Ernest Lester Jones to William C. Redfield

CONFIDENTIAL.

The Secretary of Commerce
Some days ago the question arose as to the practicability of placing at the mouth of the Skagerrak from the shore of Norway to the shore of Denmark, or in the North Sea from the shore of Scotland to the shore of Norway, a suitable net in order to prevent German submarines from leaving the North Sea. Upon this question I submit the following facts:The personnel of the committee appointed by you of the United States Coast and Geodetic Survey officers to formally consider this matter consisted of the following: Myself.
Captain N. H. Heck, hydrographic engineer, who has had ten years of experience chiefly on the sea in the study of hydrography, including deep sea sounding off the coast of the United States, Porto Rico, etc. The important feature of his work for ten years was in the development of the wire drag, which has been perfected largely through his efforts, and done valuable work on the New England, Florida, Porto Rico, and Panama coasts.
He has not only developed the wire drag from an economical and from an efficient standpoint, but he has increased the actual use of this sweep from 500 feet in length to five miles in length, and in connection with this his experience has developed devices for handling rapidly the setting of this sweep, its buoys, anchors etc. by modern devices and up-to-date practical launches. He has also been in a position to especially study currents and rough waters.
Captain R. S. Patton, hydrographic engineer, is a licensed master of steam vessels, any tonnage, in any oceans, and has had eleven years of continuous sea duty, embracing all classes of work necessary for the production of charts, including deep sea hydrography, and wire-drag work. He has had broad experience in deep sea work on the Atlantic coast, the Philippine Islands, in Panama and Alaskan waters, three years of which were spent in the Bering Sea where conditions more closely approximate those that are encountered in the North Sea. For over a year he has been in charge of the coast pilot work of the Coast and Geodetic Survey, which requires a nautical experience of the highest order.
The fourth member of the committee, Captain Robert F. Luce, hydrographic engineer, is a licensed master of steam vessels, any tonnage in any ocean, and has had eleven years of service particularly in hydrographic work, and in the study of tides and currents in the waters of the United States and those of the Philippines. He has for some time been chief of tides and currents of the Coast and Geodetic Survey.
This committee has had several conferences with you, at which time there was also present an officer of the United States Navy, and officers from the Bureau of Standards. Later this committee went to New York where it was courteously received by the Commandant of the New York Navy yard, and following a satisfactory conference, an officer of the Navy was detailed to accompany us to inspect the net at the entrance to New York harbor.
After these productive conferences and several days of mature consideration of this subject, I am in a position to offer the following tentative plan for the laying of a wire net across the Skagerrak from the shore of Norway to the shore of Denmark, a distance of 90 miles, or across the North Sea from the shore of Scotland to the shore of Norway, a distance of 270 miles:We believe that a net or series of nets can be stretched across the Skagerrak from Norway to Denmark or across the North Sea from Scotland to the coast of Norway. In view of the distances involved, we believe that the most desirable type of net to use is not the heavy net designed to stop a submarine, but rather a net of lighter construction, carrying mines to be exploded by the breaking of any wire in the net. This latter type would be light in weight, easily handled, quickly set out, and, offering comparatively slight resistance to the action of the sea, or to currents, would be much easier to maintain. In case of a break in the net, or an explosion of any of the mines, the damage could be repaired by planting a section of ample length adjacent to the original, but not in contact with it, as actual connection between the old and the new net does not appear necessary.
Such a net once in place should prove effective in blocking the passage of all submarines. However, as an additional precaution, it would appear wise to plant a second net a sufficient distance from the first net, say about 1800 yards, to permit the passage of patrol vessels between them.
The detailed description of the type of net, suggested as a basis for further consideration, is as follows:A sketch of one section of the net is attached for reference (Exhibit A). Specifications:Net to be 200 feet in depth, and to be made in 600 foot sections (for convenience in manufacture).
Sections to be shackled together as they are being stowed in the hold of the planting vessel.
Size of mesh to be 12½ by 12½ feet.
Size of wire: Horizontal wires at 100 to 200 feet in depth to be 1/2 inch galvanized steel wire, breaking strain 30,000 pounds. All other horizontal wires to be 1/8 inch galvanized steel wire, breaking strain 2,000 pounds. Vertical wires every 100 feet apart (these wires carry the buoys, mines, and anchor chains) to be ½ inch wire as above. Intermediate vertical wires to be 1/2 inch as above.
Net to be supported at 100 foot intervals by double cone steel buoys. Such buoys provide ample buoyancy, and at the same time would not subject the net to excessive sudden stresses due to the action of the sea. Net to be anchored at 600 foot intervals by 1,000 pound anchors. Mooring chains to be 5/8 inch link, and with a scope equal to twice the depth of water. The bottom of the net to be weighted by 50 pound weights placed on alternate vertical wires.
All wire intersections to be clamped in place by passing the two wires through a ring, and pouring zinc balls on the four parts of the wires immediately outside the ring.Details of Planting.1. THE VESSELS. Each vessel must be twin screw. She should be about 600 to 1000 tons capacity, with large clear holds, and flush decks, with plenty of room aft. She must have special gear for handling the net, consisting of conveyers for carrying net, buoys, mines, and anchors. She should have plenty of power, and particularly good backing wheels to facilitate rapidity in maneuvering. Propellers must be guarded to prevent the gear from fouling in them.2. Preliminary. Prior to undertaking the planting of the net, the line which it is intended to follow should be marked by small buoys spaced about five miles apart. Lines of closely spaced soundings should be run over the tracks, to furnish an accurate knowledge of the depths. In setting the net, one of the patrol boats guarding the operation should keep ahead of the planting vessle, locating buoys, and furnishing a constant guide to direction.3. Crews. The crews of the planting vessels should all be given er training to insure familiarity with all details of the operation.4. Actual planting. With vessels properly equipped, and crews previously trained, a speed of one or one and one-half miles per hour can probably be maintained.5. Reserve equipment. An ample reserve of both equipment and planting vessels should be available for immediate use. The amount required would depend on the completeness of the protection which can be afforded the operation of planting. It should scarcely be less than 100% of net, and 50% of vessels.6. Speed. It is highly desirable that the operation of planting be completed as rapidly as possible. Probably the success of the entire undertaking depends on completing it before the enemy can be informed of what is being done and can attack in force. Therefore, a total of about 24 vessels (16 for planting and 8 in reserve) should be furnished. With that equipment the entire operation should be completed in from 20 to 30 hours. No difficulty in joining the various units would be experienced, as the line to be followed would previously have been marked by buoys as already indicated.7. Weight. The net weight of the wire, including anchors and chain, per mile would be about 25 tons.8. Cost. The cost of this outfit would be about $25,000 per nautical mile, and a total for the shorter course of 90 nautical miles of $4,500,000, and for the greater distance of 270 nautical miles of $13,600,000 exclusive of mines and electrical equipment. The foregoing price is based on the best available knowledge of the state of the market.I am submitting with this letter illustrations showing various interesting equipment and other features in connection with the wire-drag work.

(Signed) E. Lester Jones.
Superintendent.