The floating structure is V-shaped with an opening perpendicular
to the current. It is composed of two long
booms (Figure 3.2), in front of which the plastic is captured,
and a collection platform, where the plastic is removed
and stored until it can be transported to land.
Collection efficiency and costs must be considered in
determining the ideal number of platforms; however, a
single platform configuration is considered for this study
for simplicity’s sake. The boom angle measures the angle
between one arm of the boom and the direction perpendicular
to the mean current and wind. Each arm of the V
will be a determined length and will be made up of several
smaller repeating boom sections. There will be moorings
at various points along the boom length to maintain
the Array’s position and shape, while also serving to limit
the forces endured by the floating barriers. The distance
between mooring points may vary based on the seabed
geography. The total collection width of the structure is
defined as the width over which plastic is captured by the
booms, equal to the distance between the outer ends of
the V.
Each boom section is composed of three elements (Figure
3.3). The buoyancy element / freeboard remains above
the sea surface and provides buoyancy. It also serves to
funnel floating plastic towards the collection platform. It
is designed to help prevent overtopping (water passing
over the top of the structure), which would likely result in
the loss of trapped plastics. The bottom weight element
acts as a ballast for the boom, keeping it upright and in
position. The skirt is a non-permeable but flexible sheet,
which spans the distance between the freeboard and
ballast and serves to direct plastic towards the collection
platform. In the final concept a tension member is used to
provide required axial stiffness.
The structure is kept in place by moorings, permanent
structures attached to the seabed using anchors. The
mooring lines are connected to the boom via submerged
buoys.