CHECK YOUR PROGRESS - MED 3 – ANSWERS:

Question 1.

List six engine room pre-departure checks on a vessel with a diesel motor.

Make sure that all work carried out to the engine has been completed and that there are no tools or rags, materials or parts lying on the engine.
Ensure that there are on the engine, especially the exhaust area. Check the whole engine is free from fuel and lubricating oil.
Sea water strainer is clean and open the sea connection valve and, if fitted, the overboard discharge valve. Ensure there are no sea water leaks.
Water level in the fresh water header tank and ensure there are no fresh water leaks.
Condition of all hoses.
Sufficient fuel in the fuel tank for the intended voyage plus a reserve amount of fuel.
Check the oil level in the sump shows full.
If a turbo charger is fitted and has its own lubricating system, check that the level in the sight glass is at the upper line.
Check that the batteries are clean, charged, the electrolyte level is above the plates and the terminals are clean and tight.
Switch on power to the starter motor. Give the engine some throttle. Engage the starter motor. The engine should rotate and fire.
Immediately check the oil pressure.
Listen for any unusual noises, especially hard metallic knocks.
Check for fresh water, sea water, lubricating oil, fuel oil and exhaust gas leaks. Ensure sea water is being discharged overboard. The engine fresh water temperature will slowly rise and stabilise at its operating temperature. The lubricating oil pressure will drop from

Question 2.

List in order and describe the details of your checks to investigate the reason why your diesel motor is apparently mechanically sound but is sluggish to turn over when the starter motor is engaged.

Battery capacity low

Check that electrolyte level is above the plates.

Try to start the engine on the other bank of batteries.

Take the specific gravity of each cell of the battery.

Battery connections dirty

Check that the connections to and on the battery is clean and tight. A dirty or loose connection can be identified by the heat it generates.

Bad electrical connection to starter motor

The starter motor draws the most load on the battery especially on diesel engines because of their high compression ratios. The electrical connections must therefore be tight and clean.

Faulty starter motor

The starter motor could be burnt out or the pinion is not engaging with the ring gear on the flywheel.

Incorrect grade of lubricating oil

If the oil is too thick, the engine will not attain sufficient speed on the starter motor to generate the amount of heat required on the compression stroke to ignite the fuel.

Engine has been overhauled and is tight

The parts of an overhauled engine are brought back to their correct clearances. In these clearances there will be a number of high spots and they will be worn away as the engine is run in. There must be sufficient air and no restriction in the exhaust gas system.

Question 3.

List the two most common reasons for a diesel engine to turn over readily with the starter activated but still fail to start.

Fuel restrictions:Air in fuel system, Fuel tank empty, Faulty fuel injectors, Faulty fuel lift pump, Choked fuel filter, Faulty fuel injection pump, Incorrect fuel pump timing

Air restriction:

Cold engine:

Other issues: Exhaust gas restriction, Poor Compression, Incorrect valve timing, Cylinder head gasket leaking, Fuel injector, Incorrect tappet adjustment, Sticking valves, Worn cylinder liner bores, Pitted valves and seats, Valves not seating correctly, Broken, worn or sticking piston rings, Piston ring gaps in line

Question 4.

With the engine at its operating temperature, the colour of these exhaust gasses would indicate:

Black smoke / Too much fuel
Blue smoke / Too much oil
White exhaust vapour / Water/steam

Question 5.

List three possible causes of an overheating engine. Describe what action you would take to avoid engine damage in each case

Sea Water Temperature Too High

Sea Water Intake Rose Or Grid

Clogged Sea Water Strainer

Thermostat Not Opening Fully

Faulty Impeller In Sea Water Pump

Keel Cooling Pipes Not Effective Due To Marine Growth
Air In Sea Water Cooling System

Insufficient Speed Of Sea Water Pump

Faulty Impeller In Fresh Water Cooling Pump

Build Up Of Scale On Cylinder Water Jackets,
Fresh Water Cooling Level Is Too Low

Air In Fresh Water Cooling System

Dirty Or Fouled Fresh Water Cooler

/ Clear or repair
Blown Cylinder Head Gasket
Fuel Injection Into Cylinders May Be Too Late
Low Compression / Repair
Engine Overloaded
Engine Parts May Be Too Tight Causing Friction / Slow down

Question 6.

List a possible causes of each of the symptoms tabled below.

1. Each time the engine starts readily but quickly fails after a few moments. / Air in fuel
2. There is a milky white scum in the header tank cap. / Lube oil in water- Blown head gasket, blowm lube oil cooler seal
3. There is excessive consumption of oil. / Worn cylinders, oil too thin
4. There is low compression in one of the cylinder heads. / Damaged rings, cylinders, valve seatings.
5. The oil pressure is very high. / Faulty pressure relief valve
6. The oil pressure is very low. / Cold engine, too heavy oil
7. The raw water cooled exhaust discharge becomes exessively loud. / Blocked screen
8. The stuffing box becomes exessively hot. / Too tight stern gland
9. Water keeps collecting in a sealed fuel tank. / Broken seals, return fuel line cooler
10. The motor has excessive vibration and runs irratically. / Timing, injecters, harmonic balance

Question 7

What is the:

a. Flash point of diesel ______60ºC

b. Flash point of petrol ______0ºC

c. Operating temperatur e of a diesel motor______85ºC

d. Specific gravity of a fully charged batteries electrolite______1250

e. Specific gravity of a fully discharged batteries electrolite______1150

f. Voltage over twin 12 volt batteries connected in series______24V

g. Voltage over twin 6 volt batteries connected in parallel______6V

h. Watts per hour used by a 2 amp light globe in a 12 volt circuit _____24Watts

i. Explosive gas emitted by charging batteries______Hydrogen

j. Poisonous gas emitted by salt water contaminated batteries______Chlorine

k. Colour of a wet chemical fire extinguisher______Red & oatmeal band

l. Purpose of a glow plug______Preheat cylinder

m. Purpose of a turbocharger aftercooler______Increase density of air

n. Revolutions of a crankcase to each work cycle in a two stroke motor__One

Question 8

Sketch the pump type below to explain its operation and give an example of its use.

Show me these pumps

a. Impeller pump ______raw water

b. Centrifugal pump______turbocharger

c. Piston pump______fuel injector pump

d. Diaphram pump______lift pump

Question 9.

a. Two 12 volt batteries joined in parallel now produce 24 volts. True / False

b. A screw lift valve only allows fluid to travel in one direction. True / False

c. Foam extinguishers can be used on electrical fires. True / False

d. Fuel is injected once for each revolution of the crankshaft of a four stroke motor. True / False

Question 10.

a. L.P.G. is lighter than natural gas. True / False

b. Blue exhaust smoke indicates unburnt fuel. True / False

c. Petrol is lighter than water. True / False

d. The crankshaft turns twice each work cycle of a two stroke engine. True / False

Question 11.

Label the typical components of a small vessels bilge system drawn below and marked 1 – 7.

1. self closing valve

2. overboard discharge

3. strum box

4. L port cock

5. bilge manifold

6. power pump

7. strum box

Audible and visual

Question 12.

Name and describe the typical applications of three different types of valves?

Gate valve Seacocks

Ball valve Fuel/hydraulic lines

Screw lift valve Bilge lines

Flap valve Exhaust stacks

Morse taper valve L port cock

Question 13.

Describe the maintenance checks regularly carried out on the equipment shown below

Grease or oil the main bearings.

Inject grease into all grease points.

Oil all linkages that do not have grease points. Use a penetrating oil if normal lubricating oil is not effective.

Oil or grease the threads on spindles of brake operating gear.

Check motors, both electric and hydraulic in accordance with the manufacturers instructions.

Loose gear (such as shackles, blocks, swivels, chains, and wires) should be examined regularly, stripped down, inspected and oiled or greased in accordance with the periodic inspection requirements.

Test and inspect all running equipment under no load to ensure it is operating freely.

Marine Orders 32 - Cargo Gear

Question 14.

Complete the table below listing four different methods of slipping.

Patent slip
Dry dock
Travel lift
Floating dry dock
Synchrolift / Show me the pictures

Question 15.

List in order the precautions you would take to prepare your vessel to be slipped and secured after slipping when using a patent slipway.

1 / Ensure the ship is upright, i.e. the angle of heel is zero.
2 / The vessel must be trimmed as near as possible to an even keel (upright).
3 / Consult the dock master to ascertain requirements for docking.
4 / Ensure all tanks are as full or as empty as possible.
5 / Empty the bilges.
6 / Lash down or secure all loose gear.
7 / Shut down all machinery not required for the docking.

Question 16.

Using the galvanic scale shown below, explain your choice of either aluminium bronze, phosphor bronze or monel for use as a bearing with a stainless steel propeller shaft.

Phosphor bronze for use as a bearing with a stainless steel propeller shaft. Galvanically close, but the bearing will be the anode and the shaft the cathode.

Question 17.

Label six components of the stern arrangements shown below. Name and discuss the survey checks that you would carry out on the system.

What is the minimum tailshaft wear permitted within survey?

The tailshaft can move inside the bearing up to 6% of the diameter of the tailshaft. For example, if a tailshaft is 50mm in diameter, the permissible movement between the tailshaft and the bearing is 3mm.

If the movement exceeds 6%, then the bearing needs to be replaced.

How would you test the proper alignment of the propeller shaft to the A bracket bearing?

Using a tight wire from inner shaft coupling to outer shaft bearing.

Question 18.

Label six components of the hand hydraulic steering system shown below. Name and discuss the safety features and list the predeparture checks that you would carry out on the system.

Show me the answer

Hard over to 35º in each direction in less than 30 seconds.

Question 19.

Explain the functions of each component of the refrigeration system shown below.

Show me the answer

Question 20

Name each of the three rudder types shown below.

Trailing semi-balanced balanced

Question 21.

A fuel tank measures 2.8m long, 1.3m wide and 1.2m high. = 4.368 Cu Mtrs

The engine develops 380 kw using 0.42 ltr/kw/hr. After the journey the fuel had dropped 520mm.

a. How much fuel, in litres, was used on trip?

2.8 x 1.3 x 0.52 = 1.8928 Cu Mtrs x 1000 (ltrs/tonne) = 1892.8 ltrs

b. How far in nautical miles did the vessel travel doing nine (9) knots?

1892.8 ltrs x 9 = 1892.8 x 9 = 106.74 NM

380 x 0.42 159.6

Question 22.

A vessel has two motors which develop 420 kw each and use 0.28 ltr/kw/hr each. If the vessel used

1296 ltr. on a trip @ 6 knots,

a.How far in nautical miles did it travel ?

1296 = 1296 = 5.510 Hrs 5.510 Hrs x 6 = 33.06 NM

420 x 2 x 0.28 235.2

b. How long did the journey take ?

33.06 = 5.510 Hrs = 5 Hrs 30.6 mins

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Question 23.

Two full cylindrical tanks - diam 860 mm and 1.8 metres high. 22 x 0.43 x 0.43 x 1.8 x 2 = 2.092 Cu Mtrs

During a voyage the vessel used 720 litres of fuel. 7

a. How far in mm. did the fuel level drop (in each tank) during the vovage ?

22 x 0.43 x 0.43 x height = 0.720 Cu mtrs 0.58111 x h = 0.360 h =0.360 = 0.619 Mtrs = 619mm 7 2 0.581

or

0.360 = 0.344 x 1.8 = 0.619 Mtrs = 619mm

1.046

b. How much fuel, in total, remained on board after the voyage?

(2.092 X 1000) – 720 = 1372 Ltrs

If the vessel was fitted with one motor which developed 320kw and uses 0.27 ltr/kw/hr

c. How far did the vessel travel doing seven (7) knots ?

720 = 8.333 x 7 = 58.33Hrs = 2 days 10 hrs 20 mins.

320 x 0.27

Question 24.

A vessel has one motor which develops 310 kw and uses 0.16 ltr/kw/hr. The vessels fuel tank is cylindrical and measures 1.1 m wide and 1.9m high. If the vessel undertook a journey of 280 nms @ eleven (l 1) knots,

a. How many litres of fuel must be loaded (including a reserve of 20%).

280 = 25.45 hrs + 20% = 25.45 = 5.09 + 25.45 = 30.54 hrs x 310 x 0.16 = 1514.8 ltrs

11 5

b.What would be the sounding of the tank before departure?

22 x 1.1 x 1.1 x height = 1.5148 Cu mtrs 0.9507 x h = 1.5148 h = 1.5148 = 1.5933 mtr

7 2 2 0.9507

Question 25.

A Vessel has a full cylindrical fuel tank which has a diameter of 860mm and is 2.9 metres high. During a voyage the fuel level dropped 630mm. 22 x 0.43 x 0.43 x 2.9 = 1.685Cu mtr = 1685 ltr

7

a. How much fuel, in litres, was used on trip?

22  x 0.43 x 0.43 x 0.63 = 0.3661 Cu mtr x 1000 = 366.1 ltrs

7

b. How much fuel, in total, remained on board after the voyage?

1685 ltr - 366.1 ltrs = 1318.9 ltrs

If the vessel was fitted with two motors which develop 410 kw and use 0.32 ltr/kw/hr each,

c. How far did the vessel travel doing eight (8) knots?

366.1 ltrs = 366.1 ltrs = 1.395hrs x 8 = 11.16 NM

410 x 2 x 0.32 262.4

Question 26.

A vessel has two motors which develop 390 kw each and use 0.39 ltr/kw/hr each. The vessels fuel tank is rectangular and measures 1.6m wide, 1.9m high and 3. 5m long. If the vessel undertook a journey of 310 nms @ eleven (11) knots, 390 x 0.39 x 2 = 304.2 ltrs /hr