I'll drink it!
Never had a hole that big, but for a long gash I would think sealant and rivets would hold up longest; you need to add some rigidity back but the seal needs to be flexible. The seams are riveted at the factory. They seal the outside of the hull around the rivets with a harder, flexible material, something like 3M 5200 Marine Sealant; this might be a better choice then silicone, will hold up better, easy to find. I use this for below water line on my boat, water intakes, transducers, etc.I used a few different patch materials on my old Radisson: 1) JB Weld type epoxy, not flexible, worked good on the ends of the keel though. 2) Duct Putty (sold in electrical stores), this is very close to if not the same putty they use to seal up the inside; very sticky and never hardens, I carry some for emergency repairs. 3) 3M Aluminum repair, works good, needs more prep work and the aluminum must be heated up; this stuff may work if it a a thin split. Link: http://www.cabelas.com/boat-care-appearance-cabelas-aluminum-boat-patch-1.shtml 4) GE silicone, tough, flexible lasts almost forever, easy to find and use.
Thanks JJ... really helpful