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Hi,
I am putting my C&C27 to Category II for a race in March. One of the requirements in Limit of Positive Stability not less than 110 deg. Does anyone know the value for a C&C27 Mark II?
http://www.ussailing.net/piya/2011%20PIYA%20Certificate.pdf
Stéphane, Sidney BC
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Hey Stéphane, it sounds like you are planning something exciting. You can get an estimate of your "Angle of Vanishing Stability" from US Sailings calculator, found at:
http://www.sailingusa.info/cal__avs.htm
However, this is only an estimate and may not be adequate for your purposes. I keep coming up with numbers between 120 degrees and 127 degrees. I would love to see some numbers calculated by a proper naval architect, which we could then hopefully post with our basic statistics on the "Evolution of the 27" page. I would be interested to know what the impact is of the Mk III's (and Mk IV's) having a keel which is not only deeper, but which was also reshaped to move more of the weight towards the bottom of the keel. When I walk through our boatyard, the Mk. II keels appear to have a uniform maximum thickness through the whole vertical range of the keel, while the later keels noticeably "bulge out" towards the bottom and are more slender up near the root. If this is correct, and not just my aging eyes, then it was undoubtedly done to offset the impact of reducing the total keel weight in the later marks.
Marcus from Carriden
Mk III, Hull #847
Oakville, Ontario
Marcus Opitz,
Formerly from Carriden, Mk III, Hull #847,
now skippering "Everdina," a 1975 Ontario 32
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I tried the formula for a Mk V, using 9.25 feet for the beam, 5000 lbs total weight ( allowing for 'stuff' on board), 1.25 for draft excluding the keel, and 1715 lbs for the weight of the keel ( this is on the low side I think ). The result was 121 degrees before the righting moment was lost. Marcus, that would indicate that 'Carriden' and 'Smoke', though relatively unalike in many ways, would both go keel-up at about the same moment.
Does that seem correct?
Alan of SMOKE 1984 Mk V 002
Alan of SMOKE 1984 Mk V 002
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