what happened when santiago first took the boy in a boat?

From the text:

“How old was I when you first took me in a boat?”
“Five and you nearly were killed when I brought the fish in too green and he nearly tore the boat to pieces. Can you remember?”
“I can remember the tail slapping and banging and the thwart breaking and the noise of the clubbing. I can remember you throwing me into the bow where the wet coiled lines were and feeling the whole boat shiver and the noise of you clubbing him like chopping a tree down and the sweet blood smell all over me.”