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does anyone know the max hull speed for a c&c 27 MKIV?
my knotmeter says i can do 7.8 at a peak for a moment, usually 7.2 is the max when conditions are good.
my friends think ime crazy and that its only capable of about 6.5 or so....
thanks
I cannot comment on whether you are crazy or not without more information, but I do believe your knotmeter is over-reading.
According to this page, the theoretical hull speed is 6.4 kt. Boats can exceed the theoretical when surfing on waves and so on, but I do think the numbers you're getting are excessive. It's time to read the section of your knotmeter's manual on calibrating your instrument against a known distance.
David Weatherston
Towser, Toronto
C&C 27 Mk IV
Last edited by (2004-06-02 02:34:38)
David Weatherston
Towser, Toronto
C&C 27 Mk IV
Offline
A good way to determine your actual speed over ground is to borrow or purchase a hand-held GPS. These things are amazingly accurate. If you sail in an area with a current, you can compensate by sailing both ways over a reciprocal course and averaging the two readings.
The Web site that David provided a link to uses the formula Max HullSd (in knots) = 1.34 * sqrt(water line length in feet). I believe that this formula would greatly overestimate the maximum hull speed of a C&C 27 Mk I - IV. The issue is the constant 1.34. This value would apply to an extreme high performace racing hull. Various "authorities" propose different values for this constant, some as low as 1.15. For an older racer/cruiser hull like a C&C 27, a value around 1.2 might be good. This would give the maximum displacement mode hull speed about 5.75 knots. I have heard of a Mk III reaching 8 knots by GPS while suring down a wave under spinnaker in heavy air!
Bob.
Having a GPS on my pedestol in front of me, I can assure you that your max Hull speed would be 6.5 knots on a MK111 up wind,we can get the boat up to 7.5 off the wind and have seen 8.0knots down wind with our spinnaker flying in heavy air no surf.
Bob Wilson
Legacy
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