Contacts moving away

[peteuplink]

When I'm on patrol and I get a position report on a convoy or ship that's near to me but moving away, I can never get myself into a good position without being seen, and if I take a round about route to avoid visual contact it means wasting a lot of fuel. I never have been able to work out a good tactic for this situation.

Is it worth going after these contacts or should I only go after ones that are heading in my general direction?

[Torplexed]

Usually, the only option is to try the high speed end-around you described to try and get back ahead of the convoy. A lot depends on circumstances. If you were low on torpedoes and headed back to base anyway, and the convoy is going in that direction, it works out. Sometimes, during the pursuit you get lucky and the convoy will alter direction so you get a quicker intercept. It can also steer away as well.

Circumstances definately dictate.

During daylight hours, in heavy airtraffic areas, it's generaly best to ignore ships that are moving away. Especialy with a low speed, short range boat, like the IIA.

Each situation stands on it's own merrit.

[codmander]

lifes a bitch sometimes and end around is correct first do your math convoy speed and direction figures where they are suppose to be at the (((hours)))) it takes you to get there

[Pisces]

If you are using a type 7 fuel is not that much of a problem. And if you stay concious of your fuel consumption during the rest of your patrol you can even do it with a type 2. But it has a bit lower topspeed, so it's harder to overtake.

The trick is first knowing where he is going and roughly with what speed. Then you can follow his moves (parallel course) and maintain distance until you are certain of his course and speed. Don't go flank right away.

Now, lets make a small drawing that makes us dance around him, instead of intercept straight towards him. Yes, that's right! This is a ballet-class.

1. Draw a line from where you are right now to his current position on the map.

2. Draw a circle on the map such that the arrow resembles the TARGET speed and course. (like 15kts = 15km circleradius, this is just a scale, not actual range) Shift it around until the arrowhead is at the beginning of the line of step 1 (in other words, your old position)

3. Draw a circle on the map, with a radius equal to the speed you are going to use to get around him. The directon of the arrow doesn't matter, but the center must be on the center of the other circle(so they must be concentric, and same scale as step 2)

Now, we need to draw in the direction inwhich you see the target. (Oh wait!, that's the reason we have drawn the line in step 1. ... carry on )

4. Take the periscope bearing/watchofficer reported bearing and add that to your course. If the result is bigger than 360, subtract 360 degrees from it. The result is the 'true bearing to target' from your position on the map. (Thats all the math that it takes!!!!)

5. Draw a protractor on the map, with the corner on the arrowhead of the target's speed circle.

6. Point 1 leg in the direction you calculated in step 4. So towards the target. (he should still be in that general direction, like the line you have drawn in step 1... so if you want you can cheat here )

7. Turn the other leg until you have a 90 degree angle, in the direction that he seems to move. If his bow is pointed to the left, point the 2nd leg 90 degrees counterclockwise. If his bow seems to move right, point the 2nd leg 90 degrees clockwise. Extend the leg until it is outside of your speed circle.

8. Start a line from the center of the circles, towards the point on YOUR speed circle where that 2nd protractor leg intersects it. THAT is the direction that makes you circle around him. Use the line to measure the direction to this point with the reversed compass ring.

For the above I VERY MUCH suggest you make use of my mousecursor tweak:

http://www.subsim.com/radioroom/show...postcount=1308

HOWEVER! That direction is only true for a short while. To make nice circles around him you need to update/redo the drawing everytime the bearing to the target changes something like 10-20 degrees. I keep re-using the same drawing, and update the leg towards the target as the target moves around in my periscope, with the second leg to follow 90 degrees in-step. It seems laborious, but it's so much fun dancing around your unsuspecting target, while you only vary in range about 1 kilometer. But that depends on how often you redo the drawing. Keep in mind that when you make a course change the relative bearing of the target also changes, but the true bearing should be the same value. (that's the reason I made you do the calculation at step 4)

A pleasant side effect of this technique is that you naturally are moving away from him if you don't make any adjustments to your drawing. (it's a bit like jumping of a Merry-go-around/Carousel/'centrifugal force') So if you get out of visual range you may need to change that 90 degree angle to 60 degrees or something until you are back in range. Maybe even a 0 degree angle, which is really a pure intercept course. If you somehow got too close, open-up the protractor until it makes a 180 degree angle. Then you only increase range from him, yet still keep up with his pace.

To test this I suggest you try this out on friendly units as you move out to sea. As opposed to in the heat of battle.

[KL-alfman]

thx for sharing this explanation!
I'll give it a try immediately (although was already successful with tracking a freighter by hydro-phone). it'll set up the realism as well, I hope.

[flag4]

i love to see the drawings - think i'm a visual rather than aural person.

thanks very much for this interesting method. it's a bit like those pictures that have an image in them that you can't see because of all the dots in different colours, i hope the ballerina shows herself as i keep looking...!

(..think i'll print it off..)

[Pisces]

Please re-read my post. I made some additional remarks and have shown them on the updated picture.

[Jimbuna]

That is a good informative post Pisces

[Pisces]

Thanks Jimbuna.

I decided to let the Sh4 folk in on it too. I see no reason why they can't make use of it too.