SAWDOC
Well-Known Member
Thanks Dave for making the point. You are not responsible for your ship's design and you are merely describing an existing real situation which i for one am taking note of.
cheers.
cheers.
Big ships v small boats at night
- Thread starter Impaler
- Start date
BlueSkyNick
Well-Known Member
[ QUOTE ]
Thanks Dave for making the point. You are not responsible for your ship's design and you are merely describing an existing real situation which i for one am taking note of.
cheers.
[/ QUOTE ]
I'll second that.
Thanks Dave for making the point. You are not responsible for your ship's design and you are merely describing an existing real situation which i for one am taking note of.
cheers.
[/ QUOTE ]
I'll second that.
BlueSkyNick
Well-Known Member
Having 'played' with AIS for 4 years now, I am firmly convinced that it is a not a reliable technology. It is merely an additional tool to provide information about other vessels. I certainly wouldn't base my decision to stand on or alter course on AIS alone, for the reasons highlighted here. Eyeballs, HB compass and radar provide a more accurate and, more importantly, real time impression of the situation.
Impaler
Well-Known Member
Yes, I did feel a bit miffed about accusations of poor design. I am sure it's up to spec and is probably a lot better than many ships. Anyway happy sailing and keep a good look out. I know sailing at night can be exhilirating but my nights afloat involve food and fine wines!
BrianH
Well-Known Member
[ QUOTE ]
Having 'played' with AIS for 4 years now, I am firmly convinced that it is a not a reliable technology.
[/ QUOTE ]
I would be extremely interested in your experiences and why you consider it unreliable. Perhaps a new thread? We seem to have quite a thread drift here from what was an important and interesting theme.
I have had three years with an AIS receiver fitted and have had no grounds to consider it unreliable. All reports and tracks displayed have tallied with my observations and augmented them with otherwise unobtainable data, e.g. speed, precise heading, ship's name, etc.
Some criticisms can be leveled at the system, however. As stated earlier, static data is sometimes late to be added to a report, and very often that static data is clearly erroneous, "moored" when underway, for example. Also, this year, I was passed by two ferries in the Adriatic that were not transmitting any AIS data at all.
Having been nearly run down by a fast catamaran ferry in 2005 (the catalyst for fitting) I value the extra information that AIS gives me and this year helped me to avoid repeating that experience by giving me the name of another fast ferry coming straight at me to call on VHF - information that was not available to the Mk I eyeball that we are exhorted to rely on, which I do but not exclusively, and in this case it confirmed what my screen was telling me.
I do find the resistance to AIS mysterious. Of course it is just another aid and no one is advocating any aid supplanting observation and seamanship. Only a Luddite would reject GPS as a navigational aid - most of us use it knowing that it is a useful aid but that it could fail us and we keep a navigational log so that DR is always in the background - I don't even carry my sextant on board any longer, instead I have extra GPS units. So why do some people reject using somebody else's GPS data, via AIS reports, to add to their multiple input data collection? Heaven knows that an AIS receiver is relatively inexpensive and easy to fit. It beats me.
Having 'played' with AIS for 4 years now, I am firmly convinced that it is a not a reliable technology.
[/ QUOTE ]
I would be extremely interested in your experiences and why you consider it unreliable. Perhaps a new thread? We seem to have quite a thread drift here from what was an important and interesting theme.
I have had three years with an AIS receiver fitted and have had no grounds to consider it unreliable. All reports and tracks displayed have tallied with my observations and augmented them with otherwise unobtainable data, e.g. speed, precise heading, ship's name, etc.
Some criticisms can be leveled at the system, however. As stated earlier, static data is sometimes late to be added to a report, and very often that static data is clearly erroneous, "moored" when underway, for example. Also, this year, I was passed by two ferries in the Adriatic that were not transmitting any AIS data at all.
Having been nearly run down by a fast catamaran ferry in 2005 (the catalyst for fitting) I value the extra information that AIS gives me and this year helped me to avoid repeating that experience by giving me the name of another fast ferry coming straight at me to call on VHF - information that was not available to the Mk I eyeball that we are exhorted to rely on, which I do but not exclusively, and in this case it confirmed what my screen was telling me.
I do find the resistance to AIS mysterious. Of course it is just another aid and no one is advocating any aid supplanting observation and seamanship. Only a Luddite would reject GPS as a navigational aid - most of us use it knowing that it is a useful aid but that it could fail us and we keep a navigational log so that DR is always in the background - I don't even carry my sextant on board any longer, instead I have extra GPS units. So why do some people reject using somebody else's GPS data, via AIS reports, to add to their multiple input data collection? Heaven knows that an AIS receiver is relatively inexpensive and easy to fit. It beats me.
maxi77
Well-Known Member
I would agree that we need to use as many tools as are available to us to help us keep safe. No one system gives us all the data we could use, Mk 1 eye is good for some bits some times but there is other data available from tools like radr, and AIS that can help when added intelligently to the pot.
As for the original point about the reliability of the watch on the average ships bridge espcially at night, it has never been that good. I did my first cross channel sail over 40 years ago and shining aldis lamps on bridge windows would make it quite clear there was no one in. Some time after that there was the famous incident where a merchant ship ran into the another partly sunk merchant ship which was marked by about 30 wreck bouys. I passed the site a few months later and the whole place was as bright as Piccadilly Circus and could be very clearly seen from over 10 miles away, the skyline was green, but that ship manage to miss it all. What chance would a yacht have had against him.
You can never rely on the other guy to keep clear so you must make sure you can keep clear if at all possible, fail and you may become another statistic, and the fact he was in the wrong and should have seen you will be of little help to you.
As for the original point about the reliability of the watch on the average ships bridge espcially at night, it has never been that good. I did my first cross channel sail over 40 years ago and shining aldis lamps on bridge windows would make it quite clear there was no one in. Some time after that there was the famous incident where a merchant ship ran into the another partly sunk merchant ship which was marked by about 30 wreck bouys. I passed the site a few months later and the whole place was as bright as Piccadilly Circus and could be very clearly seen from over 10 miles away, the skyline was green, but that ship manage to miss it all. What chance would a yacht have had against him.
You can never rely on the other guy to keep clear so you must make sure you can keep clear if at all possible, fail and you may become another statistic, and the fact he was in the wrong and should have seen you will be of little help to you.
Danny Jo
Well-Known Member
[ QUOTE ]
You are expecting a lot if you want the officer of the watch to take avoiding action at 4M.
[/ QUOTE ] I can't remember the precise distances and times but I generally aim to allow enough time for a course alteration to achieve a CPA of at least 1nm. Assuming no action by the other vessel, sailing at 5 knots requires 12 minutes to achieve that distance between oneself and a projected collision point (10 minutes at 6 knots, etc.) I was doing around 6 knots and the approaching vessel around 22 knots. If I radioed her too early, it would probably have been because I failed to subtract my speed when estimating that our closing distance was diminishing by a mile every 3 minutes. Ten minutes for action plus 2 minutes to establish radio contact equals 12 minutes; distance covered in 12 minutes equals 4 miles.
You are expecting a lot if you want the officer of the watch to take avoiding action at 4M.
[/ QUOTE ] I can't remember the precise distances and times but I generally aim to allow enough time for a course alteration to achieve a CPA of at least 1nm. Assuming no action by the other vessel, sailing at 5 knots requires 12 minutes to achieve that distance between oneself and a projected collision point (10 minutes at 6 knots, etc.) I was doing around 6 knots and the approaching vessel around 22 knots. If I radioed her too early, it would probably have been because I failed to subtract my speed when estimating that our closing distance was diminishing by a mile every 3 minutes. Ten minutes for action plus 2 minutes to establish radio contact equals 12 minutes; distance covered in 12 minutes equals 4 miles.
BlueSkyNick
Well-Known Member
Maybe I sounded a little negative - I do actually believe that AIS is useful, but only as part of the tool kit. My issues with it are
- Poor VHF reception, which I know is my own problem, causes targets to come and go.
- the timing of messages, combined with the above, means the information on the screen is not real time, in that it could be several minutes out of date
- the static information not being present all the time can cause confusion. Especially now that small boats are fitting transceivers. Yesterday in the Solent, I was looking at the PC (being down below to warm up!), and called up to the cockpit that the big ship just turned towards us. What big ship? came the reply - it was a 35ft motorboat.
To be fair, its benefits are in knowing the COG and SOG of the other vessel, and an indication of CPA.
- Poor VHF reception, which I know is my own problem, causes targets to come and go.
- the timing of messages, combined with the above, means the information on the screen is not real time, in that it could be several minutes out of date
- the static information not being present all the time can cause confusion. Especially now that small boats are fitting transceivers. Yesterday in the Solent, I was looking at the PC (being down below to warm up!), and called up to the cockpit that the big ship just turned towards us. What big ship? came the reply - it was a 35ft motorboat.
To be fair, its benefits are in knowing the COG and SOG of the other vessel, and an indication of CPA.
BrianH
Well-Known Member
This is a reply to my own post as some research shows I was not so wrong in my basic premise as I thought. My apologies for any hijacking that may be construed by this post.
The following is from IALA GUIDELINES ON THE UNIVERSAL AUTOMATIC IDENTIFICATION SYSTEM (AIS) Volume 1, Part II – Technical Issues Edition 1.1 December 2002
[ QUOTE ]
18.1 Introduction and fundamental concepts
In response to a request from IMO seeking global channels for AIS, the ITU designated two worldwide channels from the VHF maritime mobile band for this purpose (refer to ITU-R Radio Regulations (RR) Appendix S18). The channels are AIS1 – No. 2087 (161.975 MHz) and AIS2 – No. 2088 (162.025 MHz) - with 25kHz bandwidth, and in accordance with Recommendation ITU-R M.1084. Two channels were selected to increase capacity and mitigate Radio Frequency (RF) interference. AIS1 is the “primary channel” and AIS2 the “secondary channel” in “high seas” areas. This distinction will become relevant when considering some details of the transition between regions.
By default every mobile AIS station operates on these two channels, AIS 1 and AIS 2, as defined in Recommendation ITU-R M1371-1. A mobile AIS station is thus capable of receiving two messages, from two different stations concurrently, provided that it does not transmit at the same time. Every mobile AIS station transmits at its “nominal reporting rate”. This nominal reporting rate is given in tables for the respective class of mobile AIS station (refer to the appropriate chapters of these AIS Guidelines). Each of the two channels by default is used to transmit scheduled transmissions, such as autonomous and continuous position reports, at half of the “nominal reporting rate.” E. g. a Class A shipborne mobile AIS station moving at a speed of more than 23 knots is supposed to report its position in intervals of 2 seconds. Therefore the nominal reporting rate would be once per two seconds. This means, that each of the two channels AIS1 and AIS2 will receive a scheduled position report from this mobile AIS station once every four seconds, i. e. at half the rate of the nominal reporting rate. To understand this fact is crucial for the understanding of the impact of channel management on reporting rates. This behaviour is called dual channel operation.
[/ QUOTE ]
My understanding of the above is that a simplex (or dual channel switching) receiver may have to wait twice as long for the message 21 (positional data) as a dual channel, simultaneous receiver, which is only a matter of a few seconds for a ship that is underway - depending on its speed.
I hope (am sure) a more technically literate forumite will correct this if wrong.
Thanks, Brian.
The following is from IALA GUIDELINES ON THE UNIVERSAL AUTOMATIC IDENTIFICATION SYSTEM (AIS) Volume 1, Part II – Technical Issues Edition 1.1 December 2002
[ QUOTE ]
18.1 Introduction and fundamental concepts
In response to a request from IMO seeking global channels for AIS, the ITU designated two worldwide channels from the VHF maritime mobile band for this purpose (refer to ITU-R Radio Regulations (RR) Appendix S18). The channels are AIS1 – No. 2087 (161.975 MHz) and AIS2 – No. 2088 (162.025 MHz) - with 25kHz bandwidth, and in accordance with Recommendation ITU-R M.1084. Two channels were selected to increase capacity and mitigate Radio Frequency (RF) interference. AIS1 is the “primary channel” and AIS2 the “secondary channel” in “high seas” areas. This distinction will become relevant when considering some details of the transition between regions.
By default every mobile AIS station operates on these two channels, AIS 1 and AIS 2, as defined in Recommendation ITU-R M1371-1. A mobile AIS station is thus capable of receiving two messages, from two different stations concurrently, provided that it does not transmit at the same time. Every mobile AIS station transmits at its “nominal reporting rate”. This nominal reporting rate is given in tables for the respective class of mobile AIS station (refer to the appropriate chapters of these AIS Guidelines). Each of the two channels by default is used to transmit scheduled transmissions, such as autonomous and continuous position reports, at half of the “nominal reporting rate.” E. g. a Class A shipborne mobile AIS station moving at a speed of more than 23 knots is supposed to report its position in intervals of 2 seconds. Therefore the nominal reporting rate would be once per two seconds. This means, that each of the two channels AIS1 and AIS2 will receive a scheduled position report from this mobile AIS station once every four seconds, i. e. at half the rate of the nominal reporting rate. To understand this fact is crucial for the understanding of the impact of channel management on reporting rates. This behaviour is called dual channel operation.
[/ QUOTE ]
My understanding of the above is that a simplex (or dual channel switching) receiver may have to wait twice as long for the message 21 (positional data) as a dual channel, simultaneous receiver, which is only a matter of a few seconds for a ship that is underway - depending on its speed.
I hope (am sure) a more technically literate forumite will correct this if wrong.
Thanks, Brian.
BrianH
Well-Known Member
[ QUOTE ]
I did my first cross channel sail over 40 years ago and shining aldis lamps on bridge windows would make it quite clear there was no one in.
[/ QUOTE ]
Probably about the same time I too had a similar experience. It was in the early hours of a dark night and we were clear of the Humber estuary, close to the Outer Dowsing light vessel under sail showing the customary navigation lights. A ship was approaching from astern and as we could see port, starboard and mast steaming lights at a constant bearing, clearly on a collision course. After shining a powerful torch on the sails then at the ship without reaction, we tacked and stood out to the east to avoid the overtaking ship, which then passed quite close between us and the lightvessel. But amazingly, as she passed, the intense beam from the lightship swept round, silhouetted a small freighter and illuminated in sharp relief a totally vacant bridge - empty, no one on watch and within a cable or two of an obstruction, the light vessel, in days long before GPS.
I did my first cross channel sail over 40 years ago and shining aldis lamps on bridge windows would make it quite clear there was no one in.
[/ QUOTE ]
Probably about the same time I too had a similar experience. It was in the early hours of a dark night and we were clear of the Humber estuary, close to the Outer Dowsing light vessel under sail showing the customary navigation lights. A ship was approaching from astern and as we could see port, starboard and mast steaming lights at a constant bearing, clearly on a collision course. After shining a powerful torch on the sails then at the ship without reaction, we tacked and stood out to the east to avoid the overtaking ship, which then passed quite close between us and the lightvessel. But amazingly, as she passed, the intense beam from the lightship swept round, silhouetted a small freighter and illuminated in sharp relief a totally vacant bridge - empty, no one on watch and within a cable or two of an obstruction, the light vessel, in days long before GPS.
BrianH
Well-Known Member
So, your implication that ALL AIS "is a not a reliable technology" now boils down to your own on board equipment ....
- Timing of messages: this is dependent on the status of the ship, ships underway have only a matter of seconds between updating. Could your admittedly poor installation also be at fault here?
- Static information: agreed, this leaves a lot to be desired, but none of it essential for safety. If the name has not been updated (the only really useful item) all reports carry the MMSI number.
- Timing of messages: this is dependent on the status of the ship, ships underway have only a matter of seconds between updating. Could your admittedly poor installation also be at fault here?
- Static information: agreed, this leaves a lot to be desired, but none of it essential for safety. If the name has not been updated (the only really useful item) all reports carry the MMSI number.
BlueSkyNick
Well-Known Member
sorry for giving my general perception - didn't have the time or the inclination to drill into detail - will try better next time. /forums/images/graemlins/wink.gif
maxi77
Well-Known Member
In those days there would be two on watch an OOW on the bridge and an EOW in the engineroom. For the OOW as well as keeping a good lookout he would also have to do all navigation often in a chart room off the back of the bridge, make any repfreshments for himself and his relief, call his relief, alert the wireless officer if the set sprang into life, etc etc. I would suspect that in a 4 hour watch at least 1 hour was spent not looking out.
Today most of the time only 1 on watch but with decent comms from the bridge, and electronic aids more time should be spent on ship safety, but is that all head down stuff, all those screens can be so reassuring, even if they are misleading.
Today most of the time only 1 on watch but with decent comms from the bridge, and electronic aids more time should be spent on ship safety, but is that all head down stuff, all those screens can be so reassuring, even if they are misleading.
BrianH
Well-Known Member
[ QUOTE ]
The cheap sets only receive on one frequency so you won't see 50% of the transmissions. How bloody useful!
[/ QUOTE ]
After my posts to correct the misleading impression your statement may have made for those who do not, or will not, understand this technology and find it necessary to rubbish it, you may be interested to read of others, using the simplest (non-parallel) and cheapest AIS engine on the market, and "how bloody useful" they find it. It is here.
The cheap sets only receive on one frequency so you won't see 50% of the transmissions. How bloody useful!
[/ QUOTE ]
After my posts to correct the misleading impression your statement may have made for those who do not, or will not, understand this technology and find it necessary to rubbish it, you may be interested to read of others, using the simplest (non-parallel) and cheapest AIS engine on the market, and "how bloody useful" they find it. It is here.
2nd_apprentice
Well-Known Member
[ QUOTE ]
[ QUOTE ]
The cheap sets only receive on one frequency so you won't see 50% of the transmissions. How bloody useful!
[/ QUOTE ]
After my posts to correct the misleading impression your statement may have made for those who do not, or will not, understand this technology and find it necessary to rubbish it, you may be interested to read of others, using the simplest (non-parallel) and cheapest AIS engine on the market, and "how bloody useful" they find it. It is here.
[/ QUOTE ]
Are you confusing non-parallel multiplex with single frequency receivers?
[ QUOTE ]
The cheap sets only receive on one frequency so you won't see 50% of the transmissions. How bloody useful!
[/ QUOTE ]
After my posts to correct the misleading impression your statement may have made for those who do not, or will not, understand this technology and find it necessary to rubbish it, you may be interested to read of others, using the simplest (non-parallel) and cheapest AIS engine on the market, and "how bloody useful" they find it. It is here.
[/ QUOTE ]
Are you confusing non-parallel multiplex with single frequency receivers?
BrianH
Well-Known Member
[ QUOTE ]
Are you confusing non-parallel multiplex with single frequency receivers?
[/ QUOTE ]
No, are you? Are there any "single frequency receivers"?
Common terminology seems to be gravitating to alternating dual channel receivers being called "single-channel scanning", see here.
Even the Nobeltec 100, which everyone refers to as "single-channel" has both AIS frequencies and alternates between them each 36 seconds - not the 6 minutes that you earlier implied.
Are you confusing non-parallel multiplex with single frequency receivers?
[/ QUOTE ]
No, are you? Are there any "single frequency receivers"?
Common terminology seems to be gravitating to alternating dual channel receivers being called "single-channel scanning", see here.
Even the Nobeltec 100, which everyone refers to as "single-channel" has both AIS frequencies and alternates between them each 36 seconds - not the 6 minutes that you earlier implied.
[ QUOTE ]
I can't remember the precise distances and times but I generally aim to allow enough time for a course alteration to achieve a CPA of at least 1nm. Assuming no action by the other vessel, sailing at 5 knots requires 12 minutes to achieve that distance between oneself and a projected collision point (10 minutes at 6 knots, etc.)
[/ QUOTE ]
Hmmm, your habit of calling up merchant vessels based on your AIS interpretations troubles me. If all yachtsmen use AIS this way the merchant guys could be tempted to switch their AIS unit off or ignore calls from yachts. Can you not recall the CPA and tCPA figures that prompted the call? If I made such a call the numbers would be imprinted on my brain cells.
I have never called up a ship despite seeing many sub 1mn CPA's all the way down to zero. They are engaged in business so if the CPA is below 0.3mn I get out of the way in good time. More often my AIS set tells me a merchant vessel has seen me as the CPA's are usually a nice round figure before I become aware of the crossing situation.
For example I had a close encounter with the Deutschland cruise ship in Lyme Bay earlier this month. Pre AIS I would have experienced 15 minutes of anxiety armed with a compass, and would probably have altered course (not necessarily for the better). Instead I watched the cruise ship maintain a precise 0.33 CPA and so relaxed comfortable in the knowledge that a well manned German ship’s bridge had decided I was to be part of the pre dinner evening scenery for the passengers.
My AIS software counts up the seconds since the last AIS ping so there was no doubt that the position on the screen corresponded to the actual ship.
AIS in as win win win technology. I cause less trouble for the pro merchant guys with unnecessary manoeuvres, the AIS figures have provided excellent training for me in crossing estimation and back home I have been able to check out the Deutschland on the web since it seemed like the ideal cruise ship size for me should I ever consider such a holiday.
I can't remember the precise distances and times but I generally aim to allow enough time for a course alteration to achieve a CPA of at least 1nm. Assuming no action by the other vessel, sailing at 5 knots requires 12 minutes to achieve that distance between oneself and a projected collision point (10 minutes at 6 knots, etc.)
[/ QUOTE ]
Hmmm, your habit of calling up merchant vessels based on your AIS interpretations troubles me. If all yachtsmen use AIS this way the merchant guys could be tempted to switch their AIS unit off or ignore calls from yachts. Can you not recall the CPA and tCPA figures that prompted the call? If I made such a call the numbers would be imprinted on my brain cells.
I have never called up a ship despite seeing many sub 1mn CPA's all the way down to zero. They are engaged in business so if the CPA is below 0.3mn I get out of the way in good time. More often my AIS set tells me a merchant vessel has seen me as the CPA's are usually a nice round figure before I become aware of the crossing situation.
For example I had a close encounter with the Deutschland cruise ship in Lyme Bay earlier this month. Pre AIS I would have experienced 15 minutes of anxiety armed with a compass, and would probably have altered course (not necessarily for the better). Instead I watched the cruise ship maintain a precise 0.33 CPA and so relaxed comfortable in the knowledge that a well manned German ship’s bridge had decided I was to be part of the pre dinner evening scenery for the passengers.
My AIS software counts up the seconds since the last AIS ping so there was no doubt that the position on the screen corresponded to the actual ship.
AIS in as win win win technology. I cause less trouble for the pro merchant guys with unnecessary manoeuvres, the AIS figures have provided excellent training for me in crossing estimation and back home I have been able to check out the Deutschland on the web since it seemed like the ideal cruise ship size for me should I ever consider such a holiday.
DavenHelen
Well-Known Member
[ QUOTE ]
I have never called up a ship despite seeing many sub 1mn CPA's all the way down to zero. They are engaged in business so if the CPA is below 0.3mn I get out of the way in good time.
[/ QUOTE ]
Sorry, fine it very hard to reconcile this statement with your post on the Ouzo thread about blameworthiness of a ship engaged "in business". /forums/images/graemlins/frown.gif
I have never called up a ship despite seeing many sub 1mn CPA's all the way down to zero. They are engaged in business so if the CPA is below 0.3mn I get out of the way in good time.
[/ QUOTE ]
Sorry, fine it very hard to reconcile this statement with your post on the Ouzo thread about blameworthiness of a ship engaged "in business". /forums/images/graemlins/frown.gif
[ QUOTE ]
[ QUOTE ]
I have never called up a ship despite seeing many sub 1mn CPA's all the way down to zero. They are engaged in business so if the CPA is below 0.3mn I get out of the way in good time.
[/ QUOTE ]
Sorry, fine it very hard to reconcile this statement with your post on the Ouzo thread about blameworthiness of a ship engaged "in business". /forums/images/graemlins/frown.gif
[/ QUOTE ]
Why, where is the contradiction?
One is a specific criticism aimed at a company who's reported poor nautical practice probably killed 3 sailors.
The other quote above describes my attitude when on a crossing path a merchant of fishing vessel. I would not consider calling up a merchant vessel and saying "I am the stand-on vessel here" and imply I was not impressed with their adherence to ColRegs. Given a 10 to 20 minute window I would try to open up the CPA or more often these days AIS gives me the confidence to hold my course.
[ QUOTE ]
I have never called up a ship despite seeing many sub 1mn CPA's all the way down to zero. They are engaged in business so if the CPA is below 0.3mn I get out of the way in good time.
[/ QUOTE ]
Sorry, fine it very hard to reconcile this statement with your post on the Ouzo thread about blameworthiness of a ship engaged "in business". /forums/images/graemlins/frown.gif
[/ QUOTE ]
Why, where is the contradiction?
One is a specific criticism aimed at a company who's reported poor nautical practice probably killed 3 sailors.
The other quote above describes my attitude when on a crossing path a merchant of fishing vessel. I would not consider calling up a merchant vessel and saying "I am the stand-on vessel here" and imply I was not impressed with their adherence to ColRegs. Given a 10 to 20 minute window I would try to open up the CPA or more often these days AIS gives me the confidence to hold my course.
DavenHelen
Well-Known Member
[ QUOTE ]
Why, where is the contradiction?
[/ QUOTE ]
You are appearing to suggest that you as a small vessel would keep out of the way of a commercial vessel if the CPA was very small and then imply that a commercial vessel was soley to blame for a collision/near collision when a similar small vessel didn't.
Why, where is the contradiction?
[/ QUOTE ]
You are appearing to suggest that you as a small vessel would keep out of the way of a commercial vessel if the CPA was very small and then imply that a commercial vessel was soley to blame for a collision/near collision when a similar small vessel didn't.
