Jeff wrote:

JimC wrote:

stability analysis of the 26M/X. It certainly has a high center of
gravity, and the metacentric height has to be pretty low.


It operates on the same principle (ballast carried within the the
hull, in the lower portion of the hull) as most ocean-going vessels.


Yes, and more than a few modern vessels have rolled over.

----As have more than a few conventional sailboats! - And when they do
roll over, conventional sailboats sometimes don't come back up. And in
that case, they can quickly sink to the bottom (unlike the Mac, which,
because of its lightweight and flotation, will stay afloat.


Keeping track
of weight distribution is one of the primary jobs if the first officer
on most ships.

And your point is.....?


Using phrases like "operates on the same principle" is
like saying it "obeys the laws of physics." It was wise of you to avoid
those boats that don't obey the laws of physics.

Again, what's your point? Obviously, they all obey the laws of physics.
And they all use ballast, positioned within the hull and below the
waterline, to prevent capsizing and limit heeling.



When you look at the long list of warnings, such as:

NO MORE THAN 6 PERSONS, 960 POUNDS.

WHEN POWERING OVER 6 MILES PER HOUR:
- NO ONE ON THE CABIN TOP OR FOREDECK.

and

NEVER POWER THE BOAT OVER 6 MILES PER HOUR WITH THE SAILS UP.
The result could be instant capsize.

its clear that there are issues here. And I should add, the my real
point here is that these issues simply do not exist on "normal" boats.


Right you are. - Macs are different from "normal" sailboats. - "Normal"
sailboats have a weighted keel that can quickly drag the boat to the
bottom of the ocean in the event the boat capsizes or experiences a
breach below the water-line. "Normal" sailboats don't float if the hull
is breached, or if a substantial amount of water enters the cabin, for
whatever reason. The Mac, on the other hand, will stay afloat, and, even
in the event of excessive heeling, with the sails in the water, tends to
come back up.


And of course, we don't want to even consider the issues if the ballast
tank is empty.


Right. But even in that circumstance, the boat would still float,
whereas a conventional boat with weighted keel would quickly sink to the
bottom under the circumstances outlined above.


In the past you've poo-poo'd these warnings as just "lawyer talk," but I
hope now that you've had the boat for a while you take them more seriously.


The Mac 26M owners' manual includes instructions for operating the boat
without the water ballast under power in moderate conditions. It's
another example of the versatility of the boat.


And the same principle used in tall ships for hundreds of years.


I really don't think you want to use the stability qualities of
traditional ships as an example. And remember, even they used ballast
with a specific gravity somewhat greater than one.

Obviously, principles of marine design have advanced since the days of
Columbus, et al. Nevertheless, both the Mac and early (and modern)
ocean going ships use ballast positioned within the hull and below the
waterline. Most modern ships have ballast tanks that can be filled as
required. Regarding the fact that tall ships used ballast with a
specific gravity somewhat greater than one, so does the Mac 26M. - The
use of permanent ballast, heavier than water, in addition to removable
water ballast is one of the features introduced in the Mac 26M.





And the other issue is that the water ballast extends all the way
from stem to stern. This can't be helping the pitching moment at all.


Wrong again. it extends about 2/3rds, and the front and rear portions
of the tank taper to sharp end portions and are therefore of little
mass and no real consequence re the distribution of mass.

Not according to the published diagram:
http://www.macgregor26.com/drawings/drawings.htm

Its pretty clear from this that the ballast extends all the way forward,
and that in fact a substantial amount is forward of the mast. You
should really spend some time learning about your boat, Jim.

Jeff, did you happen to take courses in geometry and logic in high
school or junior high? The reason I ask is that you obviously know
nothing about either subject. - The fact that the water ballast tank in
the Mac extends toward the bow, forward of the mast, is not
determinative of whether it extends about 2/3rd the length of the boat.
(Remember that my statement was in response to Scotty's ridiculous
remark that the water ballast extends "all the way from stem to stern."
- Why didn't you criticize Scotty for making such a stupid remark?)
Also, the ballast tank is tapered at the front and back such that the
volume (and mass) of water held at the front and rear portions is
substantially less then that held toward amidships. Additionally, the
heavier, permanent ballast is positioned amidships, below the mast.

Jeff, I've sailed many boats. The Mac 26M doesn't pitch excessively and
doesn't pitch more than most others. (Have you sailed the 26M? - No?)
Seems to me that this is just one more example of the fact that the most
opinionated, inflexible critics of the Mac 26m are those who have never
sailed one.


Jim