Specifications
64
5.8 Mooring
The correct mooring of a wave buoy is essential to measuring wave parameters according to
specifications, see also section 5.2. The design of an appropriate mooring requires knowledge of
the current speed and profile, the depth, tides, wave height and sometimes the seabed structure.
To help our customers in finding a good mooring solution, Datawell has developed a standard
mooring lay-out that applies to a wide range of situations. The pivoting component is a rubber
cord that provides the flexibility to ride waves up to 40 m.
First, a general remark on mooring materials is made. After that, all previously mentioned
parts of the mooring are described in more detail from the bottom up. Finally, attention is given
to complete mooring lay out and the effect of depths and currents. Note that the DWR-G 0.4 m
buoy is used free-floating, without a mooring.
5.8.1 Stainless steel
In a marine environment corrosion is a problem and stainless steel parts are crucial for the
longevity of the mooring and buoy. All metal parts supplied by Datawell, such as the chain,
swivel and metal parts of the terminals, are of AISI316 stainless steel. Every production run is
sampled for all separate elements and tested to ensure that the composition lies within AISI316
specifications.
The only exceptions to stainless steel are the aluminium sinker, the anchor weight and the
attached shackle which is made of plain steel.
5.8.2 Anchor weight
Forces on the 0.9 m diameter buoy under normal conditions do not exceed 100 Kg. Therefore an
anchor weight of 500 Kg suffices (300 Kg for 0.7 m buoy). Datawell advises a steel chain tied
together. In contrast to concrete steel retains most of its weight under water.
5.8.3 Shackles and split pins
Figure 5.8.1 shows a shackle and split pin. After fastening the nut on the shackle bolt it must be
secured against unscrewing by applying a split pin. Push both legs of the pin through the hole in
the bolt and bend them back, one leg round each side of the bolt. Bring a suitable pair of pliers
and a few spare split pins (included). All shackles and split pins are AISI316 stainless steel,
except the one connecting the anchor weight.
Figure 5.8.1. Shackle with split pin.