the coastline out to the most dreaded source o has been imperative t one. There are lo organizations all alon large number of d organizations, in orde be avoided. However find a route avoiding often had to make sign
gunnar.berthelsen@nexans.com
HIGH RELIABILITY – LOW COST SUBMARINE CABLE DEPLOYMENT
by Gunnar Berthelsen
Nexans Norway AS, PO.Box 6450 Etterstad, 0605 Oslo, Norway. Abstract: A method is developed to utilize the topology of the anda with verydiscussion short coastal (each in the order Abstract: A method is developed to utilize the topology of the systems, seabed and detailed withcables the permitting parties seabed and a detailed discussion with the permitting parties of some km’s up to 70 km) the cost would be phenomenal. to protect the submarine cables, so that burying has become un-necessary. to protect the submarine cables, so that burying has become un-necessary. Thus, a concept has been developed (where cables are not buried) on five bebased avoided dueprinciples: to fishing and other commercial 1 INTRODUCTION 1 INTRODUCTION activity In most parts of the world submarine systems are In most parts of the world submarine systems are protected • Cable protection is achieved by detailed discussions with protected by burial of heavy cables into the seabed to xthe Cable protection is achieved by detailed mapping of by burial of heavy cables into the seabed to different depths, permitting parties to define areas that must be avoided different depths, depending on the risk of external the allowable areas in order to identify a route where depending on the risk of external damage. Normally very due to fishing and other commercial activity damage. Normally very heavy cables and deep burial is the cable is protected by the seabed topology heavy cables and deep burial is used in shallow waters, used in shallow waters, choosing gradually lighter choosing lighter burial cables and shallower • xCable protection is achieved by detailed of the The protection so successful that amapping lighter-thancables gradually and shallower as the water burial depth as normal cable can be used theincreases. water depth increases. This leads to very high costs in allowable areas in order to identify a route where the This leads to very high costs in installing installing repeater-less submarine systems, which are normally cable is protected by the seabed topology repeater-less submarine systems, which are normally x The cable is installed with a very high accuracy deployed in in “shallow” waters. deployed “shallow” waters. relative to the pre-defined route • The protection is so successful that a lighter-thannormal Norway a coastline of more 22.000 xcable As the lengths are short and the cables light, Norway hashas a coastline of more thanthan 22.000 km km withwith many canroute be used many deep fjords and dotted islands along the coast, so very small, dedicated cable ships can be used. deep fjords and dotted islands along the coast, so submarine submarine cablesway is ofa deploying natural way of deploying cables is a natural broadband networks. • 2TheROUTE cable is SELECTION installed with a very high accuracy relative broadband networks. (Fig 1) (Fig 1) to the pre-defined route Norway has a huge fishing industry, which works from to theare oceans, fisheries is the • the Ascoastline the routeout lengths short and and since the cables light, very most dreaded source of damage to a submarine cable it small, dedicated cable ships can be used. has been imperative to co-operate with them from day one. There are local and regional fisherman’s 2 ROUTE SELECTION organizations all along the coast, so thereworks have from been the a Norway has a huge fishing industry, which large number of detailed discussions with these coastline out to the oceans, and since fisheries is the most organizations, in order to determine which areas should dreaded source of damage to a submarine cable it has been be avoided. However, it has always been possible to imperative to co-operate with them from day one. There find a route avoiding fishing areas, but the cable has are local and regional fisherman’s organizations all along often had to make significant detours. the coast, so there have been a large number of detailed When it with has been which be used discussions thesedetermined organizations, in areas order can to determine to deploy the cable the route selection based been on which areas should be avoided. However, it hasis always modern from fishing multi-beam possible to charts find a generated route avoiding areas,echo-sounder but the cable Theto national cartographic hasdata. often had make significant detours.organization has recently mapped a large portion of the coast by such means, andbeen charts are therefore with veryto When it has determined whichavailable areas can be aused high resolution (objects <1m can be identified). Where deploy the cable the route selection is based on modern charts data arefrom not yet available,echo-sounder new data hasdata. to beThe generated Fig 1: Map of Norway generated multi-beam national specifically for the project using the same technology. cartographic organization has recently mapped a large portion However, it was very early (1985) realized that of the coastthese by such and charts therefore available Using highmeans, resolution chartsarethe cable route is However, was veryinvolving early (1985) realized “normal”it methods heavy cables that and “normal” heavy placing the cable in <1m the “valleys” of the withselected, a very high resolution (objects can be identified). methods burialsolutions equipment burial involving equipmentheavy wouldcables makeand theheavy submarine seabed, avoiding deployment alonghassteep slopes, Where data are not yet available, new data to be generated non-viable. Thissubmarine due to thesolutions fact that non-viable. such solutions would make the Thisaredue avoidingfor ship (Figthe2)same technology. even forsolutions long systems, and witheven veryfor short specifically thewrecks, projectetc. using to expensive the fact that such are expensive long coastal cables (each in the order of some km’s up to 70 km) the cost would be phenomenal. 18 Thus, a concept has been developed (where cables are
When it has been det to deploy the cable modern charts generat data. The national recently mapped a la means, and charts are high resolution (objec