All About Sailing · video

What this video covers

The motion comfort ratio (MCR) provides a rough estimate of a sailboat’s motion in a seaway by comparing displacement, length overall (LOA), waterline length (LWL), and beam. Developed by naval architect Ted Brewer, the formula calculates how a vessel’s inertia and hull width interact with wave energy.1:05 Scores below 20 indicate lightweight racing boats with sharp, fatiguing motion, while scores from 30 to 40 represent moderate blue water cruisers.4:25 Heavy traditional vessels often exceed 50.4:48

The formula suffers from significant limitations: it uses deck beam rather than waterline beam, ignores hull form and ballast ratio, and fails to account for weight distribution.6:13 Because displacement is a primary variable, overloading a boat artificially inflates the score.6:44 Brewer intended the ratio as a comparative tool for similar vessel types rather than an absolute performance metric.7:22 Sailors should use the MCR as a preliminary filter, recalculating with realistic loaded displacement and cross-referencing results with the capsize screening formula and sea trials.

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