Save it be for the recent increased use of composites in aircraft, we have all trusted our lives at 30,000 feet for years and years to riveted aluminum skins over aluminum or steel (welded) frames subjected to heavy loads and "G's", extreme temperatures, turbulence, and weather! I know that air is thin and requires "lift" to keep from falling from the sky BUT some of that water is awful deep and cold too! As flintocke pointed out, not too many "all welded" planes (if any?) out there.
A few loose rivets are not going to sink you very quick BUT I could see where a failed or separated seam could be a liitle more dicey. Give the aluminum and rivets some love... the wood stocked, CM blued pre-64 M70 of the boat world!!!
