On Sun, 25 Jan 2004 11:28:06 -0500, Gene Kearns
wrote:

On Sun, 25 Jan 2004 09:38:58 -0500, Harry Krause
wrote:

Very few of the large boats winterized where we keep ours are properly
supported, in my opinion.

Most of the large boats are being held off the hard by jacks or by wood
blocks jacked into place and only at four places on the boat, two at the
stern and two forward of amidships.

My feeling is that if you are storing a boat on land, it ought to be on
a cradle, a device that supports most of the bottom and spreads the
loads out fairly equally. Supporting the weight of a large boat of many,
many tons displacement on four tiny points means that most of the boat's
weight is unsupported and will put undue stress on unsupported areas.

Agree? Disagree?

Very much agree. It is not uncommon to see boats held off the hard by
two stacks of loose 4 or 6 bys at the stern and one at the bow. (Pray
that it doesn't blow...) If the same boat was aground in shallow
water supported in like manner, any of the towing services would have
clear recourse to file for salvage (*not* towing) charges. Somehow,
in the boatyard, principles of physics and common sense seem to become
mysteriously inapplicable.

Boats are designed to be supported at many point by water. While
three points may define a plane, it is a poor way to support a boat
and exposes it to stresses never anticipated by the designer.

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.

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?

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)