A port may be perfectly safe for the ships that generally use it but unsafe for others. This may be the case both in respect of physical and political risks. An example of the first is where a vessel is ordered to a port where there is a draught restriction which the vessel will exceed when loaded. In the case of political risk a charterer cannot order a vessel to a port where she may be detained because of her national flag. The leading case on this topic is an old one which concerned the largest vessel to sail to the port of London; as a result of the size of the ship tugs had to be ordered from Scotland. It was held that the port was unsafe for this particular ship and the costs of the tugs were recoverable from the charterers. In giving judgment, Roche J. said that it mattered not that 99 out of 100 ships using the port were safe if that particular ship was not. The port must also be safe when the vessel is in the condition which it will be when she uses the port. If a ship can use a port only when she is without cargo and not when she is loaded, then the port will be considered unsafe if the ship is ordered to it in a loaded condition. The same port would not be considered unsafe if that ship was ordered to go there to bunker whilst in ballast.