The Law of Tonnage

[doug748]

....

This company's approach is that yachts are more often than not capricious clowns which should not be relied upon to do anything correctly, including responding to urgent VHF calls. Best to keep out of their way where possible. ....

Sounds a lot like the standard yachtsman's attitude to ships.

.

 

[capnsensible]

That's the one! Though you may be surprised as to the actions of the 'Might is Right' brigade; I was.

Here's a question for ship masters on here taken from a major shipping co.'s training vid. You are OOW and spot a yacht travelling at 6kts at 90 Deg off your stbd bow, distance 3 miles. Your speed is 15kts STW, CPA 50m, TCPA in about 11m.

Is the yacht stand on yet? Almost certainly. What do you do? Alter to port and the yacht can do what she likes with no possible contact point. Alter to stbd (better under IRPCS) to go astern of the yacht by say 0.5m. Trouble is, unable to resolve your actions the yacht might panic and turn sharply to stbd putting herself directly beneath your bows in the mistaken belief you will pass ahead. Or she might panic and alter hard to port in the erroneous belief she will somehow manage to clear your stern. That second option is captured on one of their bridge cams, resulting in a closing speed of 20kts+ and a very lucky escape for the yacht.

This company's approach is that yachts are more often than not capricious clowns which should not be relied upon to do anything correctly, including responding to urgent VHF calls. Best to keep out of their way where possible. One French master commented that they have 'eco-ducts' over motorways in France for wildlife to safely traverse. He wondered as to the feasibility of a 'yacht duct' over the Straights of Dover! ?

Their advice is unambiguous: follow the IRPCS for everyone's safety, most strikingly the yacht's. DO NOT cook it up as you go along. Else, stay well away from busy shipping routes and by that they mean by that at least 4 miles at all times.

Might be rather helpful if the vessel when altering made the appropriate sound signal. Ambiguity resolved.

 

[Muddy32]

I sat my yacht masters' BOT ticket back in 1966 at S'hampton before not one but 3 venerable Masters.
I was really put through the mill, but passed in the end.
Two reasons- it was to skipper "yachts not big ships" , and I was only just 18 and 2 weeks old.

Refueler's comments about a bold alteration of course is relevant. It is easy for me, in a yacht to alter 40-50 degrees one way or another to avoid the other vessel if 1-2 miles off, and she can more easily see my change and it won't put me too far off my track in open sea. I am not on a time schedule.

 

[FlyingGoose]

I sat my yacht masters' BOT ticket back in 1966 at S'hampton before not one but 3 venerable Masters.
I was really put through the mill, but passed in the end.
Two reasons- it was to skipper "yachts not big ships" , and I was only just 18 and 2 weeks old.

Refueler's comments about a bold alteration of course is relevant. It is easy for me, in a yacht to alter 40-50 degrees one way or another to avoid the other vessel if 1-2 miles off, and she can more easily see my change and it won't put me too far off my track in open sea. I am not on a time schedule.

I am Offshore on paper , and try to follow the rules to the point of anal (Im aspie) but as your post I would always stay far away from big ships I tend to give clear and quick decisions by moving well away , although the rules wander about my head making me ache, But I watched our intrepid french fighter pilot on You tube sailing up the west coast of France and he tried this manoeuvre heading towards a large ship and they immediately got on the radio and told him to hold position and they will alter as per the colregs , What should we do, or is it a situation at that moment to make . (logical experienced answer please)

 

[requiem]

I suspect the 'might is right' brigade more often than not don't actually do anything against the rules and think the rules are much more restrictive than they really are.

In many congested places, like the original video, the IRPCS effectively default to "might is right" thanks to Rules 9 and 10. (I was very surprised, one summer day on SF Bay, to hear the Coast Guard reciting Rule 9 over the VHF as a general reminder.)

Here's a question for ship masters on here taken from a major shipping co.'s training vid. You are OOW and spot a yacht travelling at 6kts at 90 Deg off your stbd bow, distance 3 miles. Your speed is 15kts STW, CPA 50m, TCPA in about 11m.

Noticing that the CPA numbers don't make sense for that situation, I verify the bearing and range information, and check that a third vessel hasn't been overlooked.

 

[Uricanejack]

In many congested places, like the original video, the IRPCS effectively default to "might is right" thanks to Rules 9 and 10. (I was very surprised, one summer day on SF Bay, to hear the Coast Guard reciting Rule 9 over the VHF as a general reminder.)



Noticing that the CPA numbers don't make sense for that situation, I verify the bearing and range information, and check that a third vessel hasn't been overlooked.

No the numbers don’t add up. Even if they did, what other factors are involved.
So small sailboat, to starboard, on collision course, roughly 3 miles.

Side irrelevant, it’s a sailboat. you are give way, so give way, not complicated

3 miles? rather close for some vessels, still a long way for others.
3 miles first sighted? or Vessel alters when sailboat is 3 miles?
OOW left it a bit late, sailboat became concerned, and turned towards the ship,

Courtesy works both ways.
Unfortunately not all mariners are courteous, Some are Jerks, I have known a few Jerks, who apply might is right. Some make errors, who hasn't? Sometimes small vessels just are not seen.

If you become concerned? Turn Away.

 

[pagoda]

In many congested places, like the original video, the IRPCS effectively default to "might is right" thanks to Rules 9 and 10. (I was very surprised, one summer day on SF Bay, to hear the Coast Guard reciting Rule 9 over the VHF as a general reminder.)



Noticing that the CPA numbers don't make sense for that situation, I verify the bearing and range information, and check that a third vessel hasn't been overlooked.

I don't work on the bridge of such a vessel, however " if to starboard "red" appears - it is your duty to keep clear. OOW orders turn to STBD ? to pass astern of the yacht?

If I were on the yacht I would see this big boy coming in from my port side. Hmm, just maybe turn to STBD promptly and parallel his course for a few minutes to get him out the way and past?

Two solutions... neither is necessarily the best? Best give him a shout on 16....

 

[requiem]

I don't work on the bridge of such a vessel, however " if to starboard "red" appears - it is your duty to keep clear. OOW orders turn to STBD ? to pass astern of the yacht?

Two solutions... neither is necessarily the best? Best give him a shout on 16....

My observation was just that, for a small sailing yacht on my beam, my best avoiding action is to do nothing: at 6 knots he'll be well astern no matter his action. I'd be more worried about why the electronics were giving a dangerous CPA that's unlikely to be coming from that yacht.

Put the yacht 30° off the bow and it's a bit different. Note: I'm not on such vessels either.

 

[Refueler]

My observation was just that, for a small sailing yacht on my beam, my best avoiding action is to do nothing: at 6 knots he'll be well astern no matter his action. I'd be more worried about why the electronics were giving a dangerous CPA that's unlikely to be coming from that yacht.

Put the yacht 30° off the bow and it's a bit different. Note: I'm not on such vessels either.

I have to say I read the original and thought ... 90 of the bow ??? That makes CPA etc. unlikely ... but then just assumed that questioner was not talking relative to bridge ... but to the actual bow (stem) of his vessel ... then it makes more sense ... even then the speeds are such that I doubt there is a collision ...... (I haven't plotted it to check ... )

 

[GHA]

Put the yacht 30° off the bow and it's a bit different. Note: I'm not on such vessels either.

More like 21deg
Just happened to have cad open last night on the laptop when reading that.

 

[dom]

I have to say I read the original and thought ... 90 of the bow ??? That makes CPA etc. unlikely ... but then just assumed that questioner was not talking relative to bridge ... but to the actual bow (stem) of his vessel ... then it makes more sense ... even then the speeds are such that I doubt there is a collision ...... (I haven't plotted it to check ... )

You‘ve basically got it: calcs aren’t relative to the bridge, the ship’s speed through water doesn’t relate to the same reference frame as the yacht’s AIS (GPS), and there is always an error term. To avoid any possibility of calibration risk, many of the large shipping co.s - I am told - set a minimum open water safe clearance of at least 0.5m.

 

[zoidberg]

As a vulnerable and venerable yottie, I'd be thinking 'It's his responsibility to do something to avoid a very real Risk of Collision. If he hasn't done something evident by - say - just under 2 miles ( in accord with Rule 16 ), it becomes MY responsibility ( Rule 17 ). What are my options.....?'

My 'series of bearings' will have established a Line of Constant Bearing exists, which is 'a Risk of Collision exists'.. How can I change that...?

I could ease sheets to change speed to change the LCB. Might that be enough to resolve the situation under Rule 17?
I could stop where I am. Might that be enough to resolve the situation under Rule 17?
Could I change course? Might that be enough to resolve the situation under Rule 17?
What combination of the above might resolve the situation AS I SEE IT while retaining my capacity to manouevre should my initial 'change' prove insufficient?
What might he do to screw up all those judgements? Do I have a Plan B for Rule 17?

I would ensure my own engine was available for immediate manoeuvre.

 

[Uricanejack]

It’s really not terribly complicated.
If you are the give way vessel? Give way. Take action early and make it obvious to the other vessel.

The example given, is hard to comment on beyond this. The numbers don’t add up. The reported CPA and TCPA don’t jive with the stated relative position and speed. Never mind.
Never quoted a CPA in meters. 50m is 0.025 miles or 0 .25 cables.
CPA is virtually nil. You got 11 minutes. At 15 knots give or take a bit less than 3 miles.
for a 6 vessel at 6 knot, give or take a bit less than 1.5 miles.

The sailing vessel is roughly 2 point to starboard.
No other factors mentioned.
Easy peasy, no excuse for it to end up in a close quarters situation.

what action would I expect?

An alteration to starboard large enough to be readily apparent to the other vessel. A little 4 second toot wouldn’t hurt.
what’s large enough?
Show, her a red light, red aspect, port side.

JM gives good advice, just follow the rules. It applies to both vessels.

 

[PilotWolf]

Not sure if this is the right thread for this but...

If using AIS for any form of collison avoidance or calculations consideration must be taken into account where the antenna is mounted - if you have a 500 ft ship and the antenna is on the bridge at the stern the bow is potentially a lot closer than the CPA shown on any equipment.

W.

 

[john_morris_uk]

Not sure if this is the right thread for this but...

If using AIS for any form of collison avoidance or calculations consideration must be taken into account where the antenna is mounted - if you have a 500 ft ship and the antenna is on the bridge at the stern the bow is potentially a lot closer than the CPA shown on any equipment.

W.

When entering the details of one’s AIS class B transponder you have to give the details of the coordinates of where the positioning GPS antenna is. (metres from centre line and from bow IIRC) I assume this is used by the software to help in calculating CPA’s. I assume you have to do something similar with Class A setup procedures.

 

[PilotWolf]

When entering the details of one’s AIS class B transponder you have to give the details of the coordinates of where the positioning GPS antenna is. (metres from centre line and from bow IIRC) I assume this is used by the software to help in calculating CPA’s. I assume you have to do something similar with Class A setup procedures.

I believe so but I can't remember the details as been a while since I did

My point was the transmission point that the software is working on may not be the accurate point of the bit that is going to hit you. But that's probably too close for comfort either way!

W.

 

[john_morris_uk]

I believe so but I can't remember the details as been a while since I did

My point was the transmission point that the software is working on may not be the accurate point of the bit that is going to hit you. But that's probably too close for comfort either way!

W.

I agree, but I’d assumed that entering size of vessel and where the antenna was meant that the software took it into account.

Might be a vain hope though and I start to concentrate as soon as the CPA is under a mile or so.

 

[PilotWolf]

I agree, but I’d assumed that entering size of vessel and where the antenna was meant that the software took it into account.

Might be a vain hope though and I start to concentrate as soon as the CPA is under a mile or so.

I really don't know.

My standing night orders when surveying were to call me with CPA under 0.2 nm on survey ops, often against the traffic flow in separation zones a lot depended on my confidence on my Mate .

I'm still here and the boat is still working - I wish I was still aboard .

W

 

[rotrax]

I really don't know.

My standing night orders when surveying were to call me with CPA under 0.2 nm on survey ops, often against the traffic flow in separation zones a lot depended on my confidence on my Mate .

I'm still here and the boat is still working - I wish I was still aboard .

W

Sobering thought PilotWolf - you say 0.2 NM was your minimum distance.

Picked up the Harmony of the Seas cruise ship on AIS a couple of months after her maiden trip.

Instead of a length in Metres, the quoted length was .19 NM!

Not much room for error there I think.......................

 

[PilotWolf]

Sobering thought PilotWolf - you say 0.2 NM was your minimum distance.

Picked up the Harmony of the Seas cruise ship on AIS a couple of months after her maiden trip.

Instead of a length in Metres, the quoted length was .19 NM!

Not much room for error there I think.......................

Yes, , because I expected my Mate to make a prudent descison Below that I wanted to be called , especially if things weren't changing I wanted to be called to th bridge .

I trusted most of my mates 110% - a few less so .

Towing sonar and other equipment meant little options other than to ask other ships to respect our work, almost all were acceping and were happy to help.

W.