The TRIAXYS Directional Wave Buoy has special mooring requirements that need to be observed in order to achieve maximum performance. The key feature required is the need to de-couple the mooring from the buoy to allow unrestricted buoy motions in wave fields. The de-coupling is accomplished either by operating the TRIAXYS™ buoy in an untethered free-floating configuration, or by use of a compliant mooring section. The compliant mooring section is composed of a special extruded 32 mm (1.25”) rubber cord, 15 m in length, terminated with stainless steel compression fittings. The elastic nature of the compliant component allows the TRIAXYS™ buoy to follow waves in an unrestricted fashion. The compliant section is usually attached directly to the buoy. Please see below for links to sample mooring diagrams.

The mooring connection to the buoy should be made with a 12 mm stainless steel swivel. The swivel reduces the chance that the mooring will become fouled in the presence of rotary tidal currents. There are no requirements for external ballast as the buoy’s internal batteries provide the proper dynamic stability for the buoy’s operation.

The balance of a TRIAXYS™ mooring requires the following:
 

• For depths of up to 75m, a simple means to calculate the component lengths are as follows:
• Mooring Depth (m) x 2 = total mooring length (TML)
• TML – compliant mooring segment (15 m) = residual mooring length (RML)
• RML / 2 = length of each polypropylene line and Spacelay™ components
• Note: Spacelay™ is an anti-torque nylon coated wire.
   

The polypropylene line is lifted off the bottom to prevent any accelerated wear by using auxiliary floatation on the lower segment of the mooring. By virtue of the neutrally buoyant compliant section and the positively buoyant polypropylene line, the design of this mooring will not add any residual weight to the buoy. The only vertical weight component added to the buoy is from current drag on the buoy and mooring.

Another consideration that must be taken into account is that mooring components must be selected to ensure they are electrolytically and mechanically compatible. Isolation of dissimilar metals is imperative to prevent galvanic corrosion that will cause premature mooring failure. This can be accomplished by using “like materials” (e.g., SS 316 with SS 316) or isolation bushings (e.g., nylon thimbles) to prevent contact of dissimilar materials. For long-term deployments the use of anodes on metal components is recommended. Shackle sizes should be chosen so that safe working loads are not exceeded during deployment and recovery operations, as well as for wear factors during deployment.

Please click on the links below for sample mooring diagrams: