Specifications
70
5.8.10 Standard mooring layout
Mooring packages are available for each range of depth. All components are of high quality to
prevent corrosion, and kinking and twisting of the mooring line. Shackles and terminals for easy
mounting are included.
The main principles underlying the standard mooring ‘recipe’ are:
(1) the configuration must be neutrally buoyant
(2) the mooring line length is twice the water depth
(3) the polypropylene line length equals two times the water depth (D) minus the rubber
cord length with a minimum of the water depth plus 5 meters for retrieving purposes.
(4) there is a clearance at both sea surface and seabed to avoid interference with ships and
wrecks.
(5) the ropes are torsion-free to avoid kinking and twisting of the rope and spinning of the
buoy.
The rubber cord has a length of 15 m for de WR-SG and 30 m for the DWR-G and DWR-
MkIII. The length of the polypropylene line depends on the low tide depth of the water,
henceforth indicated by D. A sketch of the mooring is found in Figures 5.8.7(a)-(e).
Datawell rubber cords come in two diameters. To provide the same flexibility to ride the
waves, 0.9 m diameter buoys must be fitted with 35 mm rubber cords and the smaller 0.7 m
diameter buoys must be fitted with the thinner 27 mm rubber cords.
Due to its small size and little residual buoyancy the 0.4 m DWR-G is used free-floating.
No mooring advice is available for the DWR-G 0.4 m.
Sand and mud can become trapped in the open structure of the polypropylene rope. In
time the rope can become sinking instead of floating. To avoid entanglement of the rope a small
in-line float (buoyancy 3 Kg) in the PP-rope, a few metres above the seabed, is advised.
Table 5.8.1 Number of sinkers and floats for various water depths (D)
WAVERIDER
8 m < D < 17 m 1 float 1 sinker
17 m < D < 30 m
30 m < D < 75 m 1 sinker
75 m < D < 140 m 2 sinkers
140 m < D < 200 m 3 sinkers
DIRECTIONAL
WAVERIDER
8 m < D < 17 m 2 floats 1 sinker
17 m < D < 35 m 1 float 1 sinker
35 m < D < 60 m
60 m < D < 85 m 1 sinker
85 m < D < 150 m 2 sinkers
150 m < D < 200 m 3 sinkers