fighting ship
艟 centers on a type of warship: a fighting ship used in naval combat.
艟 combines 舟 (boat) with 童, which likely contributes the sound ドウ. Together they denote a type of warship.
A boat 舟 that carries a child-like figure 童 into battle: a fighting ship crewed by young warriors.
For ドウ, imagine a fighting ship sailing through a doughnut-shaped harbor: dough -> ドウ, and the ship charges into battle.
warship