Steel Version
(Lighting Strike)
Static Hydrostatics and Coefficients
Location of the Center of Bouyance
The geometry of the hull calculates displacement at 11,728.5 pounds with the 'Center of Bouyance' located at:
18.52 feet aft of of the Fore Point of the hull.
0.00 feet from the Centerline of the hull.
-0.85 feet below the Design Waterline.
Location of the Center of Gravity
The 'Center of Gravity' calculation while the simplest, its time consuming process and should never be circumvent by emperical methods, rules of the thumb methods, or past designs.
The location of the Center of Gravity for a new design is determined by documenting the weight of every component of the design and its location within the design.
The 'Weight Study' used to calculate the total weight of the steel version of 'Lighting Strike' calculated its displacement at 11,527 pounds. A difference of 201.5 pounds from the weight of the geometric shape of the hull.
18.534 feet aft of of the Fore Point of the hull.
0.00 feet from the Centerline of the hull.
.274 feet above the Design Waterline.
For additional your reference the following drawing shows the positions of both the 'Center of Bouyance' and 'Center of Gravity' for the steel version of 'Lighting Strike'.
Dynamic Stability
Summary:
With the ‘Stability’ results at hand let’s look at the results using the four (4) aforementioned ‘Points of Interest’.
Thirty-degree (30) angle of Heel : - 12,670 Pounds. This angle of heel is considered the high end of the normal sailing rangeAngle of the Buried Rail: - 27-degrees· Considering the type of hull, I thought it would be good to know when the water will meet the rail.
Maximum Righting Moment Angle: - 70 degrees at 15,000 Pounds. Beyond this angle of heel, the Righting Moment starts to decrease until it vanishes at the AVS – Angle of Vanishing Stability.
AVS – Angle of Vanishing Stability: - 115 degrees. This is the angle of heel that the hull will overturn. See the chart below to find that ‘Acceptable Stability for a displacement sailboat. You will find that 'Lighting Strike' has acceptable stability for a protected water sailboat design.
Minimum AVS – Angle of Vanishing Stability Values:
· Protected water sailboats can have an ‘AVS’ as low as 90- degrees.
· A 'Coastal Cruiser' would have an 'AVS' of at least 110-degrees.
· For offshore sailing where wind and large breaking waves are a real possibility, the 'AVS' should be no less than 120-degrees. If wind and seas overturned and inverted a boat with an 'AVS' over 120-degrees, it would probably right itself in two minutes, whereas a boat with an ‘AVS’ of 150-degree and over would right itself on the next wave.
Sailplan Ratio's
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