A Technical Description of Floats
by Elsa Garmire
Bob Breer and Fujiko Nakaya looking at the chassis for the Floats.
On the plaza in front of the Pavilion are seven white "floats" which move about slowly, emitting soft sounds. These dome-shaped sculptures are six feet high and six feet in diameter.The outer shell of each is made of a single unbroken piece of fiberglass, 3/16" thick, made by spraying fiberglass into a hollow female mold. The rigid fiberglass shell rests on a plywood skirt so that the shell comes as close to the ground as possible, giving the sculpture a floating appearance. This illusion is enhanced by a "floating" of the shell on the base frame. A number of ball bearing swivel wheels attached to the frame support the shell with a 1" freedom of motion.
The structural steel frame which supports the 800 Ib. weight (batteries are heavy) rolls on three rubber-tired wheels. Two of the wheels are mounted so as to caster slightly. This means that the floats do not travel in straight lines. If left to their own devices they would travel in very large rosettes. When, however, a float touches something, it reverses direction. Thus the float backs away from a wall, another float, or when it is touched. This capability occurs because the motion of the fiberglass shell with respect to the structural frame trips push-type snap-action switches. These switches operate a latching relay to reverse the polarity of the D.C. motor. Upon reversing direction, the wheels caster slightly in the opposite direction so that the float never retraces its path. The velocity of the floats is 2/3 inch per second; less than three feet per minute. One of the wheels is driven by a 1/3 horsepower direct current motor with the energy supplied by four storage batteries. These 24-volt storage batteries are similar to those used in cars and contain 170 ampere hours. During a single day only a quarter of the energy capability of the batteries is used up. The floats recharge at night in a special recharging bay.
Fail-safe direction reversal is provided if the snap-action polarity-reversing switch fails. An override is provided for reversing direction automatically if the armature current exceeds a certain adjusted value. In addition the entire unit will shut down if there is a further increase in armature current above the reversing level. A battery-operated tape-loop transistor player inside the float provides sound.