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Post by Overoptimistix on Sept 10, 2013 11:49:32 GMT
After much procrastination, I finally got 568 back on the water. Sadly, the plywood centreboard is now delaminating after immersion.
I have read the long Centreboards thread, and have a couple of questions.
Who makes good centreboards for British Moths and what is the approximate price? What are the measurements that I need to take from my boat to ensure a proper fit?
Alternatively, I could try making one myself either using the old one as a pattern or trying to use one of the NACA sections suggested. In this case, is the centreboard best made with a constant section and a square end (rounded enough to fit in the case) or should it taper towards the bottom and have a more pointed tip?
I do have a spare, made from a beautiful piece of solid mahogany which has parallel sides, so I can stay afloat while I consider my options. It is rather heavy though.
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Post by colin on Sept 11, 2013 7:57:15 GMT
The only way you can realistically get away with ply is to laminate the foil with glass by which time it will be as heavy as the mahogany one. As for the shape (profile) in some order of performance; fully elliptical, quarter ellipse (with the trailing edge as the straight line) tapered and parallel. A tapered profile where the chord reduces to about 45% at the tip approximates to a quarter ellipse. The more efficient the foil in terms of lift verses drag, the more complex it is to create accurately. With the centreboard always used raked back, squared off tips will create a lot of drag and should be avoided. For ease of construction, 45% taper with the tip quarter rounded is worth consideration. Make the foil as long as you can fit into the box with say an NACA0009 section.
Colin
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Post by mothling on Sept 12, 2013 10:09:59 GMT
Hi, I replaced the centreboard in 838 just before the nationals with one made by John Claridge www.johnclaridgeboats.com/British-Moth, who lists a standard one (that fits his boats) on his website for about £230, but made mine to fit the curious slot of 838 and using a cedar core to keep the weight down for an extra £50. The supplied white painted foil was a beauty and the difference in upwind performance is really significant over the old board, which before it split had (I thought) quite a decent shape. So if you decide to buy rather than making your own, it's worth giving John a call. Good Luck Toby (S)
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Post by memoryman on Sept 13, 2013 14:48:04 GMT
I must admit to coming back to Moths following a 40 year gap. What has amazed me is the new technology. The picture is of the c/board for 326. It looks like a sheet of ply with the corners rounded. There is no epoxy coating, just an under and top coat. It may have been replaced but it certainly seems to have seen some wear. One can also stand on it to right the boat. Is it worth spending a fortune on an older boat chasing what must be the 'pot of gold at the end of the rainbow'? I think I may keep it 'as is', as, when I come plodding in last, I can blame the boat and not my helmsmanship!
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Post by paultp on Sept 16, 2013 9:26:31 GMT
Hi,
I also replaced my centreboard in 2012 with a new one from John Claridge and can also recommend taking that route. I actually bought a new rudder and centreboard from John, he was really helpful and the performance of the boat improved immensely, particularly upwind.
Paul (784)
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