Hi Randy,

   down here in New Zealand there is a company that make a rotomolded kayak that does what you are talking about (and more). This could be worth a look for ideas. The company name is Switchsports, google that or 'switch kayak'. Id post a link but I'm not sure if thats cool.

 I'm into outrigger canoes. A point worth knowing is that lashing is a good way to go with hull - aka - ama attachments. Bolts etc are stress points, lashing gives a little. Probably slower to set up etc, but simple cleats at the right locations on hull and ama can be used to tie off to and will be almost unoticeable additions. Rope lashing is recommended with sail rigs although strips of inner tube are marvellous but more suited to paddling-only forces.

Akas can be laminated or hollow box construction: don't underestimate the forces - roughly speaking make them of similar material / dimensions as your mast.

Whole kayaks (even a couple of wood duck 12s) are going to make very large, draggy? high volume amas!  Set things up so they just touch the water  at normal load, deeper will be draggy, too high and you will flop from side to side annoyingly.

Allow for some fore aft pitching of your amas. Lashing helps here but also the spacing of the akas is relevant. Allowing independent motion of the hull and amas makes for a nicer ride.The 'obvious' location for akas would be immediately behind each mast, but this looks a little forward?

I think you would have some shaped spacer blocks to sit between akas and hulls, with heavy rubber on the bases to get grip and protect your hull finish. Cleats at the gunwales to lash to? Put small raised blocks on the upper edges of the akas for the lashing to sit between to prevent slippage sideways.

Add some 'polas' (longitudinal poles) across the akas and add a tramp each side! 

 Sounds like quite a beast !

  cheers, Dave
 

Dave,

Thanks very much, that's exactly the kind of info I need.  I like the lashing idea, and recently saw a large (~9m) plywood catamaran at a boat show where nearly ALL of the attachments were with high-tech line, including rudders. 

I'm surprised to hear you say that independent motion between amas and hull makes for a nicer ride...I would think that would be too wiggly, for lack of a better term.  I sense that you know what you're talking about, though, so I shall heed your advice.

With the "cat - ketch" rig of the sharpie, I think placing the forward aka behind the main mast would be too far forward, as the bow is very fine and there would be excessive torque at the attachment.  I was sort of picturing placing the forward aka just forward of the mizzen mast, across the bridge deck, and the aft aka just behind the cockpit.  These positions would take advantage of the strength afforded by the existing bulkheads.  On the other hand, they would probably place the forward attachments to the amas aft of their center of effort, as it were, potentially causing them to want to diverge from the main hull and generating a lot of yawing stress.  Another wild idea I had was to make a single aka across the bridge deck, and use high-tech line to hold the bow and stern of each ama in tension with the bow and stern of the main hull.  

I am also concerned about the weight and drag issue, so was thinking of using bare-bones 16' CLC kayaks for amas.  I have a friend who built one to be ultralight (around 25 lbs, I believe), and had a very nice result.  I feel like the John's Sharpie rig is a little overpowered, as she sails just right (to my liking) with  four adults in about 8 - 10 knots of wind.  So my sense is that adding another 100lbs in equipment, leaving one or two of the adults at home, and dramatically increasing the roll stability would result in a smooth sailer.  I guess there's only one way to find out!

And yes! Tramps!  Think I could make them just about the size of a 2 person tent?

Many thanks and good mokos,

Randy

Here's how Charlie Jones did it for last year's Texas 200. It wasn't lashed and they weren't kayaks, but it is a John's Sharpie and you can see where he placed the akas. This configuration successfully finished the Texas 200 which is a fairly strenuous 200-mile trip along the Texas Gulf Coast. Click on the image for a much larger view.

Good luck with your conversion,

Laszlo

Thanks Laszlo!  You wouldn't happen to have contact info for Charilie, would you?

Randy

Randy,

Nope, sorry, never met the man. However, if you go to the Texas 200 homepage, there's some info there, including the link to the photo and video albums. The LauraNCharlie albums have photos and video of the trimaran (it's called Traveler). You can try using the YouTube SendMessage function to get hold of him.

Laszlo

Hi Randy,

   Hope you track down Charlie, looks like he has answers to all your questions. I was wondering if your idea was feasible - well it sure is - and makes a fine looking craft too.

An ama that has a bit of movement takes on a life of its own, it skips and dances over waves wonderfully and you can't help but think a rigid setup would have to absorb all those forces, presumably slowing you down, rather than dissapating them. But this might make less sense for a tri setup? Of course too much flexibility will not be good, it needs to work like a suspension system. Traditional Tahitian (single) outriggers have a very strong foward aka and the rear one is a relatively light springy 'twig'. Depending on aka placement / mounting details this might be an option for you to consider?

Lashing is cool but if Charlie made the T200 with bolts that is obviously good too. I was following the latest T200 as there were outrigger guys in there, there were a few DNFs due to breakages amongst the fleet. Lashing really comes into its own for outriggers that go through surf launches and landings - they can get dumped and bounce rather than crack. I bet you don't want to take a tri through the surf.

I have a lashed rudder hinge on my current outrigger canoe, the lashing is best described as a 'figure 8', and this lead me to another idea. Rather than saggy tramps I want to make a folding deck. The idea is to cut (say) 1' wide planks of ply lashed along their long edges. This would make a fold-up deck, I'm thinking two seperate sections, plenty big enough for a hikers tent (with airbed!) and lots of seating options.

A peek at my design notes over here might clarify (if you can sift through all the other verbiage):

http://wikiproa.pbworks.com/Dreamboat-design 

 keep us posted, Dave 

A Kayak on each side would look ungainly to say the least, lest if everytime you saild you used the kayaks too - then it has a functional merit.  In and of itself though - a kayak hull is not the ideal shape for this at all.  A kayaks hull is the way it is to accomodate a humanbeing - that doesnt mean its also the best outrigger or ama shape for your purposes.

Here's what you want to do...

 1.  Buy a set of plans for the MAbuli and make yourself the outrigger hull that the boat uses and convert it to fint your skerry.  This is your best option.

 or...

 2. Look at the CLC Sailrig MKII and build an oversized ama for the outrigger instead. 

 I'd go with number 1. - only because its meant to float the weight of people on the trampolene that would span it.  This could truly revolutionize your skerry.  By contrast - if the over sized sailrig ama isnt big enough then you will end up submerging it.  I'd go with the No. 1 too be sure.

Pete