A couple years ago I purchased a Bell Yellowstone Solo, a new boat that had sat in a paddle shop show room for a couple of years. About the same time I purchased a Wenonah Wilderness. The Wilderness was just a couple months out of the mold. The YS hull seemed what you’d expect and the W hull seemed partially cured. My fingernail could easily mark the surface of the W and the hull had lots of flex.

The W has been stored in my garage for over a year now and when I pulled it out to introduce it to my new puppy I noticed that the hull seems to have cured over time. The W has been out of the weather in my garage.

My complaint with the W was hull flex. The flex has reduced with age. Has anyone had this experience?

Normal these days
Royalex ain’t what it used to be, and taking a year or more for it to harden up is now pretty standard. UV seems to speed the curing process a bit, but it’s still slow.

Major bummer for whitewater paddlers, since most of us don’t have the resources (or patience) to let a brand new canoe sit around in the sun for a year or more to finish curing before whacking it into wet rocks…

Royalex is flexible

– Last Updated: Aug-03-12 1:39 PM EST –

Most Royalex boats I've paddled are a LOT more flexible than I'd like them to be. I used to have a Wenonah Vagabond, and when I was in the boat, the bottom would pooch up enough that any water that splashed inside would puddle in the front and back, instead of in the middle. My friend Rena has a Mad River Eclipse who's bottom would become concave (as seen from below) if not for the pronounced V-shape that's there when the boat carries no load. The 'V' flattens out almost completely when two people are onboard. That boat is made from "lightweight" Royalex, but even so it seems to be a lot stiffer than what Wenonah puts in their boats. Even my brother's old Blue Hole had a hull that was flexible enough to pooch upward a couple of inches when scrunching over a submerged log. Back in the days when I used that boat it never occurred to me to look closely and notice how much the bottom pooched up just from the force of displacing water, but I'm sure it did that to some degree. My Mohawk Odyssey 14 is not as flexible as the old Vagabond, but its bottom pooches up noticeably due to the force of displacing water. The only Royalex boat I've paddled which doesn't flex much simply from displacing water is my Novacraft Supernova. That boat's hull cross-section is very round, which makes the material a lot less prone to bending. It would be wonderful if they invented a material as tough as Royalex or Polyethylene which had a lot more stiffness than either.

Like Twin Tex?
I know its not everyone’s cup of tea, but just sayin’.

There is a long discussion of Royalex
flexibility in a “sticky” on the forum.

I understand that the flexibility issue began when the supplier of Spartech blanks had to change formulation for the ABS layers to eliminate some noxious or polluting gas issue. The “new” formulation, now probably a couple of decades old, is flexible and dentable when new. It stiffens as some gaseous component escapes from the Royalex.

Really old Royalex (20+ years) may get rigid enough that pitoning the bow of a boat can cause jagged breaking rather than the more usual denting or tearing.