Adventure Racing Proa/cat
I’m working on a small boat design for adventure racing and expeditions, it’s primarily targeted towards the WaterTribe 1200 mile Ultimate Florida Challenge. I started out with a cat design and it had to meet a lot of design considerations and I’m pretty happy with the way it’s turning out but the more I researched about specifics, like hulls, rigs, CE, CLR I kept seeing proas. On the other forums the discussions ended up about proas. Proas? What the heck is that? I had no idea how they would sail, or how to make it work for my needs but it started to intrigue me so I started looking into it further and here I am.
My cat idea is only 16 (I call her “Bad Kitty”), the other fast boats in the EC (Everglades Challenge) are a 20 Tornado and an H18, clearly faster than me, but the EC is a different race than the UFC, sure they share the same course, but the UFC keeps going another 900 miles and it’s stage 4 (out of 5) that really separates and EC boat from a UFC boat. There’s two rivers with a 40 mile portage between the two that defines a UFC boat, I got my cat design to meet my design goals except for one, speed.
One of the competitors this year was Randy Smyth in his trimaran “Sizzors”. Yes, that’s how he spells it and It’s oh soooooo fast! While speed in this race isn’t everything it sure is nice to have. Reliability is the key to this race, and just like any race, you have to finish to win! This year Randy crashed and burned, I don’t want the same to happen to me.
Randy’s boat is inspiring though and as I started to look a his boat and then the modern proas I started to see that they pretty much looked the same except the proa was missing an outrigger. Hummm. Right off the bat that says less weight but I can have a longer hull for better speed. Ok, things are clicking ........
The biggest problem with the proa is folding it up. With my initial ideas for my cat I came up with a folding method that I can possibly adapt to the proa. cool. It’s model time and see just how this will all work out. Like the cat I still have a problem with the masts in the way. I have several ideas for ways around that.
On to some pics:
Here is a video of my cat going thru the folding stages and problems with the masts
http://youtu.be/C7eOkMzuXiM
the proa is having the same mast problems.
Note, on my youtube channel I got more videos, feel free to roam about some.
and a few more pics, there’s only a 3 pic attach limit
and I hadn’t found a way to just include pics from my website, yet.
In the attached pics you’ll see the cat and pros going thru the folding stages
Hi Dennis, glad you are posting your UFC project.
the EC is a different race than the UFC, sure they share the same course, but the UFC keeps going another 900 miles and it’s stage 4 (out of 5) that really separates and EC boat from a UFC boat. There’s two rivers with a 40 mile portage between the two that defines a UFC boat
Are you planning to use the same boat for the entire UFC or employ the “boat switch option” for stage 4?
Plan A is to portage the boat and NOT use the “boat switch rule”.
this year Sandybottom/SOS in their wooden tri “Mosquito” had planned to portage the boat,
but because of the low water problem opted for the “boat switch rule”.
I’d most likely do the same thing if the water level was a problem.
If going into the race knowing you’re gonna use the boat switch rule, then any EC boat would do I’d gather.
At http://www.cat2fold.com you’ll find a folding mechanism that is structurally better, has fewer joints and does not interfere with mast placement. There is a link to a video of a boat being folded. For some reason, that page doesn’t have a link to a much longer video on youtube: http://www.youtube.com/watch?v=n8eL2a_xqkc&feature=related. The boat shown in the longer video has a biplane rig like you are considering.
For a proa, consider making the folding mechanism part of normal sailing operation. The inspiration would be Guy Delage’s proa Rosieres. I no longer can find pictures of her on the web, though some were available about a year ago. She was 18m long and wide. The weather hull pivoted freely, being aligned with water flow by a fin at the stern. Trouble was that, because she had only drag and no lateral resistance in the ama, the most stable state was for the ama to be in line with the main hull. So when at the start of the 1986 Route du Rhum Delage was winching the ama aft some more to bring the bow up, and the line slipped, the boat just folded up. That would not normally be a disaster with a boat small enough that you can right it.
You find sketch of a modern descendant of Rosieres at http://www.harryproa.com/Texel/texel.htm. I don’t like the skimming dish idea, though. It would work if you can either keep it flying or if the water is flat, but in rougher water and with unsteady wind I would keep bouncing it off the surface all the time and would keep getting pulled off course. In my hands, this would not be fast. I would prefer a hull underneath as shown in the picture I am trying to attach, though so far I can’t see that I have succeeded. In case I can’t make it work, I have uploaded it in the files section of the yahoo group at http://groups.yahoo.com/group/proa_file/files/Robert Biegler/
That boat would still have the rudders in the lee hull. A less orthodox alternative reverses Rosieres’ setup: steer the ama and give the leeward hull a skeg (retractable, one at either end) so that it aligns with the water flow. The ama contains the single rudder blade. Wherever that blade points, that’s where the boat goes, and the main hull just follows that course. Then, of course, the ama must always stay in the water. That can be achieved by dividing the beam in two and hinging the lower part. Angle the rudder in a little towards the lee hull, so that the resultant force goes through the hinge or a little higher. Then the rudder stays hooked into the water. Sit on the beam on top. That is the second image I added to the yahoo group.
You have further alternatives. One would be to get hold of an IC-10 sailing canoe, raising the hiking plank a little, and put an ama under each end. The leeward ama would be pulled in to be just above the leeward deck, while the windward ama would prevent you from capsizing to windward. For portaging, pull out the hiking plank and strap it longitudinally to the boat. You would have a hull and rig with decades of development behind it, but with the amas, the boat would be far more forgiving than a plain IC-10.
Regards
Robert Biegler
(Robert, uploading of images is limited to 700x700 pixels and 500kb for each comment posting)
Here are Roberts drawings-
Now this would be something to see sailing!
not too sure about how it would take to a constant pounding though ......
I can see a sliding seat to help set the weight,
of course it would have to lock in position when for when the sail gets knocked over and the pilot is pitched up high .
Overall, wow, cool. pics for this mean everything!
Are you gonna make a scale model of this next?
not too sure about how it would take to a constant pounding though ......
The stub mast that holds the beams would have to be quite strong, and the hull would have to be able to take the lateral bending loads from the lines that hold the beam in position. On the other hand, you don’t have a lot of skin area, so building it strongly wouldn’t add so much weight. And I think it easier to give the moving parts better lever arms than the version of your folding scheme shown in the models. You may fix that, but this here also has fewer moving parts.
I can see a sliding seat to help set the weight
I hadn’t thought of that, but you’re right. If you really were to use such a design for the UFC, you’d spend quite a lot of time sitting there, and a backrest might make the difference between finishing or giving up with back pain. Look into the seats built for recumbent bicycles. Build a series of rungs into the beam, so that you can push yourself up and out when needed. And if you were, like Randy Smythe, to get caught out in 40 kn and unpleasant seas, then sitting right over an ama with just enough volume to support your weight should be relatively safe. A breaking crest would not lift the ama much. It might lift you, though. And you would want the back rest to shield you from the water, and it needs to be solidly enough locked down that a fast moving breaking crest can’t rip it loose. Perhaps set up a seat belt. Call the boat Armchair, and choose the water tribe name “Armchair sailor”. Please?
The second design is rather iffy. There is not only the issue whether the beam will self-align as neatly as I hope, there is also the risk of getting a limb caught between the beams when they scissor shut. That would be a recipe for instant carnage and likely death from blood loss. On reflection, I’d prefer the first and simple design. I am fairly confident that would work. After all, it’s nearly a straight copy of Rosieres, an experienced sailor put a lot of thought into her, and you know how she failed, which should give a good idea what to do about that.
of course it would have to lock in position when for when the sail gets knocked over and the pilot is pitched up high
Failing to lock it in position should be called “doing a Delage”, in honour of the first person to perform this manouvre, in front of the French yachting press. I wish I could find the pictures again.
Are you gonna make a scale model of this next?
Not in the immediate future. One, I drew it up for you. For myself, I want something I can sleep in, and at present I am constrained by a berth in which I am allowed to put a boat up 6.5 metres long and 2.2 metres wide. I suppose this proa could be folded up further by introducing a second vertical hinge in the middle of the beam. I am just a bit uneasy about scaling up something that relies on moving parts to stay upright. Somehow that seems fine for the sort of boat you sit on top of, but less so for a boat you sit in. That’s because I do worry about doing a Delage. The angle of the beam would need adjusting quite often. The forces would be larger for the bigger boat, so it would be more work. If there is no lateral resistance in the ama, the design is not passively safe and you always risk doing a Delage. Not a disaster for an easily righted daysailor, bit more annoying for a cruiser. And as soon as I try to get lateral resistance into an ama that needs to pivot, everything I can think of gets complicated. Despite any rumours to the contrary, I do try to avoid complicated.
Two, I want to know whether a very wide Pacific proa could be built without variable geometry if it gets a biplane rig. I think that could be done fairly simply with a structurally unstayed mast on the lee hull and another sail set on a stay from the mast top to the ama. The leeward sail would be McGalliard’s split junk (good compromise between simplicity and aerodynamic efficiency), the windward stay sail would also be sheeted like a junk, but it could have permanently curved flipping battens, like in the yellow model sail. Nils Myklebust, here in Trondheim, has used this at full scale, and has now developed and built a soft wing junk sail using the same battens.
Three, I am a very slow builder.
Four, I already have a pair of models that need testing. They’ve been ready since just after the ponds and lakes froze over, and I didn’t want to let them loose on the fjord, in case they get away. They are supposed to test a different idea, and are not proas.
Five, models of something very similar do exist. Have a look at http://www.mit.edu/people/robot/mh/riwuit/index.html. The Marshallese race model proas. They look like they’re wider than long, and the beam is swept back.
But if I get my biplane Pacific proa idea tested, I might well modify the model afterwards. Ask me at the end of the year, but I make no promises. My little cruiser also needs some repair, and if my first model tests pan out, extensive modification.
But is there anything to stop you from building a model?
Regards
Robert Biegler
But do consider the IC 10. I attach a picture, and also of Slingshot, a speed record contender from the 1980s. If you expect to experience a wider range of heeling angles than Slingshot trimmed just right over a 500 metre long course, you might want amas that are not so short and fat and make sure the leeward ama is higher above the water. Raise that hiking plank on the IC 10, attach some amas to make this boat easier to sail, but attach them so that the leeward ama is just above the deck. Such a boat would be sort of a tacking Pacific proa. It would be easier to mount a kickup rudder (the IC 10 seem to prefer a spade rudder under the hull, but that is easily fixed).
I think the IC 10s have daggerboards, which are risky in shallow water as I understand you often have in Florida. You could either convert to a a centerboard, or else to a shallow winged keel. Move it further forward than the daggerboard, to put more load onto a bigger rudder blade. Use that combination in deep water. If the water is too shallow for that, let the rudder kick up and avoid huge rudder loads by sailing only with the jib. A keel with a moderate aspect ratio to both foil and wings should be quite sturdy and shouldn’t risk much damage if running aground at speed. The rudders of both proas I drew up would be vulnerable.
Also, the variable geometry proa would be a real pain to paddle on a river. There you’d be better off with a catamaran with oar locks on the side for rowing, and perhaps one on the aft beam for sculling, in case you lose one oar. Or an IC 10 with Harry Bryant’s fish fin drive at the stern: http://www.youtube.com/watch?v=3PdOIXvfB3g
Regards
Robert Biegler