Submarine Boats
By G. W. Hovgaard
[Reviewed by Lieutenant Wm. W. Kimball, U.S. Navy.]
Lieutenant Hovgaard's book is particularly interesting just at present, appearing as it does at a time when the Navy Department advertises for the construction, by contract, of a submarine boat for the U. S. Navy; when the report of the Hon. Secretary accentuates the difficulties in the way of successfully employing unprotected torpedo boats, and when the interest taken in the late exhibitions of Mr. Nordenfelt's boats is an indication that the whole question of submarine navigation is at last to receive a little common sense consideration. It is quite possible that the efforts of the Department to obtain a practical vessel will result only in the bringing out of a partially successful design which, like some of its predecessors, will be subjected to trial, like them will be praised for its faults, condemned for its virtues, and then passed on to the scrap heap; but the probability that some slight advance in the curiously delayed development of the submarine boat will soon be made is quite cheering, and we of the United States, with no coast defense and no immediate prospect of having one, may congratulate ourselves that we are attempting to move in the right direction as we read Mr. Hovgaard's conclusions on page 9 et seq.
"What then will be the result of the extended application of such boats in the above suggested directions?"
"The safety of otherwise defenseless commercial seaports will be immensely increased. Blockades cannot be carried out effectively."
"The value of thick armor, heavy ordnance, and big sized vessels will under certain circumstances be diminished."
"The sea will more than ever form a barrier difficult and dangerous to pass for an army."
"To defend all seaport towns effectively by means of forts and armored vessels is next to an impossibility, but the submarine boat, if properly developed, affords a cheap and powerful weapon against the excesses of modern warfare."
In the chapter on the strategical value of submarine boats the author states his case clearly and well; but, from the fact that the coast conditions of Denmark and England are so different from ours, he has not accentuated a feature that is very valuable on this side of the Atlantic, i.e. the use of submarine boats as outlying pickets which could not be readily driven in, and which would be difficult to discover and impossible to locate after discovery. It is evident that a submarine boat lying at anchor on the surface should be able to make the spars and upper works of an approaching ship before she herself was discovered; and if she then hove down to the covered plane and showed nothing but the tops of her camera lucida tube and chimney, or hove down below the surface altogether, easing up for an occasional look at the enemy, she would not be made out till close aboard, while all the time she would know the movements of the ship and be always ready to slip and strike as conditions should determine.
The part of the book devoted to the history and development of the submarine boat gives us a very good general idea of the subject, but Mr. Hovgaard would doubtless have made a more complete resume of the earlier developments and experiences had he been in possession of the writings of Barber.
The chapter on construction is exceedingly interesting and instructive, and is in itself the best of evidence of the conscientious work done during the author's three years course at Greenwich.
Naturally the type of vessel advocated by Mr. Hovgaard is one adapted for service off the Danish coast and in the neighboring waters—is, in fact, one for a submerging cruiser rather than for a submarine boat; and just as naturally the vessel is devised in accordance with what may be called the European in contradistinction to the American idea, as regards the method of obtaining submersion; in other words, the vessel is devised as a sinking rather than as a diving one.
Why the method of submerging a boat on an even keel is so attractive in Europe one fails to understand, unless there has been an application of experiences gained in the old Plongeur to conditions entirely different from those that applied in her trials. She was designed to, and at first did, maneuver submerged without buoyancy, was constructed with too little regard to longitudinal metacentric height, and was furnished with very inadequate horizontal rudders both as regards surface and mechanism; consequently, the device of hand-worked, vertical-acting propellers, which the boat was not originally intended to carry, was put in play to control the wide oscillations in the vertical plane that were developed in the first trials, by pulling down against buoyancy. But even in the Plongeur experience showed "that it was necessary to improve the (horizontal) rudder mechanism and to increase the area of the rudders, as they were found to afford the best means of keeping a certain depth (while under way)."
In the later American boats it has been shown that there is no difficulty in so arranging the longitudinal metacentric height, the amount of normal buoyancy, and the horizontal rudder area, that dives can readily and safely be made by steering down, and that the boats can be held in any selected horizontal plane and run there by depth gauge by the use of the horizontal rudders alone. This being the case, it is difficult to comprehend why Mr. Hovgaard would, and Mr. Nordenfelt does, abandon the idea of diving, relegate the horizontal rudders to the secondary use of automatically keeping the boat on an even keel, and depend on the down hand propellers for submersion under all conditions; a method of submersion almost as dangerous and impracticable as the one of changing volume by the thrusting out and hauling in of cylinders. In the exhibitions of the Nordenfelt boats great stress is laid upon the fact that they are always buoyant; but the bearing of the statement of this fact is not very apparent when one remembers that this feature has been prominent in submarine boats for at least a century, and that much less buoyancy can be pulled down by small down haul propellers working perpendicularly to the whole horizontal longitudinal section of the boat, than can be pushed down an incline by the main propellers working against a cross section. Of course the same reasoning, proved by practice, applies to the aid given to the normal buoyancy in rising.
In this connection it may be stated that for maneuvering purposes pure and simple, the adjustable float side wheels of Hunter are more attractive than any arrangement of propellers; for the capability they give of applying the whole motive power in any possible direction that may be chosen, and of thus rendering unnecessary all rudders and propellers, horizontal and vertical, is very desirable; but these wheels are not practicable in their present stage of development because they are so very wasteful of power, and because their bulk and position are so objectionable.
The most valuable quality of a sinking boat is that she is not quite so liable to stick her nose in the mud of the bottom when dropping down, as is a diving boat when steering down in a locality in which the depth of water is entirely unknown and happens to be less than that provided for by the automatic depth check; but this possible advantage in the sinking boat is more than counterbalanced by the facts that she is much slower in getting down or up, is more limited in the amount of buoyancy she can carry, is very difficult to keep in the exact trim she requires, and is powerless to apply her main power to clear herself from the bottom when she strikes it.
The mechanical down haul by propellers or other devices is, to be sure, a most important feature, since without it a boat could not stop and hold herself at any required depth, and it will be noticed that such a device is required in the boat outlined by the Department's circular; but it will also be noticed that the circular requires that the horizontal rudders, or their equivalent, shall be used in steering up and down, since the boat "should be able to make very quickly a change of direction of at least 10° in the vertical plane."
If we compare two boats exactly similar in displacement, lines, total power developed, and with buoyancies measured by the power applied through down haul propellers, the one a sinking and the other a diving boat, it will be seen that the former while making a run under the surface must always work her down hauls, must limit her buoyancy to the amount that these can take down with the power that can be spared from propulsion work, and must be very slow in changing depth; while the latter can throw her vertical propellers out of gear and thus utilize all her power for propulsion, can take down all the buoyancy that her speed and horizontal rudder surface can control, can hold down when stopped an amount measured by her total power applied to the down hauls, and can dive and rise quickly; which last would seem to be an important matter in view of the fact that when approaching to the attack in the covered plane, a submarine boat might find it extremely desirable to quickly dive, pass under the enemy's keel, and give him a shot in the bottom, especially if he had nets out.
The boat outlined in the Department's circular could be maneuvered as a sinking, although it would be essentially a diving one.
Mr. Hovgaard's ideas on special fittings and appliances are extremely well thought out, and his remarks on pumping power and on the difficulty in the way of blowing out large bulks of water are particularly valuable.
The method of carrying a boat for saving the crew in case of disaster, as in the old Plongeur, is not particularly interesting to us in America, where, for the present at least, only submarine boats and not the cruisers are under consideration.
The author's reasons for adopting the section he does are sound, but it must be borne in mind that he is considering a sinking vessel, and consequently after insuring trim he can afford to decrease the amount of metacentric height necessary in a diving one, for the sake of getting good stowage room with small draft. For a diving boat the sections, if they be not circles, should of course have their larger dimensions vertical rather than horizontal.
On the question of motive power, which is, after all, the most important one, since if sufficient surface speed and radius of action can be secured in a submarine boat, the other necessary details can be satisfactorily arranged, the author gives us most interesting information. Like Mr. Nordenfelt he advocates a coal-fired steam boiler as the source of power and for surface work, but unlike that gentleman, he chooses to store electricity rather than heat for the submerged runs, and gives data for expected results from storage cells. Since the cells failed so signally in the Peacemaker they have been rather out of favor on this side of the Atlantic, but the difficulties then encountered from leakage, lack of power for weight carried, length of time necessary for charging, etc., etc., would, under the author's showing, be materially lessened in applying the cells to-day. Still, the great objection to Mr. Hovgaard's method of obtaining power, that of using two very different kinds of motors, remains; an objection avoided by Mr. Nordenfelt through the use of stored heat to make steam for under water work, at the expense of applying a cumbersome and extremely slow method of storing power.
In this country the favorite power is steam, derived from a petroleum-fired boiler for surface and covered runs, and from a Honigman soda or other chemical heat producer for submerged work, always applied by the same engines. The attractiveness of liquid fuel is especially accentuated in submarine boats, in which the available stowage spaces are not well adapted for coal bunkers, and in which convenience in firing and in dowsing fires is so important. With the combination of the petroleum-fired and soda-heated boilers, all that is necessary to do when diving is to close the fuel valve, open the exhaust into the soda side of the Honigman, and put down the horizontal helm. The first of the dive would be made on the steam already in the steam space of the main boiler, and when the pressure there was, by the work of the engines, reduced below that on the steam side of the Honigman, the balance valve would open and steam from this soda heater would pass to the main boiler steam space for engine supply; and thus the submerged run could continue, as the soda made steam, till the saturation point was reached. At the end of a dive, long or short, the fire would be lighted under the main boiler, and as the pressure in this ran up, the Honigman would be shut off and the exhaust turned overboard, while the surplus moisture in the soda would at once begin to be driven off by heat derived from the main boiler fires.
After this method of applying steam, the petroleum engine is a close second in favor, and is very promising as lately improved by Holland in developing good power up to a certain limit, in its feature of requiring no boiler or any fire outside the cylinders, in the fact that the compressed air stores for feeding the engine when submerged can always be drawn on for ventilation, and for the reason that these stores can be so readily renewed after making a submerged run. The space occupied by the compressed air for a petroleum engine is perhaps larger, for equal power developed, than that used by a soda boiler; but on the other hand it can be distributed about the boat in pipes in such a way as to occupy comparatively little of the space available for crew and armament. The prime objection to petroleum engines is that, so far as developed, they cannot give economical results in boats of more than thirty or forty tons displacement.
The following figures, from a design now under consideration by American builders, for a petroleum motor submarine boat intended for hoisting inboard, like a third-class torpedo boat, illustrate the attractiveness of the type: Length, 40 feet; diameter, 5 feet; shape, spindle of revolution; displacement, 15 ½ tons; weight without water ballast, 12 ½ tons; maximum surface speed, 14 1/3 knots; maximum submerged speed, 18 knots; fuel endurance at 8 knots surface, 27 to 33 hours; total submerged run, a 4 ¼ hours, of which ¼ hour at 18 knots and 4 hours at 12 knots; crew, 2 men; armament, one 8" torpedo gun, four 100 lb. G.C. torpedoes; range through water, 150 yards; range through air, ½ mile.
Of some six or eight other proposed boats, the greater number lack speed, not because it cannot be easily gotten, but because builders are cautious about guaranteeing it.
From a point of view determined by what has lately been done, the prospect of obtaining a serviceable boat is not very good. In the United States the Holland boats have lacked speed endurance and carrying capacity, and the Peacemaker is altogether inadequate, being interesting only as an illustration of the use of a simple soda boiler. In Europe the Goubet boats lack power in all directions, and the Nordenfelts are apparently failures in all respects save surface speed and fuel endurance, as their trials show nothing of practical use.
In an exhibition of one of these boats given last month the main features accentuated by the exhibitors were that the boat awash was more difficult to make out than another boat of greater freeboard—a fact that would seem to need no very extensive proof—and that she was always buoyant, a property that, as has been shown, is common to all submarine boats worthy of the name, and which she possesses in a much less degree than she might were she constructed on common sense principles for real submerged work, for which she showed less capacity than the small American boats. The showing of submerging qualities consisted in hauling the boat down to the bottom of a dock by means of her down haul propellers, and then allowing her to rise by her own small buoyancy, thus exhibiting the application of a general principle that could have been just as well shown, and with just as much bearing on real submarine boat work, by pushing a cork under the surface of the water and then allowing it to bob up.
On the other hand, in looking over the field of possibilities for the immediate future it is apparent that there are plenty of practical devices extant to make a submarine boat successful, plenty of experience to apply them, and plenty of money to pay the expenses of construction; and therefore it only remains to be seen whether or not the owners of the devices, experience, and money will have the wisdom to comprehend that in combining to give the Navy Department the boat it requires they will be working to their own advantage as well to that of the Government.
Even if the Department fail in its first attempt to obtain a practical construction of the kind, the submarine boat, as such, must soon appear as a factor in naval warfare—for just as rapidity and range of aimed fire have forced the use of earth cover ashore, so will the same causes force the use of water cover afloat—and unless "we, the people of the United States," choose to continue to be as stupid as we have been for the last score of years concerning everything that floats, we are in our own interests bound to lead in its development. When it comes it will not, like every new warlike device conceived in the brain of a cranky inventor, "entirely revolutionize warfare," but it will assume the well defined place and duties awaiting it—place and duties that will urgently require to be filled and done if there is to be even a faint attempt at placing this country in a condition of partial defense.
Submarine Torpedo Boat for the United States Navy
[Reprint of circular showing the general requirements desired to be fulfilled in the design and trial of a steel submarine torpedo boat for the United States Navy.]
Navy Department,
Washington, D. C, November 26, 1887.
Under authority conferred by the act of Congress, entitled "An Act making appropriations for the Naval Service for the fiscal year ending June 30, 1888, and for other purposes," approved March 3, 1887, to which reference is made as a part of this advertisement, sealed proposals are hereby invited and will be received at this Department until 12 o'clock noon, on the first day of March, 188S, for the construction, by contract, of one submarine torpedo boat, complete, with torpedo appendages—such vessel to be of the best and most modern design; to be constructed of steel, of domestic manufacture, having a tensile strength of not less than 60,000 pounds per square inch and an elongation in eight inches of not less than 25 per cent, and to have the highest attainable speed.
For information as to the conditions desired by the Department, reference is made to the "circular showing the general requirements desired to be fulfilled in the design and performance of a steel submarine torpedo boat," approved by the Secretary of the Navy, copies of which can be obtained on application to the Bureau of Ordnance, Navy Department.
Each proposal must be accompanied by drawings and specifications of the vessel which the bidder proposes to build. The drawings must be drawn correctly to a convenient scale, and must show clearly all the essential requisites of the vessel. The space and weight allowed for torpedoes and their appendages must also be shown in the design, and the fittings for the same are to be furnished or installed by the contractor.
A statement, in detail, of the weights in the vessel and their distribution, and full particulars and explanation concerning the kind, power, and economy of the engines, power generators, and propelling devices, and all other mechanism, must accompany the proposal.
In order that the Department may be prepared to act intelligently in making a selection, it must be clearly shown by the drawings, specifications, and statement or statements accompanying the proposal, that the displacement and stability are sufficient, and that the balance of qualities is such that everything will be carried properly and safely; and such additional information must be included as may be necessary to enable the Department to readily determine the character of the proposed vessel and the correctness of the calculations upon which the design is based.
The contractor must furnish, at his own expense, all working drawings necessary to the complete construction of the vessel, and the expense of all trials, before final acceptance of the vessel under the contract, must also be borne by the contractor.
Proposals must be made in accordance with forms which will be furnished on application to the Bureau of Ordnance, and must state the time within which the bidder will complete, for delivery, the vessel which he proposes to construct.
Each proposal must be accompanied by a certified check, payable to the order of the Secretary of the Navy, for an amount equal to five per cent of the bid. The check received from the successful bidder will be returned to him on his entering into a formal contract for the due performance of the work and giving bond for the same, with security to the satisfaction of the Secretary of the Navy, in a penal sum equal to sixty per cent of the amount of his bid; but in case he shall fail to enter into such contract and to give such bond within thirty days after notice of the acceptance of his proposal, the check accompanying such proposal shall become the property of the United States.
All checks accompanying proposals which are not accepted will be returned immediately after the award shall have been made.
Payments under the contract will be made in five equal installments, as the work progresses, upon bills duly certified. The last payment will be made upon the acceptance of the boat after trial. Twenty-five per cent of each installment will be reserved until the final acceptance of the boat by the Department.
Proposals must be made in duplicate, enclosed in envelopes marked "Proposals for a submarine torpedo boat," and addressed to the Secretary of the Navy, Navy Department, Washington, D. C.
The Secretary of the Navy reserves the right to reject any or all bids, as, in his judgment, the interests of the Government may require.
(Signed) William C. Whitney,
Secretary of the Navy.
GENERAL REQUIREMENTS.
The design for a submarine or diving boat, to be acceptable to the Department, should show the manner in which it is proposed the vessel shall be maneuvered under all conditions, but more especially how she is to be brought into action from a distance.
The most desirable qualities to be possessed by such a vessel while approaching a hostile ship under way, are speed, certainty of direction, invisibility, and safety from the enemy's fire; the design and description should plainly show the amount of each of these qualities that the boat would possess, and the advantage that results from diminishing any one for the purpose of increasing any other.
The Department has no knowledge of any method by which certainty of approach to an object constantly moving and constantly changing its direction of motion can be secured, unless the object is kept constantly in view or lost sight of for brief intervals only; consequently, if no novel method for insuring certainty of approach (when submerged) be devised, a design, showing, at the expense of invisibility, great speed for use outside the range of effective hostile fire would be desirable; providing always that submergence to a safety depth can be quickly secured, and certainty of approach still be retained when coming within the danger zone. Within the danger zone a part of the speed of approach may be given up for the sake of obtaining water cover, provided certainty of approach can be still maintained until the object of attack is so near that this certainty is virtually secure even when the boat is deeply submerged for the purpose of obtaining total invisibility or for delivering the attack at a vulnerable point.
The following definitions are adopted for convenience in describing the conditions under which submarine boats generally move:
"Surface"—i. e. with freeboard or awash.
"Covered''—i. e, protected by at least three feet of water over the highest point of the shell, not necessarily cut off from connection with the atmosphere, and furnishing a view of the object of attack through air.
"Submerged''—i. e. at any safe depth, cut off from communication with the atmosphere, and affording no view of the object of attack other than one through water.
Any boat not designed for running "submerged" cannot be considered submarine; and she should be able to run in at least one of the other ways mentioned in order to be satisfactorily effective.
The features essential to the usefulness of a submarine boat designed for offensive warlike purposes are in general terms held to be:
Great safety, facility and certainty of action when "submerged," fair speed when "covered," good speed when running on the "surface," a fair endurance of power and stores, great ease of maneuvering under all conditions, sufficient stability, great structural strength, and fair power of offense.
The Department would particularize as to these qualities about as follows:
I. Speed.—The boat should be capable of making at least fifteen knots per hour when running on the "surface," and at least twelve knots per hour when running "covered." When running "submerged" she should have a mean speed of at least eight knots per hour.
II. Power endurance.—She should be able to run for about thirty hours at full power, on the surface or "covered," while at the same time she should maintain at its greatest efficiency the power that is to be used for "submerged" running. When "submerged" she should be capable of running at least two hours at 8 knots mean speed. If intended for "covered" and "submerged" work only (without using air draught), she should be capable of running in that condition about thirty hours at full power.
She should carry about ninety hours provisions and water for the crew.
III. Ease of maneuvering—When running on the surface, "covered" or "submerged," the boat should be able, when working at full power, to turn in a circle of a diameter not greater than four times her length, and this without reversing her engines.
If designed to run part of the time on the surface, she should be able to pass from the surface to the covered plane in 30 seconds.
When below the surface, she should be able to make very quickly a minimum change of 10 degrees in direction in the vertical plane.
The conditions necessary for furnishing power for "submerged" runs must at all times during the working endurance be maintained at their maximum efficiency and ready for instant use until the first "submerged" run is commenced. After the boat has again made communication with the air, the time of renewing that part of the power that was used while "submerged," or re-arranging the conditions for submerged running, which were altered during submergence, should not be longer than twice the period of the submerged run.
While lying still the boat must be able to maintain any desired depth within the limits of safety from crushing pressure upon the shell. It is not considered that this requirement can be fulfilled simply by varying the specific gravity of the boat.
IV. Stability.—This quality must be possessed in good measure when the boat is on the "surface"; and when "covered" or "submerged" the stability must in great part depend upon "normal buoyancy"—i. e., a certain amount of buoyancy normally remaining in the boat and never given up, unless it should be necessary to sacrifice buoyancy in order to sink from under an obstruction or to lie upon the bottom for the purpose of conserving power.
The amount of this normal buoyancy and consequent stability must be sufficient to allow the necessary movement of the crew in working the machinery and torpedo appliances while the boat is "submerged" and lying still, but not on the bottom ; and it is thought this amount of buoyancy will be more than sufficient for the purpose of successful and convenient navigation when the boat is "submerged" and moving at moderate speeds.
V. Structural strength.—The shell should be sufficiently strong to withstand an exterior water pressure due to a submergence of at least 150 feet.
VI. Power of offense.—Against any part of the bottom of a ship running at speed the boat must be able to deliver, with reasonable certainty, torpedoes carrying charges equal in minimum effect to 100 pounds of gun-cotton. The mode in which this requirement is to be met is left entirely to the designer; but it is to be remarked that the method which gives the greatest under-water range, with accuracy, will be preferred. Rapidity of rate of delivery, extension of angle through which torpedoes can be delivered, number of torpedoes that can be carried, and effective over-water delivery, are all important factors for determining the power of offense.
Besides the foregoing principal requirements, the boat must be provided with means for the attainment of the following objects: Enabling the commander to see the object of attack when running "covered," and an all-around view should also be provided, if practicable; compensating or otherwise insuring the accuracy of the compass, when "submerged," and under all conditions; purifying the air for the crew so as to allow at least 12 hours submersion; keeping the temperature within the boat down to 100 degrees Fahr.; getting away from obstructions—above, below, or lateral; pulling out of mud; automatically preventing a dive below a predetermined depth; preventing the fouling by lines or other obstructions of any working parts exterior to the shell proper; lighting the interior, and for the escape of the crew in case of disaster.
These qualities are expected by the Department both because, in its opinion, they are necessary, and because they have already been attained with more or less success in submarine structures now extant. But as the bids are to be made upon the basis of guaranteed results, bidders are at liberty, in their proposals, to modify or omit, as they may think proper, any of the qualities mentioned herein, always excepting qualities of workmanship and material used in the construction of the hull, engines, power generators, and other mechanism.
Any valuable qualities not enumerated by the Department (which limits itself to pointing out those that appear to be the most useful) will be fully considered and given due weight in deciding upon the design to be adopted.
As the Department does not define the means by which results are to be attained, it will accept no responsibility as to the efficiency of the methods proposed to be used.
Designs must be accompanied by written explanations fully setting forth the operation of the boat and appendages, and stating all the advantages of the proposed vessel.
The bidder to whom the award is made will furnish detailed drawings and specifications of his boat, and the contract will be based on these. They must not differ in any important way from the general design and explanation submitted with the proposal.
QUALITY AND WORKMANSHIP.
All material is to be of the best quality, of domestic manufacture, and subject to the tests and inspection laid down in the appended instructions concerning tests to be applied to steel for use in the construction of the hull and machinery of a torpedo boat, approved by the Secretary of the Navy, July 15, 1887.
The workmanship shall be of the highest class, and subject to the inspection of officers designated for the duty. Such inspectors shall have free access to the works of the builders at all times, for the purpose of witnessing and examining the progress of the vessel and machinery, and they are to be afforded every facility and assistance for inspecting and for ascertaining that the work is done in accordance with the terms of the contract.
GENERAL REMARKS.
Conditions will be inserted in the contract requiring, upon the completion of the boat, trial sufficient to test her efficient operation, and to insure that the contract has been properly performed, and that the guarantees assumed by the contractor have been complied with.
A boat rejected under the contract may have exhibited certain important qualities in a much greater degree than was contemplated by the contract, or she may embody devices and improvements novel and very valuable but not called for by the contract.
In such a case the Department might possibly be disposed to purchase the boat, but such a course will not be pursued unless the advantages to the Department are of the most obvious character.
The Department limits the maximum displacement to two hundred (200) tons when the vessel is "submerged," and it puts the displacement at so large a figure in order that designers may not be hampered in attaining good speeds by lack of space for motors; but it is thought that designs showing about ninety (90) tons displacement will give the best results. No bidder is limited to the submission of a single design, but each is invited to submit as many as he may see fit. Independent drawings and explanations, and a separate proposal for building the vessel shown, must accompany each design.
The foregoing statement of "general requirements" is intended only as suggestive, and as embodying for the benefit of bidders the views of the Department as to what ought to be accomplished by any person assuming to offer a plan for an effective submarine torpedo boat; but the Department is of the opinion that results already attained justify the purchase of a submarine boat though the exact requirements of the circular may not be guaranteed. Bidders are therefore invited to submit their designs even though these may show qualities less desirable or less difficult to attain than those hereinbefore described: they should be careful to state what matters are guaranteed.
All bids will be considered without regard to the residence of the bidder, but the boat must be of domestic manufacture.
No bid will be accepted that does not offer guarantees of results approximating to those stated in this circular, nor unless accompanied by plans justifying, in the opinion of the Department, a reasonable expectation that results guaranteed will be attained.
All other bids will be rejected. (Signed) William C. Whitney,
Secretary of the Navy.
Steering Apparatus
Patented by Lieut. R. M. G. Brown, U. S. N.,
March 11, 1884.
The essential feature of this invention is the combination of the ordinary steering gear with the throttle of a steam pump and the sluice or gate of its discharge pipe, in such a manner that when steering with small helm neither of these is opened and the hydraulic power is not brought into play, but when the helm is put hard over, or nearly so, the hydraulic sluice (a two-way cock) is opened so as to throw the stream of water in the proper direction to reinforce the rudder, and at the same time the throttle of the steam pump is opened.
As described in the specifications of the Letters Patent (No. 295,106), a crank-arm, e, secured to the rudder spindle, is connected by a rod h to a crank-handle f operating the two-way cock in the hydraulic pipe, which is branched at the seat of the cock, one branch leading to the starboard side and the other to the port side of the vessel. This crank-handle is connected by another rod i to a crank-handle g operating the throttle valve of the steam pipe.
When the tiller is put to starboard, for instance, the end of the crank-arm e moves aft, and with it the connecting rods h and i and the crank-handles f and g. The throttle valve, however, is so constructed that no steam enters the pump engine until the tiller is put hard over, or nearly so, and therefore, as there is no flow of water, it is indifferent whether or not the sluice gate is opened. But when the tiller is put well over, the throttle opens, the flow of water commences, and the sluice having been so turned (in this supposed case) that the discharge is through the opening in the port side, the hydraulic force so created reinforces the effort of the rudder to turn the vessel's head to port. If the tiller is put to port a similar action takes place, but in the opposite direction.
The inventor distinctly states that he does not claim as novel either of the elements of the steering apparatus separately, but he does claim the combination of them all when arranged to co-operate in the manner briefly described above. S. W. V.
Jan. 17, 1888.