Groynes are structures that run perpendicular to the coastline and intercept the transport of sediment within the surf zone. As well as preventing beach erosion, groynes facilitate sand accretion by slowing down water velocities.

Conventionally, groynes consist of rock mounds or timber or steel sheet piles. For rock mound groynes, it is common practice to place a layer of Mirafi® woven geotextile across the base of the groyne prior to placement of the rock. The geotextile filter prevents the erosion of the soil foundation and the consequent undermining of the rock mound groyne. Conventional groynes composed of rock or sheet piles have lost their favour because of the unsightly appearance and public safety issues especially where they are located close to popular beaches.

An alternative groyne structure that does not require the use of rock or sheet piles utilises Geotube® units. The Geotube® groyne is installed insitu using locally available sand fill. To prevent erosion around the sides of the Geotube groyne, a scour apron such as the Mirafi® FM fascine mattress can be installed prior to the installation of the Geotube® groyne. For safety, the surface of the Geotube® groyne is smooth and cannot cause injury to the public.