I have a aluminum boat with a rivet that is leaking how is the best wat to repair this?

You said best way. The best way is to drill out the rivet. Check the hole size. If the hole is properly sized and not wallowed out, then clean it with solvent and install a new rivet, wet with sealant. Silicone sealant is acceptable, but there are many others on the market. If the hole is sloppy compared to the diameter of the rivet you removed, then carefully drill the hole at the size required for the next size rivet. Example: Removed 1/8" rivet, installed 5/32" rivet. Install the larger rivet wet with sealant. Go boating! If you want the easiest way, then just spoodge sealer all over the interior side of the rivet. :)

Yep, Threesheave has the best answer. Drill out the old rivet and replace with a new one. The temporary fix is the silicone caulk. Best of luck

Silicone caulking

Try sealing it with marine epoxy, inside and out if possible. The worst case scenario is to have the rivet replaced. Again, marine epoxy would help insure that the new rivet is well sealed.

Only the replacement of the rivet, and any other loose ones will effect a permanent repair. You will waste time with surface treatments, as they will not last near as long as doing it right the first time! All rivets are structural members so it is a no brainer they must be replaced if loose or damaged. Any rivet or other fitting should be bedded on Duralac or similar to prevent any potential future rot. http://www.rolco.com.au/p/337808/duralac---anti-corrosive-joining-compound.html http://www.binksonline.com.au/store/prod2546.htm This stuff is not to be got on your skin as it has some possible carcinogenic aspects apparently. It is why you pay us professionals to do marine work - we use stuff like this and the jobs are permanent. Good luck :)

rubber cement

first answer works for me