284 Bulletin, Scripps Institution of Oceanography 
proposed depth. An unpressurized spherical steel tank, 34 inches in diameter and 
with a wall thickness of 7% inch, has been successfully pressure-tested to a depth 
of 1,500 feet. The drag of the submerged float is small in comparison with the 
other drags of the system, and streamlining has not been contemplated. Stream- 
lining involves an asymmetry and an orientation in the system which are dis- 
advantageous where any wave action occurs, because the float will continuously 
rotate. 
An interesting modification of the spherical buoy, which will pay out addi- 
tional wire as soon as the design tension of the pennant is reached, has been used. 
This self-reeling submerged float functions as shown in figure 6. The surface line 
is wound around the large reel of diameter D,, and the bridle is wound around 
two smaller reels of diameter D, on opposite sides. All three spools have the same 
axis of rotation and are fixed relative to one another. When the tension in the 
pennant exceeds (D;/D,;) x B (buoyancy), the float winds down the bridle releas- 
ing a length of wire D,/D, times the distance traveled until the stress in the 
pennant falls below (D,/D;) x B or the buoy is two-blocked against the bridle. 
The advantages of mooring with such a float are as follows: the instrument line 
may be one with the mooring line, thus eliminating the undesirable situation of 
two lines over the side; the instrument mooring line may be retrieved for inspec- 
tion, servicing, or replacement by merely heaving in; the additional scope neces- 
sary to accommodate extreme sea conditions is provided; and a nearly vertical 
pennant line may be used, thus greatly reducing the hazard caused by surface 
traffic. This self-reeling float is normally used in conjunction with an elastic pen- 
nant (fig. 5), which is designed to accommodate the wave-induced displacements 
of the surface buoy. Therefore the self-reeling float needs only to accommodate 
the larger deflections caused by extremes of wind and current. 
In selecting the design depth for the submerged float, the following may be 
among the eriteria: (1) the submerged float should be deep enough to escape 
being run down; (2) it should be deep enough to minimize the effects of surface 
waves; (3) it should be at the greatest depth at which observations are desired 
(fig. 5); (4) it should be at a depth that divers can reach; (5) it should be deep 
enough to escape surface currents, that is, below the thermocline; and (6) it should 
be deep enough to escape surface fouling. The depth most often used at Seripps 
has been 150 feet. 
Moorine CABLES 
One of the technical problems of anchoring or of installing a mooring in deep 
water is shown in figure 7. Here is depicted the ultimate tensile strength neces- 
sary for a steel wire of uniform cross section to be used at any depth in the sea 
when bearing an additional load equal to its own weight. (Also, an allowance 
must be made for weakening of the wire by handling and by corrosion.) Figure 7 
also shows the percentage of the ocean area at a depth less than the ordinate. 
Using this allowable-depth criterion, it is apparent that wire of an ultimate tensile 
strength of 100,000 psi may safely be used to a depth of about 1,700 fathoms, or 
in about 30 per cent of the oceans. A wire of an ultimate tensile strength of 
180,000 psi, however, may be employed to 3,000 fathoms, or in 99 per cent of the 
