Since the 1850s, submarine cables have played an integral role in international data transmission and are now crucial to the growth of offshore renewables sector. Adequate protection of submarine cables is vital so that they remain safe from threats such as fishing gear, shipping anchors, dredging and other dropped objects for the lifetime of the asset. Majority of existing offshore wind farms have experienced some form of cable problem, most frequently during the construction stage. Although subsea cables account for only 11 percent of CAPEX, nearly 80 percent of insurance claims against offshore wind developments are related to cable damage. Most of these damages are due to fabrication and installation issues. While understanding the threat to a cable is essential in assessing the lifetime risk to the system, understanding the whole life cost of the system including installation cost, insurance, cable repairs or loss of revenue is essential for development decisions.
Cable burial is generally regarded as the optimal protection technique, and first came into play in the 1970s. The standard burial depth was ~0.6 meters for many years, mainly to provide protection against fishing gear. The Burial Protection Index (BPI), developed in the 1990s for fibre optic communication cables, was a best practice for submarine cables for over a decade. However, the method had several limitations including its conservative approach to anchoring and fishing and ignoring the influence of water depth and sediment mobility. Some of these limitations were overcome through the engineering acumen of design team, however, this limited the standardization and repeatability of design and led to over-conservatism from perceived threats.