Subject: Re: beams and trailers
From: Mike Crawford
Date: 2/1/2006, 6:09 PM
To: rob dalton

  You've convinced me that a Farrier type system could work, and that tilting the lw hull would be great for assembly.   I do have worries, though, about how the akas would fold given that they aren't perpendicular to the hulls.  I'm not quite sure how to get a farrier system to fold like that without cutting some sections out of the beam.

  If that can be worked out, there's something to be said for being able to insert the masts horizontally and winch the whole lw hull into place.  I don't think I'd do it on the water, but it would certainly help assembly.

  I also still like the idea of a scissors design that allows the boat to be collapsed before floating it onto a standard trailer.  I have to say that it's amazing to watch the video where Franke floats cat2fold onto a fixed trailer and drives away. 

  The scissors beams have to support a tall mast in the center pivot point, so my guess is that they can be made beefy enough to handle the proa loads (provided they aren't already sufficient).  Of course, we both know you can easily make the beams strong enough.  The real question is how much they'll weigh.  I'll eventually ask the cat2fold designer, but since I'm not in the position to order a boat any time soon, I'll probably wait for a while.

  Alternately there's a lot to be said about a lighter, stronger, simpler system that relies on a fancy trailer and some ingenuity.

  The Reynolds and Stiletto catamarans use an expanding trailer like the one shown here: .  A variation of this theme would take care of supporting the weight of the boat as it is expanded and driven to the water.  If that can be made to work for a 3,000lb catamaran, or the 44' cat Reynolds is planning, it can't be too hard to make it work for a proa of similar weight.
  With a trailer like this, beams would be pretty easy.  You could expand the trailer wider than the normal beam, support each crossbeam being inserted into the lw hull with a pivoting roller on the trailer, use the same roller to support the other end as it is lined up with the ww hull, and then winch the whole boat down to its normal beam.

  Masts would be the big question.  You'd either need a rotating bunk on the trailer for the lw hull to allow horizontal insertion (insert beams first, rotate down, insert masts, and then winch beams down to right it), or would need a self-raising system.  I've seen some pretty useful self-raising systems, so this might not be out of the question.

       - Mike

rob dalton wrote:
I had thought of the lw hull wtih rig tucking under. It should fit without widening the beam if using a schooner rig as you need less bury and the bury would come where there is a little less beam on the corredponding point on the ww hull. Putting the lw hull over can actually be a plus if you have enough room as it makes it dead easy to remove and replace the masts as the holes and masts are than horizontal. The combination could then be winched up to the sailing position.Much easier than rigging up a gantry to place them in the holes vertically. The process I imagine for getting the boat to the water if there is a wide enough ramp to take the expanded boat. Lee hull is tucked under ww hull on its side. and cross beams are separate. possibly lashed to the roof of the ww hull and supported with trailer framework. The crossbeams are tipped into the lw hull holes form the top of the roof. It may need some giuding boards and rope restraints to do it on your own but it should be possible to sort out relatively easily. Once the beams are in the lw hull sockets thay can be attached to the folding system iwth a couple of rods. The masts are taken out and possibly using something like a piano trolley guided horizontally into the mast sockets. The beams are then winched into placeand locked down.  The bottom of the lw hull would have to be supported by the trolley as it went out. Here comes the difficult part, the instability of having the boat so of centre. The possibilties are  sliding the whole boat sideways on the trailer to center the weight and supporting the boat under the wing deck and the crossbeams or rotating the trolley 90degrees and letting the trolley support the lw hull. 
The other choice is to put the boat in the water before the masts are  in and put the masts in from the beach or even from the water .
Without the folding system the main difference is that you have to manoevre the lw hull around with the masts and crossbeams in place and tip the ww hull to allow the sockets and the crossbeams to line up, and you would have to have a wide enough ramp.  On your own with uneven ground it would be dificult. with one other person to help with fine adjustment it shouldn't be too hardThe Farrier systems are very robust as they have to support a strong torque on the joints. The Harry, though having longer beams, only has to hold up the ww hull without a great deal of torque so the folding machanism really only has to support the loads of assembly.. There would be some extra weight in the flanges to hold the beams in position rather than having the sockets.
Don't know how muach extra the weight is for the horizontal  folding system but apart from the bolts you have two extra surfaces and a centreline with less resistance to sheer.
According to Robs posts, didn't Rare Bird do 18knots in 20knots of wind with a fouled bottom? Don't know how much faster a harry will be with a couple of tall Una rigs. I would avoid the hassle of screechers as it means you have to start putting in extra weight to take the loads. With the schooner rig the rigging loads are concentrated in one plane and the rudders aren't far off. There are a lot of loads trying to get decent luff tension on a foresail. It would be a pain to shunt.

Mike Crawford <> wrote:

  I did muck up the conversion.  I meant 60'/18m masts with a 50'/15m lw hull.  I have no idea how I could have come up with 23m -- none of the factors could yield that number, even if I reversed them.

  I'm starting to like an expanded Harry design.  The drop in weight would help light wind performance, and the smaller design would mean a lower cost.  That would be one fast boat. 

  One of my problems is that I've gotten addicted to the speed of the current cat, which has hit 17 knots, and hopefully will reach 20 this sailing season (new sails, more experience).  More than the top end, though, is the ability to sail in wind that keeps others at the dock.  I don't necessarily have to fly about like a madman, but it's really nice to move at a good clip in winds that would just leave my bobbing about in my old boat.  I have a feeling that a schooner rigged 15m Harry would even be an upgrade from my stiletto.  Especially when the wind is strong enough to reach, but not quite good enough to tack.  Shunting would be welcome on days like that.

  I can't see using the Farrier system because it tilts the ama down when retracted.  This works for a trimaran, tucking the short ama into the hollow beneath the deck, but would be a problem for a Harryproa with the taller leeward hull.  That would place the side of the hull in the water, would angle the mast(s), and might expand the trailering width.

  Looking at the folding method on cat2fold, I'm not sure where all the unwanted weight would come in.  It's really just a beam, cut in two, with a pivot point in the middle and a hinge at each end.  How much weight do you think it would add?  50 Kg?  Not knowing what the normal beams weigh, I can't really estimate.  Masts would always be vertical, as would the leeward hull.

  On the other hand, I think you have a good point: a well-designed trailer could do the trick, allowing you to transport a boat with standard beams, yet without requiring a boatyard lift.  It wouldn't allow you to collapse the boat in a harbor, but it would make transportation a heck of a lot easier.  Plus the boat would be lighter, and probably sturdier.

  $200 a year for storage?  My, that is nice.  Prices keep going up here in Maine as the value of real estate soars.  We're lucky to have bought property up here when we did.

  I don't know if I can swing a trip before October.  When is Bain planning to sail?

       - Mike

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