RSS Forum – latest posts

  • Sails & Aerodynamics • Re: Request for collaboration
    The picture below is an interpretation of the aerostat with (approximately) vertical wing. I say wing, although I would really prefer call it a sail since it performs the duty of a sail on a yacht rather than the wing on an aircraft. Aerostat-01.jpg I can see that you could use a bridle attached at […]
  • Sails & Aerodynamics • Re: Request for collaboration
    Could you thing at a blimp/kite that could be shaped like an thick hollow square box inflated with hydrogen or helium. Horizontal surfaces could be your wings and the vertical surfaces could serve to maintain the direction.I must be misinterp0reting something, because my mental image now is of a cube, and I don't see how […]
  • Events & other announcements • AYRS meeting at the Basingstoke Canal Centre - 21 & 22 September 2019
    All are invited to this weekend event in Surrey and If you cannot attend the whole weekend you are welcome to drop in for any part of the event. The Basingstoke canal is a very pretty stretch of water but it is not really suitable for sailing since there are low bridges and overhanging trees. […]
  • Boats • AC75 Class Rule
    The class rule for the boats that will be raced in the next America's Cup is now in the public domanin - could be te most complicated yacht class rule ever!Click here: AC75_Class_Rule v1.1 29 June 2018.pdfWould anyone care to predict which will be fastest - an AC75 or the F50 catamaran which is derived […]
  • Boats • Re: Press release: AC50 catamaran will do 20mph SOG against a 10mph tide in zero wind?
    A thought on the AC50 conundrum viewed from the basic lift equation.2L= Cl. Ro.V^2.AIf ignor the piranhas and crocodiles and tentatively suggest that for maximum veloicity the foil in the water would need to maximise its lift as will the foil in the air. (Both foils utilizing the same foil profile. The ratio of the […]

Optimization of the length of a Surf-Ski Kayak

This project has been undertaken with the aim of finding a method by which the length of a surfski kayak can be optimised in terms or having least possible resistance. Surf ski kayaking is a highly competitive international discipline that takes place on open ocean, it differs from other forms of kayaking because of the lack of regulations regarding the length of the boats. An aim of this work was to determine if the boats on the market today are fully optimised in terms of having a length with least resistance. Through use of software that incorporates thin ship theory as well as skin friction data from ITTC ’57 it was possible to calculate the wave making and frictional resistances for a series of lengths of Wigley hull forms with constant displacement and beam. This allowed a total resistance to be calculated for each length which in turn leads to an apparent ‘optimum’ length. In terms of boats currently available, it appears from the results that they have indeed been optimised effectively however only for a small weight range of user. A conclusion of this work is that there may well be scope for manufacturers to produce boats better suited for other weight ranges of kayaker or paddler as they are more often known.

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Multihull Capsize Recovery

Multihulls can be light and fast but cruising ones must never capsize: They stay inverted.
Single hulled yachts can be self-righting and seaworthy, some large and small ones can survive storms and work to windward in gales but to be quick they need deep weighted keels and a wide hull. Built in buoyancy can avoid sinking but they are outperformed by multihulls.
Can a multihull be seaworthy? Could one work to windward in a gale or sail on when mid Atlantic breakers flatten her? What about an automatic system for capsize recovery? Could a multihull heave to in heavy weather and work slowly to windward like a Contessa? Probably not, but perhaps it could be as seaworthy as the offshore racing fleet.

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AYRS NWUK Local Group – Winter meeting – 10th December 2016

As is now the custom at our Winter Meeting, members arrived just after noon for a 12.30 pm start. There were seven members and four of their wives present. Three apologies from absence were received from Roy Anderson, Steve McKenna and Colin Weir. After a short introduction, a Buffet Lunch was served which was enjoyed by everyone (thanks Col). Amply fed and watered, the Ladies retired to the conservatory leaving the Gents in the lounge to have their ‘official’ meeting.

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The Split Junk Rig

Back in 2002, AYRS Member Slieve MacGalliard was looking for a way to improve the one weak point of the modern western Junk rig – the windward performance. His conclusion was that camber is needed right to the luff of the sail, a feature that is difficult to achieve with the standard rig, which is normally pulled aft. One possible idea was to build a cambered rig with a lot of sail balance forward of the mast and split the sail in way of the mast so that the camber would be the same on both tacks and not distorted by the mast.

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