Meeting at Thorpe 20th January 2019 Part 2
I have found I can only add three attachments!
Roger Callan’s display of lashings demonstrating how important it was to stabilise round materials using small inserts to produce a stable cross with a pair of figure of eight lashings and also how a broken spar or tiller could be firmly lashed with two clove hitches each of which had extra turns incorporated and finished after tightening with the free ends being inserted into the gap left between the lashing and the pieces to be joined and jamming those ends under the turns to prevent loosening.
Chris Clark then showed us a model of a stand up rowing catamaran which had his experimental
biplane rig with the foot of each sail fastened to the deck and the luff on a spar which could be inclined aft to shape the sails or stow them at deck level; as well as producing useful drive downwind it was hoped that shelter could be gained from unpleasant weather without too much drag.
Mark Tingley then spoke about his drive system to generate an oscillating lateral motion minimising the period of acceleration at the end of each stroke unlike a crank where the speed of the oscillation varies continuously from a maximum at mid stroke to a minimum at the end. The device is intended to drive lateral type whale tail using eight blades in all.
He the went on to talk about foiling sailboards having problems with a sudden loss of lift and nose diving to an almost instant stop. He felt that the problem was related to the “tail plane” running in the water at the same level as the main lifting foil; and that the problem might be reduced by having the tail plane set below the horizontal level of the main foil allowing it to retain pitch control as the main foil looses lift.
It was then time to tidy up and prepare for the AGM.
Since I wrote this Tim Glover has emailed me the following link about bulbous bows:
http://www.mar.ist.utl.pt/mventura/Proj ... Design.pdf
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