272 Bulletin, Scripps Institution of Oceanography 
2) Hove-to or maneuvering surveys, where the geographical control requires a 
virtual fixed point in space, include serial observations to determine the character 
of local time or space fluctuations in the distribution of properties; coring, deep 
drilling, mud sampling, vertical bathythermograph casts, vertical probing for 
radioactivity distribution, light penetration, and accurate determination of cur- 
rents, waves, plankton spottiness, and other variations with time. 
The present discussion will be limited to the second group, above. The primary 
intent of deep-sea mooring is to maintain a surface float in some geographical 
position with the simplest effective system. The relatively steady forces that tend 
to displace the system are primarily the horizontal drag forces imposed on the 
components by wind and current. These are applied principally near the surface. 
Intermittent impulsive or oscillating forces, both horizontal and vertical, are 
imposed by the waves, and these forces dictate many of the design characteristics 
of the system. The force available to the designer for resisting the displacement 
of the system is almost solely shear force on the bottom material (although other 
possibilities exist). The problem thus is to conduct the horizontal drag forces, 
generated near the surface, some miles vertically so that they are resisted by the 
bottom frictional forces, and to do this in a manner compatible with the other 
forees and design restraints. 
HISTORICAL BACKGROUND 
The history of deep moorings dates back at least as far as 1888-1889, when the 
U.S. Coast and Geodetic Survey Steamer Blake, under the command of J. E. 
Pillsbury, carried out studies of the Gulf Stream. During these investigations 
the Blake was anchored at several localities in depths to 4,000 meters. Subse- 
quently, other vessels were anchored in great depths in the North Atlantic and 
elsewhere. Some vessels, including the Meteor, have been anchored in depths 
greater than 4,500 meters for periods up to two weeks, and the Meteor was 
anchored in 5,500 meters for two days. According to Sysoyev (1957), the Vitraz 
was anchored for many hours at a depth of 9,600 meters. Sysoyev’s historical 
review and critical study of the entire deep-anchoring problem (brought to our 
attention by J. D. Frautschy, Assistant Director of the Scripps Institution) con- 
tains much useful information. 
Because of the weight of the wire involved when anchoring in the deep oceans, 
the wire ropes usually are tapered, multistrand steel ropes of a nonkinking variety. 
The wire ropes used on the Blake and the Meteor had a diameter at the free end 
of about %% inch, which increased to about 5 inch at the winch end. Various types 
of anchors have been used, either singly or in pairs, which weighed between 400 
and 500 pounds. Generally, the anchors have been either of a standard variety 
with somewhat enlarged flukes, or of the mushroom pattern. The Z. W. Scripps 
was anchored successfully in depths of about 1,600 meters with a Danforth anchor 
weighing only 40 pounds. 
The actual technique and equipment used for deep anchoring has varied from 
ship to ship and with the sea and wind conditions at the time. Usually, however, 
the wire rope is led through an accumulator to ease the impulsive loading, over a 
dynamometer, through a braking device, and then over a large sheave or roller 
