Clamp on Blade (CoB) Replaceable Blade Propeller

The Teignbridge Clamp on Blade (CoB) propeller is a UK-patented replaceable-blade propeller. Individual damaged blades can be replaced, often without dry-docking, instead of replacing the whole propeller. It was developed with the Energy Technologies Institute in a 3-year project aimed at improving propeller efficiency and cutting fuel consumption and greenhouse gas emissions.

Key features

• Patented blade clamping design with a hub diameter ratio typically only about 5% higher than a conventional mono-bloc fixed-pitch propeller
• Fewer bolt heads on the hub surface than radially bolted designs, which improves flow around the hub
• Fully CNC-machined parts, so replacement blades are interchangeable and a single spare blade can be carried on board
• Blades can be changed by a diver on propellers up to 1.2 m diameter
• The propeller design can be revised later to match changes in the vessel's operating profile
• Developed and validated with CFD and FEA, physical destructive testing and Teignbridge's Hydrodynamic Research Vessel (HRV1)

Technical data

• Diameter range: 0.75 m to 5.50 m
• Shaft fitting: keyed or hydraulic
• A 5.5 m propeller fits in a 20 ft shipping container for transport

Carbon fibre blade option

• Carbon fibre composite blades on the CoB hub give a lighter propeller with lower driveline vibration and noise than metallic propellers, which is useful with electric drive where noise, vibration and harshness (NVH) matter
• Fibre layup and thickness are tailored for strength and stiffness. Controlled blade flexibility delays cavitation inception and damps vibration
• Lower weight and moment of inertia allow smaller shaft diameters

Applications

Merchant, commercial, military and leisure vessels, including superyachts.