February - Claremont Yacht Club

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THE ARCHIVE CREW Archives@claremontyachtclub.org.au Walker Log The photo is of a Walker Log. Walker made a number of such logs, this is one from the 1950s and 1960s but were common on ocean going yachts up until the 1990’s. The Walker log is a form of Marine Odometer, sometimes called a “Taffrail Log” The torpedo like rotators were streamed behind the vessel. Movement through the water created rotation in the line , the rotation drives the rotary input shaft and the clockwork mechanism recorded the revolutions which were shown on the calibrated scale in the unit of Miles and Miles/10. It was therefore a “distance measurement”. The Walker Log was but a refinement of the Chip Log. The first chip log was a float thrown overboard and as it flowed alongside the boat. A sand glass was used to record the time take between two points marked on the ships rail. Later logs involved a water “parachute” of some kind tossed overboard as a sand glass was turned, the line was drawn out astern as the ship moved and “Knots” or tassels were counted as they passed the observer. As the sand glass ran out, the line was “caught” by the observer who then checked how many complete Knots had run out plus the proportion of the incomplete “knot”. In the 1960’s I used a plastic flower pot as the drogue and a set length of line. I had a pre-computed card which showed my speed for any “time” taken for the pre-measured length of line to run out. In the cold and foggy Moray Firth the chip log, compass and a ferrite rod radio were essential to coastal navigation for the impoverished! The exact distance between knots on the line and the amount of sand in the glass varied somewhat as refinements were made to the definition of the Nautical Mile. It was finally settled at 47 feet between knots and the sand glass ran for 28 seconds The sand glass was still used to measure time because all clocks of the time required pendulums to operate and Mr Harrison had not yet invented his “movement” and K2. For those interested try Googling “ Chip log” or go hunt the junk shops of Guildford , one of them has an old Taffrail log still in its box. Thanks to the late Bob Denham for saving this specimen. 2012. Maurice Field C20/C29 1939 - 2012
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Page 1 and 2: The Official Publicaon of Claremont
Page 3 and 4: Club Trading Hours Office Monday -
Page 5 and 6: Table of Projects under Consideraon
Page 7 and 8: THE VICE COMMODORE’S VICES This i
Page 11: By Peter Tate General Commiee Membe
Page 15: DEEPDENE One of the club’s best k
Page 18 and 19: Very occasionally, an opportunity a
Page 20 and 21: POWER SECTION Peter Wilkinson repor
Page 22 and 23: Nav Rally Operation On the day of t
Page 24 and 25: SAIL REPORT Dean Caple reports: Sai
Page 26 and 27: DINGHY REPORT John Rasmussen report
Page 30 and 31: Marime Electronic Services Peter Tu

February - Claremont Yacht Club

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