Action by Give-way Vessel.
Every vessel which is directed to keep out of the way of another vessel shall, so far as possible, take early and substantial action to keep well clear.
In any potential collision situation, the remedial action required must be a partnership between the vessels involved. In the case of the ‘give-way’ vessel, the emphasis is on early and substantial action being taken: a repeat of Rule 8.
If you find yourself to be the ‘give-way’ vessel under Rule 15, approaching the port sector of another vessel, early and substantial action (again, as in Rule 8) is required, which would normally comprise of a bold turn to starboard and/or a reduction in speed. However, remember there are other situations in which you are directed to keep out of the way of another vessel.
This raises the question of what substantial action, or a bold alteration of course actually is, when taking action to avoid a collision. There are many interpretations, but these in turn depend upon varying factors such as: the speed of the two vessels involved; their size and how close to each other they are. However, a good rule of thumb is to make an alteration of course to starboard, so as you are aiming for a point astern or behind of the other vessel. This has the added advantage of clearly showing to the other vessel, that you have altered course by displaying a very different aspect to her and at night, she would see a change in your sidelights from green to red. Remember, that whatever action you take, it MUST be readily apparent to the other vessel observing either visually, or by radar alone. Most important thing to note is CPA given by radar will have errors at close range and will be misleading. You will notice that many collisions have been touch and go incidents. CPA given by radar is for Radar scanner position and not your ship’s body.
The result of the action you take, must be that you pass the other vessel at a safe distance. So what is a safe distance? This will depend on varying factors such as: company standing orders; the size of the vessel you are on; the wishes of the Master and your own experience. A good rule of thumb however, is that you really don’t want to be any closer than 1½ to 2 miles to another vessel in open water, if you can possibly help it.
Finally, you should remember that it is much easier being the Give Way vessel than the Stand On vessel. This is because you know (or should know) what you are going to do and when. A small and/or highly manoeuvrable vessel such as a Ferry, Offshore Supply vessel or a Warship might be happy to get quite close to the Stand On vessel before taking action. If the Stand On vessel was a large and/or not very manoeuvrable vessel, this might be causing the OOW to start becoming very concerned as to what (if any) action the Give Way is going to take. A large supertanker for example, may get concerned at about 5 to 6 miles and would certainly be taking action by 4 to 5 miles.
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