Shortening paddle blades

In another thread I explained how I downsized an old Epic mid wing for my 10 years old son.
www.surfski.info/forum/17-equipment/1845...le-sizing.html#24337
I grinded the blades to be 46cmx14.5cm. (was 50cmx16.5cm before).
Now, on the edge, I can see the foam core inside the blade. Is it OK to leave it like this ? Do I need to seal it with epoxy ?

It is not ideal to expose the core, but it is a closed cell foam so it will not soak up water. It will however not be very strong on the edge as there is very little material either side of the core, any impact will damage the edge quite easily.

The main issue is the balance and stability of the blade through the water. Yes you can paddle with it but to get the best stroke it might be difficult as the blade will want to track differently in the water to what it is designed for. Also the thick edge will make quite a splash and noise on entry to the water, not matter what you do this will not go away which could be frustrating.

My advice would be to seal it, or use these blade edge covers which they use for Sup paddles. the splash would be there, but the blade wil last.