Stability

Lifting keels and the loss of "Bayesian"

Submitted by Matthew on

Imagine, for a moment, that you are aboard a 56 metre luxury yacht anchored off Sicily. It is before dawn, there's some wind but the crew aren't worried, and you're coming up to take a look around. Suddenly, the yacht is knocked about as all the windows explode around you. Confused, startled, and scared, you run for a muster station, managing to get aboard a life raft moments before the yacht disappears beneath the waves. The whole event took longer to write up than it took to happen.

Dynamic Stability of a Monohull in a Beam Sea

Submitted by Matthew on

The last post in our series on yacht stability looked at the static case. We saw that a yacht's response to heeling forces can be described by a stability curve, the shape of which tells us a lot about the boat's purpose, sailing characteristics and seaworthiness.

A real yacht in a real situation is of course far from being a static case. The static stability curve is one of our best tools for quantitatively comparing different designs, and I don't mean to denigrate its importance. In practice, though, dynamic factors can often have a bigger effect on the actual stability of the boat as it relates to safety, seaworthiness and comfort.

Understanding monohull sailboat stability curves

Submitted by Matthew on

One of the first questions people ask when they discover I mess around with boat designs is: "How do you know it will float?"

Well, making it float is just Archimedes' principle of buoyancy, which we all know about from elementary school: A floating boat displaces water equal to its own weight, and the water pushes upward on the boat with a force equal to its weight. What people usually mean when they ask "How do you know it will float" is really "How do you know it will float upright?"

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