Roll Pitch & Comfort
 

There was a thread back a ways that was about roll rate and comfort Vs.
safety. Just thought if anyone was interested there are two lists on the
boatdesign.net/forums that show Ted Brewer's " motion comfort ratio" of
quite a few different sailboats. May be useful as a comparison chart for
anyone looking at buying a boat. First list is of boats with a
comparatively high MC ratio, and the second list is of boats with lower
ratios.

http://www.boatdesign.net/forums/showthread.php?t=20655
Scroll down to find the lists in two posts.

Red

Roll Pitch & Comfort
 

Red wrote:
There was a thread back a ways that was about roll rate and comfort Vs.
safety. Just thought if anyone was interested there are two lists on the
boatdesign.net/forums that show Ted Brewer's " motion comfort ratio" of
quite a few different sailboats. May be useful as a comparison chart for
anyone looking at buying a boat. First list is of boats with a
comparatively high MC ratio, and the second list is of boats with lower
ratios.

http://www.boatdesign.net/forums/showthread.php?t=20655
Scroll down to find the lists in two posts.

Red

More
http://www.mahina.com/boats.html
http://www.tedbrewer.com/yachtdesign.html
http://www.image-ination.com/sailcalc.html
and the best
http://www.johnsboatstuff.com/technica.htm
G

Roll Pitch & Comfort
 

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.

Roll Pitch & Comfort
 

On 2008-02-27 02:01:49 -0500, " said:

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.

I'd be a bit less inflammatory if I wrote on the subject, but I have to
say that I agree for the most part.

Then again, if we're heeling between 15 and 25 degrees, my lovely lady
knows not to complain as that's normal for our lovely
lady/beast/vessel. If she were longer and heavier, the acceptable heel
numbers would be a bit lower.

--
Jere Lull
Tanzer 28 #4 out of Tolchester, MD
Xan's pages: http://web.mac.com/jerelull/iWeb/Xan/
Our BVI trips & tips: http://homepage.mac.com/jerelull/BVI/

Roll Pitch & Comfort
 

Red wrote:
There was a thread back a ways that was about roll rate and comfort
Vs. safety. Just thought if anyone was interested there are two lists
on the boatdesign.net/forums that show Ted Brewer's " motion comfort
ratio" of quite a few different sailboats. May be useful as a
comparison chart for anyone looking at buying a boat. First list is
of boats with a comparatively high MC ratio, and the second list is
of boats with lower ratios.

http://www.boatdesign.net/forums/showthread.php?t=20655
Scroll down to find the lists in two posts.

Red

Best way to reduce roll is to put some sails up!

Dennis.

Roll Pitch & Comfort
 

On Wed, 27 Feb 2008 10:55:51 GMT, Jere Lull wrote:

On 2008-02-27 02:01:49 -0500, " said:

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.

I'd be a bit less inflammatory if I wrote on the subject, but I have to
say that I agree for the most part.

Then again, if we're heeling between 15 and 25 degrees, my lovely lady
knows not to complain as that's normal for our lovely
lady/beast/vessel. If she were longer and heavier, the acceptable heel
numbers would be a bit lower.

It is somewhat interesting that the antiroll fins on a cruise ship
will kill the roll completely, but the ship still pitches noticably in
one foot waves.

Casady

Roll Pitch & Comfort
 

" said:
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.

No, it's defensible on several grounds. It was invented by a
knowledgeable NA, it does model
that "bigger + heavier = more comfort" which is true, and it is widely
quoted.

None of that makes it a valuable quantity for comparing boats IMHO.
For example, if you take two boats of very similar dimension &
displacement, the one with longer
overhangs will have a higher "Motion Comfort Index." Why? Because old
salty prejudices favor boats
with long overhangs. Long overhangs were fashionable in the early
1900s but they don't make a boat
more comfortable at sea, if anything they make it wetter, slower, and
less "comfortable" by most
definitions of the word.

.... 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.

And you'd be more comfortable yet in a cheap hotel. Where does this
fit into the 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.



Jere Lull wrote:
I'd be a bit less inflammatory if I wrote on the subject,

Yeah, but where's the fun in that?


Then again, if we're heeling between 15 and 25 degrees, my lovely lady
knows not to complain as that's normal for our lovely
lady/beast/vessel. If she were longer and heavier, the acceptable heel
numbers would be a bit lower.


And most likely, slower in lighter air.
95% (or more) of all sailing is done in winds of less than 15 knots.
Therefor, any boat
which does *not* have to reef or reduce sail in 15 ~ 18 knot winds is
a *less* capable
vessel. But again, old salty prejudices lean the other way....

Fresh Breezes- Doug King

Roll Pitch & Comfort
 

"Red" wrote in message
...
There was a thread back a ways that was about roll rate and comfort Vs.
safety. Just thought if anyone was interested there are two lists on the
boatdesign.net/forums that show Ted Brewer's " motion comfort ratio" of
quite a few different sailboats. May be useful as a comparison chart for
anyone looking at buying a boat. First list is of boats with a
comparatively high MC ratio, and the second list is of boats with lower
ratios.

http://www.boatdesign.net/forums/showthread.php?t=20655
Scroll down to find the lists in two posts.

Red

There is a degree of subjectivity in that. The two largest factors affecting
comfort are the condition of the person's inner ear and their body
morphology. The inner ear obviously is the source of balance but body
morphology is interesting. These boat studies tend to be old and don't
account for obesity and the roll pitch comfort of the human body itself as a
result of mechanical displacements of large amounts of fat tissue. A thin
person may be quite comfortable in those old fashioned vibrating belt
machines but an obese one would experience extreme discomfort as they fly
about all over the place. An obese person's fat tissues can couple into the
motion of the boat in a positive sympathetic mode, increasing the motion of
the boat and also of the person itself. This mechanical regime would
increase until non linearities in the adipose tissue or transient boat
displacements introduced harmonics and dampened the overall response. The
concepts of comfort with regard to boat motion are indeed true, but the
specifics, namely rates and axis should be reconsidered due to the ever
increasing size and elasticity of boat passengers. This is exceedingly true
in the States, where eating has become full time sport.

Nigel

Roll Pitch & Comfort
 

On Wed, 27 Feb 2008 07:29:41 -0800 (PST), wrote:

No, it's defensible on several grounds. It was invented by a
knowledgeable NA, it does model
that "bigger + heavier = more comfort" which is true, and it is widely
quoted.

It also assigns a very low comfort number to the Frers 41 which jibes
very closely with my experience. It has a quick squirrelly motion
offshore and is a bit of a vomit comet.

Roll Pitch & Comfort
 

On Feb 27, 5:29 am, wrote:
" said:
IMO, Ted Brewer's motion comfort ratio is BS. ...

No, it's defensible on several grounds. It was invented by a
knowledgeable NA, it does model
that "bigger + heavier = more comfort" which is true, and it is widely
quoted.

No, the ratio does not say that "bigger" is more comfortable. Just
the opposite. It penalizes length (70% waterline + 30% overall) and
beam to the 1/3. The results of this can be silly. The idea that an
Alberg 30 is vastly more "comfortable" than a Transpac 52 is absurd.

I want to be clear that I'm not disparaging Brewer. He has drawn some
beautiful boats and written at least one very good book. It's just
his "CR" that's bogus. Brewer claims that heave and pitch response
will be slower on a boat with a heavily loaded water plane and low ppi
all else being equal. That's true for heave and probably reasonably
indicative for pitch. He also asserts that roll response will be
slower on heavy narrow boats. That may be true, but misses some major
factors. The problem is that he goes on to assert that boats with
slow initial pitch and roll and heave responses are "more
comfortable". This completely ignores major factors like period,
amplitude and damping. And, of course, begs the questions of what is
comfort is and what conditions we are talking about. Down wind boats
with high "CR" will be slow and have a tendency to roll
uncontrollably. Upwind they will be slow but wet; if you don't rise
to meet a wave you must go through it. Indeed, a high "CR" pretty
much assures slowness. It is true that slower is generally more
comfortable. It is also true that you can sail a fast boat slowly but
you can't make a slow boat fast... Theres more, but my work is
calling.

--Tom.