Q.please clarify the difference between the risk of collision and a close quarters situation.

Answer 1 Answers
Satyajit Dilip

In simple terms, risk of collsion is when you have acquired a target and the CPA from ARPA calculation shows around 0NM , then risk of collision exists. This is irrespective of the TCPA.

Close Quarter situation: These parameters are not clearly defined in ROR, but CQS is the minimum limits of CPA/ TCPA that the Master puts in his night orders or standing orders. By declaring these values, the Master has defined CQS limits and the OOW does not have the right to allow any vessels to pass below these limits. 

So for eg if he has written that the Minimum CPA is 2Nm and TCPA 15mins and you are overtaking a vessel and because of the available searoom round you, you can only keep a CPA of 1.5Nm, then the Master must be informed  before TCPA reduces to 15mins. This implies that the Master has to be informed whenever his Min CPA/TCPA limit parameters are not being complied. The Master will have different different CQS limits for different scenarios and he must ensure he writes this in his daily night orders. OOW must ensure vessel stays above these limits under any circumstances.