Waves - against the ship - verb?

The waves lapped the ship's hull.

lap³ 2. (of water) wash against (something) with a gentle rippling sound.
_{‘the waves lapped the shore’
Source: Lexico—lap}

Note that the verb in this sense is considered transitive, which means an object will follow. Lapped what? Lapped the shore or lapped the ship's hull.

You will also encounter intransitive usages of lap (where lap is followed by—for example—a prepositional phrase: The waves lapped against the shore).

For simplicity, your best bet is to consider lap to already contain the sense of against: Choose The waves lapped the ship or The waves washed against the ship, rather than The waves lapped against the ship or The waves washed the ship (unless you need a free shipwash).