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Senator GERRY. I would like to interrupt the witness just there, Mr. Chairman. I think while we are touching on this question of design we might go into it a little bit more fully. What would be the difference in modern design? Would the construction be stronger, or would there be added safety devices, or what?

Mr. SPEAR. Just this, Senator Gerry. Every part of the boat, starting even with the hull would be better built, because we know better how to build them. For instance we could build a hull for a boat of the same size as the S-4 which would weigh a great deal less than the S-4 hull does, and which would be equally strong, or we could build on the same weight a hull which would withstand considerably greater pressure. For instance, the S-4 was constructed for safe submergence to 200 feet. With the same weight of hull to-day we could build a boat that would be good for 50 per cent greater depth. That same thing runs all through the design in all the details. We are able to save weight and able to save space over what we could do then; and the consequence is that we have more margin after the military requirements are met to devote to those features which contribute to the safety of the boat, or the safety of the crew.

The biggest item of all I should say is hull design and construction, that is we gain more through that than we do in any other single item; but, at the same time, there has been great progress in all the innumerable things that go into a submarine; the special devices, and the machinery, and all those things. We can do a great deal more with the capital that is given to the designer to-day, supposing you call displacement the capital-we can produce the same military results and greater safety, or we can produce greater military results with the same safety.

There is one other point about design which perhaps I should bring out, and that is this, that the extent of the safety features that you can carry in a submarine depends to some extent upon the size of the boat. To illustrate this point, the size of apparatus designed to enable the crew to make their own escape from a sunken submarine depends fundamentally upon the size of a man. In proportion to a small boat, the size of the apparatus becomes relatively very great, in fact so great as to make the fitting of the apparatus impracticable because it would crowd out some absolutely essential military feature. But, when you build a boat ten or fifteen times as big as the small boat, the actual apparatus for the rescue of the men remains about the same size. Thus, relatively to your boat it becomes small and it is, therefore, possible in large submarines to incorporate safety features which it is not practicable to put into a small submarine.

In addition to the developments in detail of design of submarines the general tendency within the last few years has been to make them bigger and bigger. That increase in size is a help to the designer in incorporating safety features. For instance, in the earlier boats, the very early submarines, there were no bulkheads at all, and any injury to the hull that could not be handled by the pumps meant that the boat was going to sink. That was all there was to it. As the size increased we began to fit bulkheads so as to restrict the damage; and, at the time that the S-4 was designed we had reached the point where, broadly speaking, we could stand having one compartment broached to the sea and then if the ballast tanks were all

empty or could be emptied, the boat would still float. In our later designs of larger boats we can broach two compartments and the boat will still float.

The actual size of any given compartment is generally governed by some special consideration but as a general rule, as the boats increase in size, it is possible to make the compartment relatively shorter, therefore in the larger boats more bulkheads can be fitted. We also have greater relative ballast tank capacity than we used to have; and the net result is that with the very latest designs you can have a collision and broach two compartments and still your boat will float.

Senator GERRY. How many compartments did the S-4 have that would sustain her?

Mr. SPEAR. The S-4 had five separate water-tight compartments in the interior.

Senator GERRY. How many of those were needed to float her?

Mr. SPEAR. She was presumed to be designed so that any one of those might be filled, and if the ballast tanks were empty she would still float; but she could not stand to have two filled.

Senator GERRY. And in this collision two were filled?

Mr. SPEAR. In the collision one was filled immediately from the collision, and the water found its way through a ventilation valve in the battery ventilating system, into the second compartment, and filled that one.

Senator GERRY. And the second compartment was not really water-tight?

Mr. SPEAR. The water-tight bulkhead separating the two compartments was pierced by the ventilation duct to which I have just referred. A valve in this duct was fitted at the bulkhead in order to preserve its water-tightness, but apparently something went wrong with this valve so that the crew were unable to close it. The result was that the water flowed through from the broached compartment into the next compartment. So, that as the result of the accident, two compartments in the boat were flooded.

Senator GERRY. How long did it take to flood the second one? Mr. SPEAR. As near as I can tell, Senator, from an estimate, taking into account the fact that the boat was sinking while the water was coming in-the first compartment would have flooded, with the hole that the Paulding made in her, in something between 50 and 60 seconds. That is, the first compartment would have flooded in that time. Now, the water probably began to get into the second compartment say in 30 or 40 seconds. The water had to rise to a certain height in the first compartment before it could pass through the ventilation duct into the second compartment. This duct was not designed to stand the high pressures to which it was subjected under these conditions, and it naturally ruptured under this high pressure. As it happened, the rupture occurred right over the switchboard and the result was that the live switches were deluged with salt water, resulting in short circuits, fusing, etc. Senator ODDIE. And gas, too?

Mr. SPEAR. And gas, too. And that, in my judgment, is what drove the men from that central compartment into the engine room. It was in this central compartment that all the controls for the ship were located. The means of blowing the ballast tanks, and of con

trolling all the apparatus that is used to control the weight of the boat, was located in this compartment from which the men were driven. This fact had a very distinct bearing on the result in this particular case.

Senator GERRY. How long do you think it took to flood the second compartment?

Mr. SPEAR. I have not made any figures on that, Senator.

Senator GERRY. Roughly?

Mr. SPEAR. As a rough guess, I would say that it did not take more than two minutes.

Senator GERRY. That is why she settled so quickly?

Mr. SPEAR. That is why she settled so quickly.

Senator GERRY. The ballast tanks were empty, were they? Mr. SPEAR. No; her ballast tanks were all full. You see, the boat was in diving condition. In fact she was running submerged at the time with the main ballast tanks full and her other ballast tanks had the required amount of water for diving in them. Senator GERRY. But she had just come up.

Mr. SPEAR. She had only risen to the surface-what they call planed up. You do not have to change weight to come up, but just set your rudders. A submarine steers up and down just as a surface craft steers to the right or left, and you do not necessarily have to eject water to come up.

Senator GERRY. With her ballast tanks in that condition, if she had not had the water in the second compartment would she still have floated?

Mr. SPEAR. If the water had not come into the second compartment, they could have blown all of the uninjured ballast tanks and also the fuel tanks, and the buoyancy so gained should have been sufficient to have kept her just afloat. On account of the damage due to the collision, one of the main ballast tanks could not have been blown because it was ruptured near the top. As a matter of fact, the crew attempted to blow the ballast tanks before they left the central compartment. All of the valves in the air manifold leading from the air supply to the main ballast tanks were found. open, including the one leading to the injured tank. Thus there was a free connection between the air supply and the sea through the injured tank, which would naturally result in the loss of the whole of the ship's air supply.

It is obvious from what was found that the crew attempted, in the short space of time they had before they were driven from that compartment, to do the correct thing, which was to blow their ballast tanks.

Senator GERRY. And after that compartment was flooded, as you stated, the batteries were put out of commission.

Mr. SPEAR. That would not be instantaneous, Senator. There is no question but what they had voltage in the batteries, and lights burning in the ship for some time afterwards. It takes quite a little time for the battery to completely discharge itself under those conditions.

Senator GERRY. Had they been able to blow the tanks it would not have floated the ship with these two compartments flooded, would it? Mr. SPEAR. Not with two compartments flooded; no.

Senator ODDIE. Assuming that the very latest safety devices had been installed in those two compartments, would it have been possible for those men to have put them in operation with that great volume of water coming in under heavy pressure, in the few seconds before they filled?

Mr. SPEAR. Nothing could have been done, Senator, in the compartment that was breached, the one that was ruptured; it would not have been humanly possible to do anything in that compartment.

In this second compartment which flooded through this ventilation connection, nothing that required any great period of time could have been done, because it is obvious that they only had a few seconds to work before they were driven from that compartment. So they would not have been able to work any more apparatus than they did work.

There would be nothing that they could do, Senator, in the way of remedy except what they attempted to do. The first remedy was to endeavor to get the boat to float, or bring her to the surface. That the crew endeavored to do.

The apparatus was there in that compartment for doing it, and it is clear that the crew made the attempt. The failure of the attempt was in all probability due to the fact that in the confusion the air was admitted not only into the intact ballast tanks but also into the ruptured tank, through which it had free access to the sea. I have no doubt in my mind that all of the air supply of the ship was exhausted through that ruptured tank.

Senator ODDIE. Do you know of any safety devices that might have been attached to, or placed in, the S-4 that would have prevented the fatalities?

Mr. SPEAR. It is my belief that if the torpedo and engine compartments had been fitted with the latest safety and rescue devices conceived since the S-4 accident, it would have been possible to save some or all of the men.

Senator ODDIE. Would it have been practical to have put those improvements in the S-4?

Mr. SPEAR. I doubt it very much. That would be a matter of detailed calculation, Senator. A submarine differs materially from an ordinary ship in this respect, that when you have completed a ship of the ordinary kind and you wish to make a new installation in her you go ahead and do it-anything within reason, any amount of weight within reason-and the only result is to increase the draft of the ship a little and perhaps slow her speed down. But when a submarine is once completed, you have nothing to draw on except what little excess lead ballast you may have. You can not put anything new in without taking something old out; otherwise you destroy her as a submarine. You must preserve an exact relation between the weights of the ship and the capacities of her ballast tanks, which are fixed after the boat is built, so that when you once finish your submarine you are almost through with her; you can not do very much to her unless you practically rebuild her. Which is the same thing as building a new ship. Consequently, as you develop new things in the submarine business, you are generally estopped from putting them on an old boat. You must take something out of that boat to put something new in.

Senator ODDIE. If any of these devices that we are referring to, the later devices, had been placed in the S-4, do you believe it would have affected her efficiency as an effective fighting war machine?

Mr. SPEAR. I think this, Senator, that since the S-4 accident everybody has concentrated on ways of improving these things. Since the S-4 accident I believe we have developed, or at least are in process of developing-have the fundamental ideas for certain apparatus which, fortunately, can be fitted without encroaching upon military space. This is now in process of development and experimental demonstration.

Had those things, which were not known at the date of the S-4 disaster, been fitted into the S-4, my personal judgment is that all of the men, both forward and aft, could have been saved.

Senator ODDIE. But they were not known at the time of the S-4 disaster?

Mr. SPEAR. They were not known at the time of the S-4 disaster. Senator GERRY. Why were they not known? Was it because they had not been working on them sufficiently?

Mr. SPEAR. Senator, I can not say why they were not previously known. I suppose it needed a disaster of some sort to force us all to concentrate thoroughly on the subject.

Senator GERRY. In other words, they are not naval appliances that were used in other boats?

Mr. SPEAR. Oh, no. They are new things, developed solely for submarines.

Senator GERRY. Since the accident?

Mr. SPEAR. Since the S-4 disaster. No such things exist in any foreign submarines, and no such things exist, except in an elementary stage, in our own submarines. We have the root of the idea now, and to develop it further is the point. I believe myself that we are on the right track, and am convinced that we shall prove that those things can be made practicable and, fortunately, they are of a nature that can be applied to old constructions, because they utilize what is in the boat now.

Senator GERRY. What are those things that you have in mind? Mr. SPEAR. There are two things, Senator. Perhaps I can put it this way: The developments we are now making look toward two things. The first is to give the crew, under damage conditions, more ure control over the ballast and fuel. Those are the weights that you can eject from a submarine to make up for water that comes in. The universal practice all over the world in the past was to concentrate that control in one place, as it was in the S-4, and as it is in all the boats up to date.

The idea now is to provide two emergency controls in addition to the main one, one in the after compartment of the ship, and one in the forward compartment of the ship, and to lead the connections that are necessary between these controls and the air supply and the ballast tanks and the fuel tanks in such a way that there is practically no danger of their being injured in a collision.

In case of a collision, if the central operating compartment is not operable, as it was not in the case of the S-4, except for a few seconds, you then have two other controls, one forward and one aft, one of which, at least, ought to be operable, and by this means you give the crew a much greater chance of being able to raise the boat when

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