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  • #83123

    Capsize and comfort ratios seem useful to have but what do they mean exactly? It looks like the lower the capsize ratio the better, and the less likelihood of a knockdown or capsize. How accurate are these figures? What would be the threshold or bare minimum for offshore sailing? And on the same topic, what does the comfort ratio refer to? Is it creature comforts or comfort related to seaworthiness? Where can one find references to these figures or more information?

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  • #83125
    Ken A Heaton

    Motion Comfort Ratio was developed by Boat Designer Ted Brewer. The formula predicts the speed of the upward and downward motion of the boat as it encounters waves and swells. The faster the motion the more uncomfortable the passengers. Thus, the formula predicts the overall comfort of a boat when it is underway.

    A more complete explanation is here: https://wavetrain.net/2011/10/15/crunching-numbers-brewer-comfort-ratio/


    Very good! Thanks for the explanation and the link to the excellent article! Very informative, really loved reading it… and will also read about the D/L ratio and sail area/displacement ratio in separate articles he explains.


    Hey guys, just fyi… Clicking on the “help ?” on the upper right side of the Sailboat Calculations box will also give you an explanation of the different ratios/formulas.


    Hello to all.
    To my experience, the comfort ratio number is quite informative about how the boat behaves in the rough seas: I’m feeling myself much better in the Albin Stratus (35 feet, comfort ratio of 25) than in more luxurious Beneteou Oceanis 393 (39 feet, comfort ratio of 23). Of course, it may be subjective, but there are more parameters to consider than just measurements. One of these parameters (not easily described in numbers) is the hull shape, which can affect the comfort ratio greatly.


    There is a button for Definitions on right side of screen next to “Sailboat Calculations”.
    Good explanations.
    However, there are no definitions for I, J, P, and E.
    What are they?
    Venture of Newport 23 swing keel trailerable cutter
    in the eastern foothills of Shenandoah Mountains, Virginia, near Chesapeake Bay


    Hi budroberts9, For records where we have rig dimensions, click on the “help?” link in the upper right corner of the Rig and Sail Particulars box. An image will pop-up showing what each of these measurement letters stand for.

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