[Darrin Wright]

thanks guys for all your input.
I am picking up a heavy duty mig today from a friend and will look at preparing the steel this weekend and commence welding next week.

I think (and this thread has confirmed) preparation is a very important factor, so will grind a vee on both sections of the hull & panel, and ensure any slag is removed.
Weld in some braces to support the new panel, some minor tacks to get it in the right spot, adjust with a hammer, then weld away alternating from side to side so that heat expansion does not affect the new panel.
When finished grind and tidy up the welds, then run over it with a flapper sanding disc to get the surfaces right. When the hull is blasted get them to concentrate on the welded area to get the surface texture the same.

Thanks again