Deep-Diving Submarine Hydrodynamics 313 
BALLAST SYSTEMS 
Although water is ordinarily employed for variable ballast on submarines, the energy 
and pump weights required to eject water at great depths render almost essential the use of 
alternate ballast systems at such depths. Actually four ballast systems are employed on 
the Aluminaut, three of which are variable and one of which is fixed: 
1. The ballast intended for routine ascent at great depths is 4,000 pounds of iron shot, 
contained in two amidship external saddle tanks shown in Figs. 1 and 2. These tanks are 
loaded through filling tubes in the superstructure when the boat is on the surface and 
emptied as desired through hollow solonoids at the bottom of both tanks. When energized 
(they draw only 36 watts each) the solonoids magnetically solidify the shot so as to plug 
the shot-tank aperture. When current to the solonoids is cut, either deliberately or by acci- 
dent, gravity will cause the shot to flow out at any depth of operation. Thus, this system 
which was devised by Piccard for the bathyscaphes is relatively fail safe. To prevent 
electrolytic action with the iron shot, the aluminum saddle tanks are lined and the filling 
tubes molded of plastic. Special measures such as the prevention of exposure of wet shot 
to the air must also be taken to prevent the iron shot from corroding and consolidating. The 
iron shot described here has been successfully used with the bathyscaphes. 
2. To augment the preceding system and also to permit the submergence of the boat 
from the surface to be under the complete control of the pilot within the boat a conventional 
water-ballast system is also provided. The tanks of this system which are also external to 
the pressure hull have a capacity of 3,000 pounds of sea water and are always open to the 
sea. Like conventional submarines, water is excluded from these tanks by means of a 
closed air valve; it can be admitted by opening the air valve and can be ejected from these 
tanks by compressed air stored in flasks located above the pressure hull as shown in Fig. 
1. Because these flasks are initially charged for practical reasons to a pressure of only 
2,200 psi, the water tanks can only be blown at depths less than about 4,800 feet. It is 
this fact that necessitates the provision of the iron shot system for use at greater depths. 
3. For faster (and more reliable in the event of inadvertent flooding) emergency ascent, 
provision is made for jettisoning a 7,000-pound chunk of aluminum-wrapped lead stored in 
the lower keel structure. This ballast can be quickly released by the pilot by a simple 
mechanism that cuts two 1/4-inch-diameter supporting cables. The penetrations for these 
cables are the only mechanical penetrations of the pressure hull. 
4. The remaining ballast is fixed and is divided between nonwastable ballast needed 
for stability purposes and wastable ballast margin available for design, construction, or 
future growth. Two thousand pounds of nonwastable ballast for stability purposes is 
located very low in the boat in the free-flooding keel in the form of solid aluminum bars. 
Five thousand pounds of wastable growth margin (on paper until the boat is completed) is 
allowed for at the location of the center of ‘gravity of the entire boat. Upon completion of 
the boat, the remnant of this margin would actually have to be installed as ballast in the 
keel with the nonwastable ballast where it would further improve stability. The distinction 
between these two kinds of fixed ballast is further clarified in Section 5 of Ref. 2. 
The three variable ballast systems permit the submarine to be operated at a great 
variety of equilibrium and nonequilibrium conditions. The more important of these condi- 
tions for the Aluminaut are tabulated in Table 2, which also shows the freeboard to the 
deck for the surface conditions and the metacentric heights for all conditions. Some of the 
same information is illustrated in Fig. 4. 
