    I don't like this look

    http://4.bp.blogspot.com/-XVe7oF-kd9o/UVf8lVbtqnI/AAAAAAAAAAs/9o3p954DQ_Y/s1600/PSC_8429_resize.jpg

    http://4.bp.blogspot.com/-rm90BcOO0RE/UVf8pIc5zXI/AAAAAAAAAA0/Xr9YnlXUzRc/s1600/PSC_8398_resize.jpg


    http://multihullblog.com/2013/02/catamarans-and-waves/

    and did it not capsize - not sure but corley would confirm whether it did or not.


    A land cruiser will roll a lot sooner and faster than a
    Porsche on a dirt road. A Porsche will never roll on a dirt road if the correct tyres are used and has a better gear box gearing to slide around corners.

    Cats get severe slamming going to windward.

    Can you honestly say the cat in the two pics hyperlinked would get a good sleep even during the day if the owner as they always do put the crew in the grave yard watch time slot.

    Chop in a bay, must have been a wind change as I thought most boaties anchore in a lee bay - harbour or anchorage. Slight chop I would have thought a anchore on the side pontoon to prevent rocking and rolling and swing, does the trick as I have seen many tris do.

    OC
     

  15. Corley
    Joined: Oct 2009
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    Corley epoxy coated

    Those boys on Peccadillo are very experienced it's an awesome boat no capsizes and one win so far in the Three Peaks Race. They set a new course record for the first leg but unfortunately both rudders gave up the ghost during the race on the second leg. Peccadillo's back in Melbourne now and fitted with new hopefully bulletproof rudders is ready for some more ocean racing challenges.

    I've reached the stage now where after being exposed to magic carpet ride, jiggled and flung around on a variety of cat's and tri's in rough conditions that I'm not sure whether either has a particularly preferable motion they are just different sometimes worse sometimes better. Just as their owners wants and needs are different. Peter Aschenbrenner of Paradox is very happy with his trimaran in terms of comfort and ease of motion. Bigger multi's are more comfortable than small ones no doubt there.

    http://sailinganarchy.com/2013/03/07/touching-the-void/

    Modern trimarans even the racing sort are generally moving away from semi circular type section floats. The new Prince de Bretagne maxi is more of the parabolic hull section type to reduce shock loads on the structure and foil assistance to reduce wetted surface area. The MOD70's and Multi50's have very developed float shapes as well with no one shape favored over the length of the float.

    I'm not taking a dig at you Phil but I'm sure Lock wouldn't have reckoned that twiggy was a sensible design for cruising it was a racing boat designed to fit into the narrow strictures of the rules applied to the OSTAR and for single handing. I don't think you can draw many conclusions by saying it wasn't suitable for cruising.

    Likewise Greg with his GF42 cruiser/racer trimaran has his own ideas and vision for where he wants the boat to fit on the performance scale versus accommodation. It would be a dull old multihull world if people only built boats for good resale or maximum comfort at anchor or because they integrated a minimum number of staterooms and toilets.
     
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