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Second Class ME Naval Architecture




Discuss requirements, tests and care required for anchors and chain cable. Why is the stud link used? How is the bitter end secured? What markings are on the chain and anchor?
How are main frames fitted to the shell plating of a ship? Show by sketch, the means generally adopted for attaching the frame to the double bottom.
Described how a common plate rudder is connected to the ships hull. What are pintles? What are gudgeons? Explain how the movement of the rudder is limited to a certain angle or range. What prevents the rudder from lifting?
Define the following :
  1. Registered length
  2. Registered breadth
  3. Registered depth
  4. Gross tonnage
  5. Net or registered tonnage
A triple screw vessel is powered by three turbines which develops 1000 kW. When all turbines are in operation the speed of the ship is 20 knots. Calculate the speed of the vessel.
  1. When two turbines are in operation
  2. When only 1 turbine operates 
The top of a double bottom tank is 12 m long, 10 m wide and withstands a load of 9.6 MN due to being filled with sea water of relative density 1.025. Calculate the head of water above the tank top to produce this load.
A rectangular shaped barge is 70 m long, 13 m wide and floats at a draught of 2.5 m in water of relative density 1.025. Calculate :
1. Displacement
2. Draught in fresh water
A vessel floating in sea water of relative density 1.025 has a water plane area of 2000 at the load water line. The area of parallel water planes at 2 m intervals below this one are, 1800, 1600, 1200, respectively. Neglecting any volume below 400m2 area find the displacement in tonne.
A ship travels at a rate of 15.25 knots with a fuel consumption of 35.5 t/day. When 850 nautical miles from port there are only 65 t of fuel remaining in the tanks. Calculate the speed of the vessel so it will arrive in port with 4 t aboard.
A vessel has the following proportions;- the length is equal to 9.778 of the beam; the mean salt water draught is equal to 0.427 of the beam; The immersed midsection co-efficient of fineness is 0.92; the block co-efficient of fineness of displacement is 0.635; The beam of the ship is 45 ft., fins- (a) the displacement in tons; (b) the area of immersed midship section, and (c) the prismatic co-efficient of fineness.

A small coasting steamer 200 ft., long, 40 ft., beam and 14 ft., 1-1/2 ins mean draught salt water has a displacement of 2820 tons. The area of the immersed midship section is 531 sq.ft., find; (a) the block co-efficient of fineness of displacement, (b) the prismatic co-efficient of fineness, and (c) the co-efficient of the immersed midship section.

At a certain draught in water of 1028 oz., per cu.ft, the co-efficient of the water-plane area for a certain vessel is 10% greater than the block co-efficient of fineness. The vessel now moves to water of 1008 oz., per cu.ft, and its draught changes 4 ins. Calculate the original draught assuming the water-plane area is constant.

The length, beam and loaded draught of a vessel are in the ratio 16.5:1.15:1. At this draught the co-efficient of the water-plane area is 0.77, and the T.P. 1 when floating in seawater is 0.98 tons greater than when in fresh water at the loaded draught.

The “fresh water allowance” is the amount a vessel may be loaded in fresh water above the salt water load line, and is given by the expression; - F.W.A.” + D/T.P.1 x 40. Where D = displacement (tons) T.P.1 = value in salt water. Prove that this is true when salt water and fresh water densities are 1025 and 1000 oz., per cu.ft, respectively.

A ship enters a river from the sea and while in the river 270 tons of water ballast is pumped overboard. The draught of the ship after discharging the ballast was found to be 3 ins., less than the draught when at sea. If the densities of the sea and river were 1025 and 1006 oz., per cu.ft, respectively and the water-plane area of the ship was constant at 20700 sq.ft. Calculate the original displacement of the ship in tons.

A ship of 7,500 tons has its center of gravity 22-ft., above the keel. A structure weighing 300 tons is now added to the ship, the centre of gravity of the structure being 16 ft., above the original centre of gravity of the ship. 1,000 tons of fuel is now loaded into some double bottom tanks whose centre of gravity is 2 ft., above the keel. Calculate the new position of the centre of gravity of the ship and also calculate the shift of the centre of gravity when 500 tons of this fuel has been consumed.

The displacement of a ship was 7,000 tons, and when 120 tons of oil were pumped from a forward tank into an after tank which already contains 320 tons of oil, the ford and aft shift of the centre of gravity of the ship was 2.5 ft. After all the oil in the after tank was consumed the final centre of gravity of the ship was 1.5 ft., forward of the original position. Find the respective distance of the tanks from the original centre of gravity of the ship.

A vessel displaces 5,800 tons on arrival in port and the centre of gravity is 17 ft., above the keel. 1200 tons of cargo with its CG 7 ft., above the keel are discharged, 120 tons of cargo with its C.G. 10 ft., above the keel, and 600 tons of cargo with its C.G. 12 ft., above the keel are loaded, and 300 tons of cargo already on board is lowered 8 ft. Determine the final position of the C.G., of the vessel above the keel and state whether the shift was up or down.

A ship, when light, weights 1,250 tons and has its C.G. 9 ft., above the keel. During fitting the following items were loaded;- 180 tons of oil with its C.G., 1.5 ft., above the keel
250 tons of stores with its C.G., 14 ft., above the keel.
200 tons of spare gear with its C.G., 12 ft., above the keel.
200 tons of fresh water with its C.G., 10.5 ft., above keel. Find the new position of the C.G., of the ship above the keel.

A ship of 11,000 tons has a draught of 29 ft. The centre of buoyancy is 15 ft., above the keel and the transverse metacentric height is 2 ft. Find the position of the centre of gravity of the vessel relative to the keel if the second moment of area of the water-plane about the longitudinal axis is 4.35 x 10 to the exponent 6 inch to the exponents 4 units. The vessel is in sea water of 64 lbs./cu. ft.

A box barge is 300 ft., long and 40 ft., wide. Calculate the values of the BM for draughts of 2 ft., to 12 ft., at intervals of 2 ft., and plot these values against the values of draught. If the centre of gravity of the barge is constant at 15 ft., above the keel find the GM when the draught is 11 ft. Second moment of area of the water-plane about the ford and aft axis = length x beam³ 12

A ship loads 1,643 tons of oil fuel into three empty tanks, ‘A’, ‘B’, and ‘C’ without affecting the trim. The centers of the tanks are as follows;- A is 39 ft., forward of the C.G., of the ship, B is 54 ft., aft of A, and C is 90 ft., aft of A. the amount pumped into B is twice that pumped into C. calculate how the fuel was distributed between the tanks.

A vessel has three empty tanks, ‘P’, ‘Q’ and ‘R’, lettered from ford. The capacities of the tanks are 437, 475and 495 tons respectively. The C.G., of P is 36 ft., forward of the C.G., of the vessel, the distance between the C.G.’s of P and R is 495 ft., and the distance between the C.G.’s of Pand Q is 113 ft. After pumping 475 tons of oil into the tanks the trim of the vessel is unaltered. Find (a) the maximum amount of oil, which can be pumped into the tank P and (b) the minimum amount of oil which can be pumped into tank P?

A vessel has a displacement of 10,000 tons and when steaming at 16 knots the fuel consumption is 41 tons per day. Calculate the fuel consumption per day when the displacement is 13,000 tons and the speed is 17 knots. It may be assumed that the total resistance of the vessel is directly proportional to the speed raised to the power of 1.8.

A log of wood of specific gravity 0.8 has a section 3-ft., square and a length of 20 ft. It is floating in fresh water in stable equilibrium with two side’s vertical. Calculate the second moment of area of the water-plane in ft to the exponent 4 units with respect to the longitudinal axis and calculate the metacentric height in ins. Second moment of area of water-plane about the longitudinal axis = Length x Beam³. 12

A vessel has dimensions such that the length is 8 times the beam and the beam is 3 times the draught. The block co-efficient of fineness is 0.78. If the IH.P. at 15 knots is 5,500 and the Admiralty constant is 280, find the length of the vessel. If the speed was increased 17% find the new I.H.P.

A vessel of 8,000 tons displacement has a length of 400 ft., and a draught of 27 ft. The effective horsepower is 5,320 at a speed of 15 knots. Calculate the residuary resistance of the vessel in lbs., given that;- Wetted Surface = 1.7LD + vol., and D Fluid friction (lbs.) = fsv to the exponent 2.2. Where L = length D = draught S = wetted surface (sq.ft.) V= speed (knots) vol = underwater volume f = 0.0088.

The resistance of a thin plate when drawn through sea water at 10 ft.sec., is 0.25 lbs., per sq.ft. When a ship is moving at 15 knots 31,000 ft.tons per minute is required to overcome the frictional resistance. The wetted surface of the ship was 14,960 sq,ft, If the frictional resistance is directly proportional to the speed raised to the power of ‘n’ find the value of n.

A vessel has a fuel consumption of 0.075 tons per nautical mile, and the I.H.P. is 6,000. If the Admiralty constant is 273 and the fuel co-efficient is 61,900, find (a) the fuel consumption per I.H.P., hour and (b) the displacement in tons.

At a speed of 17 knots a vessel consumes 170 tons of fuel per day. It is decided to reduce the consumption to 117 tons per day. Find the new speed and the percentage saving in fuel for a voyage of 3,000 nautical miles.

At 12 knots the fuel consumption of a certain ship is 11.34 tons per day. When the ship is 2016 nautical miles from port, it is found that there are only 75 tons left in the tanks. What must be the reduced speed for this ship to reach port with 10 tons of fuel left, and what will be the daily consumption at the reduced speed?

By experiment it was found that the resistance of a flat plate drawn through sea water at 10 ft.sec., was 0.27 lbs., per sq.ft., and that the resistance varied as the (speed) to the exponent 1.9. the total fluid resistance of a sip at a draught of 26 ft., and at a speed of 15 knots was 26 tons. If the beam of the ship was 55 ft., and the block co-efficient of fineness was 0.7 find the length of the ship. Use the formula given in the data sheet to determine the wetted surface.

Prove that;- consumption per voyage (tons) = Rd v² C
Where R = length of voyage in nautical miles.
= displacement in tons
d = consumption of fuel in tons per I.H.P.,per hour
v = speed of ship in knots
C = Admiralty constant = v³ I.H.P.
Using the formula calculate the consumption for a voyage of 6,000 nautical miles at 15 knots if the displacement of the ship is 12,000 tons. The Admiralty constant is 250 and the fuel consumption per I.H.P. hours is 0.359 lbs.

When the speed of a vessel is reduced by 2 knots the daily fuel consumption is reduced by 52 tons. If there is a 22% saving of fuel on a voyage of 4,500 nautical miles, calculate the normal speed and the normal daily fuel consumption.

The fuel consumption per hour of a vessel is given by the expression;- 1.5 + 0.001456v³, where v is the speed in knots. The normal speed of the ship is 15 knots, and when the speed is reduced 21% the consumption per day decreases by 60 tons. Find; - (a) the new consumption per day at the reduced speed, and (b) the tons of oil saved over a voyage of 2400 nautical miles.

The fuel consumption of a vessel travelling at 15.5 knots is 779 tons per day. If the speed is increased to 17.25 knots for 14.5 hours and is then reduced to 12.25 knots for 9.5 hours, calculate the percentage variation in fuel consumption per day and the percentage variation in the distance covered per day.

If a vessel travels at 3.5 knots less than the normal speed of 18 knots the fuel consumption per day is reduced by 38 tons. Calculate the normal fuel consumption per day.

A twin screw vessel has engines which run at 97 r.p.m, and drive propellers of 19 ft., pitch. The apparent slip was 15%. Calculate the ships speed in knots. If the thrust horsepower was 5,320 and the resistance due to skin friction was 95,000 lbs., calculate the residuary resistance of the vessel in lbs.

A ship has an apparent slip of -4.5% when the ship’s speed is 17 knots and the engine r.p.m. is 110. Calculate the propeller pitch. If under these conditions the thrust pressure if the horsepower is decreased by 10% and the ship’s speed by 3.4%?

When a vessel is travelling at its normal speed of 19 knots the pressure on the thrust pads was 310 p.s.i, the r.p.m. of the engines was 97, and the apparent slip was -4.5%. Calculate (a) the pressure on the thrust pads when the speed increased by 7.5% while the horsepower decreased by 11.5% and (b) the pitch of the propellers.

Find the apparent slip when a vessel has a speed of 17 knots, engine r.p.m. 88 and propeller pitch 20.5 ft. At this speed the thrust pressure was 267 p.s.i. if the horse power is increased by 10% and the speed increase 7%, what was the new thrust pressure?

A bulkhead is 24 ft., deep and it is supported by vertical stiffeners spaced 2 ft., 6 ins., apart. The stiffeners are secured to the tank top by brackets containing 12 rivets, each 7/8 ins., diameter, and it may be assumed that the rivets are in single shear. If seawater rises on one side of the bulkhead to the full depth, calculate (a) the shear load in tons at the top of the stiffeners, and (b) the shear stress in the rivets at the tank top brackets.

A watertight door measures 4ft. 9 ins., by 2 ft. 6 ins., wide. The lower edge of the door is 1 ft., from the bottom of the bulkhead. The doorframe is held in position by 36 bolts each 0.733 ins., diameter. To what depth must the bulkhead be flooded with sea water on one side in order that the tensile stress in the bolts be 2,000 lbs., per sq. in.?

A rudder is 280-sq. ft. in area and the centre of fluid pressure is estimated to be 6 ft., abaft the centre line of the rudderstock when the rudder is turned through the maximum angle of 35 degrees. If the ship’s speed is 16 knots and the allowable shear stress in the rudderstock is 5 tons per sq. in., fins, for the angle the diameter of the rudder stock in inches. Given; - fluid pressure (lbs.) = 1.12AV²Sin . Where A = area rudder (sq. ft.) V = speed of ship (ft. sec.) = rudder angle.

A double bottom tank is tested by filling the tank with fresh water to the top of the air pipe while the ship is in dry dock. It was found that the pressure on the inner and outer bottom plating are 15 p.s.i.g., and 17 p.s.i.g., respectively. Calculate (a) the depth of the tank in ft., (b) the height of the air pipe and (c) the load in tons on the inner bottom plating if the tank was 36 ft., wide and 20 ft., long.

With reference to ships, what is meant by the term “Racking”. What members of a ship’s structure are most effective in reducing the effects of racking?

With reference to a ship what is meant by “Panting” and on what part of the ship’s structure does it occur? What is done to minimize the effects of panting?

A vessel is in dry-dock and has a double bottom tank filled with oil of specific gravity 0.9, which rises up to the top of the sounding pipe. The floors are spaced 30 ins., apart and the rivets securing them to the inner bottom plating are 7/8 ins., diameter and pitched 7 diameters apart. Under these conditions the tensile stress in the rivets is 4,200 lbs., per sq., in. Calculate (a) the depth of the tank in ft., and (b) the length of the sounding pipe in ft. The pressure on the outer bottom plating is 15 p.s.i.g.

With reference to ships, what is meant by the terms “Hogging” and “Sagging”? What parts of a ship’s structure are most effective in reducing the effects of hogging and sagging?

Explain the following terms;- gross tonnage, registered tonnage, deadweight capacity, moulded depth and length between perpendiculars.

The following terms are used in ship construction. What do they refer to? Keel, Keelson, Tank tops, Tank Margin Plates, Garboard Strake, Shear Strake, and TumbleHome. The answer may be illustrated with sketches.

Give definitions of the following terms pertaining to ships; - registered length, registered breadth, registered depth, gross tonnage and registered tonnage.

Give a short description of the following terms used in ship construction;- Frame, Deep Frame, Beam brackets, Reverse bar, Floor plate, Margin plate, Gusset and Bilge Bracket.

In ship construction what is meant by the terms “Deck Camber” and “Deck Shear”? Explain briefly the advantages of the camber and shear.

What is meant by the term “Load Lins”? Where is it placed on a vessel? Is there any allowance for different waters, and seasons? If so, are these different Load Lines marked higher or lower than the given Load Line, and Why? You may illustrate your answer with a sketch.

What is meant by the following terms used in ship construction;- (a) coaming, (b) camber, (c) fore peak, (d) tumble home, (e) shear strake, (f) hawse pipe, and (g) intercostal?

Show with the aid of sketches how the deck beams of a steel vessel are connected to the frames. Show also the method of attaching the hatch coaming to the deck beams and deck plating.

Describe briefly the Isherwood system of longitudinal ship framing. On what type of ships is this method of construction usually used?

Explain the following terms;- displacement, gross tonnage, net tonnage, deadwseight.

Give a general description of a stem post and a stern frame. Make a sketch of one of these members, showing hoe it is attached to the hull.

Where are the following plates located on the ship’s shell? (A) Sheer strake, (b) Bilge strake, (c) Keel plate, (d) Floor plate, (e) Breast hooks.

Sketch the midship section of a cargo ship showing the following details; - keel plate, deck beam, floor, shear strake, frame and margin plate.

How are the main frames fitted to the shell plating of a ship? Show by a sketch, the means generally adopted for attaching the frame to the double bottom tanks.

Sketch and describe a “spectacle frame” as fitted to a twin screw vessel. Show it is attached to the hull of the ship.

How is a watertight door fitted to the bulkhead of a vessel? How is it opened? What attention does it require to keep it in good working order?

Where are the following plates located on the ship’s shell;- (a) Shear strake, (b) Garboard strake, (c) Keel plate, (d) Stealer plate. State the purpose of this plate.

Describe the special strengthening arrangements that are required for the forward end of a ship.

Describe the construction of a double bottom tank as fitted in a large dry cargo vessel and by means of a sketch show how the tank topis supported and how it is secured to the shell plating. Why are double bottom tanks fitted in some vessels?

What is a cofferdam? Where are cofferdams located on a ship? What is their purpose? What connections, fittings or pipe are fitted to cofferdams?

For a vessel of approximately 5,000 tons and with engines amidships, sketch and describe the watertight bulkhead at the after end of the engine room through which the shafting passes. Note any special arrangements in the way of the shafting.

Explain how a watertight bulkhead is fitted into a ship. How does the bulkhead contribute to the structural strength of the vessel? What kind of floor fitted in the double bottom tank under a watertight bulkhead.

Explain, in the case of a vessel with engines aft, how the ship’s structure in way of the machinery space is strengthened, with specific reference being made to floors, girders and inner bottom.

Sketch floors of the solid, bracket and watertight types are fitted in cellular double bottom tanks. For a dry cargo ship what types of floors would be fitted (a) under engine and machinery spaces, (b) under hold spaces, and (c) under watertight bulkheads?

Describe the construction of a watertight bulkhead, explaining how it is stiffened and made watertight. What is the purpose of watertight bulkheads?

Make a sketch of a section through a double bottom tank showing a solid floor. What other types of floors are fitted in double bottom tanks?

Describe the rudder of your last ship. Explain how the rudderstock passed through the ship’s counter, how the rudder is supported, and also how wear down was allowed for. State the angle the rudder was allowed to turn and explain how further movement was prevented.

Describe how a common plate rudder is connected to the ship’s hull. What are pintles? What are gudgeons? Explain how the movement of the rudder is checked, and what prevents the rudder from lifting?

Describe the construction of a tailshaft, which is fitted with a continuous liner, and describe how the liner is fitted. Explain how the propeller is fitted to the shaft.

Describe and sketch a stern tube and stern bearing as fitted in a single screw steel vessel. What materials are used? Show how the stern tube is fitted in place.

Your vessel is in dry-docking and you are entrusted with the duties of a full underwater inspection. Describe fully how you would carry this out.

Your vessel is in dry-dock, and the tail end shaft has been removed, and you are instructed to examine the stern tube lining, and the shaft, for possible defects. Explain how you would make this inspection.

Describe a “Balanced” rudder, and explain how it is fitted to the ship and how the weight of the rudder is taken up. You may illustrate your answer with a sketch if desired.

What is meant by the pitch and diameter of a propeller? Describe, with a sketch, how you would find the pitch of a propeller; with the vessel in dry-dock. Is it possible to alter the pitch of a propeller?

Describe a CO2 or stern smothering system as fitted to the holds of a dry cargo vessel. Include in your description the bridge detection unit and explain how this works. You may illustrate your answer sketches if desired.

How would you inspect the rudder when the ship is in dry-dock? What parts would you normally inspect for wear and what repairs would be necessary if excessive wear was found?

Describe, with the aid of sketches how the holds of a refrigerate cargo ship are insulated. Show how the hold is closed up and states the materials used for insulation purposes.


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3 comments:

marine S said...

Great thoughts you got there, believe I may possibly try just some of it throughout my daily life.


Naval Architecture

praveena puppy said...

Hey, nice site you have here! Keep up the excellent work!





Naval Architecture

Haji Mazlan Muslim said...

How about providing some typical Nav Arch questions in metric (SI) units. Perhaps some typical solutions for those numerical calculations will be helpful. Thanks. Best regards.

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