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Senator ODDIE. Yes. Will you find that out for us?
Commander HOOVER. Yes.

Senator ODDIE. We want to find out how many the department requested of the Budget, and how many the Budget allowed.

Commander HOOVER. I will see what has been done about that. Senator GERRY. In your opinion, Commander Hoover, was there a sufficient number of pontoons along the Atlantic Coast when the accident took place?

Commander HOOVER. Yes.

Senator GERRY. Might it not have been possible, with the pontoons nearer the accident, that you could have prevented the loss of life?

Commander HOOVER. I believe not. The divers had to make the chains fast to the submarine first. Pontoons were not used for some weeks after the accident.

Senator GERRY. I understand that in this particular case, but what occurs to me is that you are placing your pontoons, or were placing your pontoons at just two ports on the Atlantic Coast, Norfolk and New London.

Commander HOOVER. Yes, sir.

Senator GERRY. If this accident had occurred say off Portland and you had had good weather, there is a possibility had the pontoons been nearer the scene of the accident that human life might have been saved?

Commander HOOVER. There is a possibility; yes. I do not know just how much of a possibility, though.

Senator GERRY. The theory of the Navy is that it takes so long to get the chains under the submarine that inevitably two or three days will elapse before the pontoons are needed; is that it?

Commander HOOVER. I should say at least two or three days, and probably more than that.

Senator GERRY. With the lifting eyes that are proposed to be put on submarines do you think that will shorten the time in which the pontoons could be attached?

Commander HOOVER. I should think so-a great deal.

Senator GERRY. Under those circumstances should not there be more pontoons?

Commander HOOVER. It might be advantageous to have more. Senator GERRY. And yet the department is only asking for one set?

Commander HOOVER. We hope there will only be one accident at a time.

Senator GERRY. Now you are bringing out the point that if two accidents should occur, which might happen, especially in maneuvers, you have not got nearly enough pontoons?

Commander HOOVER. That is a possibility.

Senator GERRY. Mr. Chairman, I suggest that that is a matter for the serious consideration of the committee in its recommendations. Senator ODDIE. Yes; and all the more reason for requesting Commander Hoover to get the data for us that we have asked, the total number that the department recommended to the Budget, and the number the Budget allowed.

Commander HOOVER. I will find out also as much as I can about the reasons for asking for the numbers they did ask for.

Senator ODDIE. Yes. Now you may proceed.

Commander HOOVER. The next question was, "What steps have been taken by the Navy to provide an air lock escape chamber or a diving chamber such as used in certain types of submarines?"

Senator GERRY. Before you go on with that I would like to ask one other question on these pontoons. Is it possible by duplicating the number of your pontoons to raise the ship more quickly, or is it so difficult to attach them that it would be a waste of time rather than a saving?

Commander HOOVER. You mean to put on an excess number of pontoons?

Senator GERRY. Yes.

Commander HOOVER. They would never put on more pontoons than were needed to lift the weight plus the suction on the bottom. Senator GERRY. And that has to be worked out by experiment? Commander HOOVER. By experiment; yes.

Senator GERRY. They can not just arbitrarily put down a large number of pontoons with the idea that it will raise the vessel more quickly? The laying of pontoons to the vessel takes so much time that it is not practicable, is it? It is not good engineering practice? Commander HOOVER. No. They also have to distribute the pontoons along the vessel at certain points so as to take the strain evenly and lift the vessel horizontally. It would be useless to have the vessel come up in a vertical position, which would be the case if too much lift were applied to one end.

Senator GERRY. Was not that your idea had the men still remained alive?

Commander HOOVER. Yes; that would obtain for raising one end. Then they would sink the submarine again and straighten her up in order to salvage her.

Senator GERRY. The saving of life is what we have primarily in mind here.

Commander HOOVER. The saving of lives by means of pontoons I believe is to be done by raising one end and allowing the other end of the boat to rest on the bottom.

Senator ODDIE. In the case of the S-4 was not one of the central compartments full of water?

Commander HOOVER. Yes.

Senator ODDIE. So in case one end had been raised the men in that end might have been saved, but the men in the other end-if they had been alive-could not have been saved?

Commander HOOVER. No; they could not.

Senator ODDIE. Without lowering the first end and lifting the other end.

Commander HOOVER. That is right. I will proceed.

The question was

What steps have been taken by the Navy to provide an air lock escape chamber or a diving chamber such as is used in certain types of submarine?

Admiral BEURET. Mr. Lake built one. One of his earliest experiments in submarine vessels was a vessel with a diving chamber, and recently, in connection with the operations on the S-4, Mr. Lake and Mr. Dannenhauer-Mr. Dannenhauer being a salvage man-called with a proposition to convert a submarine which they have by installing an air lock and diving chamber on the submarine and using it on the S-4. Their proposition did not appeal to either Admiral Hughes or myself. We both went over the plans and discussed them, but in view

of the fact that they were men who had had experience, we suggested that they go and consult with the people that were actually working on the S-4.

The finding there was that the fitting up of such a vessel would take so long that for the S-4, it meant nothing. Actually the proportion of diving days on the S-4 has been quite high, much higher than we expected. It may be that they have had an unusual run of weather, but in considerable measure it is due to the improved equipment on board the Falcon.

As I explained at another place, Mr. Lake's proposition is to sink his submarine near the S-4, for instance, and have the divers in it and work from it as a base instead of the Falcon. This scheme is, I believe, considered to be impractical by the Navy Department. There are a great many features about it which are highly problematical. I think that covers about all of those criticisms on equipment and salvage gear.

Senator ODDIE. Have you something else to put in the record? Have you a letter from Commander Ellsberg?

Commander HOOVER. No, this is an article by a Mr. Hovgaard in which he discusses the S-4 situation and the criticism of the Navy. He has handled it, I think, in a very fair manner.

Senator ODDIE. Who is he?

Commander HOOVER. He is an international authority on marine architecture, and is professor of naval construction and design in the Massachusetts Institute of Technology.

Senator ODDIE. I think that should be put in the record. (Mr. Hovgaard's letter is as follows:)

[Boston Transcript, January, 1928]

EFFICIENCY VERSUS SAFETY-THE SUBMARINE PROBLEM

NEW INVENTIONS MAY HAVE MERIT, BUT DESIGNERS HAVE TO REGARD POSSIBILITY OF MAKING CRAFT IMPOTENT AS A WEAPON

[By WILLIAM HOVGAARD, Professor of Naval Construction and Design, Massachusetts Institute of Technology]

Much has been said and written lately about the safety of submarines. Some people are of the opinion that this matter has been neglected by the constructors, others think that the naval officers of the executive branch of the service are to blame. Others again adopt an easy generalization by blaming the Navy Department. Relatively few writers have discussed the subject in a sound manner based on a knowledge of the facts.

It is unfortunate that a question which in itself is difficult enough for the public to understand, should be obscured by ill-advised and premature criticisms by people who have no knowledge of the underlying technical and military problems and who are thus unable to see this matter in its true perspective.

It must be realized that the submarine is yet a relatively new type of vessel; changing conditions and requirements as well as fresh experiences bring new points of view and the type is still in rapid evolution. Conflicting requirements, such as those to safety and efficiency have to be reconciled and it is difficult at any given stage of the development to strike an accurate balance. A compromise has to be reached, and the solution is different in peace and wartime.

First it should be noted that submarines are inherently less safe than surface vessels. A submarine in the submerged condition has no reserve buoyancy other than that which can be created by blowing the tanks, and is thus dependent on the available store of compressed air. Even in the surface condition the reserve buoyancy is smaller than in most surface vessels. It is clear that the dangers attending a collision are thus enhanced, but several other dangers exist, peculiar to submarines, such as collapse of the hull by excessive water pressure, if a boat descends much below its designed maximum depth.

No one is more fully aware of the dangers to which submarines are exposed than the naval architects who are entrusted with their design and the naval officers who operate them. No one has studied all the possible means of safety

more completely than they. Among the naval constructors of the United States Navy specially occupied with the design and construction of submarines are found eminent experts in this field, whose ability and experience are probably unsurpassed in the world. The same constructors who are responsible for the difficult design of these boats are also in general responsible for their equally difficult construction. When the critical tests of maximum submergence and of submerged maneuvering are carried out with new boats, we find again the same constructors on board the boats, sharing the risks with the operating personnel. In case of accident we even see the naval constructors sharing the dangers of deep sea diving. It may here be stated, that the new large submarines of the V class, the design of which has involved most difficult structural and engineering problems, are equally remarkable for perfection in design and for excellence of construction and workmanship. It is believed that these boats are at least equal in these respects to any submarines in other navies.

SAFETY APPLIANCES DISREGARDED

The naval officers of the executive branch who operate the boats and whose life depends upon their safety are necessarily interested in this quality, but it is natural that these officers, for whom the military qualities of the boats are of primary importance, especially in war time, are generally inclined to discard safety appliances which hamper the efficiency of the boats as warships. Thus it. appears that telephone buoys which were fitted in many submarines before the Great War, were discarded during the war because they might reveal the presence of boats to the enemy under certain circumstances, and it seems that hoisting shackles, which were rarely of use in war and which entailed considerable weight were likewise abandoned, at least in the larger boats. In fact, under the stress of war, attention was naturally fixed on the efficiency of the submarine as a weapon, and the requirements to safety were considered of less importance.

Now, after the disasters of the S-51 and S-4, the question is naturally raised, Are the submarines of the United States Navy safe? Can they be made safer than they are, and if so, why is it not done? These questions are in themselves misleading as they can not be answered unconditionally, and the public is lead to believe that there is something wrong. It is easy to suggest quite simple. and obvious features, which would unquestionably make the submarines safer, and the public wonders why such features have not been adopted. Obviously air locks, such as those used in the early Lake boats, for the escape of the men in diving suits could be provided; large detachable tanks or buoys could be fitted, in which the men could ascend to the surface; detachable lead ballast keels could be used, and, as referred to above, lifting shackles and telephone buoys could be fitted. It would be easy to make other suggestions, but, in fact, all these devices have already been used or designed at various times in various boats. The explanation why they have been ultimately abandoned brings us to the kernel of the matter, which seems to be lost sight of by recent critics and by the public at large.

THE WEIGHT AND SPACE PROBLEM

Every such feature added to a boat means additional weight and an encroachment on the very limited space in a submarine. The designers have to exert all their ingenuity to save weight, and this is expecially true of modern larger boats, where the required maximum depth of immersion is greater than formerly, calling for the utmost refinements in the design and construction of the hull and the greatest economy in weight and construction of the hull and the greatest economy in weight of the various machinery. Only thus is it possible to obtain sufficient weight for securing the required military features, speed, endurance and armament. Any addition to the weight in a given boat for one purpose means a reduction of weight devoted to other purposes. Anyone who has visited a submarine knows that in order to get about in it, he has to wind his way among a bewildering mass of machinery and instruments. Every cubic foot of space is used. Complexity and compactness are the outstanding characteristics of submarines.

By and large an increase in safety means a loss in efficiency. It becomes a question of balancing these qualities against each other, and in a new design a naval constructor is always confronted with this problem. No rule or calculation can guide him in this matter. If safety is carried to excess, the boat becomes impotent as a weapon and had better not be built. Only experience can serve

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as a guide and actually experience has so far governed the practice in this respect. From time to time new safety devices have been introduced and tried out; some of them have come to stay, others have been abandoned because they were found too cumbrous or unreliable, or because they interfered directly and indirectly with the service.

As regards the salvage operations of the S-4, it is now probably clear to the public that nothing could be done before the divers were able to work and that the unfavorable weather conditions which prevailed during the first days of the operations rendered diving most precarious. In spite of the heroic efforts of the divers, it was practically impossible to do any work in this critical period.

When accidents happen, they should of course be studied and analyzed carefully and should, as far as design problems are concerned, be regarded objectively as full-scale experiments. The utmost efforts should be made to determine the deeper causes of any accident, so as to derive the greatest possible amount of information for the benefit of future design and service.

MERIT IN NEW INVENTIONS

Submarines of the United States Navy are as well provided with safety devices as the boats of other navies and have for many years been remarkably free from accidents aue to causes residing in the boats themselves. Yet a com

plete survey of available new inventions may reveal features that can be adopted with advantage. It may be found, also, that devices already tried and discarded, such as hoisting shackles and telephone buoys, may, after all, be adopted and justified, at least for peace service.

But it is probably in the extraneous means of safety and salvage that the outlook is most promising. It seems quite possible to provide warning signals and to give regulation for navigation on the trial course-i. e., the area where tests of submarines take place habitually-so that accidents like that which befell S-4 can be prevented. Perhaps it will be possible by international agreement to require submarines to carry special, easily recognizable headlights, whereby the chances of collisions such as that by which S-51 was lost will be much reduced. Special "salvage docks"-i. e., vessels designed for raising submarines such as used by several foreign navies, may be constructed, and other special salvage appliances for this purpose may be designed and developed. The idea of using other submarines specially equipped for salvage has been suggested by a noted authority on the subject and seems very promising.

It appears, then, that a condemning criticism of the Navy in this connection has no foundation in fact, but that nevertheless a complete survey of the situation may bring out suggestions for improvements and safeguards which, especially in peace time, will reduce the risks of the submarine service.

Senator ODDIE. Have you something else to put in the record? Commander HOOVER. Mr. Griffin questioned the United States naval attachés as to the safety and salvage devices used abroad on foreign submarines. His questions were as follows:

(1) Whether grappling rings, eyelets, or shackles are attached to the hulls of submarines to facilitate their prompt raising.

(2) Whether or not a form of telephone signal buoy is in use, which may be released in case of accident and by which communication may be had with the

crew.

(3) Whether or not salvage air inlets are provided for each compartment of the submarine, or whether there is one salvage inlet communicating to the respective compartments (as seems to have been the condition in the S-4 type of vessel).

(4) Whether or not diving chambers by which the crew can escape are provided. Senator ODDIE. Right in that connection, is not there such an apparatus for escape on our submarines?

Commander HOOVER. We have at least one on every submarine, large or small.

Senator ODDIE. What section of the ship is that in?

Commander HOOVER. It is usually in the conning tower.

Senator ODDIE. Was the compartment immediately below the conning tower flooded in this case?

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