A buoyancy control system for controlling the buoyancy of a tube may
includes generally tubular length of buoyancy control material having a
selected buoyancy characteristic. The length of buoyancy control material
may be attached to a section of the length of the tube to adjust the
buoyancy of the section of the tube. The length of buoyancy control
material may be an integral, coaxial layer of the tube or, alternatively,
the length of buoyancy control material may be externally attached to
tube. In embodiments in which the length of the buoyancy control material
is externally attached, the buoyancy control material may have a
longitudinal axis that is spaced-apart from a longitudinal axis of the
tube.