Foreign Relations of the United States, Conferences at Washington and Quebec, 1943

J.C.S. Files

Report by the Combined Administrative Committee¹

secret
C.C.S. 307/2

[Washington,] 2 September 1943.

Artificial Harbors for Combined Operations

Reference: a. C.C.S. 307/1²

1. The Combined Administrative Committee has given careful consideration to the enclosed report³ of a subcommittee appointed to study C.C.S. 307/1 and, in addition, has investigated and weighed other matters related to the general subject, particularly with respect to the feasibility of making timely preparations for the construction and placement of necessary artificial breakwaters. The Committee notes the contents of the report and is in general concurrence therewith.

2. Based on the report and on the additional study and investigation, the Committee arrives at the following conclusions:

a. The effectiveness of the Lilo breakwater⁴ has not been demonstrated to the extent necessary, and requires further test.

b. The Lilo breakwater is sufficiently promising to warrant the assembly of material and facilities for its manufacture.

c. The necessary material and facilities for the manufacture of Lilo are available in the British Isles, with the exception of 750,000 square yards of canvas duck and other equipment of an incidental nature.

d. The use of floating ships to form breakwaters is not considered promising, but certain advantages in mobility, quickness of assembly, elimination of towing difficulty, etc., warrant further test. These tests should include the use of ships alone and in combination with Lilos, which they might tow to any desired locality.

e. Liberty ships or others adaptable to the purpose are not readily available for Overlord except at the cost of other operations, although ships carrying cargo to the United Kingdom might be retained in that area for further and temporary use as breakwaters.

f. Such ships will require modification to the extent of providing heavy moorings forward and aft, and it is desirable that they be equipped with considerably increased anti-aircraft protection and with anti-submarine booms and nets.

g. The construction and use of concrete caissons for providing breakwaters in whole or in part is of promising feasibility. Observing, however, that to the Committee’s knowledge a caisson of greater depth than 30 feet has not yet been used, and that the time factor is of critical importance, the nature and extent of the operation, both from a technical as well as an operating point of view, limits full assurance as to success.

h. The material and labor for the necessary caissons is believed to be available in large measure in the British Isles. Caisson construction will therefore require the shipment from the United States, under low priority, of only the replacement material for certain material used and the minimum number of personnel, having regard for the shortage of shipping space for personnel.

i. The establishment of Lilo or caisson breakwaters within the time limits allowed by the operation involves tremendous towing, traffic and mooring problems and will require the employment of approximately 90 towing vessels. In considering the urgency of this operation the Committee believes that suffiicent towing vessels can be made available by special effort in the British Isles and the United States. In view of the short period of employment and in view of the difficulties of overseas movement during the winter months, British vessels should be employed wherever available rather than vessels from the United States.

j. The determination of requirements for artificial harbors in such areas as the Southern Coast of France, the Western Coast of Burma, the Malay Peninsula and Sumatra is dependent upon logistical, topographical and hydrographical data which can be assembled only after definite areas have been fixed and logistical plans developed. In the opinion of the Committee it should be made the subject of a separate study.

recommendations

3. a. The trials and development of Lilo breakwaters should be proceeded with on the highest priority as a British responsibility.

b. That in view of the time element, preliminary work and early manufacture of Lilo be carried out with materials now available in the British Isles and that shipments, as recommended by the subcommittee in Tab “C”,⁵ be made from the United States as soon as possible.

c. That the trials of floating ship breakwaters with special regard to moorings be proceeded with on the highest priority as a United States responsibility and that, if successful, consideration be given to using a combination of floating ships and Lilos.

d. That, depending upon the success of above tests, ships in the minimum number required be provided from available sources, and that study and allocation of shipping along these lines be commenced at once.

e. That 25 tugs and suitable towing vessels be now made available⁶ from the United States in addition to similar types now being built in the U.S. for the U.K. and that maximum effort be made to provide other necessary towing vessels from suitable types (YMS, ATR, AT, etc.) available in the British Isles. That any discrepancies be considered in further study as to their elimination.

f. That a suitable agency of [the] British government be immediately designated to carry out the entire program of constructing concrete caisson breakwaters for the Overlord operation; that this agency be ordered to proceed immediately with the designing, selection of sites, planning of construction program, assembling the construction equipment, acquiring material, and mobilizing the labor required for the complete program; that the actual work be begun as soon as possible and be carried out under the highest directive.

g. That preference be given to forming shallow water breakwaters of caissons and of such hulks as may be made locally available for the purpose.

h. That all agencies to perform work on the above lines be designated immediately and directed to proceed.

1. For the action taken on this paper at the 117th Meeting of the Combined Chiefs of Staff, September 3, 1943, see ante, p. 1205.
2. “Artificial Harbors for Combined Operations”, August 26, 1943; not printed. This memorandum by the United States Chiefs of Staff recommended that an enclosed paper prepared by the United States Joint Administrative Committee be referred informally to the Combined Administrative Committee for study and report.
3. Not printed.
4. Defined in the enclosure as “an air inflated compartmented canvas bag ballasted to float in such a manner as to dampen waves and breakers.”
5. Not printed.
6. In approving the recommendations contained in this paper, the Combined Chiefs of Staff amended the first part of this sentence to read: “That twenty-five tugs and suitable towing vessels be made available as expeditiously as practicable”. See ante, p. 1205.