Too much resin in the void of broken are make it heavy. Better will be glue it tight together with resin mixed with microballs and than normally glass it over.
For a stronger repair. You should've create a complete one piece stringer. Split the foam-blank in four since it broken in half other wise split it in two to create the blank. Next step glue the pieces of foam/blank to the new stringer. Then relaminate the whole board. This on the video is quicker but not nessesary stronger and the alignment has to be perfect or you'll get a kink. If it's still working and you don't feel the misaligment/kink, then you did a good job!
Don Carbon , Thank you for your comment. In fact it is riding since then. How would you do it to make it stonger? Bigger sticks? It is an already very old board but the outside layer is much stonger now than before. I'm not going to open it again unless it breakes again. Ideas are wellcome. Thank you José Miguel Santos
It is riding with no issue. Note that it is not just the sticks that provide the strength there is also the epoxy and the fibre reenforcement band arround the critical zone.
