How to intercept?

[Pisces]

Originally Posted by Pistoliero

Are there any benefits to using so complex intercept algorithm?
Ruler and knots to km/h transfer sheet (seite 1) work just fine for me.
All you need in this case is to draw target course vector and find (on this vector) a point, to which your u-boat will arrive before the target will.

The algorithm is a geometric method. You'll get the (precise) answer in a fixed number of steps. Some prefer that because they can handle graphical representations better then numbercrunching.

Yours is a bit more trial and error in predicting where the target will be in x hours and minutes, then calculate yourself or use the waypoint marker to find out where you will be. And hopefully they match to a point. Depending on how good you are in it, you can get this in one or too steps. But to each their own preffered method.

[scott_c2911]

I used to use the nautical miles to kilometers conversion table supplied with gwx to calculate distances travelled but I played the game so long now that I almost instinctively plot intercept courses now. They are tabs kept on the top left hand corner of the chart table. I always plot them so I have enough time to get into position and set up for the attack. Early war i stay up and give em a broadside so finese isnt as critical then but late war you need to be submerged for nearly all attacks.

[vanjast]

Originally Posted by Pistoliero

Are there any benefits to using so complex intercept algorithm?
Ruler and knots to km/h transfer sheet (seite 1) work just fine for me.
All you need in this case is to draw target course vector and find (on this vector) a point, to which your u-boat will arrive before the target will.

Eggsactly.. then you turn down the course to the expected convoy, putting you in perfect 'convoy infiltration' position, if you're lucky just within the outer column/row.

This you do submerged at depth depending on convoy speed, tracking the 'convoy spread' on hydrophone, to assess your position. Once the lead escort passes over you, you start surfacing - should bring you up approximately in the first row or just after.

The juicy targets are mid-convoy.
Los

[BigWalleye]

Originally Posted by vanjast

Eggsactly.. then you turn down the course to the expected convoy, putting you in perfect 'convoy infiltration' position, if you're lucky just within the outer column/row.

This you do submerged at depth depending on convoy speed, tracking the 'convoy spread' on hydrophone, to assess your position. Once the lead escort passes over you, you start surfacing - should bring you up approximately in the first row or just after.

The juicy targets are mid-convoy.
Los

Small problem: the contact heading is only accurate to +/- 12.75 degrees. A contact reported as "Heading ENE" (ENE= 67.5 degrees) could have an actual heading anywhere from 56.25 to 78.75. If it takes you ten hours to reach the intercept, then the area of uncertainty is 50 km wide. Using a 16 km horizon, if you simply head straight down the reciprocal heading, there is a 30 percent chance you will make visual contact, provided the contact doesn't change course.

[Zosimus]

The only easy solution to that is to intercept the ship/convoy as quickly as possible. Full/flank speed with battery recharge off and prefer contacts that are closing.

[desirableroasted]

Originally Posted by Zosimus

The only easy solution to that is to intercept the ship/convoy as quickly as possible. Full/flank speed with battery recharge off and prefer contacts that are closing.

Since nothing, other than a task force, moves at more than 9kt, racing off at flank speed is a fool's errand. Especially since "East" is vague and since (in GWX at least) ships and convoys can and do change course.

If I can reasonably reach an intercept point within 4-5 hours, without turning my mission inside out, I will. Can't hurt, right? But banging off 10-12 hours a full flank.... tried that many times. Not worth it. And, yes, I am an ace at trigonometry, but the game simulates uncertainty very well.

The point is to conserve fuel so as to have as long a patrol as possible. More time on the lake, more targets, more kills. Zipping around every time BDU burps is the fastest way home with nothing in the bag.

[Pistoliero]

Originally Posted by desirableroasted

The point is to conserve fuel so as to have as long a patrol as possible. More time on the lake, more targets, more kills. Zipping around every time BDU burps is the fastest way home with nothing in the bag.

Not sure about conserving fuel, I use flank speed for intercept and rarely reach even 75% fuel remaining by the time, when all torpedoes are spent and I have to return to base.
Sure some common sense helps (don't interecept targets which are fast and moving away, don't interecept single ships 400km away etc), but it seems like only type II boats suffer from any sort of fuel shortage.

[banryu79]

Originally Posted by Zosimus

The only easy solution to that is to intercept the ship/convoy as quickly as possible. Full/flank speed with battery recharge off and prefer contacts that are closing.

When I receive a distant radio contact from BdU I do the following, just to tackle with the issue highlithed above:
1) mark down the contact reported position.
2) with the ruler plot 3 possible course: the 'exact' one and the two '+10°/-10°' courses.
3) On each course I mark down the theoretical position of the contact for each hour passed since contact position reported hour (I choose the highest among the possible theoretical contact speeds).

Then I plot I circle of 22 Km radius (max hydroph. range) and move it as farthest along the three plotted routes as possible till it still can intercept all three course-lines.

That is the maximun "area" along contact path I want to be able to intercept in time, so given my position and the total estimated time needed for the contat to get to that "area" I plot my intercept run and I'm able to compute the minimum speed I need to run.

With that "minimum speed to intercept" on my hands I can evaluate if, where, when and at which speed to actually intercept that contact. I usually do well with this method, and I rarely need to run at "ahead full" (Type VIIB) let alone "ahead flank".
My tipical intercept run speed is in the range 9-12 knoten.

[BigWalleye]

Originally Posted by banryu79

When I receive a distant radio contact from BdU I do the following, just to tackle with the issue highlithed above:
1) mark down the contact reported position.
2) with the ruler plot 3 possible course: the 'exact' one and the two '+10°/-10°' courses.
3) On each course I mark down the theoretical position of the contact for each hour passed since contact position reported hour.

Then I plot I circle of 22 Km radius (max hydroph. range) and move it as farthest along the three plotted routes as possible till it still can intercept all three course-lines.

That is the maximun "area" along contact path I want to be able to intercept in time, so given my position ant the total estimated time needed for the contat to get to that "area" I plot my intercept run and I'm able to compute the minimum speed I need to run.

With that "minimum speed to intercept" on my hands I can evaluate if, where, when and at which speed to actually intercept that contact. I usually do well with this method, and I rarely need to run at "ahead full" (Type VIIB) let alone "ahead flank".
My tipical intercept run speed is in the range 9-12 knoten.

Excellent planning, Herr Kaleun!

[banryu79]

Originally Posted by BigWalleye

Excellent planning, Herr Kaleun!

Thank you, sir!

P.S.: Guess-estimation & planning are the two aspects of the game I like the most!

[maillemaker]

The point is to conserve fuel so as to have as long a patrol as possible. More time on the lake, more targets, more kills. Zipping around every time BDU burps is the fastest way home with nothing in the bag.

I almost always intercept at flank speed, and almost always run out of ammo before fuel.

About the only time fuel is a consideration is when traveling to the coat of the United States.

If it wasn't for the weather prohibiting bringing in external stores I'd probably never return to port with torpedoes.

Steve

[Zosimus]

Originally Posted by desirableroasted

Since nothing, other than a task force, moves at more than 9kt, racing off at flank speed is a fool's errand. Especially since "East" is vague and since (in GWX at least) ships and convoys can and do change course.

If I can reasonably reach an intercept point within 4-5 hours, without turning my mission inside out, I will. Can't hurt, right? But banging off 10-12 hours a full flank.... tried that many times. Not worth it. And, yes, I am an ace at trigonometry, but the game simulates uncertainty very well.

The point is to conserve fuel so as to have as long a patrol as possible. More time on the lake, more targets, more kills. Zipping around every time BDU burps is the fastest way home with nothing in the bag.

First of all, I have intercepted and sunk merchants that were moving at faster than 9 knots so I'm going to call a big BS on the first claim.

Second, you're right that convoys can and do change course–all the more reason to intercept them as soon as possible. Every extra hour you take is an increased chance that they've changed course and thrown your calculations off.

Third, if you're using a scientific calculator in the game, then imo you're cheating. You should make your intercept with the same tools that real u-boat commanders had to use. Accordingly I don't see what an expert at trig has to do with it.

Fourth, assuming you find a convoy that is moving at 7 knots (not uncommon) then surely if you find yourself behind it you sail out and around it at full speed. You're not really trying to do an end around on this baby at 10 knots, are you?!

Finally, I've never had fuel as a consideration. You usually sail off, sink a bunch of ships, and sail back without using even half your fuel. As long as your normal day-to-day operations is ahead one-third, you're fine.

[BigWalleye]

Originally Posted by Zosimus

Third, if you're using a scientific calculator in the game, then imo you're cheating. You should make your intercept with the same tools that real u-boat commanders had to use. Accordingly I don't see what an expert at trig has to do with it.

Whoa! "Cheating" seems a harsh term to toss around at someone who plays the game differently than you do. "The same tools that real U-boat commanders had to use" would have to include a plotting party of officers and POs who were themselves trained to be "expert at trig." Because the U-boat commander didn't waste his time drawing lines on a chart. The navigator and the plotting party did, using the best available high-tech tools - slide rules and tables of logarithms. Whether you use an HP 11C or beads on a string, without a plotting party we cannot begin to approach the way real U-boat commanders did it

Do you use the stadimeter to measure range? Because real U-boat commanders didn't. Only Typ IIs and the oldest Typ VIIs had them. Is it cheating to let the computer measure the angles for you?

Do you use a periscope with 10x magnification? Because real U-boat commanders had to live with 6x magnification. Is it cheating to get a better view than was ever possible on a U-boat?

Do you use binoculars with a built-in gyrocompass readout? Because real U-boat commanders never had such devices. It's much farther beyond WW2 technology than a scientific calculator. Is it cheating when you use a device which is state-of-the-art a half-century later?

Do you use the mod called RND campaign layers with zigzagging units for GWX and NYGM? Real U-boat commanders had to deal with zigzagging, maneuvering convoys. Is it cheating to know that your contact will almost certainly hold its last reported course?

Do you use the Flaggen chart to tell when a nation has changed sides? Real U-boat commanders had to get that information from radio transmissions, which might be delayed or missed. Is it cheating to know the date South Africa entered the war?

Do you use h.sie's Diesel Damages Fix? Real commanders knew that they couldn't run the Diesels indefinitely at maximum RPM without risking a breakdown. Is it cheating to order "Ahead Flank" and not have to worry about an engine failure, which your crew might or might not be able to repair at sea?

Each of these cases represents a trade-off which we all have had to make, between historical accuracy, game capability, and personal enjoyment. You might feel that using a scientific calculator spoils the immersion of the game - for you. I might feel that using binoculars with a built-in compass readout is just plain wrong - for me. We all play the game to enjoy it, and the way you play it is the right way for you. But there is no wrong way. And there certainly is no cheating in a single-player game. If manual targeting is too hard, turn it off. And go have fun. Because, if you are having fun, you are playing the game just the way you should play it.

[banryu79]

Originally Posted by Zosimus

Finally, I've never had fuel as a consideration. You usually sail off, sink a bunch of ships, and sail back without using even half your fuel. As long as your normal day-to-day operations is ahead one-third, you're fine.

So, if I understood it the right way you are usual to intercept your contacts using very high speeds but for day-to-day ops on your patrol grid you move "carefully" (ahead 1/3).

Funny thing, I usually do it the other way around. As I already explained, I extensively plot my contacts routes and my intercept runs in such a way to try and minimize speed. Instead I normally run my day-to-day ops (grid patrol) ad at ahead standard (>10 knoten) when navigating above surface (my strategy is to cover my over-the-surface legs, where my detection radius is limited (visually based detection) in the fastest possible way till my next underwater stop-point, where I creep at 1 knoten silent running for about 20-30 minutes (this is my best chance at picking contacts because my acoustical detection range is far larger than the visual one).

Instead I usually run ahead 1/3 for my long range transitions (to/from home port) or for my strategical deployment at medium range (changing patrol zone).

[desirableroasted]

Originally Posted by Zosimus

Third, if you're using a scientific calculator in the game, then imo you're cheating. You should make your intercept with the same tools that real u-boat commanders had to use. Accordingly I don't see what an expert at trig has to do with it.

In the nine years I have been playing, I have used only the in-game tools provided by the developers and modders. No more, no less. And I don't find intercepts difficult.

I am sure you will pick it up if it is giving you trouble. The guide presented earlier in the thread, while a bit of a "buzz kill" if you just want to go do some arcade shooting, is invaluable.

Good hunting.