removing rivets

[nighthawk]

i am changing the keels on an 18ft. aluminum fishing boat...too many loose rivits and too many leaks...there are about 500 drive rivits to remove to put on the new keels..also more to do all of the bracings below the water level.
i am looking on information on the easiest and fastest way to remove all of the rivits without damageing the removed braces and the original holes.

[Arrowmarine]

Fastest and easiest? (option 1) Take a pneumatic chisel or a 60 grit sanding disc and buzz off the large end of the rivet, then use a punch to knock 'em the rest of the way out. This may or may not prove to be easy. If your hull is thick enough, you can work the chisel in between the keel and bottom and cut them in half then punch them out. You can drill them out but that can be hard to start the drill on the round rivet head.
Now, (this is me talking) there is NO WAY on God's green Earth that I would even consider using rivets for re-attaching the keels. I would (option 2) enlarge the holes a little to get clean metal, and weld up every hole on the hull. Then sand smooth and weld on the keels. Again, that's me :-) But, if you got it in you to cut, punch, sand and rivet over 500 holes(not counting if you have to drill the new keels)
Then "Mister, you're a better man than I" :-)
Now, option 3. If you can get to the rivets inside the hull, grind off the heads and weld them up. But, if you do this you have to stitch weld the existing keels in place. Possible, but not recommended.
And finally, option 4. The one I usually end up turning to whenever a leaky, noisy aluminum boat comes in for repair.

More silicone.

Hope this helps. Peace, Joey

[cyclops]

I mostly agree. You will probably find you can drill out some cleanly, but many loose and almost loose rivits will spin and cut a bigger hole or almost cut the bigger hole. I get a person on the other side of the hull with a 2-5# SQUARE edged CHUNK of steel or iron. I have a CHUNK of square ended metal 1" X 1" and use it to re-tighten the flared ends down. You are only to tap the ends SNUG, not squash or DEFORM the depression of the rivit. You can get a rythem and move along. Sound tells you to redo that one. This is a one time repair. Still use a VERY SOFT wire wheel to GENTLY - LIGHTLY clean and rough up outside and inside rows of rivits. Clean the rows with ACETONE to remove any coatings . SILICONE the rows inside and outside. Let it set up for at least 1 week!! Good as new.