Propeller, Shafting & Stern Tube

The shafting volume: what the system carries and how it is sized, bearings, the thrust block, couplings and bolts, the propeller shaft, faults and withdrawal, water- and oil-lubricated stern tubes, split stern bearings, seals, alignment, the propeller, reduction gearing and the ancillaries.

14 Topics In this Sub-topic

Propeller, Shafting & Stern Tube Topics

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01 The Shafting System — What It Carries and How It Is Sized The shafting system carries the engine's torque out through the hull to the propeller, takes the propeller's thrust back into the ship, and holds the weight of the propeller while the hull bends underneath it. Beginner · 11 min read · 9 sections 02 Shaft Bearings — Plain, Tilting Pad and Roller The intermediate shafting runs between the thrust block and the stern tube, and it has to be carried. Intermediate · 8 min read · 8 sections 03 The Thrust Block and Thrust Shaft — Clearance, Pads and Support The thrust block is the one bearing in the shaft line that takes the ship's drive out of the shaft and puts it into the hull. Intermediate · 10 min read · 9 sections 04 Shaft Couplings and Coupling Bolts — Flange, Hydraulic and Muff The shaft line is built in lengths, and every joint between them is a place where the drive has to pass from one shaft to the next and where the line has to be got true. Intermediate · 9 min read · 8 sections 05 The Propeller Shaft — Liners and Propeller Mounting The propeller shaft is the part of the line that is under water, carries the propeller, and has to be protected against the sea and against the propeller's own weight. Intermediate · 11 min read · 8 sections 06 Propeller Shaft Faults, Weardown and Withdrawal The propeller shaft is the one part of the shaft line that cannot be inspected while the ship is in service, and it is also the part that fails catastrophically when it does fail. Advanced · 9 min read · 7 sections 07 Sea Water Lubricated Stern Tubes — Staves, Water Supply and Rewooding The stern tube is the bearing at the after end of the shaft line, and the oldest way of lubricating it is with the sea. Intermediate · 9 min read · 8 sections 08 Oil Lubricated Stern Tubes — White Metal, Lip Seals and Header Tanks The oil-lubricated stern tube is the modern arrangement. Advanced · 10 min read · 8 sections 09 Split Stern Bearings and Withdrawable Stern Gear The stern tube bearing is the hardest part of the shaft line to reach, and the traditional answer — drydock the ship and draw the shaft — costs a docking every time the bearing has to be looked at. Advanced · 13 min read · 9 sections 10 Stern Tube Seals — Lip, Floating Ring and Radial Face The seal is the part of a stern tube that fails, and the part that decides whether the ship can be worked afloat. Intermediate · 12 min read · 9 sections 11 Shaft Alignment — Datums, Sighting Methods and the Jacking Check Alignment is the subject that ties the shaft line together. Advanced · 21 min read · 10 sections 12 The Propeller — Fixed Pitch, Controllable Pitch and Cavitation The propeller is the machine that turns the engine's torque into thrust, and it is the only part of the plant that works in the sea. Intermediate · 16 min read · 11 sections 13 Reduction Gearing, Flexible Couplings and Clutches A medium-speed diesel does not turn at a propeller's speed, and the machinery that sits between the two is the reduction gearbox. Advanced · 12 min read · 11 sections 14 Shafting Ancillaries — Friction Brake, Torsionmeter and Earthing Device The shaft line carries three fittings that are not part of the drive and not part of the support, but that the engineer has to know about: the shaft friction brake and the trailing collar, which are there for when the engine has failed; the torsionmeter, which is how shaft power is measured and how the torsional characteristics of the line are checked; and the shaftline earthing device, which is a small electrical fitting that prevents a large and expensive mechanical failure. Beginner · 15 min read · 12 sections