Does it matter if this is from the real MC/Navvie

Navvie wrote:
OK let me try to get you to see something else. If the beam of typical
vessels is the same inverted or the right way up would the capsise
screen be different?

Hello? The CSR is a metric for the boat. If the boat is upside down,
it's the same. If the boat is standing on it's bow, CSR is the same. If
the boat has been propped up on jackstands for years, CSR is the same.

Seems a rather easy principle to grasp, there.


Do you not agree that the underlying assumption of the screen is that
the inverted water plane width is directly proportional to the beam?

Now if you've got that, isn't the non-inverted water plane width also
likely to be directly proportional to the beam?

You're trying to get fancy, aren't you? Why not work with simple
principles first, instead of leaping off the deep end.

1- the inverted waterline section of any given could be very very
different than the normal waterline section. Usually boats are double
ended at the water line, but very often they have wide transoms.

2- volume distribution is just (or more) important. A high sheer & and a
canoe stern will force the boat, when inverted, to try and float on two
points. Obviously this will affect it's inverted stability but not it's
normal stability.

3- CSR takes none of this into account



If that's so, could there be a connection between initial stability and
inverted stability as valid as the CSR formula itself?

Looking at what I've said above, WTF do you think?


Finally, the metacentric radius (BM)

Your whole argument is a lot of BM.

But to get serious for a moment... CSR is of some value comparing
vessels of similar size & form. It is simple & quick. It is not a
substitute for formal LPOS calculations, but there may not be data on
some boats to do this. Therein lies it's merit.

In addition, the LPOS (Limit of Positive Stability) figure has a lot of
weaknesses. It takes no account of sheer, as I mentioned above, and
deliberately does not account for deck camber or cabin trunk volume. And
it does not take any account of athwartship rotational inertia (or X-mmi
if you like jargon) which is a very large factor in how likely a given
boat is to be rolled over, or to stay inverted.

In short, I don't see any benefit in continuing this discussion with
Navvie nor any sock puppet... although thanks for the gibberish, whoever
you are, it was a brief laugh and slightly brightened my morning. Maybe
later.

Fresh Breezes- Doug King
(on line since 1989 and still 100% sock-puppet-free)