Easy way to plot intercept course?

[Twicedead]

Hi all. I have looked everywhere, there doesn't seem to be an easy way to plot an intercept course in sh3. I've looked high and low and any that I've found are ridiculously over complicated and I can't make heads or tails of them.
It's a bit annoying cos I feel like I'm missing out on most of the game. Any help is appreciated. Thanks.

[Hooston]

Tonci87 does it from 3:30 on this "Utube" video. I had to sit down with a piece of paper for 10 minutes to work out how it works, but the recipe is reasonably straightforward. To be honest I don't usually need it as I like to get well in front of the convoy.

[Aktungbby]

Twicedead!

[JohnCarterOfMars]

I've been using my own home-grown (for me, but others may have previously posted the same) technique for gathering the intercept information that doesn't involve racing in front of the ship to watch the masts line up or approximate the angle on bow.

It's also good because you can do it immediately while traveling towards the sighted ship.

1. Order your Watch Officer to the bridge. You will need him.
2. Have your Watch Officer give you a reading of the sighted ship.
3. Start a 5-minute timer.
4. Draw a line from your boat to the sighted ship following the bearing and reported distance.
5. Wait 5 minutes.
6. After 5 minutes, have your Watch Officer give you another reading.
7. Draw a second line from your boat to the new bearing and distance of the ship.
8. Measure the distance between the two sighted ship positions.
9. Look up this distance on the M/Min table on the 5-minute column and note the corresponding speed. This is the speed that the sighted ship is traveling.
10. Repeat this process two more times and then measure the distance from the original position to the most recent reading. Look this distance up on the 15 minute column to find the corresponding speed to verify.
11. Take one more reading in 5 minutes, measure the distance from the original reading to this last one and add the distances on the 5-minute and 15 minute columns for the previously determined speed, and see if it matches the distance between the original reading and the latest reading.
12. After the second reading you should know the general direction of travel of the sighted ship. You can now turn the boat towards that direction.
13. After the 20-minute reading, you should have enough plots to approximate the true direction of the sighted ship.
14. You now have the speed and direction of travel of the sighted ship. Plot the intercept course from this information.
15. I usually add 2 degrees to the intercept angle to get ahead of the ship.
16. Then I draw a perpendicular line of 1.5 Km from the intercept point to find my actual destination, and then turn 90 degrees towards the intercept point to wait for the ship.
17. While I am traveling to the intercept point, I will enter my 90 degree angle attack data into the TDC.
18. You can take additional periodic readings just to ensure that the sighted ship is still on its course and that you are ahead of it. You can take an additional 5-minute reading to ensure that the ship hasn't changed speed, too.

I find this approach to be good enough for the TDC, which is 1940s technology. I don't need perfect precision for it to work, and I don't need to waste fuel, time, or exposure risk chasing ahead of the ship just to find it's perfect course.

[Hooston]

Asking the watch officer for bearing and distance works fine in the game. The problem is that getting an accurate range in real life was VERY difficult unless you had a radar. I know the H.Sie patch adds inaccuracy to the watch officer's estimates but he is still way too good. This is the problem with the "3 minutes 15 seconds" dodge for getting target speed and bearing. It's annoying because asking the watch officer for an accurate bearing and a very rough range ESTIMATE would be perfectly valid IMHO and very useful to "watch your back" while you focus on a particular target.
The stadimeter relies on an accurate ship ID, an accurate manual and a knowledge of the ship's current load! Tonci87 is usually very good in using techniques that are historically valid and refuses to use the recognition manual for merchant ship data.

Having said all that it's just a game with a zillion things wrong with it and you have to choose how to compromise. For a long time when following a convoy I used to spam the "L" key to lock on to targets i knew were there but could not actually see. Not realistic but gets round the too short spotting distances in most daytime weather conditions.

[JohnCarterOfMars]

I understand your point. I would rebut with the argument that if the Watch Officer is just estimating to the best of his ability (and the game is still too accurate), his error will be consistent and the results will be good enough to plot a course and estimate speed.

I'd also make the argument that, over time, an experienced seaman would get fairly good at approximating the distance to a ship. If most ships are of a general size within a class, an experienced officer should be able to tell (by mast count or super-structure layout) what kind of ship it is, and therefore how far away it appears to be.

Again, the idea is to get information to generally plot an intercept course to get you close to the sighted ship.

[Hooston]

When in hydrophone or visual contact the most important thing to bear in mind is that if you are on an intercept course the target will be at a constant angle to your boat. This is very useful when doing submerged daylight approaches using the hydrophone. There's an unpronounceable German word for the tactic. Of course you ideally want to get a bit ahead so you can set up a 90 degree AOB shot and not actually crash into the target, so the target should be very slowly drifting backwards from your point of view. If it is drifting forwards you are not going to catch it on your current course and speed. The speed at which the bearing changes also tells you when you are getting close.

[3catcircus]

http://www.subsim.com/radioroom/showthread.php?t=88961

[Pisces]

This image is a condensed version of the linked thread that 3catcircus posted:


I created my own drawing tool on the map which looks like this:



I have an expanded version of this to allow me to contruct courses to set to, to move in certain relative motions around the target. But this is complicated enough for now.

I draw this anywhere on the map. As your position is not actually plotted in that drawing. It only needs a line (light blue) for the direction from you to the target, the true bearing to target. As that is the direction you want your surplus speed to be pointed to close the distance.

You can get the true bearing from adding the periscope bearing to your course (and reduce it to within 0-360 degrees.
Or you can use map tools on the map with bearing-compasses on the mouse cursor to measure it (like this one I made: https://www.subsim.com/radioroom/sho...postcount=1308)

If you draw a line from your current position to the target position then you can shift the target-speed circle radius arrow ONTO you current location. And draw the rest of it based on the origin of the circles.
The arrow/radius of the target circle (red) is a scaled version of the target speed. And it's direction is the target course.
The arrow direction of your speed circle (black) isn't important. As the intent is to figure that out. The length of the radius/arrow is important, it is the speed you move at during the intercept. And needs to be in the same scale as the target speed circle.
The intercept course is the direction of the green line.

If you move, then you need to re-draw the whole thing.