My Nordkapp is a rotomold. It probably weighs in at just over 60 lbs. I have no trouble putting it on the roof of my truck or carrying it by myself. I chose the plastic version because of the amount of time I paddle on Georgian bay in Ontario. Anyone familiar with this area knows that there are almost no sand beaches, mostly stone and rock. I have paddled the boat only empty so far and find that it is "tippier" than many other boats I have paddled. But I didn't get it to use as a play boat. Tripping is what I wanted it for. I absolutely love the hatch covers and plastic welded bulkheads. The covers are a bit of a pain in the ass to properly put on but when they are on no water gets in at all. The other thing about this boat is that it is very rigid for a plastic boat. I haven't yet seen another plastic boat this stiff. Valley increased their price this year. I bought mine, a 2011 model, for $1570.00 Canadian dollars plus taxes. The price now at the same store is $1849.99. I am glad I bought it during the sale when I did.
And Strange Magic, I agree. It does look like a million bucks.

Looking at Sisson's site and quoting from it (note I said 28 lb but it should have been 30 lb) -

"All Sisson Kayaks are custom built these days. You can choose the type of footrest, type of construction lay-up and all-up weight. We can advise you on what lay-up would best suit your overall needs. We built our first Kevlar kayak in 1982. It weighed 49lb all up and was used by Paul Caffyn on his Australian trip. In 1985 we went for broke and built a 30lb (14 kg) all up Nordkapp for Paul’s Japanese trip. It is our understanding that this kayak is still in use more than a decade later. Our Kevlar experience goes back to 1977. Our early Kevlar projects involved the creation of helicopter fertiliser spreading, spraying and deer recovery equipment. Building the very best Kevlar kayaks was easy after that."

Relating to a standard order -
"Std Weight: 24kg
Kevlar Weight: 22.5kg"

Note also he says multiply kg by 2.2 to get pounds.

That's about all I know about his construction methods but they do seem to last.

Personally I stick to using wood so am not biased by Sissson's use of carbon or kevlar, flexible or not. Wood is stiff, light and strong enough. That is wood without a covering of glass, just epoxy.

Alex