There are some guidelines on service life...
...that are generated by regulatory bodies. E.g. the French stipulate that, after 10 years of age, a raft no longer will qualify to meet their offshore sailing regulations for French-registered boats. ('Offshore' re: raft regulations would be like our coastal sailing). In a circular fashion, the logic probably makes sense. Given the regulations, many sailors must carry a raft or be cited...which means raft mfgrs. like Plastimo and Zodiac produce cheap raft products that are neither as robust nor as functional as the ones we typically see in U.S. boat shows. (This is not unlike the similar 'market vs. regulatory requirement' relationship that has existed re: VHF radios in the U.S. for decades. Some of us may carry VHF radios that perform to minimum FCC specs but are neither the most capable nor longest lived products - but they offered compliance at a bottom rung price).So...a meaningful lifespan is a function of several key variables and many lesser ones. Key variables would be what material is used to build up the tubes, how are the seams built (and how well), how has the raft been packed (worst is in a cannister on deck without vacuum bagging; best is probably a valise stored below in a dry locker), and how long between individual inspections. I know of no mfgr. who suggests 5 year inspections; most I've seen are 1- or 2-year with one at 3-year, no doubt in part for liability and product performance reasons. The max period viewed as acceptable - e.g. if the boat is in situ for a while and the raft is brought home and 'parked' in a dry/cool location - is 3 years, because much of the safety gear needs to be changed out or inspected at that point.The minute you step away from a mfgr. and begin dealing with a raft repair facility, you've added another layer of variability. One repair facility may find a certain repair (e.g. attaching a new valve assembly to older tube fabric) acceptable, while the next might not. The most stringent repair facilities are those doing aviation work, because the FARs and FAA certification process is so stringent. E.g. Winslow only recommends those aviation repair facilities where the personnel have gone to Winslow for their training (which BTW is in compliance with - and inspected by - the FAA)plus their own factory as authorized repair centers, as that way the insure maximum control of everything from the temp at which the glues are stored to the details of a given procedure for a repair.I recently helped a friend buy a used raft, as he's crossing the Atlantic shortly and couldn't afford a new one. We found lots of choices (eBay being one productive source) and in the end he got a 6-person Avon offshore-rated raft that was 2 years old for half the now-current retail price. (I heard about this raft via networking; nothing rivaled this on the Web). His first stop after picking up the raft in his car was to drive it to an aviation-certified raft repair facility in Tampa, where it was inspected and repacked.Jack