I have little confidence that my critique of current submarine design, will elicit greater response than it has during the past twenty years. During that time and often before, leaders of our submarine community have suggested required design changes. They have proposed that smaller size can reduce their cost to construct, and that insufficient compartment separations endanger their survival from flooding. It’s been observed that too few harbors can accept their size, and that automation can reduce crew size to save operational costs. Others argue for increase of mission capability to lower the number of new constructions.
The standard rules of thumb for hull length to width ratios, and allowable operating depth for a platform of a certain length are no longer being observed. They also note lower safety margins, and that double hull protection is no longer afforded. Much of this results from constant construction, maintenance, and operational cost increases. The intended savings for additional operational capability is perhaps lost by that increased requirement for size and manning to operate. The current trend to replace crew by automation has significant added risk as well as its benefit. Now the threat of budget restraints could lower the number of platforms on station. Never the less, our submarines are considered the best in the world. The great concern now must be their ability to meet the next new challenges and how Jong it would take to adapt for it. The trend to copy the success of the previous design, to avoid risk of failure inherent with new concept, cannot continue. We must not attempt to fight the next war with the weapon platforms of past.
My experience during thirty plus years in submarine design, being the first designer assigned to the Trident project, and involved for its full development period, provides me considerable insight to that process. I know the things we chose not to do as well as those we did. My assignment to NA VSEA for an alternate diesel submarine proposal, provided understanding on goals and limitations. All of our current designs are cylindrical, and of single hull construction, and are most similar to that of a reinforced flexible hose. This gives limitation of their resistance to longitudinal bending, and to external pressure. That weight of required structural reinforcement gives limitation to hull plating thickness and to compartment arrangement. Hull reinforcement ring framing gives limitation from about ten percent of internal volume. Hutt diameters are limited by the platforms draft, thus size increases extend the platforms length. The accepted ideal length to width ratio of six, has never been achieved in current submarine design. The claim, of a greater expense in double hull design, must be challenged, as it provides longitudinal stiffness, removes ring framing from within the pressure hull, and can reduce hull and shaft length by twenty percent. Testing has shown hull length extension to increase drag and therefore limits hull speeds. Submarine operation in shallow water had been limited to a depth not less than its length. When submerged a submarine becomes less longitudinally stable. This all suggests an extensive opportunity for redesign.
Respectfully,
C. Clifford Ness
Inventor of U.S. Pat. 5,477,798. and 6,371,041
