Ply core would be ok for mast construction, but there does not look like there is much glass work included, let alone any carbon.

There needs to be a balance in the composite layup - have you ever seen a multi storey building stand up for long becuase they used more concrete than reinforcing steel??

My observation is not enough glass/carbon to support the ply structure & timber structure.

It looks like the ply webs with fillets may have stopped at this point or did you cut the broken section to make it clearer viewing.

marcus