Tom wrote:
IMO, Ted Brewer's motion comfort ratio is BS. Brewer is an interested
party and he admits that the "ratio" was made up as a kind of joke.
There is absolutely no evidence that it works. As a general theory is
is indefensible. On any given day I'd bet you'll be a lot more
comfortable in a Catalina 30 than you will be in a 5.5 meter both in
terms of motion comfort and amenities but you certainly will not learn
that from the "comfort" ratio. Any comfort motion rating system that
says that the Colin Archer ketch is the pinnacle of comfortable is
just plain cr@p. I'd rate the "comfort ratio" as significantly less
important than the color of the mast step in my boat comparison list.
Of course, TB has a different view. You can see his rational he
http://www.tedbrewer.com/yachtdesign.html.

-- Tom.

Hi Tom,
While I have no experience in yacht design whatsoever, I can see what
Brewer was trying to accomplish. The following is a partial copy of his
description from his website:

"COMFORT RATIO (CR): 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. It is based on the fact that the faster the motion the more
upsetting it is to the average person. Given a wave of X height, the
speed of the upward motion depends on the displacement of the yacht and
the amount of waterline area that is acted upon. Greater displacement,
or lesser WL area, gives a slower motion and more comfort for any given
sea state.

...The intention is to provide a means to compare the motion comfort
of vessels of similar type and size, not to compare that of a Lightning
class sloop with that of a husky 50 foot ketch."

So while I agree that there may, or may not be, hard "science" behind it
(and I admit I wouldn't know), it seems useful as a comparison when
looking at similar type boats for a given usage. And it seems to agree
with the descriptions and discussions that were put forth in that
earlier thread by Roger Long and others.

Red