So before i had this calc which already establishes a few things but mainly that the beam is 114.1497871cm wide. The beam wrecked in the background seems to be visually close to the same size as the beam that falls in front of the pirate and there's really no reason for them to be much different.
The beams are square so the volume has two of the same values.
Now for the length of the destroyed area. Klol recommended using the pirate's fist width for that.
Beam is 270 and the fist is 295.
114.1497871/270=0.42277698925cm/px
0.42277698925*295=124.719211831cm
124.719211831*114.1497871*114.1497871=1625113.0182 cubic cm.
This is wood frag so 6.4121*1625113.0182=10,420,387.184 joules - Wall level+