MEOclassIIexamnotes

An insert plate is used to replace any damaged steel plate of ship's hull. The insert plate must have identical characteristics with the original steel plate ( type /grade/thickness etc). The damaged part of the steel plate has to be cropped-out and renewed by welding using the same welding consumables. The minimum consumable grades. All ship's Class Societies consider the above mentioned requirements as permanent repairs for maintaining the ship’s Classification Certificates fully valid. On the contrary, doubler steel plates which are welded on top of a damaged structure plate is considered as temporary repaired with a short limit date until the full permanent repairs are dealt with

For engine seating a plate floor is required every frame  Main engine seatings are in general integral with this double bottom structure.  Inner bottom in way of the engine foundation has a substantially increased thickness.  Often the machinery is built up on seatings forming longitudinal bearers which are supported transversely by tripping brackets in line with the double bottom floors, the longitudinal bearers being in line with the double bottom side girders.  There are transverse plate floors at each frame. The thickness of the engine seating is governed by the power, weight, and length of the unit

 Pintle  For a ship in service, Maximum allowable clearances between Pintle and bush is 6 mm.   IF the actual clearance exceeds 6mm, the bush should be renewed.  Measured using the thickness gauge. The clearance is taken in four sides: forward, aft, port, and starboard.  The measurements are taken through the inspection cover, usually on the port side.  The normal clearance is about 1 to 2 mm.   Neck bush clearance Between the rudder stock and the neck bush (rudder stock upper side) is measured using the thickness gauge.  The clearance is taken in four sides: forward, aft, port, and starboard.  The measurements are taken from top of the rudder.  The normal clearance is about 1 to 2 mm.  Jumping Clearance: The designed clearance is 2.0 mm maximum.  If the clearance measured is found to be large, it can be concluded that the rudder has moved down. The clearances can be taken from rudder trunk – between the stopper and...

 Determined at the design stage based on vessel size, number of mooring lines , wind area and tidal conditions and the mean braking load of mooring lines. After selection of the  MBL of the mooring line, the winch heaving load will be set to a lower value than MBL to prevent the winch motor from applying excessive loads

The chain block contains two cogs or gears in which the chain is wrapped around. Both electric chain blocks and manual chain blocks have the same fundamental functions - when the chain is pulled, it wraps around the wheels which adds torque to the lifting mechanism, pulling the item that is on the other end of the chain (usually with a strong hook) and lifting it off the ground - the wheels inside the block are how they are able to lift heavy loads - even when operated manually. when the chain is release a braking mechanism kicks in and holds the load where it is until the chain is pulled again. A chain block has a strong chain for lifting objects and attaching hooks to, manual lifting blocks have a hand chain which can be used for pulling by hand to bring the load up (these are powered by motors in electric chain blocks), they also have a grabbing load hook for attaching the load . 

Rudder stock is carried in the rudder trunk which as a rule is not made water tight at lower end , but water tight gland at top of the trunk ;ie, where the stock enters the intact hull. Trunk kept short so that the stock has minimum unsupported length.  Watertight opening for inspection

 A 0.5 mm diameter piano wire is stretched along each side of the bedplate. The wire is loaded with 40 KPa horizontal force. At the centre line of each cross girder , the distance is measured between the wire and the machined faces of the bedplate top outside oil grooves It will thus be revealed whether the later has changed compared with values during engine installation. The measurement are taken by micrometer with laser light when touches wire.

Propeller blade system is designed for maximum efficiency in ahead direction In astern direction angle of attack is high on the back of the blade. Propeller will absorb very little available power. Severe eddying occurs on face(efficiency is low) Hence if 80% of Full ahead power is available for astern then boosting it to 100% will have minimal return in thrust

In both cases the  air coolers are  for increasing the efficiency of the compressors by inter cooling.   Both T/C and Reciprocating compressors are meant to increase pressure , however to a different degree ( T/C : 4 for single stage , and 10 bar for 2stage turbo chargers)  During the compression the air temp raises when the pressure is increased, and need to be cooled.  Cooling is by fresh water / sea water / air in the Main Air Compressors and  Either Sea water or Fresh Water(LT) Cooling is controlled in Engine Coolers to maintain the Air Temperature to the required value, to reduce water impingement on to the liners. Cooling is not controlled in air coolers of Main Air Compressors ( the lower the temp is better for the efficiency), hence there will be control valves for Engine Air Coolers and no control valves for Air Compressor coolers. Engine Coolers are very large in comparison to Main Air Compressors as the air flow is very large ( depend on the...

Parallel Keys : These keys have a rectangular cross-section and are used in straight keyways. They provide a simple and effective means of transferring torque between the shaft and the hub. Sunk Keys : Also known as rectangular keys, these keys fit into keyways that are cut into both the shaft and the hub. They have tapered sides that fit tightly into the keyway, preventing movement. Woodruff Keys :These keys have a semi-circular shape and are often used in applications where axial movement of the propeller on the shaft needs to be prevented. They fit into a curved keyway on the shaft and a corresponding slot on the hub. Tapered Keys :Tapered keys are used in tapered keyways, providing a wedging action that helps secure the propeller onto the shaft tightly. Gib Head Keys :Also known as feather keys, these keys have a projection, or gib head, that fits into a slot in the hub, preventing axial movement. The type of key used depends on factors such as the design of the propeller hub and s...

Emergency Stop Button : Install an easily accessible emergency stop button that immediately halts all windlass operations when pressed. This allows operators to quickly stop the system in case of emergencies or unexpected situations. Pressure Relief Valves :Hydraulic systems should be equipped with pressure relief valves that prevent the hydraulic pressure from exceeding safe limits. If the pressure reaches a dangerous level, the valve will open to release excess pressure and protect the system from overloading. Pressure Gauges : Install pressure gauges at appropriate points in the hydraulic system to allow operators to monitor hydraulic pressure. This helps ensure that the system operates within safe pressure ranges. Limit Switches :Use limit switches to automatically stop the windlass when the anchor chain reaches its upper or lower limit. This prevents overextension of the chain or damage to the equipment. Flow Control Valves :Flow control valves regulate the flow rate of hydraulic ...

SS is Difficult to machine for high finish Galling or friction welding when moving up and down(like piston & cylinder; valve stem & gland etc)  Most of the engines work in the range 400 to 900°C and it is called Sensitization zone and SS will lose Chromium and SS becomes steel and start rusting and cracking. Stainless steel has high thermal expansion(1.6times steel/CI) and low thermal conductivity(SS has low thermal conductivity , 25% of CS. The bore area will have high temperatures and high thermal expansion and distortion and mis-alignment of cylinder piston and engine bore are expected.

The power-to-weight ratio represents the ratio between a vehicle's power and its total weight.  The higher the PWR, the faster the vehicle will accelerate. It is for this reason that motorbikes accelerate quicker than most cars.  PWR calculations are commonly used to predict vehicle speed.  It's very easy to calculate a power-to-weight ratio. Simply divide the power output of a vehicle by its weight.  If you have a car that weighs 2000 pounds and has 250 hp, the PWR will be as follows: 250 / 2000 = 0.125 hp for every pound of car.

Engine should have run 30 mins of diesel oil before stoppage Open the indicator cocks, shut the main air starting valve and engage the turning gear close the fuel supply and ruturn valve on the fuel pump Drain the remaining fuel from the fuel pump Inspect the cams and rollers The stagnation pressure control valve has to be dismantled Note the valve desiganation S-suction , D- delivery and U- for spill valve Remove the valve cover and the springs Pressure bushes are released using special wrench The vavles are removed using a withdrawal device Examine valve seats and contact surfaces. Defective should be reconditioned or replaced The valve contact surface in fuel pump block should be in good condition.Damaged surfaces must be reconditioned After cleaning the fuel pump block throughly the suction and spill valves are cleaned in diesel oils and fitted back respectively without their springs The pressure bushes are tightened to 300Nm The dial gauges should be inspected before mounting it t...

Standby Heating  Reactor ready Dosing enabling Dosing (SCR active) Flushing

Should not be of cast iron Must be Class approved Fitted at easily accessible location as far as practicable readily visible Indicators are to provided local to the valve ie ,showing whether they are open or shut Valve spindle are to extend above the lower platform. Valves and distance pieces extended for the installation on the ship side below the load water line are to be tested by hydraulic pressure not less than 5 bar.

The cam for the air distributer serves its purpose only while starting the engine . Actually if you see there is no other requirement of this particular cam while the engine is continue in operation.  Therefore if a cam ( normal possitive ) is used then wear of this particular cam will be abviated and will be expensive to repair / replace this cam. So when the engine has started and the vessel is enroute a voyage , then this particular cam turns without any running gear touching it. It comes into play only starting

Boiler Turndown Boiler turndown is the ratio between a boiler’s maximum and minimum output. Depending on the burner’s design, it may have a turndown ratio between 4:1 and 10:1 or even higher.  A 4:1 turndown means the boiler’s minimum operating load is 25% of the boiler’s full capacity (100% capacity divided by 4).  A 10:1 turndown means the minimum operating load is 10% of the full load capacity (100% capacity divided by 10). Why is Boiler Turndown Ratio Important? Turndown ratio is important for boilers that are required to operate at a wide variation of capacities. A boiler with a higher turndown ratio will usually handle fluctuating loads more efficiently than one with a low turndown. A boiler’s burner will modulate or “turn down” as the demand for hot water or steam decreases, in an attempt to meet only the required load. The turndown ratio tells you the minimum output the boiler can handle before turning off and then cycling on and off frequently. If the demand goes belo...

Reopening of the fuel valve after the main injection id terminated is secondary injection . The sudden closing of the injector needle cause a pressure wave to be setup which reflects from the delivery valve back to the injector needle . If the residual pressure and reflected pressure together exceeds the injector lifting pressure , secondary injection takes place.

Con rods during operation are subjected to buckling loads Buckling strength is directly proportional to moment of inertia. So , I section is having maximum area moment and least weight. Hence introduce the vibration of conrod and also reduce side thrust acting on the cylinder. I section can be easily manufactured