How is sailboat stability calculated?
How is sailboat stability calculated?
To calculate the negative energy area (NEA), first subtract the AVS from 180, then multiply the result by the maximum capsizing arm (i.e., the minimum GZ) and then by 0.66: NEA = (180 – AVS) x min. GZ x 0.66. To find the stability ratio divide the positive area by the negative area.
What is a good capsize screening formula?
The capsize screening value for any boat is found by dividing the cube root of the boat’s displacement volume into its maximum beam (Bmax). The higher the resulting number is than a value of 2.0, the greater the chance that the boat will be unduly prone to capsize; if it is below 2.0, it should be safe offshore.
What is the physics behind sailing?
Sails and keels work by providing “lift” from the fluid passing around them. So optimizing keel and wing shapes involves wing theory. The resistance experienced by a moving sailboat includes the effects of waves, eddies, and turbulence in the water, and of the vortices produced in air by the sails.
What is a sailboat capsize screening formula?
The capsize screening formula (CSF) is a somewhat controversial figure. It is defined for sailboats as: CSF = Beam / ((Displacement/64.2)1/3) with Displacement measured in pounds, and Beam in feet. It came into being after the 1979 Fastnet race in England where a storm shredded the race fleet.
What is a good capsize screening number?
The answer you get is known as the boat’s Capsize Screening Number. If that number is two or less, the boat passes this important safety test. In general, anything over 2 is a failing score and indicates the boat’s stability is questionable.
How do you improve vessels stability?
How to maintain a vessel’s stability
- Keep weight low. New equipment added higher up on a vessel, or replacing gear with heavier equipment raises the centre of gravity and reduces the boat’s stability.
- Avoid overloading.
- Keep excess water off.
- Secure the load.
What makes a sailboat stable?
To sum up, the stability of the boat is directly related to two factors: her displacement, and the length of the righting arm. The heavier the displacement and/or the longer the righting arm, the greater the stability.
What is a bad capsize ratio?
The capsize ratio is a good indicator of what the boat is designed for. The capsize screen in this case can have a value below 2. A capsize of over 2 does not necessarily mean a bad thing. Boats with such a capsize value are better for coastal cruising as they offer higher form stability and a larger interior.
What is comfort ratio on a sailboat?
The Comfort Ratio is as a measure of motion comfort. Given a wave of X height, the speed of the upward motion depends on the displacement of the yacht and the amount of waterline area that is acted upon. Greater displacement, or lesser WL area, gives a slower motion and more comfort for any given sea state.