Was there a fitting/flange over that??

Marine sikaflex would do the job however I'd look at getting a plastic drain insert (if you have the existing one or can get one the same size) from a marine shop and bog this in with a mixture of fibreglass resin/thickener and chopped glass mat.

The resin/chopped mat bog mixture probably wouldn't work so well on it's own as the crack is relatively small.  Sikaflex should seal it for a number of years and would be easy to clean off and reapply again when you need to.

Either way tape the area off first for a neat finish

 Edit - Had some pics of a similar repair but can't locate them (will check work computer tomorrow)

 no there wasn't a sleeve or flange but that sounds like a good idea Paul! 

I recently did some repairs to transom and used Epifill,its a 2 part epoxy got it from bcf worked well.just key up area where you are applying it to.

 Mate

How big are those holes in the transom ? The scuppers fitted to my boat have 50mm holes and I regularly get a slow leak through these. I am replacing the entire scupper and fitting a stainless steel threaded water filler type insert. It's a bit like a recessed fuel filler cap only designed for water. Fitted with O rings they should resolve the water entry.

When I need to drain, just unscrew. can be left open on chain that secures cap to main assembly but need to be tightened when launching !

If I could work out how to post an image into this thread I could put up some pics or if you are interested I could start a new thread so you can see what I mean. PM me if you want to see.

cheers

 all good cruise control.i have put some sleeves with flanges on and refitted old scuppers as they work really well so my boat is fixed but the holes were 40mm