Greetings-
I’ve been thinking about proas for a long time. years in fact. I always thought if a model proa went “aback” it would have all kinds of problems including capsize requiring assistance of a large mother ship.
Recently I got ahold of “Building Outrigger Sailing Canoes” by gary Dierking and a lightbulb went off in my head after a perused it (book). I started imagining that the Polynesians or whoever it was that invented and sailed these ingenious and very practical boats must have had a very different philosophy about sailing than most of us westerners who love to sail in any given condition and go anywhere thats wet any time. My lightbulb idea was that
perhaps the best and simplest solution to the going “aback” problem was to sail in open water without things like large buildings creating funky turbulent wind. also if the canoe does go “Aback” there’s a further solution which is basically a springy supporting strut to relieve preassure of the rig on the suddenly leeward “Ama”.
My next lightbulb was gee if I made a model of one of these things I could put a downward pulling foil on the “Ama” which could be deep enough so that at steep heel angles the foil could remain immursed longer. The model would still need to be chased by a mother ship (kayak in my case) since it would still be inerently un-stable, but certainly a lot more stable than without the foil.
So anyway here is a youtube video of my proa which was extreemly successfull-
http://www.youtube.com/watch?v=uoNhguduu6E
Next I’m going to try making a bigger one that will only have one single servo to basically stop the model in case a motorboat is about to run it over or its getting away from me.
I like the philosophy of the simpler the better and why would I want to interfere with the model proa by trying to steer it in a different direction than it naturally goes while “Free sailing” which my first model did extreemly…well.
Also obsessed with thinking of a really simple way to shunt traditonal rig with servos. Could use swing rig, but not as pretty in my opinion nor as challenging
Thoughts anyone?
thanks
Hello John -
good to have you back to the forum.
- Do a Google search and look for a “Shunting Proa” which basically is designed to sail on a tack, and when changing to the other tack it kind of goes backwards. Not sure if you’ve looked at that technology, but it’s out there and rather unique. Sails are never back-winded - they just swing around and the hulls go off in the opposite direction. Think of how a snowboard can go the same way regardless of which end ifs forward !
Here’s a couple of links to get you going - if you haven’t looked for these:
http://outriggersailingcanoes.blogspot.com/2008/05/papua-new-guinea-shunting-proa.html
http://homepages.paradise.net.nz/garyd/
http://www.wingo.com/proa/deltro/index.html
- I’m not sure, but will look though my old magazines. I had an old Multihulls issue that dealt with all kinds of proas. Very interesting read - and while they wwere full size - a couple really had my attention. If I still have the magazine I’ll photo copy and mail to you. Stay tuned to this thread and I’ll post if I find and need your mailing address.
Again - welcome back !
Thanks, its good to be back.
by “Aback” I mean when the boom suddenly shoves itself against the mast due to a wind shift causing the rig to sink the “Ama” instead of lift it as it normally does in a puff. There are also “Tacking” proas which I gather were widely used as well. If you try to Tack a shunting proa she just comes to a stop when the boom hits the mast. A different issue than “Shunting” when the bow and stern become the stern and bow.
when “Shunting” the heel of the yard, I think its called a yard, is carried or hoisted from one end of the main hull to the other. I’d love to invent a simple low cost way to do this on an r/c model. I can think of lots of ways to do it with a drum winch but to me it seems like having all kinds of servos and such on a proa kindof defeats the simplicity of the concept of a proa. More of an esthetic thing than an engineering thing. If I could invent a similar type of rig that would only require a change of orientation to the wind to cause the rig to shunt itself, it would be really cool. A swing rig will do that but I just like the way the traditional rig looks a lot more. I guess its my backround as an artist. I’m really interested in wild exotic forms of sailing which happen to also function really well.
The way these traditional proas were steered is also very interesting to me. You can head up in the wind by simply sheeting out the sail, and head down by sheeting it in which is the opposite of of us conventional sailors. The long boom out over the side turns it one way, or close hauled it turns it the other way with the center of effort ahead of the lateral plane. And you can also steer with two daggerboards at each end by raising and lowering them altenately to control balance even more precisely. A little bit like a windsurfer which is steered by changing balance instead of a conventional rudder. IF you go “Aback” as decribed above, you can also literally spin the proa with your steering oar to get the wind to lift the rig back up from its leaning down position which as I said keeps the Ama from sinking.
There’s another proa design with the ama to leeward - as I remember. The kid who wrote the book Dove is sailing proas in the Pacific. Robb White, now sadly deceased was also messing aout with recreational proas, as was Phil Bolger. Check the magazine “Messing About in Boats”.
This does start (for me) an interesting thought/imagination thread. It’s technically possible, but um, interesting. Bolger used sort of a lateen rig - the sprit (holding the sail) was ‘tipped’, using the mast as a fulcrum. What was the tack of the sail on one tack was the head on the other tack. This simplifies sheeting, but makes for some interesting rigging on the ‘tipping’ part.
Whatcha gonna do about rudders?
I like the idea of using just a pair of daggerboards and have no rudder at all. Apparently you really can steer by just changing the balance. I also like the idea of an asymetrical main hull, meaning flat on the leeward side and curved on the windward. This compensates for the effect of the windward Ama making the boat head to windward.
to head up in the wind, just put down the foward daggerboard and she luffs up, to head downwind jsut retract the foward daggerboard and let the asymetry take over.
Don’t know if thats clear.
Yeah that Bolger rig looks like a lot to handle with the wind directly abeam during a shunt.