I use island marine
products: sealant and liquid rubber. My protocol (from talking with manuf) is 1. Patch major holes, 2. Use sealant to close smaller ones, and 3. When dink holds air, paint
sun worn areas with liquid rubber.
Per manuf, older dinks may require resealing every year as new leaks develop. But given that a replacement dink is north of 4K, it is worth it.
I found blowing the sealant in using a shop vac to be more effective, (and convenient). Then deflate and reiniflate a few times with shop vac. Hi air flow supposedly is more effective in getting sealant airborne to reach any holes. And dink does not have to be turned over. Manuf said this is the approached used by big military inflatables for years...
Just got done with my second annual treatment...happy so far..