JimC wrote:


Jeff wrote:
JimC wrote:

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.


Actually, I majored in Naval Architecture for two years before
switching to Physics. Then I worked for NASA for 6 years. Any more
questions?

Yes. If you majored in Naval Architecture and Physics, how do you
explain the fact that you know so little about them?

You really like the ad hominem attacks, don't you? But what do you
have to gain? Everyone reading this knows I'm right and that just
makes you look like an asshole in addition to being an idiot.

And, what did you do for NASA during those 6 years? - I certainly
hope you weren't designing boats for them.

No, but I did do that for an America's Cup syndicate.

(Incidentally, it happens that I worked for NASA also, for 11
years. - Does that make me 11/6 more qualified than you?)

I actually did engineering, what did you do? Write product liability
waivers? You have trouble taking the high road here, Jim, after you
explained to us that all of the warnings that come with a Mac is just
lawyer talk that can be ignored. Unless, of course, it can be used to
save the company when children die as the boat rolls over in calm
weather. It really amazes me how you can shift positions to suit your
need. Is that what you learn in lawyer school?

It starts at the bow, and it ends at the stern. The diagram clearly
shows the water ballast running the entire length of the boat. If
anything, it looks that the tanks is deepest in the forward area. The
cross-section at the forward station under the hatch appears to be by
far the largest, indicting that a large portion of the water ballast
is forward.

Here's the diagram again:
http://www.macgregor26.com/drawings/drawings.htm
please tell us if there's any other way to interpret this?

Yes, there is another way to interpret it. - The correct way. The Mac
26M has a a drainage opening and large gate valve positioned on the
lower portion of its transom, the purpose of which is to permit the
ballast water to drain out of the tank when desired. The narrow,
elongated, cross-hatched "bulges" shown at the bottom of the hull in
cross-sections 4 and 5 are actually channels that conduct ballast water
from the ballast tank to the drainage opening when the bow is elevated.
When the gate valve on the stern is opened with the boat sitting on a
launch ramp, for example, water from the ballast tank is permitted to
drain out through the drainage valve, a process that takes about 4
minutes. - In other words, the cross-hatched portions you interpreted
as being part of the ballast tank are actually conduits that communicate
with the ballast tank for permitting the ballast water to drain out, but
they are not part of the tank itself. And, because of their small
volume, they have little effect on the distribution of mass along the
longitudinal axis of the boat.

OK, you made your point, there's not much ballast aft of the mast. Of
course, my point has really been that there's a lot forward of the
mast, so you just helped prove my point.

And by the way, what happened to your claim that the entire boat was
protected by a "doubled hull" - now you're claiming it's just a small
portion. Was that just "lawyer talk" that we can ignore?

And with a 250 pound engine hanging of the stern, that's a lot of mass
in the extremities.


Nope. The boat is designed to be balanced fore and aft with an outboard
and several persons in the cockpit.

In other words, you are totally ignorant of the concept of "moment of
inertia." Perhaps you should take some time off now and review basic
physics. This is the central issue of the discussion, and now you're
confessing that you have no idea what its about. Good one, Jim.

....
Additionally, the heavier, permanent ballast is positioned amidships,
below the mast.


Just where ballast should be. Good for them.


As noted above, the boat is designed to be balanced with an outboard and
with several persons in the cockpit. And it is.


Yes, the large mass in the stern (the engine) is nicely balanced by
the large mass of the water ballast in the bow. Now explain to us the
meaning and significance of "moment of inertia."



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?)


I'd love to, but most of the Mac owners hardly ever go out. I have
sailed by them a number of times and they do seem to bob around more
than heavier boats.

And, when did you last have your eyes examined, Jeff?

Funny thing, as I've grown older my vision has improved. Now I spend
most of the time without wearing the glasses I've worn since I was
ten. I guess that means I've just gotten smarter.