Length, overall, 63 feet 4 inches.

Diameter (beam), drame No. 21, 11 feet 9 inches.

Height, bottom to superstructure deck, 12 feet 1 inches.

Displacement, submerged, 120 tons (salt water).


All transverse sections circular. Plating to be of steel laid in ten strakes.  Thickness to be 7/20" forward, 8/20" amidship, 7/20" aft.

SEAMS: Longitudinal seams, double staggered riveted lap joints, steel rivets.

Butt joints planed, with double riveted steel straps, 17- lbs. per square foot, steel rivets.

Circumferential seams, plating to frames, single riveted, liners under outside strakes.

FRAMES: 3 " x 3" x 7.8 lbs. steel angles, from frames 8 to 31 inclusive, other frames 3 " x 3" x 6.6 lbs., steel angles.  Spacing 18 in.

Stapling, 2 " x 2 " x 5.9 lbs. steel angles

BULKHEADS: Steel plate, 17 lbs. per square foot, forward and aft.  All sufficiently braced for the purposes of the ship.

DECK BEAMS: 3" x 3" x 6.4 lbs. steel angles for machinery space; 2 " x 2 " x 5.9 lbs. under expulsion tube.

DECK PLATES: Of steel, 17 lbs. per square foot for machinery spaces. 15 lbs. per square foot for forward deck, under expulsion tube.

FLOORS: With reverse framing at each frame in machinery and battery spaces and installed two frame spaces apart under expulsion tube.

TANKS: Of steel plate to be placed under decks and at sides of ship. System comprises forward and after trimming tanks, main ballast tanks, separated by a longitudinal bulkhead ; auxiliary ballast tanks,etc., and gasoline tanks for storage of gasoline for main engine.  Storage battery to be installed in water tight steel tank.

MANHOLES: To be provided to allow access to all tanks.

SUPERSTRUCTURE: Of steel plate, 10 lbs. per square foot with frames of 2 " x 2 " x 5.9 lbs., steel angles, spaced 54" apart.  A clear deck space to be provided 31 feet 6 inches in length, greatest width 4 feet 5 inches, with ample cleats for mooring ship.  Superstructure to have locker for anchor and chain.  Scuppers to be provided of sufficient area to allow superstructure to fill quickly.

RUDDERS: Two set to be provided, one pair in a vertical plane, for horizontal steering; one pair in a horizontal plane for diving and rising.  All constructed of steel, 10 lbs. per square foot, of doubled plates, braced by arms from the rudder posts.

SKEGS: Four in number, to be of steel plate, combined to provide ample stiffness to carry the rudders and their posts.  Skegs to be securely anchored to hull of ship, and braced and tied horizontally and vertically, to form one complete structure.

An additional brace and spreading member to be provided, consisting of a steel ring, which is also to serve as a shield for the propeller.

CONNING TOWER: To be of armor steel, circular, 4 inches in thickness, with a clear opening in top, 21 inches in diameter, closed by a hinged cover of steel, and made water-tight against a rubber gasket, by a toggle locking device.

Ports or peepholes to be provided, arranged to allow observation in all directions.  Ports to be covered by plate glass, with means of closing port in event of breakage of glass, thereby preventing flow of water into the boat, if submerged.

To be securely fastened to the hull, giving a resistance to impact of projectiles equal to the full value of the armor.

FORWARD END: To be provided with two bulkheads, these combined with the structural strength due to the form of the hull, to give sufficient margin of safety in event of a collision.

HATCHES: To be provided of ample size for torpedoes and machinery parts.

IN GENERAL: Hull to present no projecting parts for entanglement with ropes, etc., while submerged.


MAIN ENGINE: To be of Otto, gasoline type, with four cylinders, each single acting, balanced to pre- vent excessive vibration.

Horse-power to be 160, at 340 revolutions per minute, consuming about one pint of gasoline per horse power per hour.

Gasoline tank to have capacity of 6,850 gallons.

Speed of ship, with main engine at full power to be 8 knots per hour.

MAIN MOTOR: To be electric, waterproof type, of 70 horse-power (nominal) giving the ship a speed of 7 knots per hour, when awash or submerged.  Speed of motor 800 revolutions per minute.

GEARING: To be provided to allow, through clutches, the following combinations : main engine to pro- peller, main engine to motor (in this case to be driven as dynamo, to charge storage battery), motor to propeller, motor to engine for starting engine.

PROPELLER: To be left handed, and driven by steel shaft, 4 inches. Diameter, through gearing before mentioned.  A suitable clutch to be installed to disengage propeller shaft during the charging of the battery.

BEARINGS: Stern and thrust bearings to be constructed according to the best practice.  Inboard shaft bearings of sufficient length for continous running.

High speed bearings to be self-oiling.

ELECTRIC STORAGE BATTERY: To comprise 60 cells of "chloride" type, to have a capacity of 1840 ampere hours under normal rate of discharge, and a capacity to furnish 75 horse-power for three hours at 120 volts.

Battery to be arranged to receive charge from main dynamo (motor) in the ship, or from supply outside and independent of the ship. Battery to be positively insulated from the hull or parts thereof.


To be installed together with all safety appliances for the safe and efficient distribution of electric current throughout the ship. Motors to have proper rheostats located in the best positions for manipulation.


Of 10 horse-power to be provided for operating bilge pump.


To be installed with a view to safety and to minimize magnetic effect on the compass. In no case is the hull used as a return on a circuit.


To be arranged to distribute light to all portions of the interior of the ship. Portable incandescent electric lamps to be located at necessary points.


To consist of a series of tanks filled through outboard connection, as follows : For longitudinal trim, one tank located at each extreme position forward and aft, these to be combined, and with the addition of other means, to make trimming or ballasting automatic.


To be provided for all weights expended or received, keeping trims of the ship constant.


To be provided, one Air Compressor, driven through gearing, by main engine or main motor. To furnish air at 2000 lbs. per square inch, to welded steel storage tanks with a total capacity of 69 cubic feet.  Supply at lower pressures to be obtained from 2000 lb. Tanks, through reducing valves, operating automatically.

At 50 lbs pressure to be used for expulsion of torpedoes, operating machinery and manipulating trimming system.

At 10 lbs. pressure to empty ballast tanks, etc.


Two rotary pumps to be installed, one to be driven by auxiliary electric motor of 10 horse power.  One to be driven through gearing by main motor, or main engine, as desired.

One small hand-pump to be provided to empty the storage battery tank drip reservoir.

One duplex reciprocating pump to operate diving and steering engines.


To be of suitable strength for the pressures used in the various systems, arranged to allow of connections from either of the rotary pumps to each and every tank located in the ship.


Engines to be provided with reciprocating pistons attached directly to the leads.  Cylinders of sufficient diameter to provide quick movement to the rudders to extreme angles of movement.

Pistons to be locked through the operations of the controlling valve in all desired positions.

Through a series of connections, steering and diving engines to be under control of the navigator in the conning tower.

Hand operation of either engine to be secured through a by-pass valve.

Diving engine to be provided with automatic devices to maintain the ship in a horizontal position, to secure a constant depth during submergence ; to reverse the diving rudders to a rising position at a depth less than the desired depth, thereby bringing the ship from an inclined or diving position to one horizontal, at the depth desired, at which time the ship is to be placed under the control of the automatic devices for maintaining the desired depth and a horizontal position, until such a time as the navigator desires to rise, or dive to a greater depth.


To be of suitable strength for the pressures used in the various systems of the ship; these to consist of depth, ballast, oil, and air-pressure gauges, and all necessary appliances for determining the trim of the ship.


To be provided through exhaust of air-driven machinery, distributed throughout the interior of the ship ; by providing means of allowing flow of air from the low-pressure storage tanks.

Ventilators, with electrically driven fans, to be installed over engine and at other suitable points to allow of complete ventilation of the ship when on the surface.

Openings, consisting of hatches, conning tower opening and necessary ports in hull, to be located for inflow of outside air.

Excessive air pressure in the interior of the ship to be releived through safety valves for that purpose.

Exhaust gases from the main engine to be led directly from the ship through water jacketed piping, then carried aft under superstructure to the stern.


To be supplied, ample bell-pulls, speaking tubes, etc, for communication from the navigator to various points in the ship.  Whistle and side lights to be located on the exterior.

Compasses to be furnished in duplicate, one located outside of the hull, with means of observa- tion from the interior of the conning tower.  One to be located in the interior of the conning tower. Both to be visible at all times, to the navigator.


To consist of one Torpedo Expulsion Tube, to be constructed after the plans of the Bureau of ordnance.  To be placed at the extreme forward end of the ship, opening outward two feet below the light water line.

Cap to be hinged, lifting upwards and operated by an air cylinder, or by hand, at will from the interior of the ship.  To make a water-tight joint when closed, against a rubber gasket, and locked securely by powerful toggle lock.

Interlocking apparatus to be provided to prevent attempted expulsion of torpedo if outboard cap be closed, or in event of accident at the moment of expulsion.  Interlock to prevent opening of the breech at times when the expulsion tube is opened to the sea.

Air at a pressure of 50 lbs per square inch, to be used for expulsion of torpedoes.

Ship to have capacity for carrying, storing and discharging five 45 c.m.. x 11 8" Whitehead torpedoes and means of compensating for each and every one.


Changes in the plans submitted for armament, to be possible. Either one or two expulsion tubes can be installed, provided they be in a vertical plane.

Type of expulsion tube may be recommended by the purchasers.

November 24, 1899