Mooring Lightweight Wave Buoys – A Flexible Design Approach for a Wide Range of Coastal Conditions

Abstract

In recent years, a second generation of wave buoys have been developed that are lightweight, cost-effective and hand deployable, such as the SOFAR Spotter Buoy and the Datawell Directional Waverider DWR-G4. Originally designed as drifting buoys, their size and price compared to traditional wave measurement buoys has led both academic researchers and commercial operators to investigate using them in a moored configuration. This presents many challenges to the mooring engineer as the typical mooring designs used in coastal applications, such as chain catenary moorings or elastomeric taut moorings, are unsuitable for buoys with limited reserve buoyancy such as these.This work aimed to derive a scalable mooring configuration that would allow non-skilled operators to simply and effectively configure a mooring for the SOFAR Spotter Wave Buoy that was simple to build and deploy.Several S-tether mooring configurations were evaluated for dynamic stability, minimization of load deviation on the wave buoy and minimization of anchor load for design environmental conditions, using dynamic analysis in WHOI Cable. These configurations were then tested for robustness and ability to be utilized for a wide array of environmental conditions.A parametric design solution for an S-tether mooring with subsurface flotation was subsequently developed for the SOFAR Spotter Wave Buoy. The S-tether design reduces entanglement risks seen in other proposed mooring configurations.A simple and effective mooring configuration is considered essential for mooring lightweight, cost-effective wave buoys easily and reliably. The design approach was validated through sensitivity analyses and is recommended for similar low-buoyancy surface expressions in shallow waters. This flexible design configuration will enable a larger take up of these wave buoys and provide end users with increased data coverage.