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Gareth

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    Gareth
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    Jones

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  1. I have been measuring my A class yacht to the best of my ability and I think I am getting close to having an accurate record using the Excel spreadsheet which is part of the A class documentation. However there is one aspect that puzzles me slightly. The design is a John Lewis Phaedra 2 and feeding in my hull measurements and the John Lewis drawing sail dimensions for the top suit, the boat comes out slightly over the maximum rating. If I reduce the height of the jib and mainsail by about 25 mm I get a rating of 1000 which I would have thought would give the maximum permitted area. However in column O of the spreadsheet there are some figures in red which are said to be the suggested maximum possible values for sail dimensions and these are all greater than my input values. The maximum possible foretriangle height is said to be 1631 mm which is greater than allowed in the rules. Could someone please explain where I am going wrong in my understanding?
  2. Derek Does this exempt me from needing to do an RYA sail measuring course? Draught and freeboard I can manage on my bench. QBL I have also measured (roughly) and I think its ok. I am putting m,y faith in Bill Daniels and John Lewis's skills as designers as their relevant drawings say the QBL penalty should be zero. Slide rule still in the loft, I have progressed from inches, a calculator, pencil and paper to putting millimeters straight into the A class Excel spread sheet Bill the Milk event looks doubtful due to the arrival of Elizabeth's latest trainee hearing dog puppy Elsie, younger sister of our last dog William who has just gone out to work this week.. Best regards Gareth
  3. For those of you who are A class anoraks and have been lying awake at night wondering why the waterline length of our Serica III was so long , I now have the answer. I have almost completed a second A class to John Lewis's Phaedra 2 design. That had the same problem of excessive waterline length when measured in our garden pond. I have now measured both hulls in a 6 foot water trough using the recommended technique of gently drawing the hull towards a metal 'weir' across the tank at the surface level of the water, measuring the overhang forward and aft and subtracting these values from the overall length of the hull. This gave results much closer to the predicted design values and around 1.5 inches less than my pond based method suggested. The answer, therefore, is that it was all down to my crap measuring process which was much more pessimistic than I thought.
  4. Hi Michael, I did a bit more research into your model and came across another design by F G Draper who designed Plane Jane. It was slightly later, in 1967 and called Coquette III. It does not look quite as much like yours as Plane Jane, but it is a metre long. There is an article about it in the Sept 1967 issue of Model Boats but I don't have a copy. In the VMYG list of plans, Coquette III is described as International 10/40, 1 metre, but I have never heard of this class. It may be that your model is another design by F G Draper from the mid 60's but I am just guessing there. I have received a copy of your email to the VMYG and I will give you a ring sometime in the next few days. Gareth
  5. The shape is reminiscent of a Plane Jane 36R but its difficult to tell how close it is to that design from the photos. Maybe it was scaled up from that or something similar. Gareth
  6. Val, I believe Charles Smith of the Vintage Model Yacht Group is trying to reconstruct the lost 6M register and also has another project on older 6M yachts. It might be worth you contacting him on tradboat2017@gmail.com
  7. Derek, It would have been Serica 2, K1000, that Norman Hatfield was sailing in 1979. Serica 1 was transferred to Dr J S Rix at Poole in 1974. Serica 2 was registered to Norman Hatfield as owner in 1976, with Arthur Levison credited as designer and Belton/Hatfield as builders. Best regards Gareth
  8. The Serica rating saga The saga of Serica’s rating measurements is complicated, confusing and in some cases contradictory. It is not helped by the fact that there are three A class yachts named Serica. However for Derek, Bill and any other A class anoraks out there I will try and explain the story as best I have been able to uncover it. The original Serica, henceforth to be known as Serica 1, registered as K750, was designed by Bill Daniels and built by Arthur Levison for Norman Hatfield. When we acquired our hull in 2015, we were loaned the original Serica drawing, signed and dated 1955 from the Norman Hatfield archive and it indicates the design was to be a boat with a Loaded Waterline Length of 55 inches, displacement of 59 lb (44.9 lb lead) and, by inference, a sail area of 1600 sq inches. However, somewhere in his calculations, Daniels made a mistake and when the boat was built and measured it was seriously over rating and could not carry the expected sail area. The keel was apparently modified to reduce the weight and a further note on the drawing states that the measurements after the keel mod were LWL 55.8 inches, displacement 56.5 lbs and sail area 1483 sq inches. We have another set of displacement calculations dated 6th May 1956 which give a calculated weight of 62.2 lbs and waterline length of 58.05 inches but it is not clear what stage of the boats construction they refer to. As an addendum on these sheets there is reference to a new lead weight of 38.5 lb compared with the original design figure of 44.9 lb. After building Serica 1, Arthur Levison apparently went on to partially carve a second hull to the Serica design but it was never finished and went missing for about 45 years Some years later in the 1970’s, Jim Belton, an associate of Norman Hatfield built a plank on frame version of the design, which was registered as Serica 2. He designed a lighter weight keel for this hull with a lead weight of approximately 35 lb and a copy of this drawing was loaned to us. We know nothing more about this boat except it was registered as a radio A, K1000 in 1976. Around 2009 the ‘missing’ partially carved Serica hull re-emerged. It was progressed by John Gale and we acquired it as a bare wooden hull, without a keel in 2015. We made a ‘light weight’ keel to the Jim Belton drawing and estimates during the build suggested our Serica 3 would weigh about 58 lb and we expected it to be able to carry about 1500 sq inches of sail, i.e. comparable to Serica 1. When we measured it, to the best of our ability we found the displacement was 57.2 lbs but the waterline length was 58.6 inches. Calculations showed it would only be able to carry about 1300 sq inches of sail. This was a bit of a disappointment and I rechecked the measurements and calculations several times and had the rating calculation checked by a well respected A class measurer but the sail area for Serica 3 always came out at about 1300 sq, in. At the time I was more concerned to make sure the Serica 3 measurements and calculations were correct, rather than knowing why the resulting sail area was so much smaller than Serica 1. A couple of months ago a friend in the VMYG sent me a cryptic email asking if we had an A class yacht called Serica. I said we did but why was he asking. He sent us a copy of the October 1956 Model Maker magazine report on the Gosport A class nationals which mentions Serica and its rating problems. It quotes Serica’s measurements as LWL 55.8 inches, displacement 55.8 lb and sail area of 1472 sq inches, which are close to the original drawing figures after the keel modification. At this point my brain clicked into gear and I realised that the key factor was our Serica 3 has a significantly longer waterline length than Serica 1. I measured the LWL of our boat at a range of weights so it was easy to estimate that at 55,8 lbs, where Serica 1’s LWL is 55.8 inches, Serica 3’s LWL would be 58.15 inches, a difference of 2.35 inches. I checked the weight of Serica 3 using two sets of bathroom scales and a luggage weighing scale and all tallied to within a pound. I estimate the waterline length would not be more than +/- 0.25 inches in error so there must be another reason for the difference between Serica 1 and 3. Either:- The early modification to Serica 1 was more than just reducing the weight of the keel The Serica 3 hull carved by Arthur Levison is not the same shape as Serica 1 and was modified in some way, although the overall length and beam tally with the original drawing dimensions. Something happened to the hull in the 45 years when it was missing in limbo When John Gale worked on the hull he changed its shape I have made a silly mistake somewhere or there is some other factor I am unaware of. In the end we fitted Serica 3 with a 1300 sq inch set of sails and it is what it is. As Mervyn Cook said after checking our calculations, it should be really good (for its age) at Fleetwood in a blow. The reason why I have suddenly taken an interest in this relatively academic issue is that we are currently progressing the build of another partially built A class hull to the John Lewis Phaedra 2 design and I am curious to see how closely it is going to match up to the original John Lewis drawing. Finally, if anyone knows the whereabouts of Serica 1 and 2 we would be interested to know. Gareth
  9. Bill, Thanks for that information. I realise it's a bit cavalier to ignore QBL but Bill Daniels original calculations suggested the penalty was small so i decided to simplify matters and ignore it. However maybe that was part of his original mistake as it seems to be well established that there was a major error in the original Serica design calculations that he did back in 1955/56. I think the most likely explanation, as you say, is that either Arthur Levison or John Gale changed the hull shape of what became our Serica 3, or something else happened during the 45 years or so when it was in limbo somewhere. Its not really that important now, as Serica 3 is now what it is and I don't plan to change it. Its just one of those things that keeps niggling at me to try and understand the full story. I have a partially written up description of the story as I know it and I could finish it and paste it up on here is anyone is interested, Gareth
  10. Thanks for that Bill, it pretty well confirms what I thought was the situation. I doubt that I will get Phaedra officially measured. I will probably do what I did with Serica III and do some basic measurements myself, weight, waterline length, freeboard and draught and then work out the permissible sail area. If it comes close to the John Lewis figures I might reduce the ballast weight a bit to get the design sail area. I will leave QBL and all the other complicated stuff for someone else to worry about. Hopefully I wont have the same problem that I did with Serica III. Norman Hatfield's Serica I was eventually able to carry about 1500 sq of sail after the keel weight had been reduced, allegedly necessary because Bill Daniels got his sums wrong. Despite using the lighter keel design and repeatedly checking my measurements and sums, Serica III could only be allowed 1300 sq inches. I eventually discovered that at the same all up weight, Serica III has a two inch longer waterline length than Serica I, but I never have found out why. Regards Gareth
  11. Gareth

    Plans

    Frank Russell does a 'modern' 6m plan for a design called Cerberus. There is a link to his website here :-http://www.frankrusselldesign.com/plans/ I recently saw a video of one sailing in the UK and there is a link to it here:- https://www.facebook.com/984091914998651/posts/4550253138382493 You can probably contact the builder for information via the Facebook page.
  12. We have used knitted bow bumpers on a number of our restored vintage yachts (usually made by my wife). I think it would work quite well on our A class, particularly with a small sponge rubber ball underneath, partially impaled on the point of the bow. However, as you say, it probably won't be strictly in accordance with the latest class rules We have found that a length of hook type Velcro stuck on the stem is quite effective at stopping the knitted bumpers riding up or down the stem. It is not necessary to have a piece of loop Velcro on the bumper, the hook type alone will grip it. Derek - I hope there will be a classic and vintage Marblehead meeting at Fleetwood next year, if there is we will be there (and return the Mayoral Trophy) Gareth
  13. During the Marblehead discussion we had last year it was apparent that there were two sides to the coin. Owners of modern, measured boats may not mind competing with unmeasured 'classics' on the grounds that their significant performance advantage would probably outweigh the fact that the classic might have a bit more sail area or waterline length than the class rules allow. However the owners of a lightweight, expensive and relatively fragile A class boat might be reluctant to risk it being rammed by an old 67 pound monster with a less than ideal bow bumper.
  14. I am just starting to progress the build of an A class hull that my wife and I acquired about 3 months ago. It is a 1970 John Lewis design, Phaedra 2, possibly one of the most beautiful A class designs ever, or at least I think so. We bought the hull as a bare shell, no deck beams or anything above, and a nicely cast lead keel, weighing 53 pounds. I have been pondering whether to build the boat to be fully compliant with the A class rules and get it measured and registered on completion, perhaps with a view to competing in the classic group of some vane sailing events. We had the same issue with a classic Marblehead last year, a Roger Stollery Daredevil design which had never been measured or registered prior to us restoring it. The stumbling block was the bow bumper which could not be made compliant with the current Marblehead rules without major surgery to the stem, or ending up with a particularly ugly excrescence on the front. Neither of these options was acceptable to us so we abandoned the plan to register that particular yacht, Phaedra 2 is an even more 'pointy' design and I cannot see any easy way of making it compliant with the current A class requirement for the front 20 mm of the hull to be made from a resilient material. On our other A class yacht Serica 3, we sail with a 60 mm sponge rubber ball fixed to the stem. However I doubt that this would be considered compliant as, in the Marblehead discussion, it was suggested that the compliant section should extend down to the waterline, although the rules are not explicit in this regard. Are there any A class experts out there who have any experience of this problem and can suggest a possible way forward? Must a previously unregistered boat be measured to the current rules or can it be measured to the rules as they stood at the time of its design?
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