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The Submarine Propeller “Alligator”
The Name:
The contract to build a submarine for the United States Navy called the device to be constructed the “Submarine Propeller”
The
submarine built in
Submarine Propeller
Propeller
Submarine Boat
Submarine Steamer Alligator
Submarine Boat Alligator
Alligator
And a few other combinations of these names.
Until its arrival in the
Normally a ship's name is selected while it is being
built, then when launched it is christened and formally given that name. As the ship is accepted into the United
States Navy, it is "commissioned".
At that time an officer takes command and becomes the
"Captain" of the ship and the prefix "USS" is attached to
the ships name. The USS stands for
United States Ship, meaning it is, through Congress and the Navy, the property
of the
However, the formal use of the USS prefix as a standard
manner to mean only ships in commission in the Navy is a relatively recent
thing and did not apply during the Civil War as it does now. Before the issuance of Executive Order 549 of
8 January 1907 a ship's name could be prefixed by (in a loose manner) by the
type of ship it was or by its status.
For example, the USS Minnesota (of Civil War fame) was variously called
the Steam Frigate
After 8 January 1907 the use of USS meant the ship was formally 'in commission'. It wasn't until 1948 that the Navy formalized the precise status each ship and boat in the Navy had. Article 2001 (Navy Regulations 1948) further stated that only those ships which were on "Active status" and 'In commission' could carry the prefix USS.
To call the Submarine Propeller the USS Alligator by
today's standards is not precisely correct.
But to call her that realizing the ship designations that were in use
during her lifetime is a debatable point. It, to some, might infer the ship was
in commission which is incorrect. To
others it infers an honored status the boat holds in Naval Submarine Force
history.
The Process of Arriving At the Present
Understanding of what the “Allgator” Looks Like
The following is the best estimation of a series of folks looking at and trying to understand the drawings of Brutus DeVilleroi, the written descriptions of the ship few of which agree. The understanding we have of what was actually built from the design ideas of the inventor was reached by an exercise wherein several people looked at the design concepts from the standpoint of a builder. The group consisted of two submarine model craftsmen and two naval historians who are also illustrators and artists. Two of our group are experienced submarinists who qualified on several submarines both conventionally and nuclear powered.
We each looked at the drawings provided by NOAA. The drawings consisted of five views of the design concepts of Brutus DeVilleroi submitted by him to the French Navy. A note with these drawings indicated that the drawings reflected accurately the concept drawings submitted to the US Navy in 1861. It was obvious that these drawings were not construction drawings as we know drawings now. No metal fastening details were shown. No hull penetration stuffing tube details were shown. It was the task of the group to interpret these drawing into what we felt were accurate details of the external and internal details of what was actually built. We would ‘filter’ these drawings in the same way a builder and iron worker would if he were given the job of constructing the ship.
We used what resources we had available in texts and knowledge of submarine construction and operation techniques. We also used the knowledge gained from the excavation and study of CSS H.L. Hunley. The group assumed that the construction of Alligator followed the general form in these texts, general submarine operation requirements and those construction techniques found in contemporary objects such as ships, locomotives and the Hunley.
The group fully realizes that our interpretations might be in error. Others might have valid opinions which differ from ours. The resolution of these differing opinions will require the ‘ground truth’ of locating and studying the actual vessel.
Documentary evidence:
In addition to the drawings of DeVilleroi’s design, the following descriptions exist in documentary form.
From Hoff report of 7 July 1861
De Villeroi's salvage submarine. [the forerunner to the alligator]
"iron cylinder, cone shaped at the two extremities, about thirty three feed in length, by four feet at its greatest diameter. It is propelled by means of a screw in the stern with two trunions, one on either side resembling some what a whale in the external form and appearance. Light is communicated to the interior by means of glass bulls eyes on the back, thirty six in number. An ellipsoidal section eight inches in height, opening and closing at will, affords entrance and exit to a crew of from six to twelve men, according to the speed required. A corresponding section at the bottom of the boat admits the egress of the divers who breathing by means of tubes attached to the boat are enable to perform the submarine operations."
From clipping accompanying letter from De Villeroi to President Lincoln
"[illegible??]
ordinary exhibitions it has ever been [illegible??]
This is the testing of a submarine salvage boat invented by
a French gentleman named Villeroi, in the presence of a number of
This
submarine salvage boat was invented as early as 1831 by M. de Villeroi, and the
first experiment was made by him on 12th August 1832 in the presence of a
committee appointed by the Minister of Marine of France among which committee
the well known names of Dupin, sen [senior], Dupin, jun
[junior], Odilion Barrot, Alex. De Laborde, Barth Merillon, &c. are
found. The said committee was presided
over by the Mayor of Noirmoutier, and the experiment took place in the
The report of the committee says: " There we saw M. de Villerio enter into a boat made of iron, having the shape and appearance of a fish, ten feet long, three feet wide, which boat was manned by three men, the inventor included, but on account of sickness of one man only went down with the inventor, M. de Villeroi, who began operations at 3 P.M. After several evolutions on the surface of the water during fifteen minutes, he began to navigate about, one foot beneath the surface of the water, till thirty-five minutes past three; then descended near the bottom of the water, but in a different direction, in order to deceive the boats which were following him on the surface of the water, where, after ten minutes of different evolutions in various directions, he came up on the surface and opened his safety door. At fifty-five minutes he made his appearance out of his boat, cheered by all present having remained with his companion inside of that boat fifty-five minutes with out any communication with the exterior atmosphere, and maneuveriong his boat with greatest facility."
"The committee is of opinion that this invention can be of great advangage to the marine commerce and sciences, and that it would be desirable that the government should accept it with the eagerness and protection whis it deserves."
The French
government wished to obtain from the inventor all the designs and specification
relative to his boat without first entering into some arrangment with the
inventor, consequently the inventor M. de Villeroi refused complying with the
request and continued making some improvements and in 1835 and 1836, he made a
fiew more public demonstraions, one which is recorded in the journal called La
Reformateur, and gives a full account of one experiment at which the editor
assisted. At the same period M. de
Villeroi exchanged with the Minister of the French Marine several letters
relative to the acquisition of his submarine boat, but as the same previous
conditions were again offered, De Villeroi again declined to accept, and
continued to improve the apparatus. When
the war of the
Having seen
the plans and models of the invention, the gentlemen here who have taken the
matter in hand felt the utmost confidence in it; but in order to satisfy all,
the test was had in the
From Contract for Submarine Propeller 1 November 1861
This agreement, made and entered into
this first day of November, A.D. one thousand eight hundred and sixty one,
between Martin Thomas of one part and the
First: The party of the first part will construct and deliver to the party of the second part within forty (40) days from the date of this agreement, an Iron Submarine Propeller of the plan of M. de Villeroi, at least fifty six inches (56") in width and sixty six (66") inches in height and forty five feet in length, for the sum of fourteen thousand dollars to be paid when completed and delivered, ready for use within ten days after delivery and certificate is in all respects ready for service.
Second: The government of the United States will employ M. de Villeroi to superintend the construction of said propeller, as well as in its employment for actual service when required, and agrees to pay him for his full services at the rate of two thousand dollars per annum whilst thus employed, his pay to commence with the date of this agreement: also to pay reasonable wages to the crew of said propeller, and to transport it from Philadelphia to the place or places where the Secretary of the Navy direct it to be used.
Third: In case the said de Villeroi shall perform valuable services with said propeller for the United
States by the destruction of an
enemy's ship or vessel by direction of the Secretary of the Navy and to his
satisfaction, then the government of the
Fourth: The secret of said invention shall be divulged by the inventor, M. de Villeroi, under his solemn oath or affirmation in a written paper subscribed by him to be sealed and deposited with the Chief of Bureau of Yards and Docks, with the certificate thereon of Mr. W.L. Hirst that he has carefully examined the paper and firmly believes it to be of the secret of said invention, not to be opened until after the payment of said eighty six thousand dollars, or the death, disability or dereliction of duty of the inventor shall occur.
Fifth: The said invention shall not be used by or the secret divulged to any government, power or individual without the consent in writing of both parties to this agreement.
In
the presence of
/s/ Martin Thomas
/s/ Gideon Welles
Letter from William L. Hirst to Commodore Joseph Smith (BuYards and Docks) May 1 1861 on the launch of Alligator
"The boat proved remarkably buoyant, and requires four or six tons of lead for ballast: The Propelling fins were found to work with ease and the only fear mr Thomas entertained was on that oint and it is now removed. "
Philadelphia Newspaper coverage of launch 1 May 1961
"The propeller is built of boiler iron and is 65 feet long 6 feet deep and 5 feet wide and is sharp at each end and perfectly round. She is somewhat larger at one end, where there is a single opening for the entrance of the crew that are to work her. When the door is closed, and fastentened upon the inside. She is then sunk by means of water and moved in any direction, by means of small paddels or propellers, twelve of which are placed on each side. There is a man-hole in the bottom of this craft, intended for the egress of a man in submarine armor, whenever such a step is necessary to carry out the designs of any conteplated espedition."
Another paper article:
"When fairly in the water she lay half submerged, her iron guards being almost level with the surgace. Two men went into the interior and tried the effect of oars or paddles. Althought byt two or three were moved at once, the vessel obeyed them readily, and when the whold sixteen or eighteen are put in motion it is believed that she can be propelled with considerable velocity. She will be entirely submerged, when necessary, by means of lead or other ballasting; and it is believed a very silight varieation in weight will suffice to lower her to the bottom or to raise her to the surface. When entirely submerged, the glazed aperture in her roof will keep her lighted." … " With her gothic arched back, and conical bow, she looks not unlike a big sturgeon."
Another paper article:
" She is 46 feet in length about 6 feet deep and 4 feet 6 inches in breadth. IN shape and appearance she is much like a large iron boiler flattened with a tapering or conical end, and a rounded stern. A sheet iron guard runs around the outside of the vessel underwhich the hand paddles, 8 on a side are attached. Thes are two leaved and the leaves close on the upward or back stroke to avoid the resistance of the water. Their handles who which the paddles are at right angles, pass through the iron sides of the vessel, and are moved by the rower, the iron rod or handle acting as a hinge.
Inside whe looks somewhat like a bomb-proof man of war barge with white painted iron thwarts at regular intervals, and arched iron roof perforated with small glazed apertures.
On her conical bow is a watertight compartment connected by a small door with the main interior space, and having in the bottom a little round door called a 'man hole' throught which a diver in submarine armor may descent to the bottom of the ater and carry on his destructive work at leisure and unopserved. There is a fan like rudder, of a crescent shape, hinged on the stern, fastened at its horns to the top and bottom of the end. The vessel contains pumps, and air condenser, anchor, etc, and is entered by a man hole on the top near the bow."
Report of Samuel Eakin
Sir
By order of yourself as communicated to me by Wm. L. Hirst Esq I assumed charge of the Submarine Propeller lying at the Navy Yard Phila and report to yourself for duty on the 14th ult. I have since been diligently engaged in the duty assigned me and I now report this date May 31. [1862]
1st The absence of all the air tubes and couplings necessary for communication with the air pumps and air chamber of the boat. As well as pipes and couplings belonging the apparatus for distributing the air through the boat. All of which had evidently at one time been in place but could not now be found. These have since been replaced and the proper examinatoins made to ascertain the completeness of the other fittings. These exmainations disclosed a number of leaks and an endevour was madt for three days to make the repairs at the Navy Yard. Druing this time, so many leaks were discovered from the Air Chamber around the flanges, bulkheads as to make the return of the boat to the yard of the builders a necessity.
2nd The want of a lookout place has been supplied. For this it was to take off the upper covering of the entrance to the boat and prepare patterns and castings and this the workmen are now fitting in place. The covering of the entrance to the divers room has been altered and refitted and is now reliable and alteration has also been made on the door of exit for the divers that will improve it and I hope may be extremenly efficient and sure in its closing.
The arrangment for discharge of ballast was very defective. The lever handles being entirely too short as well as being hid away among the pipes for filling and discharging the water from the tank. New levers have been made for these and they are place in such a position as to immediately available and true in operations.
A water pressure gage and level have been place in position upon the boat and vent cocks inserted in the tanks which will insure their filling. The paddles have been overhauled and made sure of being in good working order. I have repainted the outside and a portion of the insside of the boat and some minor alterations made of the internal arrangement making the parts easier of access by the crew for working and adding to the efficiency of the boat
Very Respectfully
Samuel Eakin.
------
Sir: In obedience to your orders I have the honor to make the following report upon the submarine boat Alligator, of which I am in charge, founded upon personal examination and experiments with her.
This submarine boat, as I understand, was to have possessed the following properties:
1st Facilities of immersion and emersion.
2nd Self propulsion above and below the water.
3rd Capability of remaining with her crew a long time under water, by purifying the air contained in her, so as to admit of its being re-inhaled repeatedly, &c.
4th To be able to operate under water, and to permit a person to pass in and out at pleasure.
Most of these properties she does not possess to a practical degree, and in all she is defective.
1st Facilities of immersion and emersion. Her apparatus for sinking and rising is good, and sufficient for the purpose. She is incapable however of being suspended in the water, but must sink when once immersed to the bottom, therefore she could only operate in such depth of water, that a person standing upon her could reach the vessel above him.
2nd Propulsion above and below the water. She is in this particular very defective, being totally incapable of stemming an ordinary tide of the velocity of 1½ knots, and she is from her low rate of speed and length, difficult to manage with any exactness with the helm. Her ventilation is bad, even above water with the man hole open. On one occasion after her crew had been in her an hour, two of them became so exhausted as to be lifted from inside, and the remainder were all so prostrated, as to be obligated t leave the inside and to get I boats that were near, or upon her outside. As to propulsion under water, she never been tried, but in this respect it is hardly probable she could do any better than on the surface.
3rd Capability of remaining under water. She has no means known to me of purifying and replenishing the vitiated air other than forcing it through lime water. This though it would absorb much of the carbonic acid, would be only but partial relief. With her crew of twenty two persons, it would not be safe to remain more than an hour under the surface.
4th To be able to operate under the water. I cannot see that this submarine boat in its present state could be of any use in this particular. The means proposed by the inventor may be very pretty in theory, but in practice, they would not in my opinion be at all applicable.
By means of an air chamber, which is filled with compressed air, a person can get in and out of her but there are no means of supplying that person with air other than a common tube connecting with the mouth. It is extremely improbable that any person could be found who with only this slight means of obtaining air would remain any time under water. Such a person would be obligated to keep one hand on his nostrils and would have to be loaded as to remain below the surface, a postion that would admit of little exertion upon his part.
To sum up the whole, I consider that this vessel has such inherent defects as to preclude of her use as her name indicates for submarine purposes. If her speed was greatly increased, her steering apparatus improved and she could receive a much better ventilation, she might be made use of to operate above the surface. The manner in which she could be brought in play in this particular is very limited, confined to approaching an enemy at night, and liable in this respect to be easily frustrated by a boat pulling near the vessel to be attacked.
It seems to me, therefore under all the circumstances, of doubtful expediency to proceed any further in improvements upon her. I have the honor to be, very respectfully, your obedient servant,
Thos. O. Selfridge,
Lieutenant, Commanding Submarine Boat Alligator.
HON. Gideon Welles
Secretary of the Navy
-----
Bureau of Yards and Docks
17 July 1862
Sir
You will be pleased to have the stern of the Submarine Propeller at the yard extended and such alterations made as may be necessary to use a propeller instead of the ‘fins’ as per the plan enclosed.
Respectfully
Your Obdt Servt
Joseph Smith
Captain A. A. Harwood
(note: Both the sent copy and the received copy of this letter were located, no plans in any form were located with the letters)
Derived Description of the Submarine Alligator
Length:
47 feet. This is variously given as anywhere from 45 to 50 feet. It is neither clear nor defined as to how the 47 feet was measured. When it was decided to remove the oars and installed a screw propeller, the boat was authorized to be lengthened. How much is not known.
Beam.
56 inches as given by the specifications. This is the hull beam. The overall beam over the oar guards is given as over 80 inches
Height.
Height of main hull is 66 inches. It is not known how much the observation dome added to this height, nor is it clear how high the air tube might have extended.
Rolled and hammered iron plate varying in
thickness from ¼ to 3/8 inches (9 to 12 mm as a spec given in then notes to De
Villeroi drawings). This thickness
corresponds to 10 to 15 pound (per square foot) plate. The fastening method was riveting as arc
welding was unknown at the time. It is
not known what riveting method was used (lap, but with lap plate, double lap,
etc.). Viewing the existing
illustrations it seems that but the plates were butted then backed by a thinner
lap plate and through riveted with the outside head countersunk and planed
smooth. The rivet pattern, rivet size
and spacing were estimated by using the formulae in
Rivet Shaft Diameter: 7/8 inch
Rivet Head Diameter: 1 ½ inches
Rivet Pitch : 2 ½ inches
There may have been a system of internal stiffening by the use of inner circumferential ribs. If used, they would have been similar in thickness to the plates and from ½ to 1 inch wide in the web. They may have been rolled angles.
There were two internal bulkheads which defined the diver lockout chamber in the forward end of the boat. These would have been made of flat plate of the same thickness as the hull. It is likely they would have been riveted to circumferential angle frames. The Aft most of the bulkhead would have had a large opening for an entrance hatch. The opening would have circumferentially stiffened with a doubling plate.
The hull was originally designed with a conical section forward, a parallel midbody and a rounded stern. The sectional shape of the midbody was roughly egg shaped with the widest part of the beam at below the vertical centerline of the hull. See DeVilleroi’s drawings for details of the hull form.
Penetrations:
The following hull penetrations are known.
Along the top of the hull near the top centerline are a line of 36 glass ‘bulls’ eyes”. These are installed to allow light to penetrate to the inside of the boat for illumination. The detail of how these were installed is not known. It is surmised that they were thick sections of glass sandwiched between bolted (screwed) flanges with flax or guttapercha gasketing.
An observation dome replaced the access hatch forward. Eakin found there was no way to see out while underway unless the hatch was open. Being unsatisfactory in his mind, he had a dome cast. There are no drawings known of this dome so its shape and fastening method has been surmised.
There were nine pairs of oars aproximately 30 inches apart with their horizontal shafts extending through the hull. These penetrations were most likely similar to the packing glands used on steam engines and valves. Generically called “stuffing tubes”, they would have been bolted to the hull, with the major portion of the stuffing tube on the inside.
The propeller shaft penetration and the extension of the stern to accommodate the propeller and gearing are not known. It is assumed the shaft penetration would have been a scaled stuffing tube type penetration.
There were five internal tubes which were mounted on the centerline and spaced throughout the boat. Two were closed at the bottom and open at the top and housed the buoyancy chambers. Three were closed at the top and open at the bottom and housed the emergency release weights.
Buoyancy Chambers. No written description of the operation of these has been located. It was assumed given the scaled size from the drawings that the chambers would have provided about 130 pounds of positive buoyancy if released to the surface. It was found by one of the members when he actually operated a model of the submarine in the test tank at the Navy’s David Taylor Naval Testing and Development Center’s model basin that the chambers provided a great deal of depth control and longitudinal stability when deployed but not surfaced.
Emergency Release Weights: Three tubes in the boat housed emergency release weights. This consisted of a stack of either iron cylinders or lead cylinders held in place by a rotating latch mechanism. Upon release, the weights would give additional positive buoyancy to the boat and it was hoped allow it to surface if in trouble.
There were an inknown number of piping hull penetrations for flooding the ballast tanks and for pumping water out of the tanks. The flanging of this connection is assumed to be a standard bolted flange connection with a leather or similar material gasketing. The size of the opening is scaled from the drawing. This size flange would require four or six bolts, square headed and from ½ to 1 inch in diameter.
There is an air tube penetration on the top of the hull. The flanging of this connection is similar to that used for the air tube cited above.
Rudder pintle hull penetrations were most likely specially cast stuffing tube type fittings bolted to the top and bottom of the hull plating. These would be similar to in design but differently sized than the oar stuffing tubes.
Propulsion:
The prototype for the Alligator had a single hand crank operated screw propeller. DeVilleroi decided that for the Alligator, he would abandon that method and use a set of hand operated oars of his own design. He made this decision to trade speed for maneuverablity. The oars, he indicated in a letter, . "The boat moves by the means of 18 side propellers, invisible above the water. It can turn round in a small space and will sail backward in case of necessity."
The oars were attached to a crank shaft that when operated in a back and forth motion by the crewman inside resulted in a back and forth motion by the oar blade on the outside of the hull. This oar blade was hinged in the center, vertically, in such a manner that it would fold like a book on the forward motion and open like a book on the backward motion. This motion and folding was, like some have noted, like a duck’s foot in swimming.
It was noted in building a model of one oar station that the designer’s concept of rotating the oar 180 degrees would allow the “backing” of the oar motion and reverse the thrust was in error, There was insufficent room for that motion on the inside of the boat.
The propulsion system was changed in starting in August 1862
at the Washington Navy Yard by Martin Thomas and a crew he brought from
The hand crank system for the screw propeller would have to be offset from the internal centerline of the hull to clear the ballast chamber and emergency release weight tubes. The crewmen who operated the crank would sit sideways in the hull similar to the Hunley arrangement.
Weapons:
The primary weapon carried by the Alligator was a diver and one or more limpet mines he carried and attached to or left in the vicinity of a target. In addition, the diver himself could fulfill missions that involved removal of neutralization of obstacles and enemy devices such as mines. The auger device shown in the drawings is not mentioned in any of the written descriptions therefore it is assumed that it was not installed.
It has been conjectured by the group that there is a possibility
that the Alligator may have been equipped with a spar torpedo or a towed mine
if it had made it to Port Royal and been assigned to attack targets such as the
Confederate ironclads in
Color:
DeVilleroi stated in a letter that he painted the boat green
on the outside and white on the inside.
The green was to make the boat less visible underwater and the white was
to make enhance lightness inside for habitability. This concept of making the boat less visible
by painting it green is the first known discussion of the practice of
camouflage coloration of a
Air Purification and CO2 Removal:
To be added.
Summary:
The boat was considered by the group to be a viable weapon
system and an offensive weapon that may very well have changed the course of
the attack on
The boat could operate submerged and be stable. Diver technology was sufficiently advanced that the use of a diver as a deployed resource was easily feasible. The planned air replenishment system and air purification would have prolonged the breathable atmosphere inside the boat for a time sufficient to complete a mission.
None of these things, however, ensured success. The crewmembers risked their lives simply operating submerged without the added risk of being in hostile waters and operating against an enemy that would not hesitate at destroying the boat. That these men would volunteer for such a mission speaks volumes about the courage of such men.
Their idealism and courage led the way for the Submarine Force to follow and it did with valor and sacrifice.