Velocity
Predictions
( Double Hard Chine vs True Round Hull)
The following Velocity Predictions compare two steel versions of 'Thunder Cloud'.
The 'Velocity Predictions Charts'
- Results are given in 'Seconds per Nautical mile - (Sec/NM).
- The BTW is the Track angle with respect to the true wind direction.
- Six True Wind speeds are listed (Knots)
- Boat A is the True Round version of the hull.
- Boat B is the Double Hard Chine version of the hull.
Example One:
What would be the speed in (Sec/NM)for the True Round version - Boat-A, in a ten (10) knot True Wind Speed, at a BTW of 45-degrees?
897.82 = (Sec/NM)
Example Two:
What would be the speed in (Sec/NM) for the Hard Chine version - Boat-B, in a ten (10) knot True Wind Speed, at a BTW of 45-degrees)?
(879.82 - 11.18) = 868.64 (Sec/NM)
Looks like the Hard Chine hull is a bit faster than the True Round version at a 45-degree Btw in a ten knot wind speed.
True Round vs Hard Chine
(Speed Comparison Cart
Looking
at the above Cases, this is what I see:
- There is no real difference the Double Hard Chine and the
True Round hull as far as speed is concerned.·
- From a Stability point of view the Double Hard Chine hull
is a bit more tender than the True Rounds hull.·
- The true round hull has a bit more maximum stability than
the Double hard Chine hull.·
- The Double hard Chine hull has a higher Angle of Vanishing
Stability at, 127-degree then the True Round hull at 122-degrees.·
- The only meaningful difference and probably the most
important to most sailors is: One is
True Round and the other is not.
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