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Motion comfort Ratio (MCR)


What is Motion Comfort Ratio (MCR)?
The Motion Comfort Ratio is an attempt to estimate the overall comfort for the passengers assuming the passengers does not feel comfortable having the upward and downward motion of the boat as it encounters waves and swells. The Motion Comfort Ratio provides a reasonable comparison between yachts of similar type.
The faster the motion the more uncomfortable the passengers.

The origin of this ratio is the highly respected boat designer Ted Brewer. According to Ted Brewer[1] himself: "This is a ratio that I dreamed up, tongue-in-cheek, as a measure of motion comfort but it has been widely accepted and, indeed, does provide a reasonable comparison between yachts of similar type."

How to calculate Motion Comfort Ratio (MCR)?
Motion Comfort formula
Motion Comfort Ratio formula

Notation
Abrev.UnitDescription
BeamftGreatest beam measured
DisplacementlbDisplacement of the boat in pounds
LOAftLength Over All
LWLftLength in Water Line

Note: The formula does only provide a reasonable comparison between yachts of similar type.

How to interpret the MCR value?
Generally: Higher values denote a more comfortable ride.
But be aware!! As Ted states: "...does provide a reasonable comparison between yachts of similar type." The value itself does not tell anything, you have to compare with yachts of similar type.

Question: Is MCR = 21.5 good or bad?
Answer: You cannot tell! It depends on which other boat you compare the value with!

Question: Is MCR = 21.5 better than 20.5?
Answer: You cannot tell! It depends on the similarity of the two boats!

Question: Is MCR = 21.5 better than 20.5 for two similar boats?
Answer: Yes. But keep in mind that this is a qualified estimate, not an answer cut in stone.

References