Maritime Knowledge Base
Browse questions and answers across marine machinery, merchant navy careers, shipboard operations and maritime glossary terms.
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Marine Machinery
Troubleshooting guides for pumps, boilers, purifiers, compressors and auxiliary systems.
Merchant Navy Careers
Questions about joining the merchant navy, exams, cadetships, ranks and sea-time.
Maritime Glossary
Plain-English definitions of shipping, engine-room, navigation and regulatory terms.
Shipboard Operations
Practical Q&A for watchkeeping, safety, maintenance routines and onboard documentation.
Results for "Water seal"
Why is my fuel or oil purifier not separating properly?
The usual causes of poor purifier separation — feed rate, temperature, gravity disc and water seal, sludge and bowl condition — and how to work through them one at a time.
Shipboard OperationsWhat is an inert gas system on a tanker and why is it needed?
An inert gas system fills a tanker's cargo tanks with oxygen-poor gas so the atmosphere cannot support combustion, preventing explosions in and around the cargo.
Marine MachineryHow does a marine centrifugal oil purifier work?
A marine purifier cleans fuel and lubricating oil by spinning it at high speed so that water and solids separate out — here is the working principle.
Marine MachineryWhat is the stern tube and stern tube seal on a ship?
The stern tube is the tube through which the propeller shaft passes out of the hull; it carries the aft bearing and a seal that keeps seawater out and lubricant in.
Shipboard OperationsWhat are the key steps in a safe bunkering operation?
The essentials of safe bunkering — the agreed plan and checklist, scuppers and SOPEP readiness, communication, monitoring and verifying the figures.
Shipboard OperationsWhat are the classes of fire and which extinguishers are used on ships?
Fires are grouped into classes by what is burning, and each class needs the right extinguishing agent — using the wrong one can be ineffective or dangerous.
Marine MachineryHow does a marine centrifugal pump work?
A centrifugal pump moves liquid by spinning it with an impeller, which throws the liquid outward and converts its speed into pressure — the most common type of pump aboard ship.
Marine MachineryWhy does a marine centrifugal pump lose suction or stop pumping?
A centrifugal pump that loses suction has usually lost its prime or drawn in air — the causes lie in air leaks, blocked suctions, low levels and cavitation.
Marine MachineryWhat is the difference between a controllable-pitch and a fixed-pitch propeller?
A fixed-pitch propeller has blades set at one permanent angle, while a controllable-pitch propeller can rotate its blades to vary thrust and go astern without reversing the engine.
