Any experience with polyethelene hulls?

[Sander Rave]

Depends on how you define not "very well" A (good engineered) rotomolded part won't fall apart from a little bit of grease wear or an oil film on the surface.
It's an economical attractive material for series/mass production.

[BillyDoc]

Unfortunately, most thermoplastics will flow under stress, and actually keep flowing until the stress is removed. UHMWPE is certainly one of these. So, if you can design your boat so that no stresses are present, you are OK. But if you're the kind of guy that sails and likes a little tension on the shrouds --- then over time your mast will become your keel. Also, many thermoplastics cannot be rotomolded, and making "big" things becomes really cost-prohibitive with other processing techniques, like injection molding.

Adding fibers to the mix helps a lot, but also causes quite a few other production problems if the fibers are actually long enough to significantly reduce "creep."

Which probably gets us back to fiber and some thermoset matrix material as the most economical and practical.

[icetreader]

We use strong paint solvents and occasionally nail polish remover to clean our HDPE hulls, and have had no problems.

This company has been successfully producing high performance PE sailing cats for decades http://www.hobiecat.com/sailing/index.html.
They've recently started producing kayaks as well. In fact, most kayaks are made from PE, including whitewater kayaks that hit sharp rocks at rather high speeds on a regular basis.

PE fuel tanks are common - just run a web search for "rotomolded fuel tank"

Molding from PE is a good solution for medium and high volume production of small-size watercrafts. It can even be an acceptable solution for smaller production series if the form of the hull allows using a fabricated mold instead of an expensive cast aluminum one.
Now we're told it's possible to weld PE and achieve good results (see other thread), and that sounds interesting.

Yoav