How ships work

One enormous diesel engine turns the propeller directly — no gearbox. It runs slowly on purpose, because a big slow propeller is the most efficient way to push a heavy hull through water.

Uniflow-scavenged two-stroke crosshead engine, electronically controlled injection and exhaust valve timing, reversible, 70–105 rpm, driving a fixed-pitch propeller through a solid shaft line.

Three or four smaller engines make the ship's electricity. At sea one may be enough; in port, with cargo pumps or cranes running, most of them are on the board together.

Medium-speed four-stroke prime movers at 720/750 rpm driving synchronous alternators, paralleled on the main switchboard with automatic load sharing and preferential trips.

The wheel on the bridge sends an electrical signal aft. Hydraulic pumps do the actual work of turning the rudder, and there are always two independent systems.

Rotary vane or ram-type gear, duplicated power units and piping, capable of 35° port to 30° starboard in 28 seconds at full load draught and service speed.

An empty ship floats too high to be safe or to steer properly, so it fills tanks with seawater. That water has to be treated before discharge so it doesn't carry organisms between oceans.

Segregated ballast tanks served by dedicated pumps and an approved treatment system — filtration plus UV or electrochlorination — logged against the ballast water record book.

If the ship loses all power, an emergency generator starts on its own within 45 seconds and feeds the essentials — steering, navigation lights, emergency lighting, radio.

440 V / 60 Hz main distribution with 230 V lighting transformers, emergency switchboard fed by an independent diesel set above the bulkhead deck, plus a transitional battery supply.

The bridge is built around cross-checking. No single instrument is trusted alone — the chart, the radar and the compass all have to agree before the officer accepts a position.

Dual ECDIS with independent power, X- and S-band radar with ARPA, gyro and magnetic compass comparison, GNSS receivers, echo sounder, speed log and VDR.