Time for the Truly Stealth Submarine
By Donald J. Kazimir
Much has been accomplished to quiet submarines over the years—to make them undetectable. Methods used include sound-mounting machinery, insulating the hull to absorb sound, piping compressed air around the outer hull to absorb radiated noise, and coating the hull to absorb active sonar pings.
These all help, and U.S. submarines have been the quietest in the world for many years now. Yet they remain vulnerable to active sonar—from another submarine, dipping sonar from a helicopter, and from surface ships. To make a submarine truly "invisible" under water, we need to design it so it will not reflect a sonar ping. If we can do it with aircraft that deflect radar, we can do it with submarines.
The problem is difficult, but it can be solved with creative engineering. The sides and bow need to be sharp on the edges, the sail angled on all sides, the rudder shaped to deflect, and the propeller hidden (see Figure 1). This is an effective design; engineering creativity becomes a factor when we try to make it practical.
Deal with the Propeller
The propeller is a problem when the pinging vessel is behind the submarine. Therefore, the prop needs to be hidden. One possibility is a tunnel drive similar to that used on a recreational jet ski. Water enters an area under the pressure hull (surrounded by the outer hull) and is squirted out a nozzle due to pressure from the hidden prop. The nozzle can be swiveled to act as a rudder and a rear dive plane. If this proves impracticable, a conventional propeller could be used for propulsion, but the boat would need to show a head-on or side aspect to the pinging vessel.
Change the Rudder
The vertical rudder reflects a sonar ping and must be changed. One possible solution is a V tail similar to that used on early models of the Beech Bonanza aircraft and the submarine Albacore (AGSS-555); see Figure 2. The V tail will act as a rudder and dive planes as it did on the Albacore, to steer the boat and control its dive angle in the water. In this case, the tunnel drive nozzle will not be used as a rudder or planes, only for propulsion.
Adjust Mooring Capabilities
Because the edges of the hull will now be sharp, they need to be strengthened for mooring. If this cannot be feasibly done, crew members can cast two small anchors off the side opposite the pier to keep the boat from touching. A bow and stern thruster can be housed in the outer hull to help moor the boat. The captain can pull up alongside the pier, drop two anchors, and use the thrusters to push the boat toward the pier.
I developed this technique in 1969, when I served as captain on a Navy-NASA-Grumman mission exploring the Gulf Stream from Palm Beach to Nova Scotia. The deep-diving research sub Ben Franklin (PX-15) operated for 30 days, with an electric motor on either side of the bow and stern. When out of home port, we used the anchor method to keep the boat from touching the pier. (The Ben Franklin was designed by Jacques Piccard and built by Piccard/Grumman in Switzerland.)
With all the current global activity focused on building ultra-quiet, air-independent-propulsion diesel electric submarines, now is the time for the United States to create a truly stealth submarine. We can do it.
Water Mist Fights Shipboard Fires
By Commander John P. Farley, U.S. Navy (Retired), and Dr. Frederick W. Williams
Researchers have for the past half-century studied the use of a very fine spray-water mist-for fire suppression. After the Montreal Protocol was signed in 1987 and U.S. law changed, halon fire extinguishing agents began to be phased out and interest in water mist was vigorously renewed.1 In the commercial marine industry as well, water mist held appeal because of the need for a low-weight-impact replacement for sprinkler systems on ships driven by International Maritime Organization (IMO) regulations. These required the retrofit of most commercial marine vessels, making the development of low-water-demand, high-efficiency mist systems of immediate interest.
Halons, chemically related to chlorofluorocarbons (CFCs), degrade the stratospheric ozone layer. This results in higher levels of ultraviolet radiation at the Earth's surface and thus gives rise to serious health problems. The military is now permitted to use halons for mission-critical purposes only, until the current halon supply is exhausted. The services, in particular the Naval Sea Systems Command (NAVSEA), have made a concerted effort to eliminate halons on all future ship classes.
This effort has given the Navy a unique opportunity to develop a universal fire-fighting agent for shipboard use. For the surface Navy, this technology offers improved damage control capabilities and enhanced damage resilience compared with our previous total-flooding gaseous agent systems. It also works well with our manning goals for future ship classes.
How It Works
A system of a fine mist of droplets uses less water than do conventional sprinklers. The droplets have a high-surface-to volume ratio and absorb heat quickly. The mechanisms of extinguishment include flame cooling by droplet heating and evaporation, oxygen depletion by steam expansion, and surface wetting. Other benefits are their ability to strip the atmosphere of smoke particles and absorb soluble gases.
The USS San Antonio (LPD-17), the first U.S. Navy surface combatant ship to be halon-free, uses water mist for main and auxiliary machinery space fire protection. The system consists of uniformly spaced overhead pendant nozzles designed to operate at 70 bar (1,000 psi) and discharge 0.4 liters per minute/cubic meter (0.003 gallons per minute/cubic foot). The LPD-17 system developed and tested on board the Navy's fire-test ship ex-USS Shadwell (LSD-15) extinguished all of the unventilated fire scenarios in less than 25 seconds of activation, using less than 100 L (25 gal) of water.2 It had minimal impact on the ship's machinery space electrical equipment.3
Because of the extinguishing capabilities of mist, a major revision resulted in machinery space fire fighting doctrine.4 Water mist can discharge for an extended period and offer continuous protection, so the need to wait 15 minutes before entering the space is eliminated, and the ventilation system can be used during post-fire investigation and overhaul operations. Also, due to the high thermal capacity of water, the potential exposure to hazardous post-fire conditions and likelihood of fire spread are significantly reduced. Water mist also provides an opportunity to limit manning requirements to a rapid response team.
The successes of the LPD-17 program led directly to the use of high-pressure water mist on the Dubuque (LHD-8) and on the LHA-6- and LCS-class ships. A combined high-pressure/medium-pressure system was developed for the DDG-1000 autonomic fire-suppression system (AFSS) for total ship coverage. The base technology concepts for the new system were first developed under the Office of Naval Research (ONR)—sponsored program Damage Control: Automation for Reduced Manning (DC-ARM) and were further refined under the DD(X) AFSS Engineering Development Model test process.5
Studies Continue
In the past, there has been a reluctance to use water-based fire-suppression technologies in situations such as gas turbine engine enclosures and flammable liquid storerooms. Therefore, the Navy has maintained some halon replacement gaseous agent technology on new-construction ships. Studies are addressing this issue now, focused on eliminating the current heptafluoropropane total-flooding systems with a water-based alternative for all future ship classes.
Another advancement may include propelled extinguishing agent technology (PEAT) in future ships. PEAT is a self-contained generator comprising an initiator, solid propellant, and a fire-suppression agent (powder, gas, water). With simple installation and minimial maintenance (it does not require pumps, pressurized cylinders, or piping), this technology has tremendous opportunity to revolutionize the way we design and implement fixed fire-suppression systems.
Beyond fires, the possibility of using water for explosion suppression has also been researched for several years. Past studies relied on bulk water as a passive barrier to mitigate the effect of blast waves, but compared with the "TNT-equivalent" mass of the explosive, at least double the amount of water was needed (up to four times as much).
Recent studies have explored directly applying water sprays or mist to reduce the severity of explosive events. Current research sponsored by the Office of Naval Research has investigated the feasibility of water mist to mitigate shipboard blast. Recent large-scale detonation tests of 50 lbs TNT and two 50-lb equivalent aluminized charges (Destex and PBXN-109) demonstrated that water mist significantly reduced the impulse (40 percent TNT, 44 percent Destex, 49 percent PBXN-109), the initial blast wave (36 percent TNT, 29 percent Destex, 35 percent PBXN-109), and quasi-static overpressures (35 percent TNT, 33 percent Destex, 41 percent PBXN-109) produced by these charges.6
Even though all future ship classes will use water mist as their primary fixed fire-protection agent, and despite important advances in the technology, laboratory tests show that a significant amount of the available drop vaporization enthalpy is still not realized during flame suppression.7 In fact, it has been shown that the extinction efficiency potential for water mist is even greater when compared with Halon 1301.
To optimize the use of water mist, we need a better understanding of how different-size drops behave near flames of various geometries, and we need to perceive more clearly how they move from their source toward the flame. These insights will make future systems significantly more efficient, decreasing their size and weight for next-generation shipboard installations.
1. United Nations Environmental Programme, Montreal Protocol on Substances That Deplete the Ozone Layer, Nairobi, Kenya (1987). United Nations Environmental Programme, Report on the Fourth Meeting of the Parties to the Montreal Protocol on Substances That Deplete the Ozone Layer, Copenhagen Demark, and Nairobi, Kenya (1992). Clear Air Act, U.S. Code, Vol. 42, Title VI (1990).
2. G. G. Back et al., "Full-scale Machinery Space Water Mist Tests: Final Design Validation," NRL/MR/6180-99-8380, June 12, 1999.
3. L. R. Gauthier, J. M. Bennett, and B. H. Land, "The Effects of Water Mist Discharge on Energized LPD-17 Electrical Equipment in the Absence of Fire," Test Report AATDL-99-024, Johns Hopkins University, Applied Physics Laboratory, 29 January 1999.
4. J. P. Farley F. W. and Williams, "Water Mist Machinery Space Fire Doctrine," NRL/MR/6180- 04-8740, January 16, 2004.
5. A. C. Luers et al., "DC-ARM Final Demonstration Report," NRL/FR/6180-03-10,056, 23 June 2003., Northrop Grumman Ship Systems, "DD(X) Damage Control Concept of Operations," EPDM Vault ID 10276, updated 5 November 2004.
6. H. D. Willauer et al., "Blast Mitigation Using Water Mist: Quick Results Analysis," NRL Ltr Rpt 6180/0323, 27 November 2007.
7. T. M. Jayaweera, E. M. Fisher, and J. W. Fleming, "Flame Suppression by Aqueous Solutions Containing Phosphorous," Combust Flame, 141:308-321 (2005).
Global Partners in Maritime Security Training
By Commander Michael Hallett, U.S. Navy
With the Global Maritime Partnership Initiative, the U.S. Navy has reemphasized the importance of training with emerging partner navies to meet maritime threats collaboratively. Therefore, today one of our primary missions involves activities designed to enhance local navies and coast guards—not sink them.
The codification of principles informing our cooperative training is intended to enhance tactical-level Navy engagement with our Maritime Safety and Security (MSS) partners—in bilateral interactions; multinational exercises such as Phoenix Express, Cobra Gold, and Sea Breeze; and through platforms like the Global Fleet Station and African Partnership Station.
As with our own personnel development, enhancing our partners' MSS capabilities takes place in three domains: individual interaction through running mates and under-instruction (U/I) watchstanding; education in U.S. and NATO facilities and training programs; and combined operations and exercises.
Enhancing Partner Navies
- Running Mates and U/I Watchstanding: In the running mate program, new crew members accompany an experienced shipmate on his or her daily activities. It is a rapid and effective way to introduce new people to life and operations on board the complex artificial environment that is the ship.
A guide is necessary because individuals learning about shipboard operations are faced with not a lack of information, but rather an excess. Attention—not information—is the limiting resource. Working with a running mate provides the new Sailor with a particular perspective from which to begin the learning process.
While being trained, the shipboard U/I watchstander gradually takes on more of the active load, while the qualified watchstander retains the authority, responsibility, full situational awareness "bubble" (the full grasp of ongoing complex activities and potential dangers), and final decision making. Standing a watch under instruction is thus a more complex form of crew training interaction.
As a result, the expectations for individual proficiency are higher in the U/I context. While accompanying a running mate—simply finding one's way around and beginning to understand the nature of the environment—counts as success, as a U/I watchstander, individual status is put on the line.
- Education and Training: Cross-decking with running mates and U/I watchstanding is necessary, but not sufficient to achieve our objectives. To train with the speed and breadth that will enhance MSS capability, we must widen the channel through which this capability is developed. We can accomplish this by expanding our education and training interactions in four major ways. (These activities could perhaps be supported through International Military Education and Training funds.)
First, we should increase our support for existing national training facilities through partnerships with other maritime actors such as the U.S. Merchant Marine Academy. Partnering with the Global Maritime and Transportation School at King's Point, to leverage its experience in teaching an approved International Maritime Organization curriculum and its extensive links throughout the world, could pay large dividends for our MSS-enhancement efforts at very low cost.
Next, the number of places available for partner nationals should be increased at the U.S. Naval Academy, Naval Academy Preparatory School (NAPS), Naval Reserve Officer Training Corps programs, and NATO military academia. Partner navies should be encouraged to send students to A, C, and other military schools.
Additionally, Expeditionary and Mobile Training teams could generate similar educational effects by bringing the school to the student. On the staff officer level, a maritime fellows program, in which partner naval officers were embedded in U.S. staffs, would provide us with valuable local knowledge while also exposing our partners to the inner workings of our operations and planning processes. Regionally focused online journals would provide outlets for the strategic and operational insights of partner naval officers generated by their closer interaction.
Third, because we must do more than simply build navies, we should expand admission of partner students to the U.S. Merchant Maritime Academies and investigate the possibility of funding prospective Merchant Marine midshipmen to attend military preparatory schools.
To ensure an appropriate return on educational investment, upon graduation students would incur a service obligation, either to maritime security and safety forces or to commercial port/shipping companies based in their home regions.
Finally, foreign students studying at U.S. universities should be permitted to participate in NROTC college programs and audit naval science courses at no cost, and with no obligation. This would accomplish three objectives: introduce them to the U.S. Navy, integrate them into a positive Navy academic environment, and encourage the eventual pursuit of maritime careers.
Operations and Exercises: Individual learning within the interactive context of combined operations and exercises is guided by the shipboard training teams. High crew-member turnover has necessitated the cultivation of a specific group to shepherd this expertise. The training team is the institutionalization of the "group mind" that provides the ship with its knowledge-base continuity. Training teams provide the institutional support that enables application of expertise developed with running mates, standing watches under instruction, and formal education in actual operations.
Because training teams institutionalize crew learning, they should be the focal point of combined and international interactions. To provide training for the training teams, we need to share drill packages, casualty imposition and disclosure methods, and ideas for challenging watchstanders.
During exercises, initial workshops should focus on team-to-team interactions. For example, over the course of two days, one day the training team from a partner nation, with its running mates, writes a drill package, runs a drill, and debriefs the trainee watch section on the mentor ship. The next day the mentoring team serves as the partner training team's trainers on board the mentee ship.
Extending the Vision—and Experience
Operations and exercises build on the use of running mates, under-instruction watchstanding, and robust training teams. The underway components should be viewed as integrating events during which classroom education and an individual's preparation with a running mate are forged into an actionable understanding of how the U.S. Navy operates. This interaction will then inspire local actors' activities and procedures as they control their own regional MSS enhancement.
With this in mind, what would combined exercises-Cobra Gold, Sea Breeze, Phoenix Express, or an African Partnership Station engagement in the Gulf of Guinea-look like?
- In Port: During the in-port portion of the exercise, in addition to classroom sessions and drills, detailed underway-event walkthroughs should be held, culminating in a fast cruise for each ship. Before the pre-sail briefing, operations order reviews with key personnel on each ship will ensure that everyone is prepared for the underway portion.
Although this may sound unnecessary, in a multinational exercise (just as in many exclusively U.S. exercises), the planners who attend the initial, mid-term, and final conferences are not always able to embark for the actual exercises. Using the in-port phase to ensure that everyone has a comprehensive grasp of the plans is a prudent step to help participants extract the full value from each moment underway.
The training level (basic, intermediate, or advanced) for each event should be decided at the training-team meeting portion of the pre-sail conference. For example, a U.S. ship may have had extensive crew turnover of its visit, board, search, and seizure (VBSS) teams and prefer starting at the basic level, but a Ghanaian ship may be at the end of its training cycle and want to run advanced scenarios. The planners will accommodate these different desired levels to maximize utility of the exercise for all participants.
Under Way: Instead of doing ten different training activities once, it might be better to focus on three (VBSS, main space fire drills, division tactics, for example) and perform them at the basic, intermediate, and advanced levels. This way, each ship will be able to accomplish much of its required training in its focus areas. Completing one activity in a wide variety of events can provide an introduction to the subject, but is generally not sufficient to solidify the grasp of the material necessary to become qualified.
The multinational exercises should take full advantage of crew swaps, when members of one crew (including the training team) embark on another ship. Even if just for a day, the lived experience of being under way on a different platform will dramatically improve interoperability.
Using this approach, U.S. activities can be designed to help partners train regional maritime professionals, no matter what uniform they are wearing. Indeed, in many ways such an increase in interaction will be of greater utility to the United States than to our partners. Greater involvement of partners in our academic institutions, exercises, and operations will also expand our access to diverse perspectives, enabling us to cultivate the increasingly diverse set of approaches and skills that we need to meet 21st century maritime challenges.