On a Facebook video which demonstrated a cannon from Nelson navy, the presenter mentions that the aim was to cause devastation on the far side of the deck and showed how upon impact a large number of wood fragments and splinters were scattered behind the impact point which would have been inside the hull and inflicted injuries on the crew.
Was there any methods or techniques to reduce the devastation? Was there any changes to the training or ship design with the primary intention to address this issue?
There were a few things done to mitigate splinter-wounds, mostly in the sense that when a ship "cleared for action" they would remove furniture, hoist the boats overside to tow, and in the case of an impending battle sometimes simply jettison things like chicken coops/barrels/boxes and so forth (you wouldn't do that in practice). Captains would rig splinter nets over the top deck(s), to prevent or mitigate injury from falling rigging, but there's not a lot they could do to prevent splinters from round shot striking the hull from causing damage to the crew or the internal parts of a ship. I wrote before about what a naval battle would look like from the crew's perspective.