Boat lock

Boat lock
Creation

Activate glowing iron lump (0.6 kg) Right-click large anvil Open submenu "Create > Locks"
Result
Boat lock (0.80 kg) 1 key (0.05 kg)
Skill and improvement
Uses locksmithing Cannot be improved

Description

An ornate and intricate metal lock used to lock a ship or boat. A recommended device to prevent your mooring anchor and boat from being stolen.

The boat's inventory window must be closed to attach or remove a boat lock, otherwise the option to Lock or Unlock won't appear.
To attach a boat lock, activate the lock, right-click the boat, and select Lock.
To remove a boat lock, activate the correct key, right-click the boat, and select Unlock.
You do not need the key to access the cargohold, permissions are managed in the Manage vehicle dialogue.

Only with a boat lock, the permissions in the management dialog will take effect.
The quality of the large anvil affects your success chance when creating.
The quality of the iron lump determines the maximum quality of the resulting lock.
You will want a quality of 80 or higher to effectively protect your boat on servers with lockpicking and stealing enabled.
You might also want to moor your boat with a mooring anchor.