Nordkyn Design

Transverse stability is the ability of a vessel to resist and recover from heeling over. It important in the sense that this is what prevents a vessel rolling over and capsizing. For sailing vessels, stability is also needed to develop power under sail other than downwind. Stability is a force moment, i.e. forces separated by […]

This article follows Transverse Stability Part 1: Fundamentals The most relevant way of expressing the relation between heel and stability for a given vessel is plotting the GZ-curve or the righting moment curve. Ships and load-carrying vessels start from KN-curves, because they allow taking into account large variations in trim and loading, but at the […]

Sailing over 55,000NM in seven years on board the 9-metre sloop Yarra between the Arctic and the Antarctic resulted in a fair share of strong winds and rough seas at times. I managed to wear a set of hanks on my storm jib and pull my new #2 jib out of shape. Even so, wind […]

This article follows Transverse Stability, Part 2: Stability Curve and Knock-Down Energy If you are looking for information regarding the stability of monohull yachts hit or capsized in beam seas, the subject is treated in the next part, Transverse Stability, Part 4: Sailing Yachts at Sea. In the case of monohulls, regardless of the type […]

Inverted stability applies when a yacht remains upside down. It is a rare, but not unknown event and one situation where some understanding of yacht design and stability can become of crucial importance at sea. Two main scenarios lead to capsize: Loss of the keel or ballast Yacht rolled by a breaking sea and remaining […]

This article follows Transverse Stability, Part 3: Dynamic Stability Part 3 of this series dealt with changes in transverse stability taking place once a vessel starts travelling through the water. This article discusses the way the stability of sailing yachts can be challenged at sea as a result of wave action. Wave action doesn’t reduce […]

Wave theory is quite extensive and complex, but only a very small amount of knowledge about waves is essential to sailors to anticipate the risks that can arise from waves for small crafts. Waves are generated by the wind. There is a relation between fetch, wind speed and the maximum wave height that will result over […]

This article deals with some of the physics involved when a yacht is running before the sea, especially in heavy weather when waves are long and their front faces become steep. Yachts running in heavy weather and following seas face challenges that are very dependent on the characteristics of the design; the ability of the crew […]

With tropical cruising becoming increasingly popular and accessible in the last 2-3 decades, trends have developed in outfitting yachts for ocean cruising. Some of these trends that originated from sailing in moderate settled weather areas have resulted in significantly increased risks when a vessel is caught in severe conditions. Many of today’s cruising yachts, whether […]