Brian Whatcott wrote:

When its design displacement is 6075 lb of water, it weighs 6075 lb.

Just because you don't understand why, doesn't mean the answer is
wrong.

I have read many reviews of new boats by architects and others, and
unfailingly the review features a discussion of how close the actual boat
(i.e., the "thing" that is launched and refuses to sink) comes to the
architect's design specifications. Rarely does the "design displacement"
coincide with the weight (i.e., mass) of the boat in the water.

I am speaking of a new vessel before the owner has gotten his slimy hands on
it and starting loading the "must haves," before the sailmaker has bent on
the "absolute minimum" inventory, loading all the while the remaining bags
in the vee birth where "I thought that's where we were going to sleep," etc.

This seems to be the case not only for one-offs, but also for production
boats with long runs . My boat had (has?) a design displacement of 9000
pounds. I once had her picked somewhere in Florida by a crane with a load
sensor, and the empty boat was much heavier that the "dd." I am trying to
be fair and take into account whatever I myself did to make things heavier,
but even when I do this the difference is very significant. Very.

It's the rare architect who can do a good match between "design
displacement" and the actual weight of the vessel. Certainly a lot of the
difference must be attributed to the builder and what happens in the mold
shop and elsewhere along the way. Just to be an old codger about all this,
I'd say that most of the architects who could do this have been dead for
some time now.


--
Good luck and good sailing.
s/v Kerry Deare of Barnegat
http://kerrydeare.home.comcast.net/