Fix engine mount Terhi boat

Hi guys.

Sorry if i dont use the correct words here.
i need to fix my terri vario t45. as you see in the picture it has 2 cracks on the engine mounting plate.
how can i fix this? the boat is made out of ABS plastic. they offer a repair kit for this boat. but i dont think it is strong enough.

so my plan is to fix the cracks with a special compound made to fix this boat (terri fix). make the same part out of glass fiber. just a little bigger. so it will support the stern of the boat more. i use a release compound in the engine well and use the boat as the mold. when it has harden. i take the casting out and sand it and the boat with 40 grit paper. and use a really strong adhesive and glue the casting to the boat.




any other ideas???

here is the manual from the dealer. using the replacement part:
fix the cracks in the boat with terri fix bondoe
sant the replacement part and boat with 40 sand paper
glue the spare part to the boat with strong adhesive
use terhi fix on the edges and sand to smooth finish and paint.

Ayuh,..... My guess is, there's supposed to be wood inside there to stiffen the transom,....

It's also my guess yer's is Rotten,.....