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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"> <HTML> <HEAD> <META HTTP-EQUIV="Content-Type" CONTENT="text/html;CHARSET=iso-8859-1"> <META NAME="GENERATOR" Content="Symantec Visual Page Mac 1.1.1"> <META NAME="Author" Content="Dave Culp SpeedSailing"> <TITLE>100' Proa</TITLE> </HEAD> <BODY BGCOLOR="#FFFFFF"> <CENTER> <P> <TABLE BORDER="0" WIDTH="100%"> <TR> <TD WIDTH="20%"> </TD> <TD>From: Michael Schacht<BR> <BR> I did a few drawings of Dave's proa using the dimensions he used in his first post. It will be interesting to see if it is even close to what others are visualizing in their mind's eye.</TD> <TD WIDTH="15%"> </TD> </TR> </TABLE> </P> </CENTER> <P ALIGN="CENTER"><IMG SRC="DBP_profile.gif" WIDTH="720" HEIGHT="489" ALIGN="BOTTOM" BORDER="0"></P> <P ALIGN="CENTER"><IMG SRC="DBP_top.gif" WIDTH="651" HEIGHT="303" ALIGN="BOTTOM" BORDER="0"></P> <CENTER> <P> <TABLE BORDER="0" WIDTH="100%"> <TR> <TD WIDTH="20%"> </TD> <TD><BR> <BR> I rechecked my measurements and found that the sail area of the previous drawing was not as much as Dave had specified. I enlarged the sailplan to equal the 3600 sq. ft. of working sail, not including fortriangle. The jib is still not as big as Dave's desired 1500 sq, ft., but it looks about as big as it should go, to me. I also grew the log just a bit, and added a few artistic touches.<BR> <BR> Michael Schacht</TD> <TD WIDTH="15%"> </TD> </TR> </TABLE> </P> </CENTER> <P ALIGN="CENTER"><IMG SRC="DBP_profile4.gif" WIDTH="503" HEIGHT="411" ALIGN="BOTTOM" BORDER="0"></P> <CENTER> <P> <TABLE BORDER="0" WIDTH="100%"> <TR> <TD WIDTH="20%"> </TD> <TD>From: Hans-Dieter Bader:<BR> <BR> Hi all,<BR> <BR> Last Friday we had a small proa meeting to discuss Dave's Big Proa at the National Maritime Museum. Present were (no specific order :-)): Don Brazier (Wharram Narai, building Tongan outrigger canoe), Leith Duncan (owned an aluminium replica of a Kiribati outrigger for some years), Bernhard Rhodes (Flying carpet + small outrigger canoe), Peter McCurdy (Curator at the Maritime Museum), Neil Beken (Te Waka Hou designer - modern replica of Maori fishing canoe - several built and sailing), Gary Dierking (Te Wa), myself (Motuku, Wharram Hinemoa). Jefferson Chapple (Kiribati outrigger sailing canoe) and Harmen Hielkema (same as Jefferson) were invited, but couldn't make it. Harmen is just converting his canoe from a Tornado mainsail and daggerboards (similiar to Cheers steering) to a traditional rig with steering oar - he left his model and some very useful comments for us to discuss. Worth mentioning is that Bernhard was involved in the building of Cheers - he gave us useful insights into this concept.<BR> <BR> I try to list some points which came up during the discussion. They might be later expanded by personal messages of the meeting members. As we still rely on snail mail this might take some time. Everybody enjoyed the meeting and it was decided to have another on the water meeting on the mud flats in front of Don's house, before the NZ winter kicks in. I distributed Dave's original post to everyone beforehand and laid out prints of some of the interesting response posts out during the evening.<BR> <BR> A drawing of some of the ideas will follow soon. Thanks Michael for giving me a template!</TD> <TD WIDTH="15%"> </TD> </TR> </TABLE> </P> </CENTER> <CENTER> <P><IMG SRC="b_proa.gif" WIDTH="525" HEIGHT="793" ALIGN="BOTTOM" BORDER="0"></P> <P> <TABLE BORDER="0" WIDTH="100%"> <TR> <TD WIDTH="20%"> </TD> <TD>Bernhard was the only one not considering a traditional rig from the start. But at the end of the meeting he too was convinced that the traditional rig should be given at least a chance to be considered. His concerns towards your rig (balance and wing mast area) are reflected in other posts and need not to be repeated.<BR> <BR> The common conclusion of the discussion was that the concept of the Pacific proa is a whole one, which is based on a fine trim of all elements, hull, outrigger and rig and by changing one element this trim is lost. Traditional triangular sails provide not only a forward and heeling thrust but also an upward lift. Their CoE balances the CoE of a 'trimmed' hull, the hull trim can be achieved with crew weight in the smaller sizes or with water ballast pumped into any end of the hull (and respectively into any end of the outrigger) in larger sized proa. A reasonable rocker in the hull provides for this trim to be effective. The curved windward hullside offsets the drag to windward by the outrigger. This drag to windward of the outrigger is multiplied by the CoE of any European rig. Counteracting the large weatherhelm needs fairly effective daggerboards or the like. To create a similiar trim as on the original concept of the proa with European rig, the Atlantic proa or Newick is the natural answer. Cheers might have been successful because of its balance. It would be marvelous if Dick Newick could a bit elaborate about his ideas of boat trim when he designed Cheers. In the traditional setup by trimming the CeO of the rig (not only done by shifting the sail from end to end, but also by mast position and angle) and the CeO of the hull/outrigger combination (water ballast), the need for steering 'bits' is nearly eliminated. Running downwind with a steering oar is all which is necessary, but even that could be nearly eliminated by a flying jib set over the outrigger to the masthead, balancing the canoe. Shifting the tack of the sail on a track instead of using manpower seems to be a trivial engineering excercise to make a big proa feasable for short handed crew. On the size Dave is suggesting, two sails would be necessary for handling reasons. Again shifting them parallel on a track from end to end should be not too difficult to design. It would be desirable to step the masts also on short tracks with a car to fine tune the trim.<BR> <BR> Reefing could be done by having several complete sets of sails (on their spars, ready to go) varying in size with their own tack and halyard positions. This would add a redundancy factor for safe cruising.<BR> <BR> The outrigger should be a wavepiercing one with some flexibility (Marshallese concept of two fairly narrow spaced main cross-booms and two springs on either side could work well). The danger of beeing capsized is higher by backwinding than by overturning due to windpressure. Therefore a storage tube on top of the outrigger could prevent the outrigger from beeing pressed down into the water. This tube could also be part of the flexible cross-boom arrangement (see the drawings to come).<BR> <BR> The size of the canoe might be a real problem: Taratai with 70 feet is the largest outrigger canoe build in recent times and they reported to drive the bows through waves instead of going over them. They also run into many problems as they couldn't trim the hull against the sails properly. The large canoes reported from last century are mainly canoes built for presentation purposes, not for blue water sailing. A 45 footer seems to be the most seakindly size for the trade wind generated waves. Just another thought. <BR> <BR> Steering in close quarters could be easily done by bow thrusters (on the Walap we used long thin oars to push the ends around, which worked surprisingly well).<BR> <BR> The general conclusion was to give the traditional setup another chance and try it out on a small 'Tiny Dancer' sized canoe, before going even to the half-scale canoe. Proper trim seems to be the secret of the Pacific proa, which seems to be reflected by the experience of John Dalziel too. One open point is still the vortex lift possibly generated by the traditional sail form. If the ideas of Marchaj are correct (and they are supported by some research done at the University in Auckland), the traditional sail will provide more lift per sq metre than any other sail, if it is cut in the proper way (quite different to European sails which depend on attached air flow).<BR> <BR> The engineering problems to be solved on a traditional setup large canoe are not worse than the engineering problems on Daves proposal, but the advantages of a concept finely balanced are endless. The costs of a traditional setup are much smaller, as the sails are cheaper, the whole structure is less stressed and the need for steering through the hull is eliminated.<BR> <BR> Just some more thoughts.<BR> Cheers,<BR> Hans</TD> <TD WIDTH="15%"> </TD> </TR> </TABLE> </CENTER> </BODY> </HTML>