In the 50s, as commissioning CO of HARDER (SS-568) and then of SEAWOLF (SSN-575), I watched with astonishment as some 600 workers poured bthrough the 26″ hatches to finish construction or repair of these boats. No wonder EBCO had a large Physio-Therapy Lab for workers cramped from working in contorted positions. (Almost as in scenes from Dante’s Inferno.) The analogy came to mind of a jeweler repairing a watch through the stem-hole rather than through the open back.
One knew that in WWII the Germans preassembled their submarine hull sections for later assembly at a launching yard. In the same fashion, torpeodes and missiles are constructed by hull section and later the sections are held together by locking rings. Why not use the same concept in submarine construction?
After discussions with Adm. Andrew McKee and Capt. Ralph Kissinger–although they thought problems of out of roundness would have to be solved–the idea seemed feasible. They also pointed out that no such requirement had ever been established. This highlighted an odd sort of logic: i.e. the feasibility had not been established because the requirement had not been established because there wasn’t sufficient evidence of feasibilty. An estimate of value was evidently needed from someone outside the bureaucratic circle.
One opportunity came soon. The SEAWOLF had gone to sea in ’56 with a two-year supply of fuel in its unique sodium-cooled reactor. Though SEAWOLF’s system operated perfectly, sodium proved to be such a superb heat conductor that, unless the plant was carefully operated, the stainless steel in the primary loop could be thermally shocked by sharp temperature waves. This hazard gave the competing high pressure water plants a decisive advantage in the near tena. Still, I felt that SEAWOLF ‘s liquid metal reactor should not be prematurely abandoned, and SEAWOLF put out of commission with a year of reactor fuel still available.
Thus, in ’57 I tried to sell the idea that construction should be started on a water reactor compartment which could be used in SEAWOLF in ’59 when SEAWOLF would have burned 3 years of fuel, including one partial refueling in between. It was estimated that a swap of reactor compartments could then be done in about 6 weeks. It was my hope that a very important principle of cost reduction could be demonstrated–preassemble the pressurized water reactor compartment then join it to SEAWOLF in such a manner that it could be later separated to facilitate repairs, refits and overhauls.
Unfortunately, my scheme was badly out of phase with the planning, budgeting, and advocacy in Washington, SEAWOLF entered EBCO in ’58, and stayed 14 months for a normal kind of conversion.
Now, 25 years and many designs (success! vely larger) later, it may be time to establish the feasibility and the requirement to produce outfitted submarine compartments which can be joined together in production, and later separated and rejoined as needed for repairs, etc. In the last few years some use has been made of partial preassembly of hull sections, but full advantage of the principle is not reached until provision is made to separate compartments for repair. For this the SUBMARINE COMPRESSION RING HULL JOINT is an answer.
To envision this joint, think of a torpedo: its sections are held together by external locking rings. Under tension they compress the beveled machined surfaces near the end of each section of the torpedo. In such a system, the locking ring experiences external pressure–the same as the hull. Moreover, the ring is subjected to corrosion the same as the hull. If the ring is stiffer than the hull, the joint will tend to Change in ring circumference equals cam spreading distance . Ring diameter should clear end lips and expand to seal in operation. loosen. A best scheme for a submarine hull would be to place the ring inside the hull away from corrosion and hull compression. There it would tend to tighten the joint.
Now envision each submarine hull section with a thickened end-ring and machined face, behind which is a machined beveled surface designed to bear on a beveled compressing surface on the outside of an interior ring which forces the hull sections’ ends together as it is expanded.
Control of the expansion of the interior locking ring would be by hydraulic locking into place cam sections within the circumference of the ring. In port for repair, the hydraulic cam would be retracted, disengaging the locking ring for separation of compartments.
Development and test of such a joint would not be cheap or easy; but the designs would probably be scalable for the thickness and diameter of a submarine hull. Ancillary development would be required for remotely operated electrical and pipe couplings, and for joints in the superstructure exterior to the pressure hull.
In construction, components could be more densely loaded into compartments through the ends, personnel access and rigging space could be sacrificed. The pressure hull could be made more dense with bouyancy provided by exterior non-compressible solids like syntatic foam. Such materials could serve also in sound absorbtion and reduction of weapon damage. Target size as seen by ASW weapons would be reduced. Compartments could be made in different specializing yards for later assembly. Change of submarine mission might be accomodated by change of compartments, i.e. for mdning, anti-air, etc.
Relative to repair: who, among us submarine commanders has not spent hours in the mockups looking for interferences which would prevent strainer or zinc changes? The need for personnel access and work space within auxiliary or engine room spaces could be greatly reduced if the compartments could be separated in refit. In typical refits and overhauls, some compartments take much longer than others. The use then of spare compartments could greatly. reduce tie-up of the whole investment. Submarine tenders might be designed to enclose the submarine and separate it for repair.
What seems needed is a means to provide joints in submarine pressure hulls which allow for preassembly of submarine compartments in construction and separation of them in repair. By so stating this requirement, this intuitive design solution may generate a superior solution by some brighter guy. Someday there might be a need for speedier production of many more submarines. Such a joint could then prove indispensable.
CAPT. R. B. LANING, USN (RET. )