no ship there

Von Due · 05-07-16, 11:41 PM

If by boxes you mean the contact report boxes on the map, remember those are only where the ships were at the time of the report. The ships are moving while the boxes stay put but click on those boxes and you see some additional info like rough course and speed estimates. Use those estimates to plot where you will need to go to search for and hopefully find the ships. Keep in mind that any uncertainty in the plot increases with distance and time. Personally I never bother with those reports if I know I can not be sure I will be able to pick them up on my hydrophones.

If, on the other hand you mean the visual contact boxes that DO move and that turn into ship icons when you zoom in on the map, then I have no idea.

Jimbuna · 05-08-16, 05:36 AM

I'm sorry but I can't add anything to what Von Due has posted other than the next time it happens to one quite near go immediately towards it and see if anything tangible is there.

Welcome from another Jim on SubSim

Von Due · 05-08-16, 07:47 AM

And where are my manners again? Welcome!

Just one more thing about the course and speed estimates I mentioned.

The course estimate is one of 16 possible estimates:
N, NNE, NE, ENE and so on.
Let's say the estimate is NNE.
Because the circle is 360 degrees, and you only have 16 possible estimates*, NNE could be any course from about 11.25 degrees to 33.75 degrees.

Start the plot by drawing lines from the contact box in these 2 directions to get a wedgelike figure.

The speed estimate is a bit less informative, you only have 3* possible estimates: Slow, medium and fast, possibly a 4th very fast typically for warship taskforces.

Slow is anything more than 1 knot to about 7 or 8 knots. Say 8 to err on the side of caution.

Medium is from around 7 or 8 to less than 14, say 7 to 14 to err on the side of caution.

Fast is 14 or more knots.

Estimate how long it would take you to get inside that wedge you drew.

Use the compass to draw circles for how far the ship could possibly have traveled in the time it takes for you to get there. Make one for the minimum speed and one for the maximum speed that was estimated for the ship.

Now you have a search area. The ship can be anywhere inside that area at the time you get there, provided it didn't change its course and or speed in the meanwhile, something that can happen on occations but then it's often followed up by a new contact report for the same ship.

The hydrophone is good to up to about 20 km on a good day, less on stormy days and if you are near the surface. 40-60 meter depth is a good depth for picking up the sound at max range on just about any day.

*Convoys and task forces are different in that they will give you a pretty precice course and speed.

05-08-16, 05:36 AM	#2
Jimbuna Chief of the Boat Join Date: Feb 2006 Location: 250 metres below the surface Posts: 190,678 Downloads: 63 Uploads: 13	I'm sorry but I can't add anything to what Von Due has posted other than the next time it happens to one quite near go immediately towards it and see if anything tangible is there. Welcome from another Jim on SubSim __________________ Wise men speak because they have something to say; Fools because they have to say something. Oh my God, not again!!

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05-07-16, 11:41 PM	#1
Von Due Sea Lord Join Date: Jul 2012 Posts: 1,690 Downloads: 30 Uploads: 0	If by boxes you mean the contact report boxes on the map, remember those are only where the ships were at the time of the report. The ships are moving while the boxes stay put but click on those boxes and you see some additional info like rough course and speed estimates. Use those estimates to plot where you will need to go to search for and hopefully find the ships. Keep in mind that any uncertainty in the plot increases with distance and time. Personally I never bother with those reports if I know I can not be sure I will be able to pick them up on my hydrophones. If, on the other hand you mean the visual contact boxes that DO move and that turn into ship icons when you zoom in on the map, then I have no idea.

05-08-16, 07:47 AM	#3
Von Due Sea Lord Join Date: Jul 2012 Posts: 1,690 Downloads: 30 Uploads: 0	And where are my manners again? Welcome! Just one more thing about the course and speed estimates I mentioned. The course estimate is one of 16 possible estimates: N, NNE, NE, ENE and so on. Let's say the estimate is NNE. Because the circle is 360 degrees, and you only have 16 possible estimates, NNE could be any course from about 11.25 degrees to 33.75 degrees. Start the plot by drawing lines from the contact box in these 2 directions to get a wedgelike figure. The speed estimate is a bit less informative, you only have 3 possible estimates: Slow, medium and fast, possibly a 4th very fast typically for warship taskforces. Slow is anything more than 1 knot to about 7 or 8 knots. Say 8 to err on the side of caution. Medium is from around 7 or 8 to less than 14, say 7 to 14 to err on the side of caution. Fast is 14 or more knots. Estimate how long it would take you to get inside that wedge you drew. Use the compass to draw circles for how far the ship could possibly have traveled in the time it takes for you to get there. Make one for the minimum speed and one for the maximum speed that was estimated for the ship. Now you have a search area. The ship can be anywhere inside that area at the time you get there, provided it didn't change its course and or speed in the meanwhile, something that can happen on occations but then it's often followed up by a new contact report for the same ship. The hydrophone is good to up to about 20 km on a good day, less on stormy days and if you are near the surface. 40-60 meter depth is a good depth for picking up the sound at max range on just about any day. *Convoys and task forces are different in that they will give you a pretty precice course and speed.