Tom,
I just looked and we bought our 8 ft. PB in 1996. It did great service for all of these (16 years) years. I did upgrade from wood to plastic seats.
We just ordered a new 8 ft PB. NOT because the PB fell apart or anything like that. In the last year of use we began to get a small leak in the center bottom aft seam. It is nothing big, and I could fix it with Shoe Goo. But the real reason we ordered a new one is that after all of the years in the sun, (it was never covered) the sides are showing a LOT of chalking and it rubs off white residue on anything that touches it. The sun just ate it.
SOOOOOO.... I advise you to make a Sunbrella cover for when it is stored. Had I done that, I would still not need to replace it! And that includes a lot of dragging it across a lot of beaches and rocks!
The other advice I would like to put out is that once you get down to the Sea or tropics, make some white cloth seat covers!!!!! We used a lot of towels. Those black plastic seats are brutal!!!!
Greg