Jeff Morris wrote:

"Jim Cate" wrote in message
...

- its doesn't have

a double hull either. The portion of the hull the is protected by the

ballast

tank is about a third of the underwater surface - and its the part least

likely

to be damaged in a collision.

The water ballast chamber extends along the lowermost part of the hull
rearwardly from the bow for around 2/3rds of the length of the boat.


But is only extends one third of the width. It is more likely that you will hit
a floating obstruction on the side.




Because of its light weight, I don't think that the Mac is likely to
come apart striking something head on under sail. (Momentum and kinetic
energy are proportional to the square of the velocity, which is thus the
more significant factor.) On the other hand, if the Mac is under
power, planing at around 15 knots, for example, I can see a possible
hazard if the boat strikes floating depris, such a partially submerged
log, or some other non-visible hazard. In that event, it seems likely
that the portion of the boat that would get the major impact would be
the lower or center portion of the V-shaped hull. Below is a crude
pictorial representation:




deck
x
x x
x x x x x
x x
x x
x
water inner liner i x
~~~~~~~~~ x i i i x~~~~~~~
surface i o
~ o o o o o o o o oo ~ LLLLL
^ outer hull LLLLL
LLLLL
^^^
(partially
submerged log)


The drawing is not accurate or true to scale, and the boat would
probably be on an incline while planing, such that the lowermost,
longitudinally extending, center "edge portion" of the V bottom
was cutting through the water, and was therefore exposed to
submerged objects on the surface or just below the surface. But it
seems that under such circumstances, the lower hull
could strike the submerged object but not the inner liner,
which is higher in the boat than the lower hull. Also,
under these circumstances, it's likely that the log would be impacted by
only the lowermost, center portion of the keel (where the ballast tank
extends) but not the port and starbord portions of the V-shaped hull,
which are higher than the center of the V bottom. Of course, other
circumstances could arise in which the lower hull might be damaged

In any event, the inner liner is a safety factor, though probably not as
important one as the foam flotation that keeps the entire boat afloat in
the event water enters the cockpit.

Of course, I don't think these outcomes are likely if the limits of the
boat are respected. Of greater importance is a conservative skipper who
keeps the boat out of trouble in the first place, if at all possible,
and who is equipted and thoroghly trained for heavy weather conditions
and man-overboard, etc.







Thus, your inference that only around a third of the hull is protected
by the ballast tank is actually irrelevant,


Only to a non-boater with no experiance.


since if the boat runs over
an obstruction, the lowermost portions of the hull are the part that is
most likely to hit the obstruction and become punctured.


In a boat that only draws one foot it would take a complete idiot to hit a rock
dead on at high speed. Is that what you're claiming, Jim? That this design
feature is only there to protect the complete idiot? Far more likely is a
glancing blow to a floating object.


Obviously, the
boat doesn't have a complete second hull that extends throughout the
entire hull. (Does your boat?)


Actually, my boat has two complete hulls, running the entire length.

And which boat is that?

....


the

engine certainly wasted. BTW, they never actually say that there is enough

foam

to float the boat if the engine is attached, do they? Do you think they
destroyed a $8000 engine just to take that picture?

My engine weighs around 200 lbs., so I doubt that it is going to pull
the boat to the bottom. The picture of the boat afloat after they cut a
hole through the hull doesn't show the motor (so its not clear whether
they removed it or not), but it does indicate that, with five men aboard
the boat, the boat has sunk about a foot or so from its normal position.


Look again, Jim, its down to the rail on both sides. Given the very high
freeboard, that's closer to two feet below her lines. The question is, how
much foam floatation is left above the water?

Another question is, would four of your crew be standing on top of the
cabin in such conditions? If they remained partially submerged within
the cockpit or the top of the (open) cabin, the boat would be floating
much higher.

That tells you how close it is to
sinking. That picture is taken at the dock - in almost any sea conditions the
deck would be awash amd the boat would flip.


The new model (the 26M) has 300 pounds of permanent ballast. It would
tend to keep the boat upright.


Clearly, positive floatation is a advantage, but its not clear a flooded mac is
a better platform than a liferaft. On the other hand, the time may come when
you decided that unsinkable is a disadvantage.

Toute et possible. (Anything is possible.) But a boat that would stay
afloat, even if it didn't ride well,
far safer than a keel boat in which the heavy keel tends to QUICKLY pull
the boat to the bottom in the event substantial water enters the cabin,
from any cause. On a small boat, you aren't going to have much room for
a fully equiped life boat, and the heavier ones are not easy to launch
in high winds, according to Reese Paulley, who has made a number of
crossings.




would be far


In other words, with five adult passengers, the boat isn't anywhere near
sinking. 200 lbs of motor not make that much difference, and there is
plenty of capacity for more people, particularly if they didn't try to
stand on top of the cabin.

And, if you have any damage to the ballast tank, it could lose water and the
partially filled tank becomes dangerously unstable. This is not so bad if
you're on a lake where the mac belongs, but offshore this becomes

treacherous.

Actually, the new 26M model has a combination of both water ballast and
permanent ballast. The permanent ballast provides stability for the
boat when the water ballast isn't being used.


Not enough stability, given the stern warnings about aperating without ballast.



So the question is, would you prefer a boat with a solid hull that can

withstand

a beating without being compromised, or one that is likely to be compromised

by

a minor collision?

I would prefer a car with seat belts and air bags, and I would prefer a
boat with foam flotation. I would rather have a boat that would survive
even under critical emergency situations in which the hull was
compromised rather than one that would survive a minor collision but not
a major or critical one, in which case the keel would quickly pull the
boat to the bottom.


I would prefer a good sailboat that provides these advantages. In fact, I have
one. The mac is a poor powerboat, and a worse sailboat.

Have you sailed, or motored, the Mac 26M? No?

Jim