RSS Forum – latest posts

  • 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 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 […]
  • Power craft & engines • Aerodynamic Lift to improve performance
    Not a new idea Tony ?Blofeld and his "Speedwing" at Speed week many years ago had a wing shaped bridge deck to help generate vertical lift as well as inclined lifting foils, however it is being developed commercially for a high speed ferry; their web site is worth visiting, plenty of photos and CFD […]
  • Events & other announcements • MCA Consultation on Yacht and PowerBoat Safety
    The Maritime and Coastguard Agency Consultation on Yacht and PowerBoat Safety launched last month. Six draft Marine Guidance Notes entitled Yacht and Powerboat Safety at Sea have been issued for user consultation, which closes at midday on 18 July.The main purpose of the proposed six new Marine Guidance Notes to be issued by the Maritime […]
  • Gossip & other snippets • Chapman Sands SC threatened with closure
    Chapman Sands SC, which probably did more than most in the UK to promote the development of modern multihulls, is threatened with closure as the local council have apparently decided to tax it as a profit-making business instead of a not-for-profit club.Please consider signing the petition to get this decision reversed. See youSimon FishwickStatistics: […]

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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