The experienced ship watchkeeping engineer is aware of duties regarding auxiliary equipments. This including their location, function, and operating parameters in particular their optimum working temperatures and pressures. The following sections shows the location of these auxiliaries such as the flywheel, generator engines and so forth, noting their purpose and what the watch-keepers duties are in relation to their efficient running.
Please refer to sketch below when reading these notes.
There are normally three generators;
On standby or near coast – 2 generators synchronized on switchboard, 1 standby
At sea 1 generator on switchboard 2 on standby or 1 standby and 1 stripped for overhaul
In port- 2 generators synchronized on switchboard, 1 on standby
Note that there is always a generator on standby, in case of blackout
Watch-keeper duties are as per main engine- temperature and pressure checks, lube-oil checks, using instruments and touch.
2. Main switchboard
The main switchboard can be located in the control room or in the engine room, normally on the next level up from the generators
Remember this is a dangerous piece of equipment as it has live 240V High Voltage busbars, control breakers and panels at the rear. The front section houses the main gauges, generator synchronizing lights and speed control buttons. Notice the black rubber mating on front of the switchboard, this is for standing on to insulate one against electric shock whilst operating the controls. Watch-keepers duties are to check the voltage, cycles (Hertz) and amperage regularly, and if two generators are on line ensure they are sharing equal loads.
The purpose of the flywheel is to maintain the inertia of the engine after firing up it is usually cogged around the rim so engine can be turned using the turning gear. Watch-keepers normally paint one of the cogs white to show rotation speed when turning the engine on air prior switching to fuel. This is used as a guide to engine rotation speed as if the engine is switched fuel too soon it may not start, and on next injection of air may cause a relief valve to lift.
4. Thrust block
The purpose of the thrust block is to resist the thrust generated by the shaft rotation transmitting it to the ship’s hull. Watch-keepers duties are to check temperature regularly by instrumentation and by touch ensuring adequate lubrication.
5. Propeller shaft tunnel watertight door
This is a vertical watertight door which can be shut manually in an emergency, such as the tunnel flooding. Watch-keeping duties are to operate the door once a week, usually the same day as lifeboat duties.
6. Propeller shaft bearings
Also known as tunnel bearings, these are white metal bearings which take the load of the prop shaft ensuring even running. They are lubricated by ring feed i.e. the bottom of the ring is immersed in the oil bath and rotates with the shaft thus transferring the oil from the ring to the bearing. Watch-keeper duties include hourly checks for oil level on the bearing oil sight glass and any excessive temperature or vibration by touch.
7. Stern gland.
The stern gland prevents ingress of seawater to the shaft tunnel. It is packed in a particular manner whereby the packing strips (oil and graphite impregnated) are cut to fit precisely around the shaft and between the shaft and the stuffing box. The packing strips are mitered at 45° at the ends inserted to the stuffing box, using a hammer and a dog-leg piece of wood, staggering the ends as per the clock i.e. 3, 6, 9 and 12. Once the gland is fully packed, refit the gland ring over the studs and again tighten as per clock. It is always best when stripping out an old gland to use a special tool resembling a large corkscrew and to count the number of packing strips removed, so you know how many are required to repack it.
Remember it must be done right, you only get one shot at this in drydock, once the dock is flooded if leaks profusely despite re-tightening the gland nuts, hard cheese! They will have to pump out the dock again to investigate cause which is usually down to the gland packing method.
Watch-keeper duties include tightening the gland to minimize seawater seepage to a minimum in port (to minimize pumping of tunnel well bilge. Readjusting gland at sailaway and checking hourly by hand for heat and looking for excessive ingress of water whilst underway.