D-3 



KVAERNER MYREN TRENCHING SYSTEM 



Function : Pipe trenching. Pipe diameters ^400 to 1,200mm (l6 to UQ in.). 



Trench depth 2.5m (8.2 ft). 



Operating Depth : 500m (1,61(0 ft) 



Dimensions (LxWxH) : 9.3m x g.^km x 8.2m (30.5 ft x 31.95 ft x 26.9 ft). 



Weight (Dry) : 90t (99 tons). 



Speed : 0.3 kts (500m/hr) (average advance rate) 



Pover : Hydraulic. Signals and power (6.6 kV) are transmitted through a 



TOmm (2.75 in.) diameter cable 550m (l,805 ft) long to five electrical 



motors on the vehicle before being converted to hydraulic power. 



Propulsion : Eight thrusters (vertical and horizontal) are used to 



maneuver the vehicle into position on the pipe. Four pairs of wheels 



grip the pipe and propel the vehicle along it. Four spherical tanks provide 



positive or negative buoyancy by blowing or flooding sea water. The 



spheres are interconnected so that ballast water can be shifted from one 



to the other controlling inclination and enabling the machine to follow 



curved sections and avoid obstacles. 



Tools/Instrumentation : Cutter head 1.8m (5-9 ft) high. CCTV, sonar 



(for docking on pipe and profiling the trench). Sediment from the trench 



is transported by a suction pump and is expelled to the side. 



Navigation : Visually (CCTV) and by a surface acoustic tracking unit. 



Shipboard Components : Display/control console, A-frame for launch/retrieval, 



power supply . 



Support Ship Requirements : Dynamic positioning system. Launch/retrieval 



limits at present are km (l3 ft) significant wave heights. 



Status : Operational 



Builder/Operator : Myrens Verksted A/S 



Oslo, Norway 



