If the material around the pinhole is sound, I would second the rivet
option. I would be very concerned about cracks. They start from an area of
high stress and propagate as the material flexes. If a small crack has
started at the pinhole and has grown past the area where the rivet will be
driven, the rivet will spread the crack and drive the continued crack
formation. You need good solid metal on all sides of the rivet.

If the material has thinned to the point where it will not hold a rivet
properly it will not weld very well - even if it is a weldable alloy. When
the arc hits it well just melt through.

I would look to a doubler plate and rivets on the corners of the doubler.
Use some type of sealer as you place the plate.

Mark Browne

"Don White" wrote in message
...
I was thinking an aluminum rivet to fill the hole....

Wayne.B wrote in message
snip
If it was my boat I'd probably be inclined towards a cheap and dirty
approach such as drilling out the pinhole, tapping threads for a small
stainless machine screw, and securing with lockwasher, nut and a dab
of 3M 5200. Also put some 5200 on the machine screw before you thread
it in.