Ive just gone through this with my Zodiac
In my case the transom was plywood
and had rotted through and delaminated.
So I had to make a new transom out of 1" marine
then figure out how to glue it in the boat
which is PVC
The original design had a routed channel each side of the transom
and to this they have 9 holes drilled each side. Then they fit a plastic collar which is heat welded to mechanically adhere the plastic and the plywood
. Why am I saying this, the issue is PVC glue will not join to wood, they need the plastic ends to be able to bond the transom in.
Similar things apply to joining the PVC boat
material to the transom, so what they do is coat the part with hypalon glue, to which PVC glue will adhere. But basically I had to scrap their original plan and wished for a bit that I had made the transom out of rigid sheet PVC, but it would have been expensive.
In the end I opted for 3M 5200 to glue and fill the sockets each side along with SS 3/8" bolts and washers, and bond the skin of the boat to the transom. Ive heard from others that have had similar experiences thats it has lasted well going back as far as 2 years. But I guess because it wont come apart anymore ultimately it means that this is it for this boat, when the 5200 fails it will be time to replace the boat.
If your fix isnt this traumatic I think I would use PVC adhesive, it just wouldnt have worked for me. Do prep and clean surfaces with MEK if you can get it, acetone if you cant
show the old transom and the new part (you can just glimpse what remains of the 9 holes each side), the parts
flow coated trial fitted before 5200, and the completed boat all glued up but before the transom was painted blue with 2 pak