12-11-2017, 08:03 PM (This post was last modified: 12-19-2017, 09:56 PM by JayR2017.)
This thread shall help you to address your own questions to the Exercises 2, 4 and 5 ... you can find under "demos" in Radar Trainer 2.0, see following task (1:1 re-print at bottom and as three txt files (see zipped attachment)).
The reports of these exercises with at least one XYZ plot in every exercise is part of the examen.
Reduce the time factor from 30x to a realistic one (as in real life on board). - Click on the right of 30x and reduce the time. (Rec.: You can always accelerate the exercise)
In the Examens report write down what you did:
( a ) Which targets you consider to be dangerous ?
( b ) Make a XYZ plot of these dangerous targets and add these to the report (the plotting sheet you get as pdf here)
( c ) Write down which action you intend to carry out - related to COLREGS
(Rec.: Specifically take care for Rule 19 "Conduct of vessels in restricted visibility.")
( d ) Write down the results you expect (related to your actions from ( c ) ).
( e ) Carry out the intended course or speed change.
( f ) report if it indeed happened the way you expected or not (related to ( e )).
Delivery date of the report: before 29th of December 2017, as it is part of the exam "Instruments". It will count for 10% if made right.
Exercise Demo 2 ... CROSSING COURSES
Whenever you are moving, vessels that appear on the radar as if crossing your course from the side, cannot be on the perpendicular courses they appear to be on. To come straight at your course line from the side, they must be partly headed in the same direction as you.
If they approach only slowly from the side (as target E), their course and speed must be similar to yours, but pointed slightly toward you.
If they come rapidly from the side (targets C and D), their speeds can be higher and their courses more toward you.
Watch this demo in True View to see that target B is the only vessel approaching on the beam. Compare the true and radar motions of targets B and F.
As the true wind is always aft of the apparent wind, the true course a vessel is approaching from is always aft of the apparent direction they come from as seen on the radar. A radar target approaching the bow, is actually comming more from the beam; a radar target approaching the beam, is actually coming more from the quarter (Rec.: Quarter = stern part of a vessel on either side of the rudder.)
Put another way, the actual course of a target approaching from the right is always to the right of its DRM; the actual course of a target approaching from the left is always to the left of its DRM.
(1) Open True view and watch both views to see how the direction of relative motion (DRM) is related to the true direction of motion in light of the above discussion.
(2) In the Glossary look up "aspect," and read the related discussion in the Tutorial.
Exercise Demo 4 ... SPEED CHANGES
The relative motion of radar targets is similar to the relative motion of the wind: the true wind always comes from aft of the apparent wind, regardless of wind direction or boat heading.
Likewise, moving target vessels are always approaching from a direction that is aft of what they appear to be on the radar. How much the true track is aft of the apprarent track depends on the target's SRM and DRM.
Start with Time Factor = 30, Plot on Continuous, and Range 24.
Step (1) Run this demo till all tracks are clear (Radar clock about 12:21) and then stop vessel A.
Notice the target tracks all turn "up screen." When stopped, you see their true motion, which is from a direction aft of the relative direction seen when moving. This exercise is a good way to get a picture of what we mean by "aft of their apparent direction." View the motion in True view and radar view together to get more insight into this.
Step (2) Repeat the demo, but now increase your speed to 12 knots. By increasing speed, you increase the effect of the relative motion, so the target tracks are pushed even farther off their true tracks.
Tutorial Lesson 4 covers the relative motion diagram which illustrates this point with a vector drawing.
When you slow down, targets turn up screen; when you speed up, targets turn down screen -- the effects are small, however, when the target's SRM is large or its DRM is near parallel to your heading.
Exercise Demo 5 ... COURSE CHANGES
It is valuable to know how to anticipate the effect of your course changes on the relative positioning and subsequent tracks of radar targets. When you turn right by some angle, all targets will shift to the left by the same angle -- and vice versa.
This is a simple result of their change in relative bearing. If you are headed 000, and see a target bearing 340 R, and then you turn 40° right, this target will shift 30° left to then appear at 300 R. You can check this effect with target B, or similarily with any of the others.
It is easy to picture what is going on so far. The next step to anticipating what the radar will look like after our turn is not so simple to guess ahead of time.
Repeat the demo and watch B. The target B is coming in from 340 R at a DRM of 168 R (check this with CPA info B). We know when we turn 40° right, that it will shift left to 300 R, but now what will its new DRM be? The answer is 145 R. In other words, when we turned away from the target, its DRM turned towards us. Or put another way, when we turned right, the target appeared to shift left and then turn left on the radar.
To see this, repeat demo and run at time factor 30 till about 12:20 -- long enough to see its DRM established. Then change trime factor to 1 and execute a 40° right turn. We have set vessel A in this demo to be a large vessel so on time factor 1 you will see this slow turn evolve on the radar screen.
After Target B reaches the 300 R position, you can switch time factor back to 30 to more quickly see the new DRM. Notice that it has turned left.
In more general terms, to account for targets on either side of us, we can put it this way: when we turn clockwise, targets will shift counterclockwise and then appear to turn counterclockwise. Look at the trails from this last exercise to verify this description.
Turning the other direction, the reverse occurs.
Use the Set Targets option to change the speeds of several of these targets or your own to see how this effect depends on relative speeds.
Maybe helpfully the User's guide for Radar Trainer 2.0 (dowload here)
12-11-2017, 09:58 PM (This post was last modified: 12-12-2017, 05:24 PM by JayR2017.)
For me personally I'd start first with the basic question, before going into the RadarTrainer and different exercises: How relates Radar to COLREGS ? - Let us remind when "radar" came accross our path in the COLREG lessons ...
Applying the Rule(s) and comments: In accordance with Rule 5 (Look-out ), every vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate in the prevailing circumstances and conditions so as to make a full appraisal of the situation and of the risk of collision.
Comments: Look-out by sight means observing another vessel by naked eye or binoculars.
Look-out by hearing means detecting another vessel by her sound signals.
Look-out by other available means may include using:
- Night vision equipment,
- Information and communication via VHF (vessels or VTS),
- Information from navigational warnings.
Applying the Rule(s) and comments:
In accordance with Rule 6 (Safe speed ), every vessel shall at all times proceed at a safe speed so that she can take proper and effective action to avoid a collision and be stopped within a distance appropriate to the prevailing circumstances and conditions.
In accordance with Rule 6 (a) (Safe speed ), in determining a safe speed for all vessels the following factors shall be among those taken into account:
(i) the state of visibility;
(ii) the traffic density including concentrations of fishing vessels or any other vessels;
(iii) the manoeuvrability of the vessel with special reference to stopping distance and turning ability in the prevailing conditions;
(iv) at night the presence of background light such as from shore lights or from backscatter of her own lights;
(v) the state of wind, sea and current, and the proximity of navigational hazards;
(vi) the draught in relation to the available depth of water.
In accordance with Rule 6 (b) (Safe speed ), in determining a safe speed for vessels with the operational radar the following additional factors shall be taken into account:
(i) the characteristics, efficiency and limitations of the radar equipment;
(ii) any constraints imposed by the radar range scale in use;
(iii) the effect on radar detection of the sea state, weather and other sources of interference;
(iv) the possibility that small vessels, ice and other floating objects may not be detected by radar at an adequate range;
(v) the number, location and movements of vessels detected by radar;
(vi) the more exact assessment of the visibility that may be possible when radar is used to determine the range of vessels or other objects in the vicinity.
Rule 7 ...
( a ) Every vessel shall use all available means appropriate to the prevailing circumstances and conditions to determine if risk of collision exists. If there is any doubt such risk shall be deemed to exist.
( b ) Proper use shall be made of radar equipment if fitted and operational, including long-range scanning to obtain early warning of risk of collision andradar plottingor equivalent systematic observations of detected objects.
( c ) Assumptions shall not be made on the basis of scanty information, especially scanty radar information.
( d ) In determining if risk of collision exists the following considerations shall be among those taken into account: (i) such risk shall be deemed to exist it the compass bearing of an approaching vessel does not appreciably change; (ii) such risk may sometimes exist even when an appreciable bearing change is evident, particularly when approaching a very large vessel or a tow or when approaching a vessel at close range.
If the bearing (compass or relative) taken visually or with radar at interval of time does appreciable change (increasing), than the risk of collision shall not be deemed to exist.
Applying the Rule(s) and comments:
In accordance with Rule 8 (b) (Action to avoid collision ), any alteration of course and/or speed to avoid collision shall, if the circumstances of the case admit, be large enough to be readily apparent to another vessel observing visually or by radar.
Small changes of course and/or speed are not easily noticeable to other vessels since, the aspect during day time and the navigation light aspect at night may not appreciably differ from what it was before the small alteration of course. In this situation, the other vessel would be in doubt as to whether you have taken action or not.
Rules in this Section shall apply to vessels in sight of one another.
Rule 3(k) states that vessels shall be deemed to be in sight of one another only when one can be observed visually from the other. The Rules in Section II do not apply to a vessel which has detected another vessel by radar, and has established that risk of collision exists, if the other vessel cannot be sighted visually. Rule 19 of Section III applies only to vessels navigating in or near an area of restricted visibility which are not in visual sight of one another. In restricted visibility, therefore, vessels may initially have to comply with Rule 19 of Section III then subsequently have to comply with the Rules of Section II when they come into visual sight of one another. A vessel is unlikely to be excused for not complying with the appropriate Rule of Section II if it is considered that failure to sight the other vessel was due to a bad visual look-out.
It is conceivable that instantaneous sighting may not occur, even if both vessels are keeping an efficient visual look-out, due to such factors as different intensities of navigation lights or to patches of low fog obscuring the bridge of one vessel but not her masthead lights. A vessel must comply with the Rule which relates to the situation which applies at the particular instant.
In the discussions which took place before the 1972 Conference serious consideration was given to the possibility of formulating one set of manoeuvring rules which would apply in all conditions of visibility. The Conference decided against adopting this principle, however, mainly because it is usually possible for vessels to sight one another in sufficient time to recognise the lights or shapes being displayed so that the degree of responsibility can be based on the vessel's ability. to take effective avoiding action.
Vessels engaged in such activities as fishing or underwater operations and vessels not under command may be incapable of manoeuvring effectively. A slow vessel being overtaken by a vessel of high speed may not observe the overtaking vessel until it is too late to get clear by her own action. Even in a crossing situation involving two power-driven vessels, if both were to be required to keep out of the way, the vessel expected to pass ahead of the other is likely to be less capable of achieving a safe passing distance by her own action than the vessel expected to cross astern of the other.
Rules 13 and 18 of Section II are based on the principle of allocating prime responsibility to the vessel which will usually be more capable of keeping out of the way. If no such distinction were made the vessel with the greater ability to take effective avoiding action would be more likely to wait for the other to keep out of the way. It is, of course, not possible to allocate greater responsibility to the vessel which is more capable of taking avoiding action when the visibility is restricted and the vessels are not in visual sight of one another as all vessels do not have an operational radar and a means of identifying a hampered vessel by radar has not yet been established. Fortunately, there are few areas of the world in which serious restriction of visibility is likely to be frequently experienced.
A vessel is only required to maintain her course and speed in a two vessel situation. In the unlikely event of one vessel finding herself on a collision course with two other vessels at the same time, being in one case the give-way vessel and in the other case the stand-on vessel, she could not be expected to keep out of the way of one vessel and maintain her course and speed for the other.
One vessel is to keep out of the way
Rules 12, 13, 15 and 18require one of two vessels to keep out of the way. The "give-way vessel" is required to take early and substantial action to keep well clear by Rule 16. Rule 17 lays down provisions for the other vessel, referred to as the "stand-on vessel". Rule 17 does not apply if the two vessels concerned are not in visual sight of each other, or if there is no risk of collision. This means that, for instance, a power-driven vessel which detects another vessel approaching from the port bow, or from more than 22.5° abaft the beam, and determines by radar that the bearing is not changing, is not required to keep her course and speed if the vessel cannot be sighted visually. There is also no obligation to keep course and speed for a vessel sighted at long range, before risk of collision begins to apply, even though the bearing may not be appreciably changing.
Keep course and speed
A vessel which is required to keep her course and speed does not necessarily have to remain on the same compass course and maintain the same engine revolutions.
May take action Rule 21 of the 1960 Regulations required the stand-on vessel to keep her course and speed until collision could not be avoided by the give-way vessel alone. At that precise moment action was made compulsory. This requirement imposed a mandate on the stand-on vessel which in many cases was impossible to fulfill without making collision inevitable. The moment for action was related to the other vessel's size and manoeuvering characteristics which are difficult to assess, particularly at night. When the vessels are so close that collision cannot be avoided by the give-way vessel alone it should still be possible for a relatively small and highly manoeuverable stand-on vessel to avoid collision by her own action, but it can be shown that, in the case of two merchant ships of equal size and speed in a crossing situation with no change of compass bearing, continued failure to keep out of the way by the give-way vessel would make collision inevitable, irrespective of any action taken by the stand-on vessel.
An important new provision is made in Rule 17 (a)(ii). This permits a stand-on vessel to act at an earlier stage, to avoid collision by her manoeuvre alone, without having to justify such action as a necessary departure from the Rules in order to avoid immediate danger.
A stand-on vessel is not specifically required to take action to avoid collision as soon as it becomes apparent that the give-way vessel is not taking appropriate action. She is permitted to keep her course and speed until collision cannot be avoided by the give-way vessel alone. However, the provision for permissive action places greater emphasis on the obligation of the stand-on vessel to continuously assess the situation when risk of collision exists to indicate any doubt by use of the signals prescribed in Rule 34 (d) and, subsequently, to take action before collision becomes inevitable. A stand-on vessel which fails to take action in sufficient time to avoid collision by her own manoeuvre is likely to be held at fault if a collision should occur. The difficulty of determining the precise moment when action becomes compulsory is less likely to be accepted as a valid excuse for waiting too long now that a stand-on vessel is permitted to manoeuvre at an earlier stage.
Earliest moment for permitted action
When risk of collision first begins to exist the stand-on vessel must keep her course and speed. The give-way vessel is required to keep out of the way in good time and to take substantial action which will result in passing at a safe distance. The method of keeping out of the way is not specified but in the case of two power-driven vessels crossing the give-way vessel must avoid crossing ahead. A stand-on vessel which takes avoiding action before it can reasonably be assumed that the give-way vessel is not taking appropriate action is likely to be held mainly to blame if practically simultaneous action by the give-way vessel causes a confused situation which results in collision.
The stand-on vessel is required to keep her course and speed until it becomes apparent that the give-way vessel is either failing to take action in ample time or failing to take sufficient action to achieve a safe passing distance. The obligations of the give-way vessel are specified in Rules 8 and 16. Rule 16 requires every give-way vessel to take early and substantial action and the provisions of Rule 8 include requirements to take action which will be readily apparent to the other vessel and will result in passing at a safe distance.
Action should not be taken by the stand-on vessel without first determining that risk of collision does in fact exist. Compass bearings should be observed accurately and the radar should be used to measure the range of the approaching vessel. The earliest moment for permitted action will obviously be related to the range and the rate of change of range.
In the open sea a give-way vessel which approaches to within a distance of about two miles in a crossing situation involving two merchant ships can usually be considered to have waited too long, but smaller or greater distances may apply depending upon the size and manoeuvrability of the vessels and depending particularly upon the rate of approach.
Action to be taken by the stand-on vessel
When vessels are in sight of one another any vessel which fails to understand the intentions or actions of an approaching vessel, or is in doubt whether the other is taking sufficient action to avoid collision, is required by Rule 34 (d) to immediately indicate such doubt by giving at least five short and rapid blasts on the whistle. The sound signal may be supplemented by a light signal of at least five short and rapid flashes which may be more effective as a "wake-up" signal, especially at distances over 2 miles. If these signals bring no immediate response further precautionary measures should be taken aboard the stand-on vessel, depending upon the circumstances, such as calling the master, changing to manual steering and putting the engines on stand-by.
A stand-on vessel which takes permitted action to avoid collision by her manoeuvre alone, when it becomes apparent that the give-way vessel is not taking appropriate action, must obviously take full account of the possibility that the give-way vessel may also take simultaneous or subsequent action. The stand-on vessel should avoid taking action which is likely to conflict with the probable action of the give-way vessel.
Rule 8 (e) requires a vessel to slacken her speed if necessary to avoid collision. A reduction of speed made by the stand-on vessel would make it more difficult for the give-way vessel to cross astern, which is her most likely method of keeping out of the way. An increase of speed might even be appropriate in certain circumstances, particularly in association with helm action, but any alteration of speed should be substantial and a vessel is unlikely to be proceeding at reduced speed if the Rules of Section II apply. A change of speed is usually slow to take effect and will be less readily apparent to the other vessel than helm action.
An alteration of course away from the direction of the other vessel will usually be the safest manoeuvre, if it is made in sufficient time. Such a manoeuvre could hardly contribute to a collision, even if made too early, provided it has been established that the bearing is not, in fact, closing on the bow. Turning away from the other vessel in a crossing situation will, at least, slow down the rate of approach. If the give-way vessel is approaching from less than about 60° on the bow the best action may be to turn away until the other vessel is approximately abeam, but if the give-way vessel is overtaking or approaching from near the beam an alteration on to a parallel or slightly diverging course would probably be the safest action.
Although turning away from the give-way vessel may be the safest form of avoiding action the presence of other vessels, the proximity of navigational hazards and other factors must obviously be taken into account in deciding how to manoeuvre. If a hampered vessel takes action to avoid a give-way vessel approaching from fine on the starboard bow, which fails to keep out of the way, it may be safer to make a substantial turn to starboard. The give-way vessel is not required to avoid crossing ahead in this case and is likely to turn to starboard, especially by day when she may have failed to recognise the shapes displayed by the hampered vessel. When vessels are in sight of one another a power-driven vessel which alters course to port or to starboard, or operates astern propulsion, is required to indicate the manoeuvre by the whistle signals prescribed in Rule 34 (a) and may supplement the sound signal with the light signal referred to in Rule 34(b). It is particularly important for both the give-way vessel and the stand-on vessel to make such signals, when taking action at a relatively late stage, in order to reduce the possibility of conflicting action being taken by the other vessel.
Compulsory action by the stand-on vessel
When the stand-on vessel finds herself so close that collision cannot be avoided by the give-way vessel alone she is required to take action. The distance between the two vessels at the moment when action becomes compulsory for the stand-on vessel will vary with the direction and speed of approach and will also depend on the give-way vessel's manoeuvring characteristics. In a crossing situation this distance will usually be about four times the length of the give-way vessel.
As it is difficult to determine exactly how close the give-way vessel could approach before she is unable to avoid collision by her own action alone, the stand-on vessel should preferably take action before reaching this stage. An alteration of course to starboard to avoid a vessel approaching from the port bow could be a dangerous manoeuvre if there is insufficient time to get clear. In the open sea it is suggested that a stand-on vessel should not allow a give-way vessel to approach to a distance of less than about twelve times her own length in a crossing situation without taking avoiding action.
When collision with another vessel is considered to be inevitable, the foremost concern of the officer must be to manoeuvre his ship so as to reduce the effect of collision as much as possible. The consequences are likely to be most serious if one vessel strikes the other at a large angle near the mid length. The engines should be stopped, and the helm should be used so as to achieve a glancing blow rather than a direct impact. The damage would probably be the least serious if the impact is taken forward of the collision bulkhead. When a vessel is approaching on the port bow an alteration to starboard may well be the worst possible action to take.
Obligation of the give-way vessel
A disadvantage of permitting the stand-on vessel to take action to avoid collision by her manoeuvre alone is that the give-way vessel may be tempted to wait in the hope that the stand-on vessel will keep out of the way. The purpose of Rule 17(d) is to emphasise that the give-way vessel is not relieved of her obligation to take early and substantial action to achieve a safe passing distance by the provisions of Rule 17(a)(ii). A stand-on vessel is not permitted to manoeuvre until it becomes apparent that the give-way vessel is not taking appropriate action in compliance with the Rules. The give-way vessel should take positive action in ample time so that the stand-on vessel can maintain her course and speed. If the stand-on vessel takes action in accordance with Rule 17(a)(ii) the give-way vessel is not relieved of her obligation to keep out of the way and to achieve a safe passing distance.
Rule 19: Conduct of vessels in restricted visiblity
Vessel A: Power-driven vessel
Vessel B: Power-driven vessel
Visibility: Restricted (vessels are not in sight of one another)
Vessel A detects by radar alone the presence of vessel B
Vessel A and vessel B are crossing so as to involve risk of collision
Vessel A has vessel B on her own port side (relative bearing PORT 053°)
Applying the Rule(s) and comments: In accordance with Rule 19 (d) (Conduct of vessels in restricted visibility ), a vessel which detects by radar alone the presence of another vessel shall determine if a close-quarters situation is developing and/or risk of collision exists. If so, she shall take avoiding action in ample time, provided that when such action consists of an alteration of course, so far as possible the following shall be avoided:
(i) an alteration of course to port for a vessel forward of the beam, other than for a vessel being overtaken;
(ii) an alteration of course towards a vessel abeam or abaft the beam.
In accordance with Rule 7 (b) (Risk of collision), proper use shall be made of radar equipment if fitted and operational, including long-range scanning to obtain early warning of risk of collision and radar plotting or equivalent systematic observation of detected objects.
2. The use or exhibition of any of the foregoing signals except for the purpose of indicating distress and need of assistance and the use of other signals which may be confused with any of the above signals, is prohibited.
3. Attention is drawn to the relevant sections of the International Code of Signals, the International Aeronautical and Maritime Search and Rescue Manual, Volume III and the following signals:
(a) a piece of orange coloured canvas with either a black square and circle or other appropriate symbol (for identification from the air);
(b) a dye marker.
Applying the Rule(s) and comments:
In accordance with Rule 37 (Distress signals) and Annex IV 1(o) (Distress signals), when a vessel is in distress and requires assistance she may use approved signals transmitted by radiocommunication systems, including survival craft radar transponders.
so we should do 02, 04 and 05.
We should make a shor report on these exercise and deliver it.
I dont get it.
The 02 is bacically done with clicking start, reading the description, and realizing that ships going towards A (centerpoint) on the radar going to a place where A is going to be in real life. The closer it comes to A/the centerpoint in the radar, the closer it gets to A in real life.
I also made 3 sketchings on a piece of paper.
And then? brigning it on Paper in an XYZ plot, mark dangerous targets, write down the actions i would take according to the Col Regs.
Then i go back to the simulator and feed it with the course changes and see whats happening and write a report on it?
Its not just about "Radar plotting". Or handling a radar instrument. Its more about to write a fully report about to give a clear understanding you understood the situation on the bridge well under given conditions and circumstances, specificaly related to COLREGS (here Bernt links to the teaching of COSMO). So its up to you to tell your own story (e.g. which kind of ship you are on board, weather conditions etc. ....)
P.S.: I will close the single post/thread, pls post in following to keep all datas together. Tks.
It's worth to use the RadarTrainer intensively. Related to Nicole's questions one is doing well, to go through the fully Tutorial, which is accessible inside the Radar Trainer. See screenshots attached.
It teaches well all abbreviations, Radar Terms, the correct method of "paper sheet plotting" ...
(12-20-2017 04:44 PM)sembeiudon Wrote: Then i go back to the simulator and feed it with the course changes and see whats happening and write a report on it?
To calculate the new CPA by course change and plotting is a task for GZV. It goes too far for KZV. As stated in the COLREGs book, a minimum course change is at least 30-45 degrees, so at "reduced visibility" it also can be noticed clearly by the other ship on radar screen.
A course change of maybe just 10-15 degrees to increase CPA (closest point of approach) from maybe 1.5 nm to 2.5 nm would not be enough and not be seen legally as "safe manoever" to avoid (risk of) collision. Rule 8 b states an alteration of course to be large enough.
To keep observing the radar screen is part of "safe navigation" and good seamanship and also stated in COLR to take steadily observation (Rule 8 a/b) till the object is finally and safely past and clear, until danger is over (e.g. Rule 19 e for restricted visibility).
Reporting in the examens abt what happens after the course change was done can be seen like a notice in a ship's log, where every change of course must be noticed (and also addressed the reasons for with time and ship position).