It seems more sensible to me that a light, strongly built
boat with a fast hull, would carry loads much better than a
boxy hull that was heavier to begin with.



Wayne.B wrote:
It really boils down to what is the impact of your cruising gear on a
light displacement boat vs heavy displacement.

Agreed. But I think it's easy to overgeneralize in a way
that reinforces one's prejudices.

... Let's for the sake of
argument say that you've got 4,000 lbs of cruising "stuff", e.g.,
extra water, extra fuel, larger batteries, extra anchors, chain,
windlass, solar panels, cruising canvas, food, refrigeration, tools,
spares, dinghy, motor, etc, etc.

On a 10,000 lb boat, that is a 40% increase, a considerable amount
which will no doubt adversely affect performance.



Same gear on a 20,000 lb boat is only a 20% increase.


Except that it doesn't quite work that way. What you need to
know is how the load will affect the center of gravity and
the wetted surface area, mostly... lighter weight boats
generally have higher ballast displacement ratios and more
reserve stability, and have so much less wetted surface than
a crab-crusher that the increase from loading is negligible.

A useful figure would be the pounds-per-inch-immersion for
each hull. Just a percent of gross displacement isn't going
to say anything that can be generalized about how the two
boats sail, comparatively.


Assuming both were the same speed to begin with, the lighter boat will
be more severely impacted.


Well, show me two boats of the same LWL with the same PHRF
rating, one at 10k and the other at 20k!

Another factor is that the heavier hull will have a lot more
volume and tend to be more heavily loaded. And the faster
boat will have more sail area, so the SA/D ratio isn't going
to take such a hit (given equal increases in disp).

Of course, my prejudices tend towards performance boats and
so I work towards justifying that.... but there is a good
bit of logic along with some real world experience in the
justification also.

Fresh Breezes- Doug King