DSK wrote:
Gary wrote:

Okay, my turn again. I just googled you and see you may be a Nav Arch.


I've met Mr. Gatehouse and he is indeed a Naval Architect and a good one.

So why don't you calculate the AVS?


Because (as he's been trying to tell you) it requires more data.


I am quite confident (and I am not a Nav Arch) that the boat will have
a better stability curve than is represented by the one posted.


Based on what? Your gut feeling?
No, based on the claims of Tayana of 0 degrees AVS (LOPS). Also based
on the high freeboard and massive pilothouse.


If it doesn't, and it has an AVS of 110, I wouldn't touch it for
anything but coastal wandering.


Now here I agree. An LPOS (or AVS or whatever the TLA de jour is) of 110
is far too low for any kind of rough weather sailing even near coasts.

Going back a little bit

You also earlier said :
"- the ballast/displacement ratio is overly low, meaning a tender
boat with not enough stability "
A Nav Arch would know that initial stability is more than lots of
ballast.


Right, in fact the B/D ratio has little effect on *initial* stability.
But notice that in the original sentence, the word "stability" was used,
not the phrase "initial stability".
In fact he used the term tender which is normally associated with
initial stability. He said the boat would be tender (tippy or lack
initial stability)

A boat can have very high initial stability and great sail carrying
power, but a very low LPOS (think scows or catamarans). A very different
type of boat can have low initial stability and lots of ballast for lots
of *reserve* stability... ie steeply increasing righting moment at
higher angles of heel. A lot of old fashioned narrow heavy boats are
said to "heel only so far, and then stiffen up like a rock." A boat like
this can sail well at higher angles of heel if the hull shape is fair &
the rig/rudder are balanced well. It can also have a very high LPOS yet
be very unsearthy.... think of the Twelve Meters.

No-one ever claimed that LOPS is the only factor determining seaworthiness.


... A raft has no ballast and is not tender. Wouldn't you say that
you are jumping to conclusions by not taking into account hull form
and the location of the ballast?


Umm, no... from the discussion so far, I'd say that you are the one
doing exactly that.

I am simply trying to understand how the inclining experiment can come
up with an AVS (LOPS) of 110 on a boat that claims a much greater AVS.
In the above statement, I was pointing out to Mr. Gatehouse that his
estimate of the 460 being "tender" based on the LOPS and ballast ratio
was not necessarily correct. But he should know, he sails a cat. (No
ballast)

In other articles on the net, they also talk of the boat as "stiff"
and "stands up to her sails well".


That can easily be a function of her SA/D ratio as much as hull form &
ballast.

Fresh Breezes- Doug King

Umm, no... from the discussion so far, I'd say that you are the one
doing exactly that.


Gary wrote:
I am simply trying to understand how the inclining experiment can come
up with an AVS (LOPS) of 110 on a boat that claims a much greater AVS.

Well, the incline experiment is a real world measure of
actual stability. In the absence of a test to, say maybe 100
degrees or so, I'd be inclined to consider the incline
experiment as a less certain way of finding LPOS than the
longhand method using the full lines plan.... but a far more
certain way of determining it than using the "short hand"
method based on simple ratios & a fixed input number.

AFAIK nobody ever said the Tayana had an LPOS of 110 degrees
but Evan Gatehouse was pointing out that the mathematical
formula used to derive it's claimed LPOS used 110 degrees as
a fixed input no matter what the boat or hull type.

In the above statement, I was pointing out to Mr. Gatehouse that his
estimate of the 460 being "tender" based on the LOPS and ballast ratio
was not necessarily correct. But he should know, he sails a cat. (No
ballast)


Before that, he owned & sailed & cruised a real crab
crusher. IMHO the gentleman knows that of which he speaks.

Fresh Breezes- Doug King

DSK wrote:
Umm, no... from the discussion so far, I'd say that you are the one
doing exactly that.



Gary wrote:

I am simply trying to understand how the inclining experiment can come
up with an AVS (LOPS) of 110 on a boat that claims a much greater AVS.


Well, the incline experiment is a real world measure of actual
stability. In the absence of a test to, say maybe 100 degrees or so, I'd
be inclined to consider the incline experiment as a less certain way of
finding LPOS than the longhand method using the full lines plan.... but
a far more certain way of determining it than using the "short hand"
method based on simple ratios & a fixed input number.
I am aware of how incline experiments work. I'm not sure which way is
the better to calculate AVS.

AFAIK nobody ever said the Tayana had an LPOS of 110 degrees but Evan
Gatehouse was pointing out that the mathematical formula used to derive
it's claimed LPOS used 110 degrees as a fixed input no matter what the
boat or hull type.
The original graphs posted by Popeye calculated the AVS at 110. That
was the genesis of the discussion.

In the above statement, I was pointing out to Mr. Gatehouse that his
estimate of the 460 being "tender" based on the LOPS and ballast ratio
was not necessarily correct. But he should know, he sails a cat. (No
ballast)


Before that, he owned & sailed & cruised a real crab crusher. IMHO the
gentleman knows that of which he speaks.
What's a crab crusher?

Fresh Breezes- Doug King