The general rule in time chartering is that matters of navigation are for the shipowners to control, while matters of employment are for charterers to control.
The Hill Harmony ruling in the House of Lords in 2000 made it clear that ocean routeing of a time chartered ship is an emplovment matter, since it affects the amount of fuel and money that the charterer saves. When, however, the master of a ship following time charterers’ route as directed actually encounters a hazard (e. g. ice or heavy seas) on that route, the matter becomes a navigational one and the master may leave the route and find a safer one. The master may not refuse to follow the time charterers’ voyage instructions only on the basis that he anticipates adverse conditions on the route. If hazards are actually encountered whilst on that route, the master may, however, always take navigational avoiding action.