Method and apparatus for entrenching an enlongated under-water structure

Apparatus for entrenching an elongate submarine structure such as a pipe or cable comprising

• a vehicle having a front and a rear and adapted to be moved along the floor of a body of water;
• a first auger assembly mounted at a location offset toward one side of the vehicle;
• a second auger assembly mounted at a location offset toward the other side of the vehicle;
• means mounting said assemblies on said vehicle for movement to a first position in which the augers are spaced apart to receive therebetween the pipeline to be entrenched, and to a second position in which the augers are inclined inwardly and lower end portions of the auger assemblies are adjacent to each other beneath the elongate structure;
• motor means on said vehicle for moving said augers to said first and second positions;
• each auger assembly comprising
• an auger having an upper portion and a lower portion;
• motor means for rotating the auger;
• a casing partially surrounding said lower portion to leave a front face of the auger exposed for cutting, said casing cooperating with said auger to convey bottom material toward the upper portion of the auger;
• and
• casing means substantially enclosing said upper portion and cooperating with said upper portion for conveying the material away from the trench thus formed by the augers.