View Full Version : How do I locate and kill a ship?
canadabear07
10-06-12, 02:31 AM
what is the whole procedure for locating and killing a ship?
Thanks
Watch the map for reported locations of single vessels or convoys. Then go there using this technique:
http://www.subsim.com/radioroom/showthread.php?t=88961
The intercept drawing in synopsis:
http://www.kylania.com/sh3/Intercept_Plotting.png
Or else be in the right spot (traffic chokepoint) and make sure your crew looks around. Or ever so often dive to periscope depth and do a hydrophone listen yourself. That allows much further detection. (atleast 2x)
i like this diagram Pisces. i am always looking for new ways to do this. could you explain what 'scaling factor' is to me. i have no idea what it means or how to use it.
or expand the 1-5 points a little more
cheers:up:
i like this diagram Pisces. i am always looking for new ways to do this. could you explain what 'scaling factor' is to me. i have no idea what it means or how to use it.
or expand the 1-5 points a little more
cheers:up:The function of the scaling factor is to make the speed triangle (made by blue line, red circle and yellow protractor) similar in size to the distance triangle. (made by black bearing, and black target course and green intercept angle) It's just to make it visually more appealing, and easier to compare the shape. Or avoid the use of excessive map-zooming if the actual distances are in the order of hundreds of kilometers.
If you ignore this scaling factor (which I suggest you do in the beginning), then you would simply draw the blue line and red circle with 1km for every 1 knot. This would result in a triangle that is around 5 to 30km in size, depending on your approach. However, your actual distance to the target could be hundreds of kilometers away. And so the intercept point might be also multiple hundred kilometers away. So you'll end up with a tiny speed triangle inside a massive distance triangle. This speed factor is used to even out the size disparity. It scales up the speed triangle to match (within) the distance triangle.
"But what scale value is needed?", you might ask. Well it depends on the distance to the target, and the closing velocity between you and the target (the yellow protractor leg along the target bearing). So, in essence the time the intercept would take. Choose whatever makes the speed triangle fall within the target distance. Because otherwise you don't get a closest intersection of the red circle and the target bearing-line. (the red circle would envelop beyond your position, and you would have to extend the bearing line backwards beyond your position to get the intersection point B)
Whatever you decide on ignoring the scaling factor or not, make sure the red circle and blue line are scaled by the same amount!!! Or else the intercept drawing becomes gibberish.
TLDR: keep the factor 1 (for simplicity's sake),
or if the distance is really really long, 10 km for each 1 knot of speed. It's easier to displace the decimal mark by one, than it is to multiply with odd lot numbers.
The link I provided does explain the steps of the procedure in more detail. But perhaps not what the parts of the drawing actually mean. If I need to explain further please say so. This message is getting long already.
..im sorry Pisces i just dont understand. ive studied the drawing and can not quite figure it out. maybe going through point by point would help?
ie 1 through 5. but i understand if this is too much!
thank you anyway:up:
Woolfman
10-11-12, 11:25 AM
:yeah: I use the "4-F" method:
Find him
Fix him
Flank him
Finish him
Woolfman :arrgh!:
Andrewsdad
10-12-12, 12:02 AM
Allow me to take a crack at it :)
1. When a contact appears on the map take your protractor and draw the angle from your boat to the contact and along the direction the contact is moving. (You may have to make a estimate of that course, but use your best judgement.)
2. Take your ruler. Start at the contact and run a measurement along the targets course. Make the length some multiple of the targets speed. Remember this multiple.... (In the diagram example you will see the value is 6. Since the estimate of the convoy speed is 6 knots and the multiple selected was 1 so line is 6k in length)
3. Now, decide at what speed you wish to sail your boat to intercept the convoy. Take the compass and draw a circle whose diameter is the speed you selected x the multiple you selected in step 2. ( In the diagram example the speed selection was 12 knots, and the multiple is 1 so the circle is 12k in diameter.)
4. Take your protractor again and draw the angle from the center of the circle to the point where the circle intercepts the line from the target to your boat and along that line toward the target. (That is the Yellow lines making angle #1 in the diagram example.) Take note of that angle...
5. Again with the protractor, start at the target and go to your boat and make the same angle as above and extend it to the convoy course line you made in step #1. This is your intercept course. (This is the Green lines in the diagram example.)
6. Now take your course setting tool and set it along that intercept line and you will sail right to the enemy. It will even tell you how long it will take to get there.
Remember, the scaling factor you select is only to make the drawing easy to build. Just be sure you use the same factor for both steps #2 and #3.
Once you have performed this navigation task and are on course to intercept the target you will find it a good idea to actually sail at a somewhat faster speed than you used for the plot. It is better to get there ahead and set up for the attack.
Hope this helps, Herr Kaleun.
Salute !!
AD
And as to the why:
The idea behind intercepting is you want to meet the target at a certain place in the future. But ideally, the sooner the better. This calls for butting your head with the other skipper. You are going for a near-collision course. By the time you detect the target you change your approach to overtake him, or whatever else you feel like. The point is: you want to merge. But where to go?
Merging means closing the distance (only). You don't want to move around him, or he around you. That can be left to the final stage. You want all your energy spent to be focussed on distance. So let's head directly towards him.
1a: plot a line between you and the target.
Oh dear, he's not playing dead, or even comming directly towards you. He is moving at a course, with some angle to the bearing of step 1a.
1b: plot a (long) line representing his course.
(or 1a+1b: plot a protractor/angle thingy: from you, to the target, to his heading)
He having a course not in-line with the bearing means that going directly towards him isn't going to help us. He is stepping sideways, so you need to do that too. Not the same angle mind you. But the same steps for his side steps. Or else you and him will end up doing a swirl around each other. Let's see how much he moves sideways from the bearing line.
2a: Plot a line along the target course, ....
Do you actually know how quickly he moves? Do you need to make a guesstimate of it? Or are you relatively sure, because the convoy speed was given. Oh well. At worst slow contacts move 8 knots when slow, and 12 when medium. (Secret: actually, it's 7.5 and 11.5 due to rounding numbers)
Hmm?... , he moves to the interception point in the same time as you do. Does time then really matter? If you move sideways just the same amount as much as he does, does it matter at all? No! So time, or the actual units of measure used for the length do not matter. Let's imagine we are going to start a drawing that represents a shortended version of the intercept. A period where target moves 6 km at 6 nautical miles per hour (6 knots) (if you insist, it's 32.5 minutes)
2b: Make the length of the line along the target course equal to the target speed. From the starting (or current) position.
Erhm, how quick can you go anyway? Are your engines in fit shape? Are you still required to charge up the batteries? Are the weather-gods favouring you? Whatever the case. Choose a speed that you can maintain all throughout.
Ok, in the same time you also move your last kilometers, at your speed. So you would need to draw a line of your own. Let's say 16km, because your moving at 16 nautical mile per hour (knots).
But you don't yet know where it has to start. It can't be your current position, because we are creating a make-believe drawing first. You don't even know in which direction to pull the endpoint. Just that it must be 16 km (units) of length. And that it ends where the target will be. Ok, so you need to consider all possible directions.
3: Draw a circle around the target endpoint, with a radius of 16 km. It doesn't matter where the arrow is pointing too.
Now you have the collection of all possible starting locations that gets you to end up at the meeting point. All you need to do is choose which one (or two ;) ) it is going to be.
Well, for starters, you currently are on the bearing line. And that is also the shortest path to the target. So, could there be 1 or 2 places that meet those conditions?
Well, yeah. Or, .... probably. It depends. If he is not doing a marathon like a taskforce gone wild. If you are faster than he is, you can bet on there being exactly 1 point on the circle and bearing line. It doesn't matter where he goes, he's toast sooner or later. (Assuming he doesn't change course) If you are slower than he is, then you might get 2 points on the circle and bearing. If he is then also moving away (with more than 90 degrees AOB) then there isn't going to be a point matching the circle and bearing line. And he's a lost cause.
Either way, if there are 2 points on the circle that cross the bearing line, then take the closest one to your current position. The far one will work, but it leads to the the slower, rather than the quickest direction to close the distance. Let's not go there, will you. ;)
4a: Locate the closest intersection of the circle and the bearing line. (from your real position) If there is any. If none, then speed up, or forget him.
Ok, so now you know where you would need to start from. In order to move 16km at 16 knots, while the target is moving his 6 km at 6 knots. And you both whould be meeting each other at the CENTER of the action. (from step 3)
Cool, now you know the direction. To go from the intersection, to the center of the circle. You could also consider this to be the angle you have to steer away from the bearing line, to be meeting the target in the face.
4b: Draw a protractor (angle thingy) from the center of the circle, to the nearest intersection point, to along the bearing line.
Now you know how much you need to lead the target with your bow.
"Any other information I can glean from this triangle?" You sure do, smart cookie!
Measure the length between the intersection point, and the current target location. That length is the rate at which the distance is shortening. Closure rate. The value is in knots, because all the other speeds are in knots too. But you wouldn't have to bug your navigator about calculating it. Oh wait, you are the navigator. Oh well, remember that closure rate! Convert it to km/hour by multiplying it by 1.852. Or use the nomograph.
"Homo... , say what?"
See the vertical scales on that colorful map drawing! Wiki hint! (http://en.wikipedia.org/wiki/Nomogram)
"Ok, whatever! But remember this was only make-belief. I'm way much further away than that. I'm never going to meet him in 32 minutes, ... and a bit."
Correct, but do you remember that you only had to steer exactly so many degrees (as step 4b) away from the bearing line? Yes? Then do that.
5: Draw another protractor/angle thingy: from the target, all the way to you. And then match the angle in the corner to step 4b. Drag it out until it crosses the target course.
"Got it!"
Good! Now, what's keeping ya. Set sail. Drop a waypoint on the new meetingpoint. And keep an eye out on that (true) bearing. If you did your speed guessing right, someone is going to be lingering on it. At least you'll know where to start looking.
Godspeed friend. I hope that is step by step enough.
Allow me to take a crack at it :)
1. When a contact appears on the map take your protractor and draw the angle from your boat to the contact and along the direction the contact is moving. (You may have to make a estimate of that course, but use your best judgement.)
2. Take your ruler. Start at the contact and run a measurement along the targets course. Make the length some multiple of the targets speed. Remember this multiple.... (In the diagram example you will see the value is 6. Since the estimate of the convoy speed is 6 knots and the multiple selected was 1 so line is 6k in length)
3. Now, decide at what speed you wish to sail your boat to intercept the convoy. Take the compass and draw a circle whose diameter is the speed you selected x the multiple you selected in step 2. ( In the diagram example the speed selection was 12 knots, and the multiple is 1 so the circle is 12k in diameter.)
4. Take your protractor again and draw the angle from the center of the circle to the point where the circle intercepts the line from the target to your boat and along that line toward the target. (That is the Yellow lines making angle #1 in the diagram example.) Take note of that angle...
5. Again with the protractor, start at the target and go to your boat and make the same angle as above and extend it to the convoy course line you made in step #1. This is your intercept course. (This is the Green lines in the diagram example.)
6. Now take your course setting tool and set it along that intercept line and you will sail right to the enemy. It will even tell you how long it will take to get there.
Remember, the scaling factor you select is only to make the drawing easy to build. Just be sure you use the same factor for both steps #2 and #3.
Once you have performed this navigation task and are on course to intercept the target you will find it a good idea to actually sail at a somewhat faster speed than you used for the plot. It is better to get there ahead and set up for the attack.
Hope this helps, Herr Kaleun.
Salute !!
AD
And as to the why:
The idea behind intercepting is you want to meet the target at a certain place in the future. But ideally, the sooner the better. This calls for butting your head with the other skipper. You are going for a near-collision course. By the time you detect the target you change your approach to overtake him, or whatever else you feel like. The point is: you want to merge. But where to go?
Merging means closing the distance (only). You don't want to move around him, or he around you. That can be left to the final stage. You want all your energy spent to be focussed on distance. So let's head directly towards him.
1a: plot a line between you and the target.
Oh dear, he's not playing dead, or even comming directly towards you. He is moving at a course, with some angle to the bearing of step 1a.
1b: plot a (long) line representing his course.
(or 1a+1b: plot a protractor/angle thingy: from you, to the target, to his heading)
He having a course not in-line with the bearing means that going directly towards him isn't going to help us. He is stepping sideways, so you need to do that too. Not the same angle mind you. But the same steps for his side steps. Or else you and him will end up doing a swirl around each other. Let's see how much he moves sideways from the bearing line.
2a: Plot a line along the target course, ....
Do you actually know how quickly he moves? Do you need to make a guesstimate of it? Or are you relatively sure, because the convoy speed was given. Oh well. At worst slow contacts move 8 knots when slow, and 12 when medium. (Secret: actually, it's 7.5 and 11.5 due to rounding numbers)
Hmm?... , he moves to the interception point in the same time as you do. Does time then really matter? If you move sideways just the same amount as much as he does, does it matter at all? No! So time, or the actual units of measure used for the length do not matter. Let's imagine we are going to start a drawing that represents a shortended version of the intercept. A period where target moves 6 km at 6 nautical miles per hour (6 knots) (if you insist, it's 32.5 minutes)
2b: Make the length of the line along the target course equal to the target speed. From the starting (or current) position.
Erhm, how quick can you go anyway? Are your engines in fit shape? Are you still required to charge up the batteries? Are the weather-gods favouring you? Whatever the case. Choose a speed that you can maintain all throughout.
Ok, in the same time you also move your last kilometers, at your speed. So you would need to draw a line of your own. Let's say 16km, because your moving at 16 nautical mile per hour (knots).
But you don't yet know where it has to start. It can't be your current position, because we are creating a make-believe drawing first. You don't even know in which direction to pull the endpoint. Just that it must be 16 km (units) of length. And that it ends where the target will be. Ok, so you need to consider all possible directions.
3: Draw a circle around the target endpoint, with a radius of 16 km. It doesn't matter where the arrow is pointing too.
Now you have the collection of all possible starting locations that gets you to end up at the meeting point. All you need to do is choose which one (or two ;) ) it is going to be.
Well, for starters, you currently are on the bearing line. And that is also the shortest path to the target. So, could there be 1 or 2 places that meet those conditions?
Well, yeah. Or, .... probably. It depends. If he is not doing a marathon like a taskforce gone wild. If you are faster than he is, you can bet on there being exactly 1 point on the circle and bearing line. It doesn't matter where he goes, he's toast sooner or later. (Assuming he doesn't change course) If you are slower than he is, then you might get 2 points on the circle and bearing. If he is then also moving away (with more than 90 degrees AOB) then there isn't going to be a point matching the circle and bearing line. And he's a lost cause.
Either way, if there are 2 points on the circle that cross the bearing line, then take the closest one to your current position. The far one will work, but it leads to the the slower, rather than the quickest direction to close the distance. Let's not go there, will you. ;)
4a: Locate the closest intersection of the circle and the bearing line. (from your real position) If there is any. If none, then speed up, or forget him.
Ok, so now you know where you would need to start from. In order to move 16km at 16 knots, while the target is moving his 6 km at 6 knots. And you both whould be meeting each other at the CENTER of the action. (from step 3)
Cool, now you know the direction. To go from the intersection, to the center of the circle. You could also consider this to be the angle you have to steer away from the bearing line, to be meeting the target in the face.
4b: Draw a protractor (angle thingy) from the center of the circle, to the nearest intersection point, to along the bearing line.
Now you know how much you need to lead the target with your bow.
"Any other information I can glean from this triangle?" You sure do, smart cookie!
Measure the length between the intersection point, and the current target location. That length is the rate at which the distance is shortening. Closure rate. The value is in knots, because all the other speeds are in knots too. But you wouldn't have to bug your navigator about calculating it. Oh wait, you are the navigator. Oh well, remember that closure rate! Convert it to km/hour by multiplying it by 1.852. Or use the nomograph.
"Homo... , say what?"
See the vertical scales on that colorful map drawing! Wiki hint! (http://en.wikipedia.org/wiki/Nomogram)
"Ok, whatever! But remember this was only make-belief. I'm way much further away than that. I'm never going to meet him in 32 minutes, ... and a bit."
Correct, but do you remember that you only had to steer exactly so many degrees (as step 4b) away from the bearing line? Yes? Then do that.
5: Draw another protractor/angle thingy: from the target, all the way to you. And then match the angle in the corner to step 4b. Drag it out until it crosses the target course.
"Got it!"
Good! Now, what's keeping ya. Set sail. Drop a waypoint on the new meetingpoint. And keep an eye out on that (true) bearing. If you did your speed guessing right, someone is going to be lingering on it. At least you'll know where to start looking.
Godspeed friend. I hope that is step by step enough.
thanks to both of you for taking the time with this. i have printed them both off and will try each one.
many thanks
flag4.:up:
Red October1984
10-19-12, 01:33 PM
:yeah: I use the "4-F" method:
Find him
Fix him
Flank him
Finish him
That's how i get stuff done.
Or i just harbor raid. Best harbor raiding boat is the VIIC. IX is too big IMO.
Woolfman
10-24-12, 04:18 PM
Watch the map for reported locations of single vessels or convoys. Then go there using this technique:
http://www.subsim.com/radioroom/showthread.php?t=88961
The intercept drawing in synopsis:
http://www.kylania.com/sh3/Intercept_Plotting.png
Or else be in the right spot (traffic chokepoint) and make sure your crew looks around. Or ever so often dive to periscope depth and do a hydrophone listen yourself. That allows much further detection. (atleast 2x)
The Hunt is the greatest U-Tube videos on the subject of target interception in my opinion! I very rarely miss my intercepts unless they're close to land on the initial map update...probably because they turn in to port before I reach them.
The scale on the right side of the chart is also good for target speed estimates...when we use manual tergeting, of course.
With all of this information at hand I insert the data straight into the target speed dial; lock the target on the TDC and click 90 degrees on the notepad (port or starboard depending on target heading). CLICK the "X" to erase the notepad info. before firing!.....adjust target distance approximately; open tube doors; position your bow as perpendicular to the target as possible and fire away.
:smug: I'm not sure if you could qualify this technique as the lazy man's approach but it work for me.
woolfman :arrgh!:
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