Jeff wrote:
It really amazes me how you can shift positions to suit your
need. Is that what you learn in lawyer school?

Sure thing Jeff. - Of course, it's clear that you cherry-picked and

I love that expression "cherry-picked"! I think that would be a good
defense - "Your Honor, the prosecution is just cherry-picking. What
about the 6 billion people that my client didn't kill that night?"

substantially misrepresented what I said. I never said that the
warnings that come with a Mac can be ignored, and you know it.

Your comment was:
"Jeff, have you had many dealings with corporate attorneys?
Or tort lawyers? If you had, you would recognize that these
warnings, if taken literally, are something like the warnings
posted in our health center warning us to be sure to
wear our seat belt when using the Nautilus weight
training equipment. Or, like the long list of warnings
you get when you purchase any electrical appliance,
audio equipment, etc. "


You've tried to "un-ring this bell" many times, but I think everyone
here understands what you meant.
....

Once more, Jeff, where did I say that those warnings could be ignored?

Once more, Jim, no one is buying it.
....


Here's the diagram again:
http://www.macgregor26.com/drawings/drawings.htm
....

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.

I think it's pretty clear by now that you lost on that point, Jeff. The
sections you thought were extensions of the ballast tank were drainage
tubes for permitting the tank to drain out the valve on the stern when
parked on the launch ramp.

Actually, they look a lot bigger than tubes - but since my argument is
that there is a significant mass in the extremities your point really
doesn't mean much.




More significantly, your original theory was that, because the ballast
extended "the entire length of the boat," you thought it would
contribute to pitching of the boat.

And it does, though the mass aft largely comes from the 250 pound
engine hanging off the transom.


As should now be understood, the
volume and mass of the ballast is in an area slightly forward of
amidships, rather near the mast.

No - here you're wrong. The diagram clearly shows the largest
cross-section by far at the first station, which is halfway between
the mast and the bow.

Moreover, the ballast tank is tapered
at its forward and rear end portions, further reducing the mass of
ballast spaced furthest from the central or largest portion, thereby
lessening the moment of inertia of the ballast when the boat pitches
upon a wave, etc.

Nice words, but wrong. Anyone can clearly see that you're wrong, so
why do you can insisting otherwise? Much of the mass of the tank is
in the forward 20% of the boat. Because the tank is on the
centerline, there is little tapering forward until you get very close
to the bow.


As to the fact that the ballast tank extends forward
to the bow, two factors apply. First, the distance from the longitudinal
center (largest or widest portion) of the ballast tank to the bow is
substantially shorter then that to the stern, so it's appropriate that
the ballast tank extend to the bow

In simple English, you're saying that the water ballast is close to
the bow. Yes, that's my point exactly! Thank you!

(remembering also that the forward
portion or the tank is tapered, thereby reducing pitching inertia).

Actually, the tapering has little affect until the last few feet.

Secondly, for balancing the boat in the water to compensate for the
weight of crew and motor at the stern, it would again be appropriate to
position the longitudinal center of mass of the ballast tank somewhat
forward along the length of the hull.

Yah think???




Jeff, you again misquote what I said to make your point. - I never said
that the "entire boat" was protected by a doubled hull. Only that
adjacent the ballast tank. - Do you have any ethics at all?

Once again, we have a case of you making a claim of and inner and
outer hull and than after you were called on that you started
backpedaling and trying to explain that its only the vulnerable part
that is "protected." In fact, now you're claiming that its only a
small portion that is protected. There are two basic facts he
First, the water ballast does not extend the full width, it is
concentrated in the middle, so that any blow off the centerline is not
protected. And while the bow area is protected, at high speed that is
lifted out of the water and thus needs no protection. And now you're
claiming there is little protection aft. And the second point is that
MacGregor itself never touts this as a feature - it one that you made
made up!

You tried to sell this one and got caught, so don't complain to me
about "ethics."


You also again cherry picked the statement you relied on, since in later
portions of that discussion some months ago I made it quite clear that
the boat didn't have a doubled hull protecting the entire boat. - But
you knew that when you decided to misrepresent and cherry pick my
statement, didn't you Jeff? You shamelessly misquote and cherry-pick
when you think you can get by with it. - Do you have no self-respect
whatsoever, Jeff?

Sorry Jim, this is another bell that you can't un-ring! When you made
the comment originally you were quite happy to make it sound as if the
boat had all the protection of a double hull. It was only after it
was clear that the "protection" was very limited that you admitted
that it doesn't have what is commonly referred to as a double hull.



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."


Moment of inertia in this context relates to rotational inertia, that
is, the tendency of the boat during pitching movement to keep rotating,
or pitching, in the same rotational direction. The moment of intertia of
a body with respect to any axis is the sum of the products obtained by
multiplying each elementary mass by the square of its distance from the
axis.

not bad so far.

Since it's proportional to the square of the distance from the
axis of pitching rotation, MacGregor's design (positioning most of the
mass near amidships rather than evenly distributed along the entire
length of the boat) was proper.

Excuse me???? What about that large mass called "the engine" which
is about 10% of the dry weight and hanging of the stern??? And what
about the huge amount of water ballast that get loaded near the bow of
the boat???

Only a lawyer could say this with a straight face!


Incidentally, Jeff, there are other forms of inertia (e.g., resistance
to upward and downward movement, resistance to deceleration of the boat
during forward movement) that are in some respects disadvantages to
small, light boats such as the Mac. As I have consistently stated, the
Mac has good and bad features, and one of the disadvantages to any light
boat is that it doesn't sail as steadily, with as much forward momentum,
as does a large, heavy vessel. (You would have done better to ignore the
ballast issue altogether and concentrated instead on some of the
obvious disadvantages of small, light boats.)

So you're saying that in addition to having a large pitch moment it
has other problems? I was trying to deal with just one at a time.

I'd love to, but most of the Mac owners hardly ever go out.

Really? And do you have any evidence to back up that bit of propaganda?

As I've said, There have been a number at the marinas I've stayed in,
but I've hardly ever seen them go out. Also, I've almost never seen
Mac owners hanging out at the dock. At my new marina there are two
in nearby slips - I've never met the owners.

In any event, I was out sailing my Mac yesterday. - When was the last
time you took your boat out Jeff?

Being in Boston, we had to haul our boat a few weeks ago. For the
last 5 years we've averaged 50-60 nights on the boat - never at the
slip, usually 50 to 200 miles away. Before that we were out for a
full year.


I have
sailed by them a number of times and they do seem to bob around more
than heavier boats.

Actually, it's probably true that the Macs, weighing only around 4,000
pounds with ballast and crew, "bob" around more than a 20,000 lb vessel.

Actually, the question at hand is whether the Mac bobs around more
than other 4000 pound boats. That's the issue of having a large
moment of inertia.

Then again, its also true that a Ferrari or Porsche weighs less than and
has a stiffer ride than a Lincoln Town Car. It sort of relates to
personal taste, and what you're going to do with the vehicle or vessel.
For example, I motored back to the marina at around 13 knots, despite
rather choppy water conditions, which gave me more time out on the Bay
for sailing.

I've never argued the virtues of fast powering, that by itself is a
reasonable feature. The question is, what are the other properties of
the boat, and is this a worthwhile compromise. The only way the Mac
makes sense to me is if it is trailered to different locations.
Keeping it in a slip makes no sense to me.