In The Sea of Monsters, Tyson has been telling Clarisse that they cannot push the boat any harder or the engines will not hold up. When she dismisses his warnings the boat's engines begin to fail. While they are under attack, Tyson goes below to try and save the engines. The ship blows up while Tyson is below decks. Percy did not see him surface or get on board any life vessels. He fears that his 1/2 brother is dead.