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Old 02-06-2010, 20:50   #151
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Thanks Jack... I think it is important to get a good consensus on this before we discuss the pros and cons... hope to hear from many others
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Old 03-06-2010, 01:10   #152
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Rule 7 Risk of Collision

I believe Lodesman covered this fairly comprehensively.
I have always found it good practice to try and imagine your on the other vessel. On a small manoeuverable boat, you may think 2 or 3 miles is a suitable distance to take action. The other vessel may be a 500,000 tonne tanker or a large box boat doing 28 knots. Theyíll not be happy with a 2 to 3 mile separation distance as an appropriate distance to take action.
Also consider the actual watchkeeper on the other vessel, he/she may be inexperienced, lacking confidence, or just plain incompetent.
Having spent many years towing rigs and other awkward objects, I rely on discretion being the better part of valour. If I detect a close quarters situation is likely to develop, I will normally take action before the rules can be considered to apply, and make an alteration to open up the CPA.
Some of my worst experiences having been transiting the Singapore Straits, where we have been towing a cantankerous rig, making 4 to 5 knots, strong tidal streams, sometimes crap vis, in narrow lanes, and we have everyone, his wife and dog overtaking us, other vessels crossing, and the odd idiot navigating on charts so old they do not show the TSS, and deciding to head straight for us in the opposite direction. Its in that type of situation when we find our options to avoid a close quarters situation are very limited, and I am really appreciative when other vessels take early action to avoid us.
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Old 03-06-2010, 07:53   #153
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Radar Setting:
I absolutely prefer true motion ( North up). I also run my chart machine north up. This way it is very easy to compare the radar to the chart. Usually I use the chart machine with AIS to look for the big guys. ( range 10 to 20 nautical miles), and the radar for closer range pick up of the little guys who do not transmit AIS and usually do not hold a steady course

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Old 03-06-2010, 07:54   #154
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Agree with Jack; heads up. Especially true if you have a watch-stander who is a "chart-turner" (has to have the chart turned to match the heading of the boat).

Fair Winds,
Mike
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Old 03-06-2010, 08:00   #155
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The US Navy defines the risk of collision to exist when there is a CPA within 10,000 yards. That's when all the captains want their watch to call them and tell them how they intend to maneuver to keep the CPA outside 10,000 yards. As has been mentioned, narrow straits are a completely different animal. I once ran the English Channel at night going 25 kts. The captain reduced his notification limit to 2,000 yards and basically said maneuver as needed.

I think many commercial vessels have similar standing orders from their masters. The watch has to notify them if they need to change course more than a small amount, say 5deg. They are very conscious about fuel usage and generally run on autopilot because it can steer straighter than a helmsman. I've seen commercial vessles willing to accept very close cpa's on the open ocean. So when calculating risk of collision, remember the guy coming at you may be on autopilot and doesn't want to wake the master or change course appreciably.

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Old 03-06-2010, 09:15   #156
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The US Navy defines the risk of collision to exist when there is a CPA within 10,000 yards. That's when all the captains want their watch to call them and tell them how they intend to maneuver to keep the CPA outside 10,000 yards... I've seen commercial vessles willing to accept very close cpa's on the open ocean.
I vividly recall receiving a VHF call from a "Naval unit" that was well over the horizon, telling me that he calculated a CPA of 5 miles in 45 minutes and asked what my intentions where. We had a good laugh on the bridge discussing whether I should tell him we were bracing for impact or abandoning ship - in the end I just said that I would maintain my course and speed as I was comfortable passing at 5 miles.
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Old 03-06-2010, 09:28   #157
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Which Radar settings do you prefer to use in conditions of poor visibility for collision avoidance?
I really have no preference - if the system allows I normally default to North up, true motion, but toggle to relative motion frequently. I also keep my chart north up. If in a canal, narrow channel or wending through a fleet of fishboats, I switch to head up, relative motion. for greater efficiency. I think there's little practical difference in how the radar is used so long as the operator is capable and confident in the manner he or she chooses.
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Old 03-06-2010, 14:25   #158
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I think many commercial vessels have similar standing orders from their masters. The watch has to notify them if they need to change course more than a small amount, say 5deg. They are very conscious about fuel usage and generally run on autopilot because it can steer straighter than a helmsman. I've seen commercial vessles willing to accept very close cpa's on the open ocean. So when calculating risk of collision, remember the guy coming at you may be on autopilot and doesn't want to wake the master or change course appreciably.

Brett
You are correct Brett. Large commercial vessel Masters have a set of standing orders that the bridge officers are required to know (and sign at the beginning of the voyage) which, among other things, states a minimum CPA to be maintained. Generally, in open ocean, this will be 1.0 nm. You should try your darndest to maintain this, but if you must violate it, or the course change required is impractical to do (maybe more than 30 degrees or so), you must call him (when in any doubt, CALL!!!!). Depending on the circumstance, as well as your experience level (and his comfort level with you), he may simply say "fine, do what you need to do, thanks" or he may come up to the bridge and asses the situation himself. That's by his own discretion. (sidenote: a company I recently worked for refused to install an ECDIS and radar repeater in the Master's office for the reason that they wanted him to make these kind of decisions from the bridge, not from down below).

When making landfall, or transiting a busy strait (English Channel, Gibraltar, Malacca, Hormuz, etc), many captains will drop the minimum, in my experience to as low as 0.5 nm. When maneuvering in port/pilotage waters, there's really no set minimum CPA per se, but every encounter is assessed individually (a small powerboat or light tug is treated differently than a loaded tanker). Such decisions are entirely the Master's and this will vary with visibility, traffic density, time of day and basically every factor listed in Rule 7. The bridge team must also work with the pilot to make sure that his comfort level regarding CPA's is acceptable too.

Also note that most Master's watchstanding orders begin with the phrase "All bridge officers are expected to know and conduct the vessel in accordance with the International Rules for the Prevention of Collisions At Sea" or something similar. His orders in no way supersede the COLREGS (and/or local rules) or the responsibility of the watchstander to follow them. There's an old saying that basically goes "You can always get another job, but you can't always get another license." Follow the law in this matter - it will do you much better in the long run.

However, I will say that in my experience, I have never been pressured by a captain to shave closer to traffic because he's concerned about fuel savings and certainly never to be hesitant about making a course (or speed) change at any time it may be necessary, even without his "permission". Safety of the ship and crew is #1. Putting the rudder back and forth 10 degrees will certainly get you a talking-to (probably from the Chief too), but it takes remarkably little rudder to turn a large ship running at sea-speed, particularly fast container ships (<5 degrees, usually). Yes, the autopilot does the vast majority of steering, but they are sophisticated enough these days to be very responsive to any ordered course change and it's rare that we have to switch into hand-steering to steer for traffic at sea . In addition to steering better than most humans under normal circumstances, use of the autopilot frees up the helmsman to focus on his lookout duties only. I guess it comes down to a comfort level that merchant captains have compared to the Navy. No offense, but we are used to maneuvering around very crowded ports on a daily/weekly basis, for six months a year in all types of weather and time of day. A 1.0 nm CPA in open ocean with good visibility is generally considered appropriate for us. Other companies and Masters may feel differently, either way.


Now, as for my own encounters with Naval ships, hehehe... I think we all have a story similar to Lodesman's.
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Old 03-06-2010, 14:36   #159
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Discussion point:

Which Radar settings do you prefer to use in conditions of poor visibility for collision avoidance?

Heads up?

Course Up?


North Up?


True Motion?
I grew up pleasure boating and sailing and my early, non-commercial radar use was all un-stabilized, head-up. That was all I knew until I went to college.

Now, with all the goodies at my disposal, I prefer North-up, relative motion with true trails and alternating between true and relative vectors depending on circumstances. In narrow channels or rivers, I'll switch to Course-up to have the near perspective of Head-up, but maintain stabilization. I can't say that I've ever used true motion (other than for demonstration) and frankly, never have felt the need to. I even prefer my ECDIS to be in relative motion, with the ship staying still on the screen and the land passing by. I'll also change radar modes depending on if I'm using it primarily for navigation fixes or pure collision avoidance.

EDIT: Probably should've actually answered the question...

The question is a little loaded, since it depends on many factors (to me), but in general, I want a stabilized picture always (if available). Some PPI (screens) on smaller radars are in a vertical format, so if you're heading is not somewhat close to due north or south, you won't be seeing much in front of you (unless you offset the display). On those units, I would probably go into Course-up, resetting it as necessary.

It should be noted that many radar functions (ARPA, parallel indexing, relative trails/vectors) only work (whether through best practice or by actual programming) when the unit is in a stabilized mode (North-up or Course-up).

It's also important for radar users to be familiar with the different kind of false echo phenomenons that occur with radar, particularly those that happen at very close ranges. Practice using it in perfect, sunny conditions!
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Old 03-06-2010, 20:20   #160
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Now, as for my own encounters with Naval ships, hehehe... I think we all have a story similar to Lodesman's.
To be clear, not all Naval ships are alike - my story refers to the US Navy, who are unique in their need for personal space. My reference to "Naval Unit" is a bit esoteric - the USN ships tend to identify themselves on VHF by their side numbers rather than their names (eg. "this is Naval unit 42"). In this particular case, I was on the bridge of a Canadian Navy ship. He called us by name; since this was long before AIS existed and we were offshore, it was obvious he got our name from the Link track (TADIL-A - Wikipedia, the free encyclopedia) so it should have been clear we were friendly.
Our standing orders are individual to the CO, but tend to follow a standard. Our major combatants, despite their size (135 metres long, displace 5000 tonnes) are very manoeuvrable and can go from 30 kts to fully stopped in a little over a ship's length. Typically we are required to only report other vessels that will come within 2 miles, but most COs are happy to pass abeam or astern of a merchantman at 1000 yards if we are the give way vessel or a couple hundred yards if we are the stand-on vessel. Ahead of the other vessel would typically require separation of 3000 and 1000 yards respectively. But that varies widely with the Captain and depends on how much he or she trusts that OOW. If the other vessel is much smaller and slower, the minimum passing distance can get into a couple hundred feet. On the replenishment ships the "reporting window" is pushed out to 5 miles ahead of the bows, 3 miles on the beams and 2 miles aft of the quarters; and the CPA minima are more conservative too. I think this is similar in other non-US NATO navies.
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Old 03-06-2010, 22:31   #161
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I think this is great that we are hearing from the commercial guys as well as yachtsmen on their perspective about radar display as well as what is considered a minimum CPA in open water.

My standing order on Super yachts was minimum CPA of 0.5nm if conditions were benign and 1nm otherwise. Many times vessels would adjust for a closer look, more in the hopes of seeing something topless, rather than the rich and famous, so we had that to factor as well.

Watermann’s terrific analysis of preferred radar display pretty much matches my own experience and heads up is rarely used these days because the targets all slurry around when you change heading.

In other words… “Appropriate to the prevailing circumstances” is your guideline

North up stabilized or true display makes it much easier and faster to accurately determine the course changes and movements of other vessels than heads up or unstabilized display

This is reinforced from historical/ legal cases where for example a Dutch court found the Pilot at fault for using a 1nm Heads up display in congested approaches instead of the Master’s preferred 3nm range True Bearing presentation.

The courts also found the Master to be ultimately at fault for allowing the Pilot to make that decision, so the lesson learned as a skipper of any vessel is to insist that your crew or pilot use the presentation you are most comfortable with.

For those who think heads up is intuitive, when we begin to discuss “aspect” in collision avoidance, it will become obvious, that training yourself to relate to a North up presentation will give you a more complete picture.

As far as those who cannot wean crew from chart turning, train them and insist upon it. Navigation is based on a North up system; do not allow them to confuse it because they forget port and stbd when heading south.

Out of curiosity, are you able to turn around electronic charting displays if you have a setup something like what Motorbad showed us?
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Old 04-06-2010, 02:31   #162
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Rule 7 Risk of Collision

My preference for radar is North Up, relative motion, and the ARPA set to relative vectors. Thatís probably just due to the way I was brought up, when I first went to sea, North Up was considered a sophisticated radar, and only the very new ships had true motion. No ARPA, I spent many years using the chinagraph pencil to work out CPA and the other vessels course and speed. However, I donít mind what the OOW uses, so long as it sensible. My standing orders require the OOW to check the radar set up when they take over a watch, especially with regards to vector / trail modes, true or relative
As we have two radars, the S band is normally set to the longer range, with the X band on the shorter range. Ranges chosen are dictated by proximity to land, traffic density, sea state and vis.
I donít like radar overlays on the ECDIS, I find it tends to clutter the display, but we do have a toy called a Chart Radar, which is a dedicated radar with built in electronic charts, which does give a better display, but is something we rarely use, information overload. It was very handy when we were running anchors for a pipe laying barge on the Dogger Bank, as we drive the tug from the aft end of the bridge where there is no ECDIS display, but we do have a slave radar display which we used in ECDIS/Radar mode, so we did not have to rely totally on the barge surveyors not to run us aground.

CPAís, normally deep sea, my standing orders call for 1 mile, congested waters, its 0.5, or even less, in pilotage waters (we donít normally take pilots), primary collision avoidance is down to eye ball. Towing deep sea its 3 miles. I donít normally expect the OOW to call me if he/she has to alter course, I expect them to be competent enough to use their own judgement, obviously if they are inexperienced this will be different, and normally, if we have an inexperienced OOW or one new to the boat, they stand the first few watches with another OOW or myself. Of course, my Standing Orders have the usual ďIf in any doubt, call me ď

When we are rig towing, deep sea, we are considered RAM, but we carry out long range plotting and usually take action to avoid a close quarters situation when at ranges of about 20 miles. If we stand on, and the give way vessel does not follow the Colregs, it leaves us in a very bad situation. Altering course with 20,000 to 30,000 tonnes of rig on a 1000m tow wire is not quick, and if there is any significant sea state, the rig will be ballasted down, and speed is down to 2 knots or less, which severely limits our options.

And what is it with the USN requiring such large CPAís I have been called on \VHF by them a few times requiring 5 mile CPA, itís like the Colregs donít apply to them. I have never had this from other countries navy ships.
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Old 04-06-2010, 02:36   #163
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Some of my worst experiences having been transiting the Singapore Straits, where we have been towing a cantankerous rig, making 4 to 5 knots, strong tidal streams, sometimes crap vis, in narrow lanes, and we have everyone, his wife and dog overtaking us, other vessels crossing, and the odd idiot navigating on charts so old they do not show the TSS, and deciding to head straight for us in the opposite direction. Its in that type of situation when we find our options to avoid a close quarters situation are very limited, and I am really appreciative when other vessels take early action to avoid us.
Nigel's experiences in the Singapore Strait is really relevant - using 5 year old figures, over 62, 000 commercial vessels transited this narrow strait annually.
It was/is imperative that one knew the strength and direction of the current and how long it would run West >> East before it switched to East >>>West.
In that galaxy of vessels would be Mega Super Tankers - Container Ships - Warships - Trawlers - Tugs with tows, Etc... . The 170 ships each day do not include the hundreds of other boats.

Pelagic and I remember well the waters of Hong Kong where on an annual average over 220,000 ships visited, including ocean going vessels and river craft. The above figure did not include some 23,000 local boats. If one looks at a current chart of Victoria Harbour one will understand there is very little space or time to use navigational aids such as radar - Because Ships, Boats and every type of Craft by the hundreds will be moving around you - High & Low Speed Ferries, Tankers, Cruise ships, Police & Pilot boats,Tugs moving Lighters, Lighters not moving, Barges, Bulk carriers, River traders, Sampans,
powered pleasure boats and sailing boats! So in those waters 600 ships a day PLUS all the local craft.

Singapore Strait and Hong Kong's waters require some local knowledge, prior study of the charts - notices to mariners - good understanding of the vessel one is helming or skippering. Being able to judge when and how to pass a vessel safely without reference to compass bearings or radar was a skill that ferry coxswains demonstrated daily. CPA and T-CPA's were probably mere overlays in their mental images of the harbour's environs that were continually being updated.

Irrespective of the poor visibility that pervades Hong Kong and Singapore,
Radar is of little use in very close quarters - good eyesight and being alert for almost anything is required.
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Old 04-06-2010, 03:06   #164
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we're having a conversation about Colregs.....in SE Asia
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Old 04-06-2010, 09:21   #165
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And what is it with the USN requiring such large CPAís I have been called on \VHF by them a few times requiring 5 mile CPA, itís like the Colregs donít apply to them. I have never had this from other countries navy ships.
Unfortunately I think you can find your answer here: USS Cole Bombing
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