I have been putting a floor in my Jon boat and put a screw through the hull. Short of welding, what can I use to patch the screw hole.

I have used a machine screw with silicone with good results in this situation.

You could put in a pop rivet and JB Weld around it.

Try some aluminum repair

I've patched some pretty big holes in my duck boat - like 1/2" holes where the old side mounted steering was mounted.

I just put the largest size machine bolt I could thru the hole with a flat washer on each side and good silicone or 3m 5200.

I used this stuff with a hand-held propane torch to repair a 10 1/2 tear in my Durcraft Jon.

BAC Industries Propane Torch Kit for Welding Aluminum, Galvanized Metal and MORE, Model# AP201

Item# 11070

Only $14.99

Here is a link to Northertools.com wher I got it at!

http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_31687_31687

For a small hole like that the easiest thing I could think of is plumbers putty. I costs about $4 and is easy to put on. Once on it drys like a rock and can be sanded etc to make it look better.

As far as aluminum goes I'm not sure you would have to make sure the stuff is campatible with Aliminum.

I bought mine at Ace hardware you could get it at Lowes etc easily.

Let us know what you decide and how it comes out.

The putty IS compatible with aluminum but I would still go with the short bolt/nut/washer on each side, 3m 5200 suggestion.  I've used this on quite a few rivets.  The putty, once hardened, is not conducive to flexing surfaces.  Seal eventually breaks, which is no big deal, throw some more putty in there, it's cheap enough, but I'd rather fix it once and forget it.

I couldn't use a nut & bolt because it is right next to the seat, so I used the machine screw with silicone method. I put it in the water today & it didn't leak a drop. Thanks for the sugestions.