To quote the Collision Regulations—‘Risk of collision can, when circumstances permit, be ascertained by carefully watching the compass bearing of an approaching vessel.’ Most seamen are so familiar with this injunction and with the practice it describes that any particular significance in the wording probably escapes them. It is, however, important in considering the operational use of radar to note that the compass bearing and no other kind is specified and to appreciate that this is so because the relative bearing will only give quite comparable assurance when own ship maintains a perfectly steady course during the approach.