Does anyone know how long plastic kayaks last?

I have two 10+ year old kayaks, a 16' Necky Zoar (poly) and a 17' Prijon Kodiak (HTP), the hulls on both appear to be in good shape. I also have three 5 year old Wilderness Systems Tsunami's (poly and Duralite).

I'm wondering if I'll be willing them to my grandchildren, or whether I'll be replacing all of them after 15 years or so of life.

I don't think that polyethylene has an expiration date and how long it lasts is totally dependent on how it is cared for. My poly boats are as good as the day they came out of the molds and maybe even better in a couple of respects. I've made some minor, but important (for me) revisions.

Time might be an issue in the very long run, but ultraviolet rays and use abuse are the prime factors.

Poly degrades mostly from heat and UV. Keep em out of the sun and they will last a long time.

Plastic Jaskson poly wheelbarrows last about 7-8 years then get brittle and split when they hit them with a hammer to clean them. Boat should last easy 12 years if cover and 303 Protectorant once in a while.