Subject: [harryproa] Cantarry report
Date: 5/8/2007, 3:28 AM


The Cantarry


The Cantharry was conceived by a friend of Harryproas, Col Campey. He has sailed on an Elementarry and a Visionarry, liked the look of our Texel racer but didn’t like the juggling with two rudders and sheet. Col wondered if it was possible to have a boat like our Texel racer but have a windward hull steered with your feet.


At first look I wasn’t convinced as it seemed the balances would be wrong but the fact that the Elementarry steers well with just a back daggerboard/rudder made me wonder.  Col is one of those rare breed who is willing to put his money where his ideas are so we started building.


This boat also gave us an opportunity to try out a different building method and material. We would use 6mm Polycore glassed on one side as a flat panel and pushed into female moulds for shape. The method worked giving us a 6m lw hull of 34kg complete with mast step etc.


Col came down from Brisbane to join me for a week at a time for the building. We used as much existing materials as we could find around the workshop including using a broken mast and a leftover carbon tube for the canting beam. We also used some leftover polycore for the ww hull so the shape is more optimized to materials rather than good hydrodynamics. The idea is that it wouldn’t spend much time in the water. The rudder/board was going to be retracting but for expedience we stuck it on and decided to stay away from the shallows for now. As it turned out that became a problem.


The rig is free standing with a wishbone boom. The sail is a standard Dacron A class cat sail of about 13 sq m. The boat fully rigged weighs around 80kg.


The general idea of the boat is the beam can swing fore and aft allowing the sailor’s weight to shift aft to keep the bows up. The ww hull can also swivel and has the rudder fixed under the pivot point. This provides both steering and lateral resistance and is operated by pushing with your feet. A line to each end of the hull controls the swing of the beam. An endless sheet controls the boom.




We assembled and launched Cantarry on Thursday. Only about 5 knots of wind and a bit of swell to make things interesting. As usual the time got away so we didn't get it together till fairly late. We launched her through the surf but the fixed keel made it difficult. Col got on too early and amusingly sat on top of the ww hull while the surf passed under him. He then jumped off, swam it out, mistakenly let go of the beam swing control line so the whole lot collapsed on top of him. I swam out, we pulled the mast out just before a wave picked the whole lot up and sent it all towards the beach in a heap. Looked a bit sad but amazingly, nothing broke. 


We tried again Friday. This is a very quick boat to rig and could easily be done by one person. Same wind and swell (which was much bigger than the photos suggest). Col took her out for half an hour and seemed to sit still a lot while he pulled strings and swung hulls. He got going a few times and looked fine crossing the harbour. I took her out and did a fair bit of the same thing. Light wind and flat sail made it all a bit inconclusive.


Does it work? I’ll reserve judgment until we take it out in more wind but I tend to think it isn't going to work as is. As predicted it wants to sail around the ww hull. It is hard to get the Centre of Lateral Resistance and Centre of Effort balanced correctly. I think the problem is the lw hull is so light and buoyant and the ww hull (with pilot) so heavy and not buoyant. The ww hull needs to be in a certain position in relation to the rig to get the CLR right. To do this the lw hull is hauled back via lines to the lw hull. The sail is also controlled via the lw hull. Trouble is there is nothing keeping the lw hull in the right direction so it is free to point where it wants. I had trouble getting it going until I realised the relationship between the rudder (on the ww hull) and sail is most important and not in relation to the main hull. As soon as I had the ww hull canted right back and pointed 30 degrees to leeward it got going, but the lw hull was skidding sideways. She didn't like reaching at all.

Not sure what the answer is. Maybe when it gets going faster it may line the lw hull up better and sort itself out though I doubt if it will ever be particularly manoeuvrable. Maybe a small skeg on the front and back of the lw hull may help.


Col is off to Europe for a few months so we have hung it up for the duration. I may get time to try in stronger winds before then.


It may not have worked as hoped but I think the weather was against us. More playing around and a few changes could bring out the huge potential that this boat has. When she did get the odd puff she was raring to go so I’d imagine she would be a rocket with the windward hull flying.






Mark Stephens

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