Triple-layer, rotomolded polyethylene canoes are not bad and are in fact pretty tough. The main disadvantage is their weight. The do tend to deform over time. Many will develop some permanent rippling of the hull bottom over time, but so long as the hull is not significantly hogged (bottom pushed upwards in the center) this is really more a cosmetic issue than a functional one.
Polyethylene canoes can be repaired. G Flex epoxy, made by West Systems, will bond acceptably to PE but only if you pretreat the material with flame oxidation. Flame oxidation is not difficult to do, and only requires an inexpensive, hand-held propane torch. To repair the crack pictured, it would be easier to first remove the deck plate. That would require drilling off the heads of the rivets securing it, and afterward replacing it, which would require a pop riveting tool.
Old Town made canoes they called the Charles River in both polyethylene and Royalex. But if the boat in question is truly 15' 8" in overall length, I would bet it is polyetheylene rather than Royalex. The Royalex version was very similar to look at, but had an overall length of 16' 3". An experienced eye can usually tell the difference between Royalex and roto-molded polyetheylene. If the boat has wood gunwales that sandwich the hull leaving the top on the hull visible between the inwale and outwale, you can see the separate inner and outer layers of vinyl on the Royalex material. But the boat is probably going to have synthetic gunwales that hide the hull top. Rotomolded PE boats sometimes have a salt and pepper appearance to the hull interior with small darkish specs. On Royalex boats, the interior vinyl is uniform in color. If there are areas of wear on Royalex hulls, usually on the hull bottom or exterior stems, in which the outer vinyl layer has worn through, the outer solid layer of the ABS material of Royalex will usually have a distinctively different color. On three-layer PE boats, the color of the outer solid layer will be uniform until you get to the foam core.
