"DSK" wrote in message
.. .
One point I don't know if anybody else has mentioned-
ballast/displacement ratio. If this boat's *sailing* displacement (which
is a different figure from it's weight as it left the factory, a figure
often quoted as 'displacement') is really 16K# then it's b/d ratio is a
tad under 40%... close to the minimum for a seagoing boat IMHO. And if
the displacement figure is fudged, as they often are, then it is in a
grey area. Furthermore the stability will be degraded as you load stores
(true of almost any boat, but much less important as the B/D ratio gets
up towards 50%). Rather a nit-picky technical issue, but one that is
important.

Ok, I got intrigued and ran some numbers applying your above methodology to
three other boats (I'm in accounting, numbers interest me):

Pacific Seacraft 37 .38
Tayana 37 .30 (!!)
Cabo Rico 37 .37

Now, I am not a naval architect, but the people who designed the above
(well-respected) sea-going yachts are, and their numbers prompt me to ask
what you base your 40% number on. I'm not calling your assertion
questionable, I just want to know what I am missing here- help me out.

Wendy

Wendy wrote:

Ok, I got intrigued and ran some numbers applying your above methodology to
three other boats (I'm in accounting, numbers interest me):

Pacific Seacraft 37 .38
Tayana 37 .30 (!!)
Cabo Rico 37 .37

Now, I am not a naval architect, but the people who designed the above
(well-respected) sea-going yachts are, and their numbers prompt me to ask
what you base your 40% number on. I'm not calling your assertion
questionable, I just want to know what I am missing here- help me out.


There are a lot of numbers and B/D is probably going to be lower
on heavy displacement boats - like the ones you are looking at.
More useful will probably be Displacment to Waterline Length,
Motion Comfort Ratio, and Capsize Ratio.

Looking at my notes, a Catalina 30 we looked at had a B/D of .41,
a D/Wl of 291.4, a Comfort ratio of 24.8, and a Capsize ratio of
1.99. The Crealock 37 we looked at was .383, 344, 34.3, and 1.7
respectivly.

It's important to remember that these numbers will only give you
a suggestion of how a boat will perform. In reality there are a
lot of factors that go into performance that these numbers can't
account for.

Cindy

--
the return email is a spam trap
send legit emails to cindy_at_ballreich_dot_net

"Cindy Ballreich" wrote in message
...
It's important to remember that these numbers will only give you
a suggestion of how a boat will perform. In reality there are a
lot of factors that go into performance that these numbers can't
account for.

Yes, I understand this concept. I think it's probably safe to say that any
one number in and of itself is almost meaningless; these figures probably
become important through their interrelationship- the old "whole is greater
than the parts" idea. Sailboat gestalt, if you will A familiarity with
the basic concepts of aerodynamics is essential to flight, but one need not
be able to design a wing in order to understand how it works. I strongly
suspect that the same principle applies to nautical design and operation.

Wendy

I strongly
suspect that the same principle applies to nautical design and operation.

except that aero engineers are seriously trained before let loose. naval
architects are, for most all states, just people who claim to be naval
architects.

Badly designed airplanes never get on the runway, let alone airborne. Badly
designed boats that float are boats that float. I have seen people who claim
to be highly qualified naval architects claim that the "slot" between an
overlapping jib and the main _increases_ lift, something no aero eng on the
planet would say of a biwing aircraft.

In article ,
(JAXAshby) wrote:

Badly designed airplanes never get on the runway, let alone airborne.

You haven't seen some of the "planes" of the EAA ;-) I saw one lifting
body shaped like a flying saucer that even actually flew once, but no
sane pilot would take it up for a second flight.

Truth be told, the Quickie has some bad design flaws, but it sure proved
the power of canards. (12 hp, 100 mph and 60+ mpg, but I believe every
one of them was ground looped at least once.)


I have seen people who claim
to be highly qualified naval architects claim that the "slot" between an
overlapping jib and the main _increases_ lift, something no aero eng on the
planet would say of a biwing aircraft.

You don't win many races in multi-sail boats, do you?

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

I was part of the EAA for years, and my baby brother used to write technical
articles for them. To get an amateur built aircraft into the air requires a
serious inspection by the FAA and flight testing in an out of the way area. To
get an aircraft design "type certified" is a much long and expensive process,
and must be completed before an aircraft can be manufactured for sale.

No such thing is needed to produce a boat for sale. Anyone -- in most states
-- can call themselves a naval architect. Even an 8 year old girl in pigtails.

(JAXAshby) wrote:

Badly designed airplanes never get on the runway, let alone airborne.

You haven't seen some of the "planes" of the EAA ;-) I saw one lifting
body shaped like a flying saucer that even actually flew once, but no
sane pilot would take it up for a second flight.

Truth be told, the Quickie has some bad design flaws, but it sure proved
the power of canards. (12 hp, 100 mph and 60+ mpg, but I believe every
one of them was ground looped at least once.)


I have seen people who claim
to be highly qualified naval architects claim that the "slot" between an
overlapping jib and the main _increases_ lift, something no aero eng on the
planet would say of a biwing aircraft.

You don't win many races in multi-sail boats, do you?

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

I was part of the EAA for years, and my baby brother used to write technical
articles for them. To get an amateur built aircraft into the air requires a
serious inspection by the FAA and flight testing in an out of the way area. To
get an aircraft design "type certified" is a much long and expensive process,
and must be completed before an aircraft can be manufactured for sale.

No such thing is needed to produce a boat for sale. Anyone -- in most states
-- can call themselves a naval architect. Even an 8 year old girl in pigtails.

(JAXAshby) wrote:

Badly designed airplanes never get on the runway, let alone airborne.

You haven't seen some of the "planes" of the EAA ;-) I saw one lifting
body shaped like a flying saucer that even actually flew once, but no
sane pilot would take it up for a second flight.

Truth be told, the Quickie has some bad design flaws, but it sure proved
the power of canards. (12 hp, 100 mph and 60+ mpg, but I believe every
one of them was ground looped at least once.)


I have seen people who claim
to be highly qualified naval architects claim that the "slot" between an
overlapping jib and the main _increases_ lift, something no aero eng on the
planet would say of a biwing aircraft.

You don't win many races in multi-sail boats, do you?

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

In article ,
(JAXAshby) wrote:

Badly designed airplanes never get on the runway, let alone airborne.

You haven't seen some of the "planes" of the EAA ;-) I saw one lifting
body shaped like a flying saucer that even actually flew once, but no
sane pilot would take it up for a second flight.

Truth be told, the Quickie has some bad design flaws, but it sure proved
the power of canards. (12 hp, 100 mph and 60+ mpg, but I believe every
one of them was ground looped at least once.)


I have seen people who claim
to be highly qualified naval architects claim that the "slot" between an
overlapping jib and the main _increases_ lift, something no aero eng on the
planet would say of a biwing aircraft.

You don't win many races in multi-sail boats, do you?

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

I strongly
suspect that the same principle applies to nautical design and operation.

except that aero engineers are seriously trained before let loose. naval
architects are, for most all states, just people who claim to be naval
architects.

Badly designed airplanes never get on the runway, let alone airborne. Badly
designed boats that float are boats that float. I have seen people who claim
to be highly qualified naval architects claim that the "slot" between an
overlapping jib and the main _increases_ lift, something no aero eng on the
planet would say of a biwing aircraft.

"Cindy Ballreich" wrote in message
...
It's important to remember that these numbers will only give you
a suggestion of how a boat will perform. In reality there are a
lot of factors that go into performance that these numbers can't
account for.

Yes, I understand this concept. I think it's probably safe to say that any
one number in and of itself is almost meaningless; these figures probably
become important through their interrelationship- the old "whole is greater
than the parts" idea. Sailboat gestalt, if you will A familiarity with
the basic concepts of aerodynamics is essential to flight, but one need not
be able to design a wing in order to understand how it works. I strongly
suspect that the same principle applies to nautical design and operation.

Wendy