RSS Forum – latest posts

  • Events & other announcements • Re: AYRS meeting at the Basingstoke Canal Centre - 21 & 22 September 2019
    With the proposed towing tests now less than 2 weeks away I spent yesterday rigging up a load cell with an arduino microcontroller. It will need to be connected to a laptop to use it, I don't think I have time to include data display and storage at this stage. The need to take a […]
  • Monohulls • AC 75 Now Afloat
    Well, the first AC 75 is now afloat, there are a few videos on the internet, e.g. https://www.youtube.com/watch?v=VuI1ILwo7tIWhen we first saw the concept I expect that some of us wondered if it would even stay upright in a flat calm. Well I expect it will but we still dont have confirmation of that since there […]
  • Events & other announcements • Re: AYRS meeting at the Basingstoke Canal Centre - 21 & 22 September 2019
    This event is now two weeks away. Not all our members read the posts on this forum so I have sent an announcement to all members within approximately 80 miles of the venue in Surrey UK, using email for those members who have provided the AYRS with an email address and post for those who […]
  • Events & other announcements • Water speed record talk
    Brooklands Museum in Weybridge periodically holds evening talks on various subjects and this week August 15th a talk about the Quicksilver project a British attempt to regain the World water speed record.To book your place email talks@brooklandsmembers.co.uk or phone 07880 670359 and leave a messageCost £7 (£2 for Brooklands members) Pay on the nightTime 7.30-9.30 […]
  • Sails & Aerodynamics • Re: Request for collaboration
    It is by all accounts a typical misinterpretation that winding of a multihull structure is opposed basically by the torsional solidness and torsional quality of the cross pillars. For some viable plans, without a doubt I would state most functional structures, it is the twisting quality of the crossbars that issues more than the torsional […]

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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