Seabed Plow Over-the-Stern Release and Retrieval
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Solution Overview
Problem
Current seabed trenching equipment for pipe and cable laying is inefficient, requiring large, costly vessels and cranes for operation, and faces challenges such as boulder clearance, trench cutting, and backfilling, which are time-consuming and risk the integrity of the pipeline.
Innovation Solution
A multi-mode seabed-plow chassis with a skid and tools for boulder clearing, trench cutting, and backfilling, featuring a transition surface for over-the-stern launch and retrieval, reducing the need for large vessels and enabling efficient operation with smaller vessels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional trench cutting plows are used, then trench cutting capability is achieved, but the equipment requires large vessels and cranes for launch and retrieval, increasing cost and complexity
Solution Approach 1:
The plow is divided into separable components including a plow body, skid, and moldboards that can be independently assembled and disassembled. This segmentation enables the plow to be launched and retrieved without requiring complex crane operations, as components can be deployed individually or in simplified groups.
Solution Approach 2:
The plow design incorporates multiple functions within a single device structure. The same plow body and skid assembly can perform trench cutting, backfilling, and boulder clearing operations by attaching different tool assemblies, eliminating the need for multiple specialized vessels and equipment types.
2Ease of operation
If traditional backfill plows with skids riding in the trench are used, then backfilling capability is achieved, but the pipe integrity is compromised due to contact risk
Solution Approach 1:
Instead of having the skid ride in the trench near the pipe as in traditional designs, this invention inverts the approach by positioning the skid to ride on the seabed surface outside the trench. The moldboards then extend backward to engage and move the spoil, reversing the traditional sequence and spatial arrangement to eliminate contact between the skid and the buried pipe.
3Productivity
If traditional boulder removal methods are used, then boulder clearance is achieved, but the process is time-consuming and requires divers or ROV to connect cables to boulders
Solution Approach 1:
The invention merges the boulder clearing function with the plow assembly by integrating moldboards directly onto the plow body. This combination allows the plow to clear boulders during its normal towing operation without requiring separate boulder removal operations, divers, or ROV interventions, significantly reducing time loss.
4Productivity
If traditional trench cutting plows are used, then trench cutting capability is achieved, but the number of passes and trench depth are limited by skid width
Solution Approach 1:
The plow incorporates adjustable and reconfigurable components including the skid position and moldboard angles. This dynamic capability allows the plow to adapt to different trench depths and widths, enabling multiple passes at varying depths and configurations to overcome the limitations of fixed-width skid designs.
Data Source
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AI summary
A seabed plow capable of over-the-stern release and retrieval is usable in any of boulder clearing, trench cutting and backfill modes. In its boulder clearing mode, the plow uses its skid in torquing configuration followed by moldboards to push boulders out of the path to be trenched. In the trench cutting mode, the plow uses the skid in the same configuration with its share and moldboards for initial trench depth and the same share and moldboards with moldboard extensions for increasing trench depth in subsequent passes. In the backfill mode, the plow uses its skid in trench-straddling configuration following a blade with a passage designed to discharge fragmented spoil directly onto the pipe being covered. Thus, a single plow can be reconfigured for all modes for release and retrieval to and from a relatively small vessel without use of heavy lifting equipment.