On Sun, 25 Jan 2004 13:12:06 -0500, Gene Kearns
wrote:

On Sun, 25 Jan 2004 16:51:46 GMT, Short Wave Sportfishing
wrote:


If that is the case, then why are there three defined "strength" or
lift points on the Contender - all above water? In fact, the Ranger
can be lifted in a similar fashion to the Contender - one bow and two
stern lift points.


Guess who decided where those lift points are... and why!

I'm assuming that the engineers who designed the boat did.

Intuitively, you should see that picking *up* on predetermined lift
points should be different from three "sorta flat" points chosen
merely for convenience by dock hands to support the boat's weight by
"pushing up".

Correct - the stresses involved in using three lift points would be
greater than those used when the vessel is in storage.

Again, I'm not a structural engineer, but it seems intuitive that load
stresses should be distributed evenly from any point on the hull.

Right/Wrong?


Wrong. Hulls are not made that way... they aren't the "same strength"
all over. Hull thickness is not the same all over and structural
members don't run "everywhere."

Let's take my Ranger as an example. The bottom is thicker glass and
has a stringer system with a "tub" and foam is poured inbetween - the
entire structure is one solid mass - of differing densities for sure,
but still. I can't quite understand how supporting a fairly solid
mass on three or four points, beyond the stability factors, would be
more or less detrimental than a complete stem-to-stern cradle.

Later,

Tom
S. Woodstock, CT
----------
The years will bring their Anodyne,
But I shall never quite forget,
The fish that I had counted mine
And lost before they reached the net.

Colin Ellis, "The Devot Angler" quoted
in A. R. Macdougall, Jr's "The Trout
Fisherman's Bedside Book" (1963)