Gentlemen,
A recent discussion between some of the schoolhouses has led me back to this forum seeking some feedback from the greater maritime community. I think this one is best posed as a scenario:
You’re out and gain another contact 045R at a range of 4 nm
Radar solution indicates a CPA of .2 nm
You hold the other contact visually and assess a crossing situation
You determine you are the give-way vessel
Additional:
Operating in Open Ocean
No Hazards to Navigation
No Other Interfering Contacts
In general, if you alter you’re course to Starboard and pass astern of the other vessel (to avoid crossing ahead), at what range are you comfortable taking the contact?
I understand that there could be more circumstances that influence your decision, but in general at what range would you give-way?
Depends on vessel type. On a tug/barge I’m good with 1/4-1/2 mile, as long as it’s obvious and course/speed of both vessels have been steady, but I imagine that would be pretty uncomfortable between two ships.
I tend to make my initial course change very large and obvious, then ease back to a smaller CPA as I see fit.
0.0 NM CPA if you’re using torpedoes.
As long as you pass astern of them and it’s obvious that you’re not going to risk collision anywhere larger than .5nm should be good. I’ve seen some people do closer but I’d be more comfortable with a larger one.
[QUOTE=ARINALDI;160095]Gentlemen,
A recent discussion between some of the schoolhouses has led me back to this forum seeking some feedback from the greater maritime community. I think this one is best posed as a scenario:
You’re out and gain another contact 045R at a range of 4 nm
Radar solution indicates a CPA of .2 nm
You hold the other contact visually and assess a crossing situation
You determine you are the give-way vessel
Additional:
Operating in Open Ocean
No Hazards to Navigation
No Other Interfering Contacts
In general, if you alter you’re course to Starboard and pass astern of the other vessel (to avoid crossing ahead), at what range are you comfortable taking the contact?
I understand that there could be more circumstances that influence your decision, but in general at what range would you give-way?[/QUOTE]
You don’t say what type of vessels. On a large vessel at 16 - 19 kts I would expect to see another large ocean vessel at 15 miles or more away. The course change would be made before 6 miles or more. Standard CPA (closest point of approach) on another large vessel at sea is 2 miles.
In your scenario standard practice would be to change course immediately (4 miles) with a one mile CPA.
Most mariners would be “comfortable” passing much closer but passing distance for watch-standing officers are not determined by each individual’s comfort level.
Nothing to be gained by passing close but risk of a high-consequence incident in the highly unlikely event of something going wrong.
[QUOTE=Kennebec Captain;160125]You don’t say what type of vessels. On a large vessel at 16 - 19 kts I would expect to see another large ocean vessel at 15 miles or more away. The course change would be made before 6 miles or more. Standard CPA (closest point of approach) on another large vessel at sea is 2 miles.
In your scenario standard practice would be to change course immediately (4 miles) with a one mile CPA.
Most mariners would be “comfortable” passing much closer but passing distance for watch-standing officers are not determined by each individual’s comfort level.
Nothing to be gained by passing close but risk of a high-consequence incident in the highly unlikely event of something going wrong.[/QUOTE]
Exactly. CPA limits are determined by the Captain and only the Captain, and one does not normally get to be Captain by taking unnecessary risks. I’ve run across the occasional Captain who would explicitly state that a CPA, in clear visibility, good visual contact, on smaller vessels (tugs, fishing, sailing, etc.) of one mile was fine. Any situation where a contact was gained late and the required CPA could not be reasonably achieved without a round-turn, would necessitate a call. Unless it was a small vessel, however, I would expect the Captain to have some very serious questions about keeping a proper lookout.
Smaller vessels are probably going to be perfectly fine with smaller CPAs, as z-drive says. On my ship, two miles is less than fifteen ship lengths. On, say, a light tug, at roughly 150 feet LOA, the same ratio is roughly a third of a mile.
On OSV’s I’m good with a quarter mile when taking someone stern when vis is good and contact has been made. I generally like to keep it at half a mile though.
Way out in the open like that with no other interferences? I’d give it a mile or more, just because I can. Confined waters would be a case-by-case basis.
Like stated, all depends. I do generally make it a rule to not mess with ships and leave them at least 1NM CPA crossing their stern in the day and 2NM at night. I only really run into this when crossing the sea lane heading to and from Galveston. Me personally will not even cross a big boats bow even if the BCR is 3NM. If something happens to their steering and they turn towards me, my vessel just can’t out run them like a crew boat. That’s just my chicken ass. I go by the rules of gross tonnage a lot, seeing how long it takes an Aircraft Carrier to turn going 16 kts I just don’t mess with it.