I was sitting on the beech at my windsurfing club here in Thailand waiting for the wind and started to fantasise about building a boat that my wife might consider as an alternative to a two bedroom condo . It will never happen but I can dream . So what I need to come up with I said to myself is a live aboard cruiser for temperate climates. It must not be dependant on marinas fuel docks or boat yards and hence capable of navigating(at least under engine), and anchoring in extremely shallow water.It should be fast enough under sail to avoid tropical depressions. Accommodations would be such that a reluctant women might embrace a seafaring life (IE condo like ). All systems would have manual back up and be with in the physical capacity of a small women to operate. It would have to be owner built at a cost equal to or less than a 45' catamaran or a 55' mono hull. A 47' Gun Boat would be nice if they were a fifth the price. The great thing about dreaming is its free. Its a year later now and whenever I have had nothing to do I have been at my computer stealing other peoples ideas and fooling around with the concept. This iteration began as "Fish Head Soup" another fantasy I indulged in for a thread here on proas ,"Atlantic vs pacific" I think it was. IT occurred to me I might use that exercise as the basis for something that might meet the requirements of my dream mandate. I am now thinking a weight to windward proa is the way to go, but with the sleeping accommodation and heads in the Leeward hull, and the galley up and outside in a tent covered cockpit on the bridge deck. The wind ward hull would in effect be a power plant. It would be a platform for solar panels and contain the batteries, and fore and aft lifting electric azimuth drives. It would house an Atkin's Rescue minor style dingy ( draft 8" 30 miles to a gallon at 18 knots)) powered by a 30 hp diesel generator coupled with an electric azimuth drive, The generator could also be connected to the main drives and charge the batteries. The dingy would have a large water tank and sleeping accommodation for two and be used to fulfill all ship to shore functions( provisioning transportation ,a night at a marina or yacht club ).The windward hull would also hold a substantial sailing and rowing dingy with electric Torqueedo engine that could be used for the same purpose, as well as for recreation .I like Michael Storer's Goat Island Skiff. I considered a wing with a flap but am now thinking wing mast with a high aspect full battened main square top main and a solid wing flap at the end of the boom; the whole rig to rotate on a bearing surrounding the cockpit( the idea is that the center of effort would remain in the same position relative to the center of lateral resistance even when reefed and also be near the center of rotation so that a single balanced solid wing flap a distance from the center of rotation could be of reasonable size, require little mechanical advantage and still effectively trim the main. A Balestron rig would no doubt be as or more effective and be easier to build but hell this is a dream. The windward hull could be moved thwart ships to increase righting moment and fore and aft for longitudinal stability There would be no rudders only two high aspect asymmetrical foils with a section shape of the C3 series that Tom Speer describes in his paper on proa foils. The foils would be hinged and cant in opposition to each other. Increasing the angle of the forward foil would decrease the angle of the rear foil moving the center of resistance aft and vice vesa. The angle of both foils could also be increased or decreased simultaneously to provide lift going down wind or greater lateral resistance up wind . If either foil were to hit an object ,as they would be mounted on drums they should both swing aft and up reducing the draft of the boat to about 12". I would hope that manipulation of the hinged foils movable ama and sail flap would be sufficient to steer, shunt and balance the boat on all points of sail. With both foils up and the hinged azimuth drives down the boat could be maneuvered under engine in a foot of water. Construction for the most part would be of stitch and glue flat panels of ply or resin infused composite panels made on a flat table. If the boat as represented in the renderings and video, is to sit at the designed waterline it would have to displace only 17000 pounds Including the dingies. I am aware that that's probably an overly optimistic estimate. Likewise the size of the flap and the foils are just best guesses based on what looked right to me and are purely for representational purposes. I would also add that I have never sailed a proa and that the only basis I have to believe that the steering system might work is my experience with windsurfers which steer by moving the sail in relation to the fin and with my cat ketch which I can steer reasonably but not in all conditions with the sails and the centerboard. I post this knowing that most of my musings are the ill conceived notions of an indolent amateur who smokes to much pot but I am curious to see if anyone thinks any part of the "design" has any merit and is worth pursuing.
Shes definitely Thai . I have her windsurfing now but fully clothed. Surprisingly she picked it up rather quickly. Recently I have noticed she has abandoned the white stuff they cover their faces with. She is actually getting a tan .Maybe there is hope.
I was sitting on the beech ...... I am now thinking a weight to windward proa is the way to go, but with the sleeping accommodation and heads in the Leeward hull, and the galley up and outside in a tent covered cockpit on the bridge deck. ..... but I am curious to see if anyone thinks any part of the "design" has any merit and is worth pursuing.
Ok, so weight to windward ( ala HarriGami ) I get, so then you load the leeward side up ...
Got a bit of sorting out to do there - its not really for your wife, its your own personal daydream
R WATSON O f course you are right. It is my dream. My wife would like to me to build a house near her Mothers in Issan. If you have ever been to Isaan you would have to agree it is no place for a sailor. The weight of the windward hull with the dingies and gear is only marginally more than the leeward hull. I made it that way simply so that its draft would be the same as leeward hull with the boards all the way up and allow for the azimuth drives to be partially deployed, still function and not have their props below the hull. When motoring the wetted surfaces of both hulls is about the same. When sailing the idea is that If I want to accept the risk, the ama could be extended only enough to almost fly, and the trim flap set so as to be over powered and spill the main if boat nears capsize. Rayaldridge When I started investigating the proa concept I read somewhere that the pacific wtl proa is the way to go and that if you wanted the extra rm that a wtw proa provides then a catamaran configuration is a better choice because of it's superior longitudinal stability. Thats why I have the ama able to move aft . I wanted to approximate the way a cat works flying a hull and still retain what I perceive to be the primary benefits of the proa configuration; greater length to displacement ratio for a given cost and the least weight for the most rm.
02-05-2011, 11:00 PM
Similar Threads 
Linear Mode
