MarkGrubb
Well-Known Member
Would a ferry be doing 20knts in the channel in poor visability? Doesn't quite seem in the spirit of the Colregs.
yet another YM question
- Thread starter Phoenix of Hamble
- Start date
Stemar
Well-Known Member
[ QUOTE ]
Don't ask me to sail with you /forums/images/graemlins/smile.gif
[/ QUOTE ]Why not? You should welcome the opportunity to share your knowledge! /forums/images/graemlins/wink.gif
From the other comments, I didn't think I'd got it that far wrong.
In real life, since since Jissel hasn't got radar, I'd remain in blissful ignorance until the (my? /forums/images/graemlins/frown.gif ) last minute.
But then, if there's enough wind to get a Snapdragon 24 doing a steady 6kts, I don't think I'd be leaving the Solent - SWMBO enjoys a bit of bumpy, but not when it goes on all day!
Don't ask me to sail with you /forums/images/graemlins/smile.gif
[/ QUOTE ]Why not? You should welcome the opportunity to share your knowledge! /forums/images/graemlins/wink.gif
From the other comments, I didn't think I'd got it that far wrong.
In real life, since since Jissel hasn't got radar, I'd remain in blissful ignorance until the (my? /forums/images/graemlins/frown.gif ) last minute.
But then, if there's enough wind to get a Snapdragon 24 doing a steady 6kts, I don't think I'd be leaving the Solent - SWMBO enjoys a bit of bumpy, but not when it goes on all day!
dom
Well-Known Member
The answer is they would. Only thing is these guys are IMO pretty hot at wiggeling in and out of all different types of boat -at least I thought that until Ouzo! Aynyway spirit or not ---- They Would.
Phoenix of Hamble
Well-Known Member
I didn't say that the vectors hadn't been done!
All I meant was that from the information known, its precise course, speed, CPA etc could readily be calculated
All I meant was that from the information known, its precise course, speed, CPA etc could readily be calculated
dom
Well-Known Member
You are right in that you did not say they had not done the vectors. However, 99% of people do not do the vectors and simply watch whether the bearing is constant. In fact many boats don't even have plotting sheets.
I just wanted to makes sure nobody reading this makes the mistake that a constant bearing alone allows a determination of the other vessels course. It might seem silly but I know many people make this mistake.
The question you posed is therefore a very good one i.e. Do you really know the other boats track? As you know a proper vector calc can often surprise even an experienced crew. For example in a shipping lane one can assume that all boats in view are travelling in the lane. Some are not. Some are crossing it in the opposite direction to you and others are doing something else entirely.
I just wanted to makes sure nobody reading this makes the mistake that a constant bearing alone allows a determination of the other vessels course. It might seem silly but I know many people make this mistake.
The question you posed is therefore a very good one i.e. Do you really know the other boats track? As you know a proper vector calc can often surprise even an experienced crew. For example in a shipping lane one can assume that all boats in view are travelling in the lane. Some are not. Some are crossing it in the opposite direction to you and others are doing something else entirely.
Phoenix of Hamble
Well-Known Member
[ QUOTE ]
While we are on such an interesting discussion what are the experienced Formites opinion of how far is it safe to cross in front of a ship in bad visibility and using Radar?
Following that how far in good visibility using eyeball?
[/ QUOTE ]My opinion?
No less than 3nm in poor visibility, and probably more, in good visibility it would depend upon a number of circumstances such as his relative speed and his size.... if he is a monster doing 20kts, then perhaps 2nm or a bit more, if he is doing 10kts and is an average fishing vessel, then perhaps 1/2nm or evena bit less...... I just do what 'feels right', allowing for the fact that if my engine dies suddenly, then I need to have left enough room for the ship to avoid me!
While we are on such an interesting discussion what are the experienced Formites opinion of how far is it safe to cross in front of a ship in bad visibility and using Radar?
Following that how far in good visibility using eyeball?
[/ QUOTE ]My opinion?
No less than 3nm in poor visibility, and probably more, in good visibility it would depend upon a number of circumstances such as his relative speed and his size.... if he is a monster doing 20kts, then perhaps 2nm or a bit more, if he is doing 10kts and is an average fishing vessel, then perhaps 1/2nm or evena bit less...... I just do what 'feels right', allowing for the fact that if my engine dies suddenly, then I need to have left enough room for the ship to avoid me!
Phoenix of Hamble
Well-Known Member
[ QUOTE ]
The question you posed is therefore a very good one i.e. Do you really know the other boats track? As you know a proper vector calc can often surprise even an experienced crew. For example in a shipping lane one can assume that all boats in view are travelling in the lane. Some are not. Some are crossing it in the opposite direction to you and others are doing something else entirely.
[/ QUOTE ]A good point.... I heard twice this year the coastguard call up a vessell and tell them they were going the wrong way up the TSS and would be reported...... look both ways!
The question you posed is therefore a very good one i.e. Do you really know the other boats track? As you know a proper vector calc can often surprise even an experienced crew. For example in a shipping lane one can assume that all boats in view are travelling in the lane. Some are not. Some are crossing it in the opposite direction to you and others are doing something else entirely.
[/ QUOTE ]A good point.... I heard twice this year the coastguard call up a vessell and tell them they were going the wrong way up the TSS and would be reported...... look both ways!
dom
Well-Known Member
I think with radar one should always bear in mind the old saying:
"What you don't know can the be dangerous. What you don't know but think you know can be much worse!"
"What you don't know can the be dangerous. What you don't know but think you know can be much worse!"
Robin
Well-Known Member
[ QUOTE ]
While we are on such an interesting discussion what are the experienced Formites opinion of how far is it safe to cross in front of a ship in bad visibility and using Radar?
Following that how far in good visibility using eyeball?
[/ QUOTE ]
This is harder to answer than giving a simple black and white distance figure. The problem mid-Channel isn't usually one lone vessel but a group approaching in line astern AND abreast. One vessel alone is relatively easy to both plot and if necessary avoid in good time. With several I will wait longer for the situation to resolve more clearly, because the options for #s 2 and 3 might be better seen by so doing. If asked to put a figure on it then not less than one mile ahead in fog and only IF I'm really sure we are crossing. In clear visibilty one mile would still apply but there are far more options available here like heaving to, slowing down, speeding up, stopping, turning on his tail, turning 180 degs etc all of which would destroy any radar plotting accuracy for many minutes.
This is why an answer that says make an alteration immediately a target is detected isn't helpful, life is not that simple and to do that would mean in practice you would never cross the 'lanes' at all or would wait a very long time before making a run for it!
We do not have MARPA, we do have a fluxgate compass feeding the radar but only use our radar in head-up mode. I would not contemplate MARPA without a stabilised compass and even then wouldn't trust it. We do have a proper radar plotter board with range rings, bearings (compass Rose) and scales pre-marked, it is a plastic write on wipe off one from Davies in the USA. It has the instructions on use clearly on it so can be quickly referred to if we are out of practice - BUT if I am close enough to NEED it I did something wrong earlier.....
While we are on such an interesting discussion what are the experienced Formites opinion of how far is it safe to cross in front of a ship in bad visibility and using Radar?
Following that how far in good visibility using eyeball?
[/ QUOTE ]
This is harder to answer than giving a simple black and white distance figure. The problem mid-Channel isn't usually one lone vessel but a group approaching in line astern AND abreast. One vessel alone is relatively easy to both plot and if necessary avoid in good time. With several I will wait longer for the situation to resolve more clearly, because the options for #s 2 and 3 might be better seen by so doing. If asked to put a figure on it then not less than one mile ahead in fog and only IF I'm really sure we are crossing. In clear visibilty one mile would still apply but there are far more options available here like heaving to, slowing down, speeding up, stopping, turning on his tail, turning 180 degs etc all of which would destroy any radar plotting accuracy for many minutes.
This is why an answer that says make an alteration immediately a target is detected isn't helpful, life is not that simple and to do that would mean in practice you would never cross the 'lanes' at all or would wait a very long time before making a run for it!
We do not have MARPA, we do have a fluxgate compass feeding the radar but only use our radar in head-up mode. I would not contemplate MARPA without a stabilised compass and even then wouldn't trust it. We do have a proper radar plotter board with range rings, bearings (compass Rose) and scales pre-marked, it is a plastic write on wipe off one from Davies in the USA. It has the instructions on use clearly on it so can be quickly referred to if we are out of practice - BUT if I am close enough to NEED it I did something wrong earlier.....
DeeGee
Well-Known Member
In fog? In daylight, I don't try to cross a ship's bows, I try to cross his stern (yes, even if I was stand-on). In fog, I see no reason to change that. The channel shipping lanes seem usually to be pretty busy, and they come along like buses, with gaps. Radar, even in daylight, as it gives range very accurately, definitely assist this:- Mk 1 eyeball, I find, causes one to under-estimate distance at sea.
BlueSkyNick
Well-Known Member
[ QUOTE ]
...Radar, even in daylight, as it gives range very accurately, definitely assist this:-
[/ QUOTE ]so does AIS, which is why I have got into the habit of using both, as well as eyeball with a handheld compass if only to keep the crew interested.
...Radar, even in daylight, as it gives range very accurately, definitely assist this:-
[/ QUOTE ]so does AIS, which is why I have got into the habit of using both, as well as eyeball with a handheld compass if only to keep the crew interested.
DeeGee
Well-Known Member
I would be interested to know your technique with AIS. I have developed a technique with radar which I am rather hesitant to declare here, in the light of the shower of hailstones it may bring down - however... I effectively set up a collision course with the vessel I am aiming to pass astern, maybe when I am 3 or 4 miles away. Before that is not much point as things vary so much. That means I would start to appear on his radar as a possible collision. Then I make a deviation of about 20deg. when about 1.5 miles or so from collision. That deviation is usually followed by another, back onto the original course, after about half a mile. The second change, back onto original is necessary, or the next bus will be getting into the picture.
deep denial
Well-Known Member
the original question becomes harder if we imagine the ship approaching from starboard, In this situation, forward of the bow, poor vis, what to do? I can't see anyone being happy about turning to starboard!
peterb
Well-Known Member
If I were crossing ahead I would want to be at least one mile ahead of him during the crossing. I would start the crossing from at least half a mile of his projected track, and would want to be still a mile ahead of him when I'm half a mile past his track. That means that (assuming I'm crossing his track at rightangles) that I will have travelled a mile during the crossing. At 6 knots, that takes 10 minutes. If he's doing 24 knots, then he will travel 4 miles in that time. So I must start the crossing when he is still 4+1 = 5 miles away.
In fact many ships prefer to have a CPA of at least a mile, and would probably take some avoiding action if they saw a small and slow target on their radar with a CPA of less than half a mile.
In fact many ships prefer to have a CPA of at least a mile, and would probably take some avoiding action if they saw a small and slow target on their radar with a CPA of less than half a mile.
landaftaf
Well-Known Member
1. is the other vessel on a steady bearing - no ...... no problem
yes - potential problem, answer break the steady bearing by either altering course, speed or both
2. is it in poor vis ? no - normal 'in sight of another vessel' col regs apply
yes - if you detect another vessel in a close quarter situation you must take avoiding action
break the bearing (as above) - in good time and make a substantial alteration so IF the other vessel has radar he will detect your action. if the other vessel hasnt radar or hasnt seen you - your actions alone will avoid a close quarter situation.
3. and avoid crossing in front of another vessel /forums/images/graemlins/cool.gif
yes - potential problem, answer break the steady bearing by either altering course, speed or both
2. is it in poor vis ? no - normal 'in sight of another vessel' col regs apply
yes - if you detect another vessel in a close quarter situation you must take avoiding action
break the bearing (as above) - in good time and make a substantial alteration so IF the other vessel has radar he will detect your action. if the other vessel hasnt radar or hasnt seen you - your actions alone will avoid a close quarter situation.
3. and avoid crossing in front of another vessel /forums/images/graemlins/cool.gif
peterb
Well-Known Member
[ QUOTE ]
3. and avoid crossing in front of another vessel
[/ QUOTE ]
Anyone crossing the Channel cannot avoid crossing in front of another vessel. It may be 20 miles away (and below the horizon) but you're still crossing in front of it. So the question of how far away it should be to allow safe crossing is a good one.
3. and avoid crossing in front of another vessel
[/ QUOTE ]
Anyone crossing the Channel cannot avoid crossing in front of another vessel. It may be 20 miles away (and below the horizon) but you're still crossing in front of it. So the question of how far away it should be to allow safe crossing is a good one.
Bergman
Well-Known Member
Heave to
Get crew to put on kettle
Suggest a bacon sandwich (refused)
drink coffee
Gybe out
Carry on.
Get crew to put on kettle
Suggest a bacon sandwich (refused)
drink coffee
Gybe out
Carry on.
Robin
Well-Known Member
[ QUOTE ]
Anyone crossing the Channel cannot avoid crossing in front of another vessel. It may be 20 miles away (and below the horizon) but you're still crossing in front of it. So the question of how far away it should be to allow safe crossing is a good one.
[/ QUOTE ]
That is absolutely right.
There is a lot said by people that either don't know the mid-Channel area and the volume of traffic in it or are simply putting forward a dodge everything or stay at home approach. The fact is that if you sail in this area, even if you never set out in fog or with fog forecast, sooner or later you will be out there in it. Even in good visibility people are advocating passing astern of all ships, wow that must result in some wild detours at times waiting for a lull in the traffic!
There is no easy answer IMO because every case is different. Sometimes, especially in clear visibility, you can pass very close to a ship that is crossing ahead of you with no need to make any alteration of course or speed. Sometimes it is clear from bearings or aspect changes that you will pass clear ahead, but maybe by only a mile. There are (a few) other times you might chicken out and say stop and let the ship pass ahead, but then realise you had more than enough time to cross safely ahead had you stood on, probably recognised by the ship and maybe even why they did not alter if give way vessel, however no harm done. Actually the time taken to cross the width of the ship isn't that long, it is in the bit before that happens that seems to take ages and when the cycle clips come out!
Also the CPA isn't always equal to the distance that you pass ahead if you are crossing but the nearest the two tracks his and yours get, you may cross a mile ahead yet he passes only say half a mile astern of you and the CPA is 0.5ml
We cross the Channel maybe 5 or 6 times per year, so 12 times (out and back), it used to be a lot more often. Busy as it is out there we frequently cross both ways without need to alter course or speed at all, occasionally we might have to dodge 3 times in one area. I don't like doing it fog, won't deliberately set out in it, but with radar (and years of practice) it can be done, at least big ships are very predictable. More frightening is fog in a small boat area like the Solent because now you have a radar screen full of targets that are totally unpredictable!
Anyone crossing the Channel cannot avoid crossing in front of another vessel. It may be 20 miles away (and below the horizon) but you're still crossing in front of it. So the question of how far away it should be to allow safe crossing is a good one.
[/ QUOTE ]
That is absolutely right.
There is a lot said by people that either don't know the mid-Channel area and the volume of traffic in it or are simply putting forward a dodge everything or stay at home approach. The fact is that if you sail in this area, even if you never set out in fog or with fog forecast, sooner or later you will be out there in it. Even in good visibility people are advocating passing astern of all ships, wow that must result in some wild detours at times waiting for a lull in the traffic!
There is no easy answer IMO because every case is different. Sometimes, especially in clear visibility, you can pass very close to a ship that is crossing ahead of you with no need to make any alteration of course or speed. Sometimes it is clear from bearings or aspect changes that you will pass clear ahead, but maybe by only a mile. There are (a few) other times you might chicken out and say stop and let the ship pass ahead, but then realise you had more than enough time to cross safely ahead had you stood on, probably recognised by the ship and maybe even why they did not alter if give way vessel, however no harm done. Actually the time taken to cross the width of the ship isn't that long, it is in the bit before that happens that seems to take ages and when the cycle clips come out!
Also the CPA isn't always equal to the distance that you pass ahead if you are crossing but the nearest the two tracks his and yours get, you may cross a mile ahead yet he passes only say half a mile astern of you and the CPA is 0.5ml
We cross the Channel maybe 5 or 6 times per year, so 12 times (out and back), it used to be a lot more often. Busy as it is out there we frequently cross both ways without need to alter course or speed at all, occasionally we might have to dodge 3 times in one area. I don't like doing it fog, won't deliberately set out in it, but with radar (and years of practice) it can be done, at least big ships are very predictable. More frightening is fog in a small boat area like the Solent because now you have a radar screen full of targets that are totally unpredictable!
Richard10002
Well-Known Member
[ QUOTE ]
the original question becomes harder if we imagine the ship approaching from starboard, In this situation, forward of the bow, poor vis, what to do? I can't see anyone being happy about turning to starboard!
[/ QUOTE ]
If he is on a steady bearing, the collision will happen somewhere dead ahead of you. 10 minutes @ 6 knots = 1nm.
So why not slow to steerage way? the other vessel will pass ahead of you.
Alter 90 to starboard? how could you hit the other vessel when he was on the bow?
Alter 180 to starboard? putting more distance between you and the collision point.
If he alters to starboard as well, so much the better.
the original question becomes harder if we imagine the ship approaching from starboard, In this situation, forward of the bow, poor vis, what to do? I can't see anyone being happy about turning to starboard!
[/ QUOTE ]
If he is on a steady bearing, the collision will happen somewhere dead ahead of you. 10 minutes @ 6 knots = 1nm.
So why not slow to steerage way? the other vessel will pass ahead of you.
Alter 90 to starboard? how could you hit the other vessel when he was on the bow?
Alter 180 to starboard? putting more distance between you and the collision point.
If he alters to starboard as well, so much the better.
Phoenix of Hamble
Well-Known Member
If you slow to steerage way, and he then turns to starboard, you haven't solved your problem.....
90 deg to starboard, OK
180 to starboard, also probably OK, but still slight risk of him making/having just made lareg alteration to starboard....
I know that the risk of him making an alteration to starboard is probably low, as if he has seen you, he would probably have made the alteration a while ago, but not impossible, as you might not have seen what he has.... there may be another ship off to your starboard, over your radar horizon that he is allowing for.....
90 deg to starboard, OK
180 to starboard, also probably OK, but still slight risk of him making/having just made lareg alteration to starboard....
I know that the risk of him making an alteration to starboard is probably low, as if he has seen you, he would probably have made the alteration a while ago, but not impossible, as you might not have seen what he has.... there may be another ship off to your starboard, over your radar horizon that he is allowing for.....