Why do you need submarines?

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Why do you need submarines?

#1 Post by Pontius Navigator » Fri Apr 23, 2021 12:15 pm

In wartime, like 80 years ago, submarines were useful for sinking enemy ships.
Today they are useful (?) for hiding missiles, tracking someone else's submarines, and spying.

If you don't have any missiles you want to hide, don't have anyone upon whom you might spy, or anyone else's submarines that you want to track, then what?

Now China might serve that latter need, but what use is a small coastal submarine, and a very old one at that, against the number that China might deploy?

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Re: Why do you need submarines?

#2 Post by TheGreenGoblin » Fri Apr 23, 2021 1:47 pm

Pontius Navigator wrote:
Fri Apr 23, 2021 12:15 pm
In wartime, like 80 years ago, submarines were useful for sinking enemy ships.
Today they are useful (?) for hiding missiles, tracking someone else's submarines, and spying.

If you don't have any missiles you want to hide, don't have anyone upon whom you might spy, or anyone else's submarines that you want to track, then what?

Now China might serve that latter need, but what use is a small coastal submarine, and a very old one at that, against the number that China might deploy?

Very useful for anything clandestine. Any nation worth their military salt should have one or two at least...


https://en.wikipedia.org/wiki/Operation_Nobilis
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Re: Why do you need submarines?

#3 Post by Pontius Navigator » Fri Apr 23, 2021 4:25 pm

TGG, as I said, but what sculduggery could Indonesia have in mind?

OTOH they have several straits that a single SSC could block, until it is sunk. To be serious they would need at least two per strait.

I see Malaysia has 2 and Singapore has 4

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Re: Why do you need submarines?

#4 Post by TheGreenGoblin » Sun Apr 25, 2021 2:49 am

Pontius Navigator wrote:
Fri Apr 23, 2021 4:25 pm
TGG, as I said, but what sculduggery could Indonesia have in mind?

OTOH they have several straits that a single SSC could block, until it is sunk. To be serious they would need at least two per strait.

I see Malaysia has 2 and Singapore has 4
Indonesia is within the arc of China's immediate sea lane and territorial claims. One doesn't have to have to much of an imagination to see how a submarine might be very useful in such a disputed environment.
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Re: Why do you need submarines?

#5 Post by TheGreenGoblin » Sun Apr 25, 2021 6:56 am

https://en.wikipedia.org/wiki/KRI_Nanggala_(402)
The submarine conducted a number of intelligence gathering operations in the waters around Indonesia, including one in the Indian Ocean from April to May 1992, and another around East Timor from August to October 1999, in which the boat tracked the movements of the International Force East Timor as it landed in the region. In addition, after the Indonesian KRI Tedong Naga [id] and the Malaysian KD Rencong were involved in a minor collision in waters near Nunukan, North Kalimantan, Nanggala was tasked with scouting, infiltrating, and hunting down strategic targets in the area during May 2005
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Re: Why do you need submarines?

#6 Post by FD2 » Tue Apr 27, 2021 10:20 pm

Even an antiquated conventional sub like this has the power to disrupt offensive action by the local bully boys, given the huge number of islands that make up Indonesia and the difficulty of detection over such a big area. Many more are needed though, to cause any more that a scratch in the side of an offensive fleet. It's not an easy choice but nuclear would be a better alternative for Australia's present replacement programme or at least co-operation with those countries which need to band together to stand against the Chinese 'acquisitions' of vast areas in the South China Sea, to order a large number of up-to-date and effective conventional boats. Perhaps it's already too late.

Submarines do founder from time to time - the Argentine one seems to have been explained but the wreckage of this Indonesian one needs to be raised or very carefully inspected to find the cause of such a sad 'accident'.

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Re: Why do you need submarines?

#7 Post by Pontius Navigator » Wed Apr 28, 2021 8:01 am

Does Australia permit nuclear boats into port? I don't think NZ does.

I am curious as to what would cause a submarine to break up into 3 pieces.

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Re: Why do you need submarines?

#8 Post by FD2 » Wed Apr 28, 2021 10:59 am

NZ still doesn't, not sure about Oz. I think the Australian Government could get around that one, but not the NZ one...

Hopefully the cause of the sinking will be apparent when the wreckage is examined.

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Re: Why do you need submarines?

#9 Post by G-CPTN » Wed Apr 28, 2021 11:26 am

Did someone leave a door open?

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Re: Why do you need submarines?

#10 Post by Undried Plum » Wed Apr 28, 2021 2:42 pm

Circa March 1987 I worked on a seabed search for a lost Israeli submarine off the coast of Egypt. At the time, there was intense sensitivity as we had a serving Israeli naval officer with us as an advisor. In the Cairo office in Ma;adi he pretended to be a British officer, because the office boys and girls could not be trusted to keep their mouths shut. Although this was long after the peace agreement, among the ordinary population there was still a lot of distrust of the Yehudis and such co-operation, if made public, would have caused great embarrassment to the Gyppo government.

The WW2 era sub had been sold by the RN in the late 1960s to the IDF and the Israeli crew had been trained in the UK. She was being sailed by her new owners to Haifa when she simply disappeared. There had already been many unsuccessful searches for the wreckage and our fruitless search fared no better.

We were looking close to the Egyptian coast, NorthEast of Alex. The search was paid for by the USN for political reasons and was based on a crackpot theory that the skipper was playing silly buggers in shallow water when he lost control of trim on a practice dive and stoofed the bow into the putty. Nuts!

I got into a lot of trouble for saying that we were looking in entirely the wrong place. She had been giving six-hourly radio reports on her voyage, the last three of which did not include position reports. I simply used her previously known speed and extrapolated forward towards Haifa by that speed for 24 hours from her last known position to deduce what I thought should be the search datum. I was admonished by my boss, who pointed out to me quietly that we were not being paid the find the submarine. We were being paid to look for it. That's not my work ethic, so we agreed to disagree. I did keep my calc notes though.

Approximately 13 years later a different search crew, using a much more intelligent methodology to derive their datum, found the wreckage just 7nm from the centre of my proposed 36nm search radius. It was short of my position, but directly along a Great Circle track towards Haifa harbour entrance. I emailed my former boss with the news and attached a scan of my calc notes, reminding him of what I had said about the idiotic search datum that we'd been using off the NorthEast coast of Egypt. He sent me a one word reply: "Bastard!".

The sub had broken apart into three chunks and the conning tower had broken off. That part was subsequently recovered, but the exact cause of the demise is still not known. There are several plausible theories, but the wreckage is too deep for an affordable recovery of the main parts of the hull.

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Re: Why do you need submarines?

#11 Post by TheGreenGoblin » Wed Apr 28, 2021 3:39 pm

Undried Plum wrote:
Wed Apr 28, 2021 2:42 pm
Circa March 1987 I worked on a seabed search for a lost Israeli submarine off the coast of Egypt. At the time, there was intense sensitivity as we had a serving Israeli naval officer with us as an advisor. In the Cairo office in Ma;adi he pretended to be a British officer, because the office boys and girls could not be trusted to keep their mouths shut. Although this was long after the peace agreement, among the ordinary population there was still a lot of distrust of the Yehudis and such co-operation, if made public, would have caused great embarrassment to the Gyppo government.

The WW2 era sub had been sold by the RN in the late 1960s to the IDF and the Israeli crew had been trained in the UK. She was being sailed by her new owners to Haifa when she simply disappeared. There had already been many unsuccessful searches for the wreckage and our fruitless search fared no better.

We were looking close to the Egyptian coast, NorthEast of Alex. The search was paid for by the USN for political reasons and was based on a crackpot theory that the skipper was playing silly buggers in shallow water when he lost control of trim on a practice dive and stoofed the bow into the putty. Nuts!

I got into a lot of trouble for saying that we were looking in entirely the wrong place. She had been giving six-hourly radio reports on her voyage, the last three of which did not include position reports. I simply used her previously known speed and extrapolated forward towards Haifa by that speed for 24 hours from her last known position to deduce what I thought should be the search datum. I was admonished by my boss, who pointed out to me quietly that we were not being paid the find the submarine. We were being paid to look for it. That's not my work ethic, so we agreed to disagree. I did keep my calc notes though.

Approximately 13 years later a different search crew, using a much more intelligent methodology to derive their datum, found the wreckage just 7nm from the centre of my proposed 36nm search radius. It was short of my position, but directly along a Great Circle track towards Haifa harbour entrance. I emailed my former boss with the news and attached a scan of my calc notes, reminding him of what I had said about the idiotic search datum that we'd been using off the NorthEast coast of Egypt. He sent me a one word reply: "Bastard!".

The sub had broken apart into three chunks and the conning tower had broken off. That part was subsequently recovered, but the exact cause of the demise is still not known. There are several plausible theories, but the wreckage is too deep for an affordable recovery of the main parts of the hull.
Bayesian inference search (theory) technique?
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Re: Why do you need submarines?

#12 Post by Pontius Navigator » Wed Apr 28, 2021 3:57 pm

Nah, assume a 9 kts SIM

😁

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Re: Why do you need submarines?

#13 Post by FD2 » Thu Apr 29, 2021 6:17 am

INS Dakar (formerly HMS Totem) leaving Portsmouth Harbour. https://en.wikipedia.org/wiki/INS_Dakar

Dakar leaving Portsmouth.jpg
Dakar leaving Portsmouth.jpg (90.08 KiB) Viewed 499 times

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Re: Why do you need submarines?

#14 Post by Pontius Navigator » Thu Apr 29, 2021 7:19 am

An obvious reason for submarines is to act as targets for aircraft. In the 70s the US actually had a padded as a target. That would have been stressful for the crew knowing your friends would be deliberately trying to hit you.

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Re: Why do you need submarines?

#15 Post by TheGreenGoblin » Thu Apr 29, 2021 7:32 am

Pontius Navigator wrote:
Thu Apr 29, 2021 7:19 am
An obvious reason for submarines is to act as targets for aircraft. In the 70s the US actually had a padded as a target. That would have been stressful for the crew knowing your friends would be deliberately trying to hit you.
A padded submarine as a target? Sir you jest, or I need a padded cell! :p ;)))

They do use submarines as targets though... vide.

The USS Yellow Target Submarine

No Beatles were injured in the posting of the factoid...

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Re: Why do you need submarines?

#16 Post by Pontius Navigator » Thu Apr 29, 2021 7:42 am

TGG, I was not Sir. It was one of the last USN conventional submarines. In searching I found this:
http://rnsubs.co.uk/articles/service/star.html
A fascinating story.

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Re: Why do you need submarines?

#17 Post by TheGreenGoblin » Thu Apr 29, 2021 7:55 am

Pontius Navigator wrote:
Thu Apr 29, 2021 7:42 am
TGG, I was not Sir. It was one of the last USN conventional submarines. In searching I found this:
http://rnsubs.co.uk/articles/service/star.html
A fascinating story.
Dear Sir,

I retract my scurrilous questioning of the veracity of this story, thereby, perhaps, implying you were padding the truth. If this retraction is not sufficient for you, your seconds may find me at No.2 Humble Pie Lane, in order to make arrangements so that honour may be satisfied. I feel it only fair to point out to you, that I am an expert with the sharpened paw-paw, particularly when in my white underpants, protected by my padded straitjacket, so that you may choose your weapons appropriately.

I remain...

Yours in Amphibia

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Re: Why do you need submarines?

#18 Post by Pontius Navigator » Thu Apr 29, 2021 8:38 am

Dear Sir, I reserve the right to chose the weapons. I think a Mk 44 torpedo would be suitable. On one occasion we dropped a warshot torpedo programed to hit the seabed.

It missed.

A second worked.

Your obedient servant

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Re: Why do you need submarines?

#19 Post by TheGreenGoblin » Thu Apr 29, 2021 9:39 am

TheGreenGoblin wrote:
Wed Apr 28, 2021 3:39 pm


I got into a lot of trouble for saying that we were looking in entirely the wrong place. She had been giving six-hourly radio reports on her voyage, the last three of which did not include position reports. I simply used her previously known speed and extrapolated forward towards Haifa by that speed for 24 hours from her last known position to deduce what I thought should be the search datum. I was admonished by my boss, who pointed out to me quietly that we were not being paid the find the submarine. We were being paid to look for it. That's not my work ethic, so we agreed to disagree. I did keep my calc notes though.

Approximately 13 years later a different search crew, using a much more intelligent methodology to derive their datum, found the wreckage just 7nm from the centre of my proposed 36nm search radius. It was short of my position, but directly along a Great Circle track towards Haifa harbour entrance. I emailed my former boss with the news and attached a scan of my calc notes, reminding him of what I had said about the idiotic search datum that we'd been using off the NorthEast coast of Egypt. He sent me a one word reply: "Bastard!".

The sub had broken apart into three chunks and the conning tower had broken off. That part was subsequently recovered, but the exact cause of the demise is still not known. There are several plausible theories, but the wreckage is too deep for an affordable recovery of the main parts of the hull.
Bayesian inference search (theory) technique?
  • Formulate as many reasonable hypotheses as possible about what may have happened to the object. <<Starting in the wrong place, is bit like the Irish joke>>
  • For each hypothesis, construct a probability density function for the location of the object.
  • Construct a function giving the probability of actually finding an object in location X when searching there if it really is in location X. In an ocean search, this is usually a function of water depth — in shallow water chances of finding an object are good if the search is in the right place. In deep water chances are reduced.
  • Combine the above information coherently to produce an overall probability density map. (Usually this simply means multiplying the two functions together.) This gives the probability of finding the object by looking in location X, for all possible locations X. (This can be visualized as a contour map of probability.)
  • Construct a search path which starts at the point of highest probability and 'scans' over high probability areas, then intermediate probabilities, and finally low probability areas.
  • Revise all the probabilities continuously during the search. For example, if the hypotheses for location X imply the likely disintegration of the object and the search at location X has yielded no fragments, then the probability that the object is somewhere around there is greatly reduced (though not usually to zero) while the probabilities of its being at other locations is correspondingly increased. The revision process is done by applying Bayes' theorem.
  • In other words, first search where it most probably will be found, then search where finding it is less probable, then search where the probability is even less (but still possible due to limitations on fuel, range, water currents, etc.), until insufficient hope of locating the object at acceptable cost remains.
The advantages of the Bayesian method are that all information available is used coherently (i.e., in a "leak-proof" manner) and the method automatically produces estimates of the cost for a given success probability. That is, even before the start of searching, one can say, hypothetically, "there is a 65% chance of finding it in a 5-day search. That probability will rise to 90% after a 10-day search and 97% after 15 days" or a similar statement. Thus the economic viability of the search can be estimated before committing resources to a search.

Apart from the USS Scorpion, other vessels located by Bayesian search theory include the MV Derbyshire, the largest British vessel ever lost at sea, and the SS Central America. It also proved successful in the search for a lost hydrogen bomb following the 1966 Palomares B-52 crash in Spain, and the recovery in the Atlantic Ocean of the crashed Air France Flight 447.

Bayesian search theory is incorporated into the CASP (Computer Assisted Search Program) mission planning software used by the United States Coast Guard for search and rescue. This program was later adapted for inland search by adding terrain and ground cover factors for use by the United States Air Force and Civil Air Patrol.
-Bayesian Search Theory

https://projecteuclid.org/journals/anna ... 49665.full
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Re: Why do you need submarines?

#20 Post by Boac » Thu Apr 29, 2021 11:14 am

PN - a few of us would like to know what 'a padded' is? Is it one of these? https://www.thelingeriestoreuk.com/prim ... arine.html

Could entice me to join the RN.

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