Correct method to join fibreglass panels

I have two section of fibreglass which a need to butt up against each other and join. I was going to use polyester resin with 4 layers 450gm CSM on the un-seen side. Then I was going to grind out the front joint line to about 20 mm wide x 1 mm deep and fill this with epoxy filler.
Is this suitable method or should I be adding some reinforcement to the front side as well before filling, or should I be doing the whole job differently. The last thing I want is a cosmetic crack appearing at a later date. All advise appreciated.

 

If you do not want the crack to appear, beef up the rear side as you suggest, then grind out the front, tapered 1:8 or even 1:12 and replace the lost glass nicely. Sand smooth, re-gelcoat or paint.

 

Bit of a knowledge gap here.

What kind of pressures are going to be applied to the panels - are we talking structual hull, inner shell, deck, cuboard doors ,8x4, 6inches by 18inches

Thickened epoxy might be enough for some applications.

 

Whatever the use, herman has it about right anyhow.

 

Failing to taper the repair, which it is basicly, will always make the crack re-appear.

 

It wouldnt be enough for exterior hull with high loadings - you would need inner and outer laminations, and not just of chopped mat either.

 

Thanks Herman,
the joint in on the inner shell in the deck area. I will go with the 1:8 tapper fill with glass and then finish with epoxy filler.