Model of flooding and reasons for the death of the squadron battleship "Oslyabi" in the Battle of Tsushima
As a result of the discussion of the previous article, it became clear that there was a need to adjust the data presented in it.
Some errors
There are three of them:
1. The moment that changes the list of the Oslyabya by 1 degree is more like 883 ton-feet, and not 976 ton-feet, which I adopted based on the model of the Borodino-class battleships.
2. My assumption that the Oslyabya did not have a trim by the stern before the battle is considered unacceptable: sailors usually loaded the ship so that the stern sat in the water slightly deeper than the bow, which improved seaworthiness. Therefore, for further calculations it is accepted that the Oslyabya had a trim by the stern of 2,5 inches before the battle. Accordingly, the point at which the living deck adjoined the ship's stem was 6,35 cm above sea level.
3. My assumption that at the moment of the failure of the Oslyabya, its stem sank into the water "up to the hawse holes" by 2,438 m, that is, to the height of the living deck, was considered overly optimistic. Therefore, in further calculations I am guided by the assumption that at the moment of failure, the battleship's stem sank one meter more, that is, 3,438 m from the living deck, and taking into account the trim by the stern - by 3,5015 m (3,438 m + 0,0635 m) from the pre-battle state of the ship.
Taking these adjustments into account, the amount of water in the battleship's coal pits, necessary for the Oslyabya to have a list of 12-15 degrees, was reduced from 320,8-404,6 tons to 277,9-350,4 tons. However, even these values seem maximum, if not excessive.
First. I did not take into account at all that Sherbachev 4th, who observed the failure of the Oslyabya from the stern turret of the Orel following in front of him, could have indicated and, most likely, did indicate the list at the moment of the doomed battleship's rotation. And this gives a significant correction to the calculations.
At the moment of the rudder shift, the ship acquires a small list in the direction of the turn. But this list is only active during the rudder shift – as soon as the ship begins to turn, it acquires a list in the opposite direction. The magnitude of this list can vary, as it is determined by many parameters, including, but not limited to, the ship's speed and the radius of the turn. But whatever the "circulation" list, it is always there.
During the rudder shift, the Oslyabya slightly reduced the list to port, but then, upon starting the turn, on the contrary, increased it. Therefore, it should be assumed that before the turn, the ship's list was no more, and most likely even less than 12 degrees. The list of 15 degrees could have formed only at the moment of the turn: if it had been like that before it, then during the turn, the water should have flooded the lower gun ports of the Oslyabya, and the ship would have capsized. Consequently, the list of the Oslyabya before the start of the failure could well have been 9-10 degrees or even less, and not at all the 12 degrees that I took as the minimum value.
Second. I most likely underestimated the effect of the flooding of the Oslyabya in the bow, below the living deck, on the list. The thing is that my calculation method is very simple: taking as initial data the presence of a list of 12 degrees in the Oslyabya, I determined how much of this list was created by water on the living deck of the battleship (taking into account the above corrections, it turned out to be 3,65 degrees and 4,6 degrees with a list of 15 degrees), then assumed that the water that "leaked" into the bow compartments below the living deck provided another half a degree of list. In total, it turned out that the flooding in the area of the coal pits formed 12 - 3,65 - 0,5 = 7,5 degrees of list, for which, in fact, taking into account the new input data, 277,9 tons of water would have been needed.
But the whole point is that as a result of changes in the initial data, the amount of water below the Oslyabya's living deck to ensure trim "by the hawse holes" increased sharply, amounting to 162-199 tons in the most realistic scenarios. A list of half a degree is provided by only 35 tons of water, whose center of gravity is removed from the centerline by 3,85 meters. Considering that water through cracks and damaged ventilation on the living deck flooded primarily the compartments on the left side, and the water in the under-turret compartment also flowed toward the left side, to which the battleship was listing, it can be expected that these masses of water gave both 1,5 and 2 degrees of list, and possibly more. Let us also take into account that in a normal case the list of ships during circulation is at least 1-2 degrees, as well as the fact that the damaged Oslyabya cannot in any way be considered a “ship in a normal state”, which is why its last circulation could have given a greater degree.
In view of the above, with the Oslyabya listing at 12-15 degrees, which was observed by Shcherbachev IV, 4-3,65 degrees were "formed" by water flowing onto the living deck in its forward part, and another 4,6-3 degrees could have arisen due to water entering the forward compartments below the living deck and due to circulation. Taking into account the above, the amount of water in the coal pits, necessary to form the observed list of the ship at 5-12 degrees, could well have been only 15-154 tons.
Accordingly, the most realistic option is the assumption that the mass of water in the coal pits, which participated in the formation of the Oslyabya list at the time of the latter’s failure, but before the start of circulation, was in the range of 154-278 tons.
But why such a reservation - "water that participated in the list formation"? The fact is that by the time of the failure on the Oslyaba, counter-flooding of the corridors on the starboard side was carried out, as a result of which part of the weight of the water in the coal pits and adjacent rooms was compensated and did not participate in the list formation to the port side. For example, 270 tons of water could have entered the coal pits and adjacent rooms, of which the effect of 70 tons was compensated by 70-80 tons of water received as a result of counter-flooding.
That's all about the Oslyabya's list. Let's move on to the trim.
About the trim of the Oslyabya and the reasons that caused it
As I wrote earlier, all the flooding of the Oslyabya can be divided into three zones:
- 1st and 2nd compartments of the living deck (Zone No. 1);
- Forward compartments under the living deck (Zone No. 2);
- Coal pits and adjacent rooms (Zone No. 3).
It is known that as a result of a 12-inch shell hitting the area of the 1st compartment of the living deck, water gained access not only to the 1st, but also to the 2nd compartments, which gave both of them free communication with the sea. However, such damage in itself could not have submerged the bow of the Oslyabya in the sea up to the hawse holes.
Let's conduct a small thought experiment. Let's take the squadron battleship Oslyabya and fill its bow compartments No. 1-2 on the living deck with water completely, right up to the ceiling. What will happen in this case?
The shape of the compartments along the specified length is similar to a triangular prism with a volume of roughly 654 cubic meters, which, taking into account the density of sea water of 1,025 tons per cubic meter, gives 670,6 tons. The intake of such a quantity of water would increase the draft of the Oslyabya by almost 13 inches, or more precisely, by 32,6 cm. Using the rule of similarity of triangles, we will determine the center of gravity of this water - it will be located from the 0th frame towards the stern by approximately 21,8 m. At the same time, the center of gravity of the Oslyabya was 4,74 feet from the midship to the bow, accordingly, the center of gravity of the received water would be located from the center of gravity of the ship by almost 137 feet.
In this case, the water received on the living deck would create a force equal to 137 * 670,6 = 91 ton-feet (since I calculate with a large number of decimal places, but do not write these decimal places in the article, the calculator will show a slightly different figure), and will cause a trim by the bow of almost 851 inches or 80,4 cm. Accordingly, the stem of the Oslyabya would have immersed by 204,2 + 204,2 = 32,6 cm, never reaching the level of the battery deck, which rose above the living deck by 236,8 cm. It is quite obvious that in this case, a certain part of the 243,8st and 1nd compartments of the living deck would have remained above the water (highlighted in red on the diagram)
Which, of course, is physically impossible. At the same time, according to our estimates, the stem of the Oslyabya sank into the water by more than 3,5 m (6,35 cm of the elevation of the living deck above the sea due to the trim by the stern + 243,8 cm of the height of the interdeck space to the battery deck + 100 cm from the battery deck). Consequently, for the Oslyabya to sink into the water up to the hawse holes, the flooding of the living deck alone could not have been enough.
In fact, if the damage to the Oslyabya had been limited to water entering the living deck, the battleship would not have been in any danger: by analogy with the Peresvet, which received similar damage in the battle in the Yellow Sea, it would have taken on a layer of water of approximately 1,5-2 feet (46-61 cm) onto the living deck and continued the battle, getting off with an insignificant (measured in tens of centimeters) trim.
Interdependence of floods
The sinkings of the Oslyabya are closely interrelated. Each new ton of water pouring into the lower deck and hold compartments (zone No. 2) led to an increase in draft and trim, thereby increasing the flow of water onto the living deck (zone No. 1). But as a result of the increase in list, the water on the living deck and in the coal pits (zones No. 1 and 3) spilled over to the left side, their center of gravity shifted, thereby creating an additional list.
Each new ton poured into the 10th and 12th coal pits (zone No. 3) also increased the draft (which increased the flow of water onto the living deck in zone No. 1) and created a list to the left side (which contributed to the overflow of water to the left side on the living deck and in the compartments below it in zones No. 1-2).
These relationships are taken into account in my calculation as follows:
Step 1. It is assumed that the trim of the Oslyabya increased by 3,5015 m at the time of its failure.
Step 2. An increase in the Oslyabya's draft due to flooding in the area of the 10th coal pit and counter-flooding was determined. Since the exact mass of the incoming water is unknown, we make a calculation for each value from 300 to 700 tons of water in 100-ton increments. In this case, we assume that out of the incoming 300-700 tons, 277,9 tons had an effect on the list and trim (the remaining mass of water partially came in during counter-flooding, and partially was balanced by counter-flooding). Naturally, all 300-700 tons of water retained their effect on the draft.
Step 3. We determine the volumes and mass of water on the living deck for each of the values calculated in accordance with Step 2 and taking into account that the ship's stem, in accordance with Step 2, must be submerged in water by 3,5015 m.
Step 4. During Step 3, it turns out that the amount of water received on the living deck and in the area of the 10th coal pit is not enough for the Oslyabya to sit down with its bow at 3,5015 m. Accordingly, we calculate the amount of water that should have entered the compartments of the lower deck and the hold to ensure the required trim.
The calculations are certainly very simplified. But, unfortunately, without having any drawings of the Oslyabya, or the ability to calculate the volume occupied by its structures and equipment in the compartments, or, most importantly, an exact understanding of where exactly and in what quantity the water spread, it is impossible to perform accurate calculations according to all the rules of shipbuilding science. On the other hand, the simplifications I use should not fundamentally change the overall picture of what happened to the battleship.
The resulting figures are:
The most realistic options are 1-3, according to which the mass of water that entered the coal pits, adjacent rooms and received as a result of counter-flooding is 300-500 tons. Accordingly, in the bow compartments below the living deck of the Oslyabya there were 162,7-199,3 tons of water.
In this case, I write "there was water" and not "water entered". Why? Because, without a doubt, much more water entered the bow compartments of the Oslyabya below the living deck, but some of it was pumped out by turbines, as V. N. Zavarin (or is it V. N. Zavorin?) writes:
I opened the drain valve and the water went into the hold, then I started the turbines.
Accordingly, in the bow compartments below the living deck of the Oslyabya, at the time the battleship was disabled, there were only 162,7-199,3 tons of water, but significantly more entered, since some of the water that had flowed into the compartments was pumped overboard.
The above calculations and eyewitness accounts allow us to reconstruct the picture of the death of the Oslyabya with acceptable accuracy.
Consequences of hit #1
A twelve-inch shell hit the area of the 1st compartment of the living deck:
1. Opened access for water not only to the 1st, but also to the 2nd compartment, since its rupture damaged the watertight bulkhead between them. As a result of this hit, the living deck from the 0th to the 30th frame, that is, over a distance of more than 30 m, turned into a kind of "scoop" directed towards the ship's movement and "scooping" water through the hole.
2. Damaged the living deck and ventilation system, allowing water to enter the rooms below the 1st and 2nd compartments of the living deck. Moreover, the damage to the deck and ventilation was so significant that the crew of the Oslyabya could not cope with it, which is why the flooding of the compartments below the living deck became uncontrollable.
We know that damage to the living deck took place from the report of the mine officer, Lieutenant M.P. Sablin, who stated in his report:
Through the hole caused by this shell, water entered the first and second compartments of the living deck, and through the cracks formed in the deck, through the hatches and broken ventilation pipes, it went into the left bow 6-inch cellar and into the under-turret compartment <…> in the holds, the water reached the compartment of the bow dynamos and underwater vehicles.
We know from the testimony of the mine-engine conductor V. N. Zavarin, who was at the dynamo machines and mine apparatuses, that it was not possible to stop the spread of water in the bow of the ship below the living deck. V. N. Zavarin testified that water was constantly flowing below the living deck of the Oslyabya until the very end:
Although the hole was patched up, water got into the underwater mine launchers before it was patched up. I temporarily left the mine launcher compartment to batten down the neck of the armored cover, which I succeeded in doing, but when I returned to the compartment I saw that water was getting in through the ventilation pipes and the ship began to list. I opened the release valve and the water went into the hold, then I started the turbines to pump out the water, but apparently this did not help, since water began to penetrate into the under-turret compartment, which was soon flooded, and I ordered the room to be patched up and everything to be tightly closed. At this time I saw the wounded Lieutenant Tunderman, who was looking for a way out above; in view of the fact that everything was battened down, I indicated the way through the forward turret. Seeing that the water was still rising, I wanted to talk to the mine officer and receive the appropriate orders, but it turned out that the telephone was out of order and the speaking tubes were broken. At this time I heard a command from above: “Save yourself if you can.”
R. M. Melnikov, V. Krestyaninov and S. Molodtsov indicated that Peresvet and Oslyabya had 10 compartments separated by watertight bulkheads: ram, forward ammunition magazines, forward under-turret, three boiler rooms, two engine rooms, aft under-turret and a tiller. I have no reason not to trust this data. But according to the testimony of M. P. Sablin and V. Zavarin, it turns out that the watertight bulkhead between the forward ammunition magazines and the forward under-turret compartments could not prevent flooding below the living deck - both sank.
In fairness, it should be noted that the watertight bulkhead may not have anything to do with it, but rather another Japanese shell that hit the bow of the Oslyabya opposite the 2nd compartment of the living deck. But this version seems extremely dubious, since, according to available data, this shell hit the battleship much later than the flooding of the compartments under the 2nd compartment of the living deck was noted. Thus, Mr. A. Rytik, relying on the testimony of sailors, indicated the time of impact as “around 14.30” or “14.25-14.30”, that is, shortly before the battleship was put out of action. At the same time, although V. Zavarin does not indicate the exact time when he recorded the ingress of water into the torpedo tube compartment through ventilation, it should be considered that it happened at approximately 14.00, at the latest at the beginning of the third hour. Two circumstances indicate this.
Firstly, the water inflow coincided with the list, which apparently occurred when the Oslyabya received a hole in the coal pit, where water began to flow, causing the ship to list to the left side. But the Japanese shell that hit the Oslyabya in the area of the 10th coal pit hit the ship a few minutes after hitting the living deck compartment, that is, around 14.00:XNUMX.
Secondly, Zavarin’s subsequent actions – opening the release valve, turning on the turbines, flooding the under-turret compartment, sealing the room, talking with Lieutenant Tunderman, evacuation, etc. – could hardly have occurred between 14.25:14.30-XNUMX:XNUMX and the destruction of the battleship.
But even if I am mistaken and the water entering the forward compartments below the living deck is a consequence of a shell hitting opposite the 2nd compartment of the living deck, it will still have to be stated that such flooding – through ventilation and other “leaks” in the living deck when the end of the Oslyabya was hit – happened twice. While the sister ship Peresvet, which also received hits from large-caliber shells in the areas of the 1st and 2nd compartments of the living deck (but on the other side) during the Battle of the Yellow Sea, did not experience this in either case.
Perhaps the only contradiction in this reconstruction is the story of the senior topman F. S. Lebedev, who was directly involved in sealing the hole in the first compartment of the living deck and claimed that the hole was sealed. However, this testimony is extremely doubtful for two reasons.
Firstly, it is practically impossible to patch a large hole at the waterline, which quickly became semi-underwater, measuring at least two and a half meters (according to F.S. Lebedev) in the bow of the ship, in conditions of rough seas, an oncoming flow of water and without applying a patch from the outside of the hull.
Secondly, there is information from a much more qualified member of the Oslyabya crew, senior officer Pokhvistnev. When asked by M. P. Sablin about the hole, he replied that:
The hole cannot be repaired, but the water was dealt with and the hole no longer poses a danger.
By "we dealt with the water" we obviously do not mean "we stopped the water from entering the ship" (otherwise Pokhvistnev would have reported that the hole was sealed), but "we localized the area of flooding and did not allow the water to spread further." It is also obvious that Pokhvistnev meant that the water spread only along the living deck: being on it, he could not have known that the water was "leaking" into the compartments below, and the trim was not yet great enough to tell him this.
As for F. S. Lebedev, we can assume the following: a group of sailors actually managed to erect some kind of barrier in the area of the hole, which limited (but did not stop) the flow of water into the first compartment of the living deck, after which they, considering the task completed or having received an order, went about other things.
Consequences of getting into the area of the 10th coal pit
The twelve-inch shell hit the area of the 10th coal pit of the Oslyabya literally a few minutes after the hit described above. It can be assumed that it exploded when passing through the 102 mm upper belt, or immediately after passing through it. The consequences were quite impressive: either the armor plate was split, with most of it ending up overboard, or the force of the explosion broke it off, sending it into the water. The latter option is so specific that it may, perhaps, fall under the category of naval curiosities. But it is by no means impossible.
As an example of such an impact, let us consider shot No. 41 at the “excluded vessel” Chesma, carried out during the testing of the then newest 12-inch shells of the 1911 model. The shot was fired at a 125-mm armor plate, similar to that which protected the traverse of the Sevastopol-class battleships. They fired a high-explosive shell
As a result of the hit, the armor plate was driven into the compartment and turned along its axis, with one edge facing inward, and the other sticking out.
Pay attention to the hole in the deck - this is where the armor plate was located when the shell hit, exploding on contact with the armor. The distance from the hole in the deck to the lower edge of the plate is the path that the armor plate made into the compartment. For greater clarity, I will also provide a sketch of the consequences of this hit:
And for those esteemed readers who strive to know everything down to the millimeter, I am pleased to present a description:
"Chesma" was in calm water, at anchor, and the damaged armor plate was quite high above sea level. Therefore, it is not surprising that the plate, although greatly displaced, still remained in place. "Oslyabya" was moving in rough water, its 102-mm belt was located right at the water's edge, so there is nothing strange about its loss.
Of course, the Japanese 12-inch shell was much weaker than the Russian model 1911. During tests, the Russian shell hit the armor at a speed of 527 m/s, while the Japanese shell, which hit the area of the 10th coal pit, probably hit within 400 m/s, hardly more. The weight of the Japanese shell was 386 kg, not 170,9 kg, and it carried about a third less explosive.
But, on the other hand, it was confronted with much weaker protection. The Sevastopol's traverse armour was a quarter thicker and was cemented, while the 102 mm plate of the Oslyabya was not cemented. In addition, the Sevastopol was protected by Krupp armour, while the plate of the Oslyabya was produced in the era of hardened armour. In addition, as we know from the research of Mr. A. Rytik, the 102 mm armour belt of the Oslyabya consisted, among other things, of "substandard" armour plates that had not passed the tests.
Another interesting case is shot No. 10 at the Chesma's conning tower. Here the shell penetrated the plate and exploded, and the force of the explosion turned the adjacent armor plate out by a meter - not into the conning tower, but outward.
Externally it looked like this:
Of course, this was not the first hit to the conning tower, and the fastenings could have been weakened by previous shells. But the conning tower was protected by 250 mm of cemented armor, also fastened using the dovetail method, which, of course, represents much stronger protection than the upper armor belt of the Peresvet-class battleships.
In view of the above, the variant in which the 102-mm plate of the Oslyabya received such damage that its fastening was almost destroyed, and the plate itself “put its edge overboard” as the battleship moved, turning into a ladle, and was finally broken off by the impact of the oncoming wave, is undoubtedly a rarity, close to a curiosity, but there is nothing impossible about it.
What happened next?
The repair division, led by engineer Zmachinsky, began the fight for survivability, but did not succeed. The water not only spread along the slope and flooded the 10th upper coal pit, but, apparently, began to flood the 10th and 12th lower coal pits located under the 10th upper, the compartments between the side and the coal pits, as well as the adjacent corridors and the ammunition cellar of the 6-inch guns. From there, the water penetrated into the 2nd, and soon into the 1st boiler rooms. Moreover, in considerable quantities, since M. P. Sablin reported:
After the hole in the coal pit, I received an order to start turbines No. 4 and 6, which was done.
Thanks to the work of A. Rytik, we know that the discussion was about turbines “serving” the 1st and 2nd boiler rooms.
According to M. P. Sablin, after this hit the Oslyabya's list began to increase rapidly. This is not surprising at all - every 35,4 tons of water that flowed into the coal pits and the space between them and the side increased the ship's list by approximately 1 degree (883 ton-feet necessary and sufficient to form a list of 1 degree / 24,93 feet of distance from the centerline to the center of gravity of the incoming water = 35,42 tons). But this is only the direct effect of flooding in the coal pits, and there was also an indirect effect: under the influence of the list, the water in the flooded bow compartments below the living deck and on it spilled over to the left side, causing its center of gravity to shift and the list to increase further.
At the same time, the water entering the 10th and 12th lower coal pits caused not only a list, but also a trim by the bow. If we assume that both of these pits and the rooms next to them were flooded more or less evenly, then it is reasonable to consider the center of mass of the water entering the hull of the Oslyabya to be the partition between these pits. It was located approximately at the 49th frame of the ship.
The distance between the frames (length of the frame space) was 0 m from 18 to 0,9, and 18 m starting from the 1,22th, where the ship's double bottom began. Accordingly, the distance from the 0th to the 49th frame consisted of 18 0,9 m spaces and 31 1,22 m spaces, or 54,02 m in total.
The length of the Oslyabya at the cargo waterline was 130 m, respectively, the distance to the center of the ship from the 0th frame was approximately 65 m. The center of gravity of the ship was shifted from the midship by 4,74 feet to the bow, respectively, from the zero frame to the center of gravity of the ship the distance was 63,56 m. Subtracting the 54,02 m calculated earlier, we get 9,54 m or 31,28 feet (taking into account the decimal places, it turns out to be 31,28, not 31,3). Accordingly, the 35,42 tons calculated by me earlier, causing a list to the left side by 1 degree. (not counting the multiplier effect of the overflow of water in the bow compartments), also led to an increase in the draft of the Oslyabya by 35,42 tons / 52,2 tons = 0,68 inches (1,7 cm) and a trim of 35,42 tons * 31,28 feet / 1143 ton-feet = 0,97 inches.
It can be concluded that if the hole opposite the 1st compartment of the living deck led to such an influx of water into the hull of the Oslyabya that the trim increased sharply and the list slightly, then the hit in the 10th coal pit “worked” differently: the water poured into this hole greatly increased the list and slightly increased the trim.
But we should not forget that the Oslyabya crew was fighting for survivability. M. P. Sablin mentioned counter-flooding of the corridors on the starboard side, and then of the ammunition magazines. I do not know which compartments were flooded, but we should assume that counter-flooding was used to reduce not only the list, but also the trim - in fact, this is how the fight for survivability is built. In this case, counter-flooding was supposed to reduce the already small trim to a very small value.
Conclusions
The above calculations show that:
1. "Oslyabya" could easily have been destroyed by hits from just two 12-inch shells;
2. The flooding of the bow compartments below the living deck really took on an uncontrollable character – in total, about 200 tons of water or more entered there.
Regarding the latter, I would like to note that if the shell had hit the area of the 16th coal pit, and not the 10th, then even more water would have flowed into the bow compartments. The whole point is that the 16th coal pit is located aft of the midship, which is why, if it were flooded, the Oslyabya would acquire a trim by the stern, that is, such damage would become a counter-flooding in relation to the holes in the bow of the ship. In this case, the amount of water in the bow compartments of the living deck, sufficient to sink the Oslyabya "up to the hawse holes", would be significantly greater than the "about 200 tons" I calculated.
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