Folding arm materials - Any reason not to use Aluminum?

Discussion in 'Multihulls' started by Jetboy, Feb 7, 2012.

  1. Corley
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    Corley epoxy coated

    I personally think that 15-20 minutes is too optimistic and more about marketing than reality. Some of our club members have farriers and they are stored with masts up in Hastings Yacht Club. It takes with helpers about 30 minutes to launch, tie off to pontoon, unfold and lock floats down and get rig ready for sailing. The mast raising isnt too scary but to work methodically check for no twisted or caught halyards or control wires would take another 15-20minutes
     
  2. warwick
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    warwick Senior Member

    May be some thing else to think about is the width of the float deck around the cross beams. on the scarab 22 the deck is narrower than mid way down. with a full width deck you may have more mounting area to work alloy tubes. Then may be able to put the swing arms either side.
     
  3. guzzis3
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    guzzis3 Senior Member

    It took me about 20 - 30 minutes from pulling up at the ramp to sailing off in my caper cat, which is essentially the same as a hobie. There is no way you can take a farrier or any of these from pulling up to sailing off in 20 minutes. I doubt I could get a boat out of a marina in that time. Consider this:

    Pull up, get out of the car, undo the things you use to secure the boat. How long so far ?

    Get the mast base in position and attached as required. Stand it up (your back shrouds are already attached and you've removed any straps you use to secure them) and attach the forestay and any forward shrouds. How long ?

    Then you find the boom, attach the gooseneck, attach the halyard, remove any sail bags or straps you use to keep the sail on the boom and all tidy.

    If you've got a furler then attach the sheets for the jib,otherwise hank it on and attach. Attach main sheet. Do a walk around to make sure everything is right.

    Now you wait in line for the ramp, back down, get the trailer in position, run the boat out, secure the boat, park the car. Now your ready to sail.

    If you can do all that in 15 minutes your a better man than I.

    If the tri is properly designed it only adds seconds to splay the floats and minutes to bolt them down. Farrier uses an inner stay to hold the mast upright through lifting, a jin pole on the bigger boats. As it goes vertical the aft shrouds tension, attach forestay attach forward shrouds. Remember he's been redesigning and perfecting the same boat for 30 years now. It's about as sorted a thing as any you will ever see.

    Either a mini bridgedeck or a 18' tri are going to be heavier than a beach cat to drag about but otherwise it shouldn't be too much more complex than your hobie. Can't see 15 minutes though. Maybe 30 if your organised. I'd want an hour to drop an F82 or an F9 in the water.

    2c.
     
  4. Jetboy
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    Jetboy Senior Member

    I'm counting on having at least one partner in crime to drive the car. A helper definitely makes life easier.


    Untie the two tie downs traps on the sides. 1 minute.

    Slide the mast back in the cradle and attach the foot to the mast step pin ~ 2 minutes

    I currently leave the shrouds attached and just coiled in the cockpit of my current boat, I assume the same should work for the tri - so raising the mast involves pulling on the forestay and attaching it - 30 seconds?

    Pulling the mast cradle and dropping in the rudder - 2 minutes. (the rudder lives in the cockpit for trailering, the cradle goes in the cabin.

    Hang the outboard on the mount - 1 minutes. It also lives in the cockpit when trailering.

    And I'm ready to go splash. So well under 10 minutes to hit the water.

    While my wife parks the car, I'll motor to the dock and tie up. I have quick attach lazy jacks that I pop on in a couple seconds, then drop the boom on (I leave it attached to the main sail which is leafed over it and bound with three ball bungies and lives in the cabin when not in use) Drop the goose neck in and tie hook the downhaul. I use sail slugs so I feed about 8 slugs into the track. Next I hook on the mainsheet clip (I also leave this ready to go, just drop in the cockpit to trailer). This whole process is very quick. The next is hanking on the jib. Also pretty quick.

    I'm ready to go by the time my wife has parked the car and is at the boat. I'm sure it's well under 10 minutes, and we're motoring out of the marina. Raising the main with slugs already fed is a 10 second affair. The jib is pretty much the same thing.

    Anyway, if I hustled, I'd bet we could be set up for sailing and raising the sails at the edge of the marina 15 minutes.

    That's on my current boat - a 17' sloop. The hobie cat required a bit more assembly before hitting the water. I couldn't just store the boom and sails in the cabin like I can with the current boat. Plus I almost always have someone with to park the trailer while I get the sails set up. That's a key reason I'd really like to be able to fold on the water rather than having to do it on the trailer.

    I also only have a single jib, so it makes the prep a lot faster than if I had a spin up front too.

    Corsair IIRC claims trailer to water times under 10 minutes. I don't know if I believe that. There is a video of an Astus 20 going from trailer to sailing in 12 minutes. I'm not really in a huge rush, but when it's 100* F, quicker to get out on the water is better.

    I think the speed of assembly is what really sold me on the farrier style folding mechanism. None of the others seem as simple and smooth. Being able to leave both tramps on and ready to go is a big plus over a lot of the other folding options.
     
  5. warwick
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    warwick Senior Member

    From what I can tell by looking at the Ray kendrick and Ian ferrier folding systems, is that Ray Kendrick uses flat bar to form the swing arms with a GRP insert between and
    is mostly external on a beam strucure to take the loads, where with Ian Farrier there had been some internal intrusion.

    So for unfolding I would expect to be similar to each other.
     
  6. Jetboy
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    Jetboy Senior Member

    Warwick,

    I think they are very similar. Farrier beams are more like a closed tube cross section while the Kendrick is more like a channel. I'm not sure there's any meaningful advantage to one over the other. The geometry is nearly identical. If you're going that route for folding, there's really only one a small window of linkage geometry that will work.

    Of course that's assuming you're going to rely on fixed length linkage members and fixed connection points.
     
  7. guzzis3
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    guzzis3 Senior Member

    2 people obviously makes it quicker, but you're also doing a lot of your rigging after you've launched.

    I am sure you could launch a corsair in 10 minutes if you had a 20 man drilled squad to help you :)

    As I said the issues isn't the floats. It's trivial. It's the logisitcs of getting ANY boat from a road trailerable condition to a sail away condition and the vehicle and trailer secured. The only difference between the 18 and say an F32 is the mast is too heavy to lift by hand so you need to rig the jin pole. The floats on both take about a minute or so to splay and secure.

    Swing wings can fold on the water and splay with a tug on a line. The problem is with the nets. Because the net attachments become a parrallelogram you have to figure that out. Otherwise there isn't much in it.

    For swing wing you need good pivots, farriers arms are not hard to make. I should mention I'm a metalworker by trade so perhaps they are less daunting to me, but as I recall from the F82 plans there is no welding, just filing or sanding to shape and drilling and bolting.

    Going back to your origional question, if we assume you going to build the 18 in my opinion the path of least resistance is to follow the plans. The beams should all be the same so once you've built the mold you should be able to lay up the beams pretty quickly. The thing here is your doing rather than thinking, planning had scratching and trying to sort all the unforseen things that will go wrong with another approach.

    Second least trouble would be aluminium fabricated to the origional shape. If you go for section beams sure they are quick to make but you will lose at least that figuring out the connections. How to attach that square, oval, round parabolic or whatever it is "cheap" "simple" beam to the hull and float ? Nightmare. Fine for B24, Crowther has already figured it out for you. Sticking it on the 18 - nightmare.

    Modifying for sliding beams or swing wing. No, just start with another design. Buckets of trouble.

    Obviously you'll do what you want and as long as your having fun that's all that matters, but I have to ask: do you want to sail a boat build a boat or design a boat ?

    One more thing. Ian Farrier came up with that system in the early 80's, maybe late 70's. He patented it and no one developed it apart from him until the patent expired. Ray Kendrick picked it up and ran with it over the last 14 years or thereabouts. He has done some innovative things with the idea. Initially he had aluminium ring frames, which were a lot of trouble to make. With the scarab 22 he attached the struts to a thick plywood outcrop which was part of the bulkhead. Really neat solution. I assume the 18 uses this system. Neither set of struts are hard to make, but can be time consuming depending on your skill and equipment. Also metalwork is a bit alien to some boatbuilders. IF has all the problems worked out. Once you get the plans and read them properly there are systems to overcome every problem. Some of it is time consuming and complex, but follow the bouncing ball and it all comes together. Deviate at your peril. The later Kendrick designes should be properly sorted. Whether you like chine or rounded is your business. Ply chine is potentially cheaper on materials. Whether it's faster or slower to build is a subject of ongoing argument. The one thing that is very clear is the farriers sell like hotcakes second hand and for very good money. A better return on invested time than any other design by far.

    2c.
     
  8. Jetboy
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    Jetboy Senior Member

    Guzzis3,

    The only reason I was looking at aluminum is because my parents own a metal fabrication shop. Working with aluminum is easy for me. I can buy it at wholesale prices so it's not quite so expensive and I have a spool gun set up in my own hobby shop, or I could go tig weld it at their shop. I can also get patterns cut on a plasma table for free. I'm not a big fan of plasma cut alumunum though. Not only does it lose the temper on the outer rim where it's most important, but it also isn't nearly as nice of a cut as a laser or water jet. The only water jet I have access to is too small for this.

    I could possibly find a local CNC router shop that might do it, but I'm not sure about that either.

    With aluminum I was intending to use all the original geometry, but just change the mounting a bit and use a different arm material. I have very limited fiberglass experience and this is the first boat I've built, so I'm much more confident in my metal fabrication skills than fiberglass layup skills.

    At this point I'm leaning toward just going back to the original plans for the beams, but I still have a bit to decide.

    I think I'm going to build the hull out of Plascore/fiberlass/epoxy. The honeycomb is really popular here for river raft bottoms because of how durable it is. It's also really reasonably priced. To get a sheet of marine ply is over $100 USD for 6mm. After looking around there's no reason to go marine ply - it's not cheaper at all. It's actually more than double the cost of 10mm honeycomb core and about the same as foam cores.

    I wish there was a farrier 18. I think the designs are great. The f22 is just an entire next league of build time, complexity, and cost.
     
  9. guzzis3
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    guzzis3 Senior Member

    Now your talking. I for one would be very interested in how the substitution of plascore goes, ie what panel you end up using, how much they cost and how well they adapt to curving. I looked at nomex years ago but it's become as dear as PVA foam and is harder to work with in double curvature.

    I get the aluminium thing. As I say I'm a metalworker by trade and while I try to do woodwork I know I'm hopeless at it. It's a totally different situation to dealing with ductile metal.

    The trouble as you have seen is that aluminium beams are easy, sorting the connectons for a design not meant for them really isn't. I went thorugh all this years ago seeing if I could adapt timber designes to my metalworking skills to produce a boat. Of course the problem there is that aluminium hulls under about 36' just don't work because the skin thickness gets so small the boat becomes impractical. And possibly unbuildable.

    I recommend you look into the KISS system. You won't use it for this boat, but the layup techniquies they have for building flat panels could be useful to help produce a smooth outer on your panels. Your still going to have to fair all the tape though which is a pain.

    Pity it isn't offered with rounded lines, I'd build it in strip paulownia and use light uniaxial layups. Pretty boat, pretty quick, pretty light. You could leave a bright finish inside aswell, paulownia is blonde so not too dark. Not much grain though....

    Some day I might get around to doing a design for an 18' mini bridgedeck rounded in strip or foam. Like the little barrier only smaller with cockpit stepped mast and offset hatches. THAT would be a nice trailerable.
     
  10. warwick
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    warwick Senior Member

    I have just stumbled on an idea that may work with the original pivot arm structure and alloy cross beams.

    On the tnt 34 it uses a combination of swinging and telescoping.

    What yo may be able to do is to make a pivoting sleeve that uses the top hole, with the cross beam sliding though it. Then attach a water stay to the bottom hole and outter end of the cross beam.

    the sleeve may be able to be the next size up with a pivot point added below to allow for folding and sliding.
     
  11. warwick
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    warwick Senior Member

    possible folding sliding arrangement

    I have just created a diagram, as to how it may work. Hopefully I can now attach it. its been a while ince had donee attachment.
     

    Attached Files:

  12. basil
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    basil Senior Member

  13. spidennis
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    spidennis Chief Sawdust Sweeper

  14. spidennis
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    spidennis Chief Sawdust Sweeper

    I'm looking forward to seeing what your aluminum fab skills create. I too have a folding system that I'm working on for my beach cat. I got no skilz in Al, so it's gonna be very basic straight cuts and drilling for holes. Any Al welding will have to get done elsewhere.
     

  15. Corley
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    Corley epoxy coated

    Heres a photo of a friend of mines trailerable pod cat 28' he welded his beams up in stainless with custom fabricated bearings for folding the hulls against the pod hulls are foam/kevlar composite. Its designed to be a cruiser with a custom unstayed aero rig. I'll see if I can get some better photos next time I'm down there. It's beautifully constructed and has some innovative solutions on board.
     

    Attached Files:

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