"William R. Watt" wrote:

Brian Nystrom ) writes:
Most people wouldn't understand these numbers, so they're rarely published.

what the sales literature had were vague statements like "for weekends" or
"for multi-day trips". I think they should be more spacific and say "this
boat is designed to perform best with a load between 250 and 500 lbs". I
don't see the value of interior volume since its more important to know
how much the boat will float the size of what it will hold. Room sizes are
more appropriate to buying houses which don't have to float their
contents.

I don't disagree with you, but what they're doing is catering to the market.
Categories such as those you mention are useful for the average person who's trying
to figure out what boat suits their needs. Carrying capacity is commonly published,
but moreso for higher-end boats. It's also easily misinterpreted. Is it the designed
cargo weight? Is it the weight at which the boat submerges? How much of a safety
margin is built in? Etc, etc. If the manufacturer provides enough detail, it can be a
useful number to know.

If you were looking at plastic boats, that's typical. There are a few out there
that use better materials that are more distortion resistant (Prijon, P&H), but
most polyethylene hulls will distort due to heat and/or pressure. They will
usually return to shape if left out in the sun.

I was careful to distinguish between design weakness and temporary
distortion. I've seek a kayak come off a trailer after a long trip with a
big dent in the side which will strighten out. No, the flat spot on the
chined boat was due to the material being too thin. Housing standards
specify the span beteen joists for plywood of a given thickness. There are
similar standards for boats from insurance associations and naval
architects (eg military), and guidelines such as David Gerr's "Elements of
Boat Strength" of which our public library has a copy. The hull design
programs I've seen don't cover "scantlings", but do cover a lot of
other things like shape, initial stability, capacity, resistance, etc.

There are several kayak companies that are notorious for making flimsy hulls. For
them, it's all about marketing and not about performannce, though in some cases, the
problem is limited to specific models, typically short, wide, low-end boats. It's
good that you picked up on this.

--
Regards

Brian