Hi,
I think you all know the problem of setting up an attack when your target is still far away. AoB can be estimated roughly at best and therefore the ship's course also.
Without radar for long distance range estimation you would usually have to get pretty close (something about medium range) before you can make any precise assumptions about your target's movement. Here is a little workaround, that will allows one to estimate the target course when it is still far away. It's more like a little trick than a complex technique so it might be well known already. But let's start:
I got in front of the little convoy to do the rest of the approach from beneath the surface. The approach was already on the way for ~20min now.
First thing to do is to mark your own position on some empty spot on the map and use it as starting point for your observations.
Keep course, take a reading of the ship's bearing (don't forget to calculate true bearing from that) and draw a line from your position onwards in the direction of the true bearing to target. The length doesn't matter as we don't know the range to the ship yet.
From all the previous observations when getting in front of your target on the surface or from using passive sonar you should have already gotten an idea how fast the ship is traveling. Then you approximate it's speed which is mostly a thing of experience values here.
You should be able to tell whether it is moving at fast, medium or slow speed. But what that means for the actual ship depends on your judgement. A slow moving passenger/freighter convoy for instance, I would estimate as ~6.5kn from my previous experiences, so I'm using this value here.
You then wait a fixed period of time. In this example I'm using 5 minutes.
Use the stopwatch and after this time expired let the stopwatch keep running. Otherwise you won't be able to continue tracking your own movements afterwards.
While doing this there's enough time to estimate and draw you position after 5min. Here I'm moving at slow speed underwater = ~1kn, meaning that I will travel ~150y (heading south).
When the 5min have passed, take the second reading and draw another line only now originating from your new position.
So far nothing new. What I'm gonna use now is the fact that the target's speed will have it travel ~1100 yards during this time. See the nomograph on the right for this.
Now, with both bearing lines in place you only need to pick *any* spot on the first line and draw a line that will end on the second bearing line and has the lengh of 1100y.
Note that the first spot you picked there is most likely not the actual position of the target (relative to yours) because we don't make any attempt to get the range yet. The only thing that's important here is that the speed estimation is roughly correct. (And that your drawings are o.k. of course
).
But after encountering many many freighters at a speed of ~6.5kn (when moving at slow) you would accept this as a reasonable base for these estimations.
Here is an image of my in-game nav map to show what I mean.
The small line with length 150y is the way I travelled during those 5 mins and the lower circle shows the spot I picked arbitrarily for the target ship.
The target's course line reads something like 310° and when the vessel gets close enough to do a reliable range estimation you can draw it's real course line (relative to your position at least).
Knowing the course allows you to position yourself precisely, set a course perpendicular to the one of your target (for fast 90 or dick o kane).
Also the target AoB is then only one step away, especially when using an AoB-wheel.
Hope it's not all old news, just figured it might be helpful in some situations.
happy sailing
