vyv_cox
Well-Known Member
Hope soI can't see where it's gone wrong otherwise. 8mm chain ages it down to 157kg, less than 2 blokes.
http://moondogmoving.co.uk/js/testcat8mm.html?
The straight line vs catenary length turned out to be a bit of a red herring as the calc does it from the numbers, but the visual looks wrong. Which it does anyway
I checked some figures against the John Knox calc for my boat. That gives 359 kgf in 40 knots of wind, 202 kgf in 30 knots. I have watched the chain fully off the bottom in wind speed somewhere between the two.
Force in kgf = 1/500 x LOA^2 x wind speed in knots^2. Prof Knox tells me he sees good agreement between values from this expression and Anchorwatch measurements.