magic oar
Uh
#Boat shakes so violently...
random moat
Drop the anchor, that's what it's for.
IRL, it is standard practice to anchor at dock in combination with with mooring lines. Depending on the size of ship and location it may even be illegal to dock without anchoring due to safety and/or environmental reasons.
Unlike "Real Life", mooring cables in game are currently only useful for towing right now. Either towing the ship to dock or towing things with the ship (jetski, sharks).
Mooring cables alone have not been a reliable method of docking since Early Access began. Due to cable physics, Mooring cables are likely to continue pulling your ship to dock and can cause damage by pinning or ramming the ship against structures in rough seas. Contrary to reality, dropping anchor is the only reliable way to keep your ship stationary in game.
Just speculation, but there's probably a lot of work to do under the hood to ensure mooring cables function properly at all locations and in all weather conditions. I wouldn't hold my breath for it, and even then it's not wise to dock without dropping anchor.
Also, stabilizers help... and lots of medium batteries to power them over night.