-- Last Updated: Feb-28-13 8:25 PM EST --
who are clearly masters of the warped and defective.
In all seriousness, I have seen the term "oil canning" applied to paddle craft in two different ways. The most common usage (I think) refers to the phenomenon of some rather thin Royalex and polyethylene boats (especially thermoformed poly boats that lack a keel ridge or keelson) to visibly flex upward under stress symmetrically over a sizable area, and then "pop" back to their original configuration.
I have also heard the term oil canning applied to permanent pan wave deformation of hull bottoms of some boats. Old Town Discovery 3 layer rotomolded poly boats seem especially prone to this. This deformation is not necessarily associated with a hog backed state (although it may be).
I don't usually refer to that type of permanent rippled deformation as oil canning because it invites confusion with the dynamic phenomenon of bottom flexing. It might not be inappropriate to do so though. Architects and roofers refer to a static pan wave deformation of thin metal sheeting as oil canning, which is caused by thermal expansion, probably the same mechanism at work on the Discovery hulls.
I have generally reserved the descriptors "hogged" or "hog backed" for hulls that have been permanently deformed in such a way that the midpoint of the hull along the center line draws less water than the hull at the stems. I suppose one could refer to a hull that is permanently deformed in such a way that the rocker has been reduced, but the center is still deeper than the stems as "hogged", but I don't.
Flexing could I suppose refer to any number of temporary deformities. Have you ever balanced a Royalex hull on a 2 x 4 placed under the midsection transversely? I have done so quite a few times when determining pedestal placement in symmetrical hulls. Many Royalex hulls will "droop" enough at the ends that both stems touch the ground surface, even though the hull bottom does not indent visibly. I'm certain the same thing happens all the time in whitewater even though the deformity is not visible (or permanent).