On Wed, 16 Apr 2008 21:10:11 -0500, Brian Whatcott
wrote:

On Tue, 15 Apr 2008 20:41:41 +0700, Bruce in Bangkok
wrote:
/snip/
There are conflicting factors (as usual): the pro-stability factor is
the considerable mass far from the roll center (called moment of
inertia) /snip/

Certainly the weight of the rig slows the roll speed by some figure
but whether it has an effect on the boat rolling over I seriously
doubt.
/snip/
Bruce-in-Bangkok

This is not the first time that you have not quite understood an
engineering input, but felt comfortable about doubting it.
The concept is "second moment of inertia" Bruce, not mass.

Easy to look up though.....

Brian W

Well, I do understand "moment of inertia" but I do not understand how
a rig that when you put it in the water has a negligible effect on
stability, i.e., the boat rights itself, is going to have a major
effect on a boat rolling over.

Now, for argument's sake we are talking about my boat. the mast can be
picked up by four Asians so lets say, for argument's sake it weighs
500 lbs. It is desk stepped and is forty feet long with the spreaders
about half way up the mast.

I can carry one set of shrouds with no problems so say 100 lbs X 2
sets = shrouds = 200 lbs. Four terminate at the spreaders and two at
the mast head. The fore and aft stays probably weigh a little less
then the stays so say 75 lbs together, both terminating at the mast
head.

The boat displaces 12,000 lbs. It was built in 1971, sailed across the
Pacific Ocean, among other places and hasn't rolled over to date.

It would be a kindness for you to explain it to me the real life
dynamics that will cause my rig to make my boat to roll over.



Bruce-in-Bangkok
(correct email address for reply)