Yacht stability down 50% over the past 50 years

At last we know why so many modern yachts are so tippie or in other words uncomfortable and even unsafe. And maybe this explains why some even need opening windows in the bottom.

“Yacht design since the 1960’s has followed a steady downward trend in terms of stability. According to C. A. Marchaj (Seaworthiness: The Forgotten Factor, International Marine, 1987; Adlard Coles Nautical, 1986) “The positive area under the righting moment curve has been reduced to less than half, at the same time the negative area has increased dramatically.”

Marchaj also notes that the angle of vanishing stability has been reduced from about 180 degrees to about 120 degrees, and that the righting moment maximum is now ” about half of that characteristic of the traditional yacht form.”

This entry was posted in Asian Yachting, Capt. Marty, classic sail boats, H/V Vega, Historic Vessel Vega, Historical Ships, Humanitarian, Ketch, Raffles Marina, Restored Ships, Sailboats, Sailing Ships, Shane Granger, Ships, Singapore, Top Sail Ketch, Vega, historic sailing, jacht, sailing, wooden boats. Bookmark the permalink.

4 Responses to Yacht stability down 50% over the past 50 years

  1. sailvega says:

    I can’t help but ask myself how much of this progressive loss in stability is due to changes in shape or design I call it and how much is due to cost cutting measures by the builders in order to increase profits or perhaps a combination of both?

  2. Pingback: Are we (North America) buying too much boat ? - Page 2 - SailNet Community

  3. Jeff Halpern says:

    This statement is often quoted out of the context in which it was originally written.
    To understand this statement in context it should be noted that the quote from Marchaj was based on research on boats designed in the period prior to the the 1979 Fastnet Disaster.

    In the 32 years since that fatefull race, there has been tremendous research (of which Marchaj was both a pioneer and an advocate) on stability, motion comfort and general seaworthiness. This research has resulted in a major shift in the hull forms, weight and buoyancy distribution, rig proportion, methods of construction, and so on that have become the norm in modern yachts.

    While there are still extreme examples in the racing world for which this next statement would not be true, in a broad general sense, the newer boats that we sail today, are far more stable (both initial and ultimate), seakindly and resistant to downflooding than the boat designs that were designed during and prior to the fifty year period to which Marchaj and Coles were referring.

    One of the by-products of this research was also a better understanding of the limited stability (both initial and ultimate) that was the norm in traditional working craft.


    • sailvega says:

      Thank you Jeff for taking the time to post that. And yes I understand and fully agree that work boats like Vega do have a limited stability when compared to a yacht. Yachts can take a full knock-down and right themselves again. Most cargo boats cannot do this. I have never tested Vega that far and never hope to but she was built for the North Sea and the Arctic ocean so might have just a tiny bit more than is normal. What we have noticed is that boats like Vega take much much more to heel them than most yachts. Thanks again for posting

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