A container ship operator does not normally clause its bills of lading for “on deck” carriage, even though deck cargo is often carried. What should the company do in this case?

The company, as carrier, should incorporate a suitable liberty clause permitting on-deck stowage at the carrier’s option. 

This is recommended by the P&I clubs even when the custom of the trade permits on-deck stowage, e. g. when closed containers are carried on purpose-built container ships. The purpose of these clauses (which are nevertheless ineffective in a few jurisdictions which don’t follow the generally accepted principles of maritime law) is to ensure that the carrier has a contractual right to stow cargo on deck at his option. However, the clause must be used reasonably, and cannot be used to justify deck stowage for cargo which is unsuitable for deck stowage.