Static Search Vs. Dynamic Search

[gi_dan2987]

I would like to interject on all of these thought-provoking topics. First off, what is the name of this book by Mr. O'Kane?

Every skipper has different methods that could work given the circumstances. I believe that every situation is different and requires the ability to adapt. That being said, sometimes surface patrol courses are more effective than submerged static/dynamic sonar sweeps and vice-versa.

Captain Morton of the USS Wahoo took a sub that was once commanded by a cautious man who lacked proper incentive and aggression, and turned it into a tonnage logging, effective war machine. Mr. Morton spent a lot of time actively patrolling on the surface. Granted his crew paid the ultimate price for their bravery and aggression, but they also are listed in the records as one of the most successful submarines of the war.

[Stealhead]

O'Kane wrote two books one was about the Wahoo it is called "Wahoo: The Patrols of America's Most Famous World War II Submarine" O'Kane spent much time on this boat but obviously was not aboard when she was lost but he does his best to estimate her last patrol and hed have the best idea seeing as he was the XO for Morton.

The other book is called "Clear the Bridge" it is about the USS Tang which was O'Kanes boat she was lost to a circle runner but O'Kane a few others survived.Both books go into great detail the methods used by O'Kane and Morton while on patrol and they stayed in one place rarely.

"Thunder Below" is another excellent book written by a submarine commander Gene Fulckey who received a Medal of Honor for his exploits his book is very detailed as well.Fluckey who clearly from reading the book was a very good officer and cared greatly for his men and defends both O'Kane and Morton who had bad reputations with some war is war people die even when you make the correct choices and neither man made any obviously huge errors in judgment it was just a better day for the Japanese that day.

Personally I after reading these books largely used the same tactics and I had a lot of fun doing so therefore ever since then that is how I play.It seems to me that most of the successful boats generally searched actively most of the time but if the situation warranted they might stay immobile that can be very useful in some situations like if you are near a cost line and seeking a ship hugging the coast staying stationary is wise because you know generally where the vessel is going to be this tactic is also useful in several locations in Japanese home waters.

[TorpX]

I'm still not entirely sure everyone understands what I am trying to say. When I use the term 'static search', I don't mean that one spends weeks firmly anchored to the same spot. More like moving 20 or so miles each night, so that you work the patrol area bit by bit. You could, if you wanted, cover the same distance in a single night, but if it is a light traffic area, the odds are you will not come up with anything in a single day, no matter how far you go. Realistically, I think there were many areas where there would be only one or two potential contacts moving through the vicinity each week. Also, I am assuming that there is quite a bit of movement in attack and evasion, whichever search method you use. Perhaps the term 'static search' is not really the most appropriate term. I think we all agree it is preferable to remain surfaced as much as possible. I more or less assumed this in my example, as submerging reduces your detection radius.


I had not thought of it before, but the Kriegsmarine used a variation of this idea. When they wanted to attack a major convoy on the Atlantic route, they had a idea where it would pass, but of course had no way of knowing exactly. Their solution was simple, but effective; arrange a line of U-boats accross the expected path, 15 or so nm apart, and wait for one of them to make contact and report. As long as the boats (pickets) remained fuctional and on station, they were sure to locate the convoy. Donitz called these 'rake operations'. These sorts of tactics may strike many as too "passive", but the passive phase comes to an abrupt end as soon as contact is made.


Here is a slightly different example to further illustrate the concept:

Suppose you are astride a N-S sealane and want to "search" it. I will assume, as before, freighters traveling 9 kts. and a 10 nm detection radius. (This is good for SH 4, since nothing is rendered beyond 10 nm anyway.) If you sit still you will detect 100% of ships in a 20 nm "slice" (10 nm East and 10 West). If you want to move E-W across the sealane (in effect yo-yoing back and forth), how far can you go East or West, without letting ships "slip through"? If you are cruising at 10 kts., you can go 11.1 nm on either side, and still make sure nothing gets by in the center. Why do I say 11.1 nm? Because in the time it takes you to go 11.1 nm East and 11.1 nm West (back where you started), an enemy ship could move through the 20 nm deep band you are searching. Going any farther would allow some ships to slip past. Following this plan, you will detect 100% of ships within this 22.2 nm zone, and some of the ships within a 10 nm 'fringe' zone on either side. If you wanted to cruise at 15 kts., the figures would be 33.3 nm with a 10 nm 'fringe'.


The point I'm trying to make here is not that a dynamic search is no good, but only that it doesn't necessarily improve your chances as much as it would appear.

[Armistead]

I get the concept and Wahoo certainly did it to a degree. I am in fact reading "Wahoo" again for probably the 10th time. One thing our game lacks is historical realism that would make submerged static hunting viable since we play against AI.

Near Japan Morton did more submerged static hunting, but would place himself in shipping lanes and choke points. When he sunk ships, he usually quickly moved to another location 50-100nm's away and attacked again hoping the enemy would think two subs were in the area and split their ASW effort. Near Japan if you were spotted it usually prompted a ASW response, so one stayed dived more during the day. Many of the island chains also had land radar which would pick you up.

The other factor missing in game is ocean currents.

I added a lot of China coast traffic in 44 and 45 that basically hugs the coast and travels between the small islands and reefs, in and out of ports, not to mention many patrol boats, fishermen, minefields, shoreguns, coastal lights, air patrols, etc.. In such shallow water it's a dangerous game. I go in at night and attack and slip back to the deeper edge during the day and static hunt where I can still pick them up on sonar. It's fun playing, but hard and mistakes or risk can easily get you killed.

[TorpX]

Originally Posted by Armistead

I get the concept and Wahoo certainly did it to a degree. I am in fact reading "Wahoo" again for probably the 10th time. One thing our game lacks is historical realism that would make submerged static hunting viable since we play against AI.

It might work better than it should. In SH4 your view doesn't improve when your higher. Did you ever play SHCE? You could actually see farther when you raised the scope higher (or surfaced).

The other factor missing in game is ocean currents.

True. Another thing is the sea state. I remember O'Kane describing how in rough seas, there was "green water coming over the bow", causing them to waste fuel. I think this is a big part of the reason fuel is less of an issue in this game. Something else that was modeled much better in SHCE.

In such shallow water it's a dangerous game. I go in at night and attack and slip back to the deeper edge during the day and static hunt where I can still pick them up on sonar.

I agree. I've come to the conclusion that operating in shallow/coastal areas is fundametally different than deep water ops. O'Kane used the term 'horizontal evasion'; if you cannot use vertical evasion, all you got left is horizontal evasion.

I just finished OPERATION DRUMBEAT recently. U-boat ace Hartigen would roam around wreaking havoc at night, then go back out to deeper water before daylight, submerge and just lay there resting until the next night. It was a shooting gallery; no trouble finding enough targets there.

[magic452]

Originally Posted by TorpX

Here is a slightly different example to further illustrate the concept:

Suppose you are astride a N-S sealane and want to "search" it. I will assume, as before, freighters traveling 9 kts. and a 10 nm detection radius. (This is good for SH 4, since nothing is rendered beyond 10 nm anyway.) If you sit still you will detect 100% of ships in a 20 nm "slice" (10 nm East and 10 West). If you want to move E-W across the sealane (in effect yo-yoing back and forth), how far can you go East or West, without letting ships "slip through"? If you are cruising at 10 kts., you can go 11.1 nm on either side, and still make sure nothing gets by in the center. Why do I say 11.1 nm? Because in the time it takes you to go 11.1 nm East and 11.1 nm West (back where you started), an enemy ship could move through the 20 nm deep band you are searching. Going any farther would allow some ships to slip past. Following this plan, you will detect 100% of ships within this 22.2 nm zone, and some of the ships within a 10 nm 'fringe' zone on either side. If you wanted to cruise at 15 kts., the figures would be 33.3 nm with a 10 nm 'fringe'.

A couple of points here.

First a sea lane is not a narrow straight line even in the heavily traveled choke points. Markassar Strait is about 50 nm. wide. Luzon three times that.
Shipping lanes are no doubt about the same. You can sit in the center and still leave more than enough room for convoys to sail right by. Why give up the higher percentage for contacts just to save some fuel that is for the most part not an issue.

Second ships and convoys don't run straight courses they zig zag and can very easily sail right past you. Again a dynamic search will increase your chances of making contact and I would think the increase would be greater than what your figures suggest. The zig zags put them in your contact zone longer than a straight course would. The course changes reduce their overall progress on their base course. I do your yo-yo across the lane almost exactly as you describe but I'm also moving North or South. I described this in my second post.
Again your giving away contacts to save fuel you most probably won't need.

Third Radar. 20 nm. range Your search area doubles and enabling you to cover most of area of a choke point if you're moving.

If I'm in a dead area I'm going to patrol in a way that searches the greatest area in the shortest amount of time. Your not going to find much no matter which method you use.
Your mission is to interdict shipping not stay on station for 60 days. They have other boats to replace you in that area.

I'm wanting to RTB knowing I gave myself the best opportunity to have success.

And when I get there I'm going to say "I one of the top guns and don't send me to the Marshals again." I'm sure they will listen.

But I do see what you are saying and your points are well taken, I can see several places that a static search might be the best tactic especially early in the war where fuel is a little bit bigger concern. Armistead has pointed out a couple as well.

Magic

[TorpX]

Pardon for the double post.

Originally Posted by magic452

A couple of points here.

First a sea lane is not a narrow straight line even in the heavily traveled choke points. Markassar Strait is about 50 nm. wide. Luzon three times that.
Shipping lanes are no doubt about the same. You can sit in the center and still leave more than enough room for convoys to sail right by. Why give up the higher percentage for contacts just to save some fuel that is for the most part not an issue.

The math I used does not require a particularly wide or narrow sea lane. You can use different figures with these calculations and get substantially the same results. Fuel not being as much an issue is due to shortcomings in the game. In RL rough weather would slow you down much more. Even as it is when I am playing an S-class, fuel is indeed an issue. If I cruised continously in an S-class, it would be a short and unhappy patrol.

Second ships and convoys don't run straight courses they zig zag and can very easily sail right past you. Again a dynamic search will increase your chances of making contact and I would think the increase would be greater than what your figures suggest. The zig zags put them in your contact zone longer than a straight course would. The course changes reduce their overall progress on their base course. I do your yo-yo across the lane almost exactly as you describe but I'm also moving North or South. I described this in my second post.

I'll grant you targets zigging will give you more of a chance to detect them, but this doesn't fundamentally alter the math.

Again your giving away contacts to save fuel you most probably won't need.

I would say you are giving away contacts by wasting fuel and terminating the patrol prematurely.

Third Radar. 20 nm. range Your search area doubles and enabling you to cover most of area of a choke point if you're moving.

I'm not disputing the usefulness of radar (or sonar or anything else). Anything that doubles your detection range will double your chances, likewise anything that halves your detection range will halve your chances. This is true whether you are moving or not. Radar really has nothing to do with it. If you want to compare a radar equipted boat to one without radar, the radar boat will obviously win.

In any case, if you have a 20 nm radar, you can cover most of the area of a choke point even if your not moving.

If I'm in a dead area I'm going to patrol in a way that searches the greatest area in the shortest amount of time. Your not going to find much no matter which method you use.

OK, lets say you arrive at your patrol area on monday. No matter how quickly or intensely you search search your box. You will have to do it again tuesday, and wednesday and thursday....... However quickly you search, you cannot pull the targets to your location. If the area has an average of 2 ships transiting each week, it will take weeks to obtain a good number of contacts. And it is unlikely you would find them all. Realistically, most areas would not give you a contact every day, but by continuously cruising you would be burning a lot of extra fuel each and every day.

Your mission is to interdict shipping not stay on station for 60 days. They have other boats to replace you in that area.

I'm wanting to RTB knowing I gave myself the best opportunity to have success.

And when I get there I'm going to say "I one of the top guns and don't send me to the Marshals again." I'm sure they will listen.

But I do see what you are saying and your points are well taken, I can see several places that a static search might be the best tactic especially early in the war where fuel is a little bit bigger concern. Armistead has pointed out a couple as well.

Magic
[/INDENT]

Look, I can see your just a bit skeptical. I am not trying to convince you to do it my way, but the math is the math.

The bottom line is a moving search is not as big a help as you like to think. When you are moving to the east, targets can slip by to the west, when you move to the west, targets might slip by to the east. If you go farther to the east to "cover more ground", a target could go past in the center or the west. You cannot be in two places at once, nor can you hasten or delay their arrival.

[gi_dan2987]

So what is the MOST optimal search method, please let me know, because right now I'm driving around in the Marshalls about ready to head to the area between Rabaul and Truk. I've only Sunk Nibu Maru in the Marshalls, and that was because I picked up a hydrophone contact while surfaced.

[Rockin Robbins]

Originally Posted by TorpX

Pardon for the double post.

Look, I can see your just a bit skeptical. I am not trying to convince you to do it my way, but the math is the math.

The bottom line is a moving search is not as big a help as you like to think. When you are moving to the east, targets can slip by to the west, when you move to the west, targets might slip by to the east. If you go farther to the east to "cover more ground", a target could go past in the center or the west. You cannot be in two places at once, nor can you hasten or delay their arrival.

You're confusing yourself by uncalculable random effects. If you are standing still they can miss you in any direction. If you are moving the same is true. You can't count the ones you miss. That's the defect in your method of calculation.

It is much better to think of searching in the same way Eugene Fluckey of the Barb did. He spent a lot of time explaining the situation, so I'm going to condense it.

The fact is, we don't know the disposition of the enemy on the ocean. If you are static in the middle of the horde, you're going to be successful. If you're static in a vacuum, you're coming back with a goose egg.

So you say, if you get a goose egg in 24 house, move! That's fine. Murphy's Law says you just moved from the next hot spot.

The only thing we can say for sure is that in any moment in time, the enemy is distributed in an unknown array over the surface of the ocean.

According to Fluckey, and I agree, the odds of finding a target approach unity when the distance between your sub and a target is within sensor range. So your job is to get within sensor range of as many targets as possible in a 24 hour period.

The corollary of that statement is that the number of targets you encounter is directly proportional to the number of square miles of ocean surface you search each day.

Let's do the math! You're static with a visual search radius of about 5 miles and a sonar search range of 20 miles on a good day. So you're searching a circle 20 miles in radius. The area you've searched is 3.14*20^2 square miles or 1,256 square miles.

Let's move out! We'll assume a 20 mile range for our radar and we're moving on the surface for 24 hours at our best fuel economy speed of 9 knots. Now your searched area approximates a rectangle 40 miles wide and 216 miles long. That's 8,640 square miles.

Since the enemy is moving and the effect of that movement is random we can safely ignore any effects on our results. Our movement will bring as many targets in range as it will leave beyond range. Therefore the comparison in the number of targets we develop can be expressed as the ratio between the two numbers of square miles searched.

So you are 8640/1256 times more likely to develop a target when moving. That is 6.88 times more likely. Another valid way to interpret the data is that a patrol during which you are actively searching at 9 knots, you will develop 6.88 times more targets in the same number of days as you would be searching statically.

But that is not the entire story. There are monstrous advantages to searching on the surface as opposed to searching submerged. Of most importance is the value of fully charged batteries. They can save your life, you know!

[gi_dan2987]

Therefore I choose to surface patrol

[TorpX]

Originally Posted by Rockin Robbins

You're confusing yourself by uncalculable random effects. If you are standing still they can miss you in any direction. If you are moving the same is true. You can't count the ones you miss. That's the defect in your method of calculation.

Not true.

It is much better to think of searching in the same way Eugene Fluckey of the Barb did. He spent a lot of time explaining the situation, so I'm going to condense it.

Fluckey did a lot of unorthodox things. As I recall part of his efforts involved probing/ raiding coastal anchorages where enemy ships were hiding out during the night. Is this what you are refering to? Looking for anchored ships or raiding coastal locations is not quite the same as searching for ships moving thru an area.

The fact is, we don't know the disposition of the enemy on the ocean. If you are static in the middle of the horde, you're going to be successful. If you're static in a vacuum, you're coming back with a goose egg.

How does this invalidate anything I said?

So you say, if you get a goose egg in 24 house, move! That's fine. Murphy's Law says you just moved from the next hot spot.

The only thing we can say for sure is that in any moment in time, the enemy is distributed in an unknown array over the surface of the ocean.

According to Fluckey, and I agree, the odds of finding a target approach unity when the distance between your sub and a target is within sensor range. So your job is to get within sensor range of as many targets as possible in a 24 hour period.



The corollary of that statement is that the number of targets you encounter is directly proportional to the number of square miles of ocean surface you search each day.

This is only true if you are searching for things that are not moving. While you are searching one end of your area, targets can move through the other and you'll never know it. Moving from one part of an area is not the same as being in both places at once.

Let's do the math! You're static with a visual search radius of about 5 miles and a sonar search range of 20 miles on a good day. So you're searching a circle 20 miles in radius. The area you've searched is 3.14*20^2 square miles or 1,256 square miles.


Let's move out! We'll assume a 20 mile range for our radar and we're moving on the surface for 24 hours at our best fuel economy speed of 9 knots. Now your searched area approximates a rectangle 40 miles wide and 216 miles long. That's 8,640 square miles.

Again, the square area is not what is important. If you were trying to find sea shells on a strip of beach, this would work ok. You could search an area, cross it off your list and move on to the next section. However, if the "sea shells" have the ability to move out from the water to the beach, and back into the water again, you will not be able to find nearly as many. They would be moving about in sections that you had "cleared". Your search efforts are only effective if there is a target nearby at the moment you are there. If the target moves thru either before or after you go by, you won't find it. Based on your analysis, it doesn't matter how fast enemy targets move, or if they move at all! An enemy cruiser moving at 30 kts could be found as easily as a drifting barge. You should see this is obviously not the case.

Since the enemy is moving and the effect of that movement is random we can safely ignore any effects on our results.

This is patently absurd if you think about it for two seconds.

Our movement will bring as many targets in range as it will leave beyond range. Therefore the comparison in the number of targets we develop can be expressed as the ratio between the two numbers of square miles searched.

If the first statement were true, it suggests there would be no difference.

So you are 8640/1256 times more likely to develop a target when moving. That is 6.88 times more likely. Another valid way to interpret the data is that a patrol during which you are actively searching at 9 knots, you will develop 6.88 times more targets in the same number of days as you would be searching statically.

OK, if this was really true, then you would get 2*6.88 times the number of targets in two days and 7*6.88 the number in a week. Do you really think just by moving at 9 kts this will get you 48 targets for every one I get in a single week? At this rate you could sink nearly 200 times as many targets in a month. Nice try, but your math does not hold up. Assuming that the number of contacts found will be proportional to the sq. area is a gross oversimplification.

But that is not the entire story. There are monstrous advantages to searching on the surface as opposed to searching submerged. Of most importance is the value of fully charged batteries. They can save your life, you know!

I never suggested submerged searching was better than surfaced searching. In fact the opposite is implied. Anything which increases your detection range (visual or otherwise), will improve your number of contacts by the same proportion. People seem to be reading things into this that I didn't write and don't intend. I never said it was better to drop anchor and remain motionless as if in a coma, or hide on the bottom of the ocean. Please, if you want to criticise what I've written, at least read it a little more carefully.

Ughh, too much typing. I'll try to find the relevent page in O'Kane's book.