Fiberglass and related.

[Elmo Rodge]

I would respectfully disagree. After doing the inside, taper the outside (grind) and do scarf layups to fill. It will reduce the tendency to crack across the joint.   
Wayno

[tauruck]

You are right Wayno. I never read Jerry's question properly.
This is difficult to describe without pics or video.
I was going to say he should sand the two edges to a razor sharp finish (into the Gel Coat).
That's the stuff that will crack.

[floydjer]

Indeed..Pics would be a great help...The screws are close to the seam to assist in getting the surfaces flush w/ one another....So the cleco`s would end up bonded to the fender..I used screws so I could grind the points off  and even w/ the surface.  But I think I am on the right path. Thanks Bro`

[jdincau]

I have used aluminum pop rivets and drilled them out after glassing the inside.

[floydjer]

Another for you Mike...Should I re-apply gel coat over the spliced area??

[tauruck]

I said remove the Clecos when the resin goes green (just before initial cure).
That way you save the Clecos and keep them in a jar of thinner or Acetone.
Gel Coat and I are enemies. I was told that gel coat lacked certain chemicals
but those missing compounds were in the resin. Gel Coat only fully cures when
resin is applied to the surface. Could be BS but I'm not a chemist so I don't know.
In saying that I've seen Gel Coat stay tacky when applied to an already cured surface.
There is a coating for what you need but the name escapes me now. I'll check with
my supplier later this morning. I don't work with Polyester resins anymore but if the splice
is a good fit, grind the surface and use a filler you can mix yourself. Buy some Microballoons
from a composite supply store. That works.

[Speed Limit 1000]

You can spray PVA over the Gel Coat. I beleave that air keeps it from curing.