Found an old Grumman rowboat.  There is a crack in the gunwale (top edge).  What can I use to reinforce this. All I need is a short length of something that would fit over the edge and then be tightened by rivet or screwed down.  Seems like a simple repair, but I cannot find any aluminum extrusion that can be used for this repair.  Anyone have a tip for repairing/reinforcing an edge crack like this.  Thanks

Have it welded

Alum. welding is pretty expensive

fishizzle, when I need some aluminum repaired or parts made, I go to a place that specializes in doing it. It costs less than getting random parts and putting it together with screws or rivets. The company that I use makes and modifies aluminum boats for jet drive use and they do outboard skeg repair/replacement.

An aluminum boat's gunnel is part of its strength.

I had a transom extension made to clamp a trolling motor on the steering cable side of my boat. $21 for materials and labor:

I think I am just going to put a nice cleat on the gunwale.  The underside is flat. I can just put a 1/4" thick piece of aluminum under there and the cleat will span the crack. A bolt through both sides of the cleat down through the gunwale into the aluminum will hold it together and give me something to tie stuff to.  

You may want to consider drilling small holes at the ends of the crack to prevent it from spreading further. And then, like Wayne said, find a welder to run a simple bead down the crack would resolve the problem. Taking the boat to a welder / welding shop would make it a quick and pretty inexpensive repair.