|Load Lines||Rudder & Propeller|
Mechanical Hatch covers
The figures shown below illustrate the various parts of a mechanical hatch cover. These hatch covers may be made up of several individual pontoons (so named because prior to the MacGregor type of rolling hatch covers the pontoons had to be individually lifted and battened down).
The pontoons (individual parts of the hatch covers) are connected to one another and can easily and quickly be rolled into or out of position leaving clear hatchways and decks. The normal practice for the lengthwise opening of hatches but sideways opening hatchways are found on large bulk carriers and OBOs.
The smaller versions are mainly operated either manually (using wire and winch) or electrically. The larger ones are nearly all operated hydraulically.
The wheels on the side on which the pontoons rollere are eccentric in their construction thus when in the battened (lowered) position the clearance between the wheel and the trackway is minimum and the pontoon sits on the trackway, the rubber gaskets being compressed by the compression bar.
The cross wedges are used to ensure the pontoon rubber gaskets compress against the compression bars of the forward pontoons.
The side cleats ensure that the pontoons stay compressed to the trackway compression bar and the ship motion is effectively compensated or removed.
These hatch cover systems consist of various parts:
The pontoons, eccentric wheels, trackway wheels, cross wedges, and the side cleats.
Battening down a hatch is to be done after reading the operations manual.
A hatch cover should not be battened with cargo on top.
The Channels are to be swept prior battening so that the packing do not rest on dirt.
The drain channel on the front of the hatch pontoons are to be cleaned prior closing the hatch.
Once the wheels are turned the next item to be engaged are the cross wedges and the side cleats are to be fitted last.
Prior proceeding to sea (long voyage) the hatch cover sealing should be tested with chalk marks made on all the compression bars on the hatch coaming as well as on the pontoons. The hatch is to be battened and then opened to see if all the rubber gaskets have got chalk mark on them or not if not hen rectification to be done.
Oil tight hatchcover
These hatch covers are small in size and may have butterfly nut locking arrangement. The sealing is done by Hi-nitrile rubber which is not affected by oil.
Manhole covers do not vary much in design, their shape however are sometimes different for different places.
When fitted outside a tank they may be either circular or elliptical. But when fitted inside they are almost always elliptical to facilitate their removal.
Usual size openings vary between 450mm to about 600mm.
Roller, Multi‑angle, Pedestal and
A roller is to be found on the forward and after stations area generally at the leads to the mooring ropes as well as on top of old man pedestals.
These facilitate the hauling of ropes since they reduce the friction when the rope is hauled through a panama fairlead which has no rollers.
A panama fairlead
is o named since they were mostly used in the
A multi angle
fairlead again is a fairlead used due necessity when in the great Lakes. The
ship moves through numerous locks as the ship is made to climb a great height
Mooring bitts are prefabricated and then are welded onto the deck. The size of the bitts are dependent on their use. Thus a small set may be fitted next to an occasional winch while the larger ones are fitted at the mooring stations.
The bitts are hollow and as such require care to ensure that the sides do not corroded and holed.
A typical forecastle mooring and anchoring arrangement, showing the leads of moorings
Securing anchors and making spurling pipes watertight in preparation for a sea passage
Once the anchor has been washed the anchor is hove right up into the hawse pipe, the bow stopper is lowered and the locking pin inserted.
The winch is reversed a little to make the chain sit properly into the slot of the bow stopper and then the brake is tightened and the windlass gear removed.
The anchor chain at the deck level (hawse pipe) is lashed with extra lashings as provided by the shipyard, if none are present or if expecting heavy weather, then extra wire rope lashings are taken, The wire rope to be used should be tested one, if an old (good condition) life boat falls are available then this makes a very good extra lashing wire. This wire is flexible and can be used by hand. A number of turns (figure of eight) are taken around two sets of bitts. The free ends being fastened by bull dog clips at least two fixed in opposite directions.
Generally the shipyard would have provide lashing point as well as short length of wire attached to a bottle screw. These should be well oiled and are the most efficient for lashing the anchor. The wire should be tight.
Once the anchor is lashed the hawse pipe covers are not placed but stowed under deck or in their stowage positions.
The spurling pipe area is chipped to remove any residual remains of earlier cement.
The metal spurling pipe covers are placed around the chain and over the spurling pile. The clips provided at the edges of the covers should be hooked to the lips of the spurling pipe.
A new canvas cover is then placed over the metal covers just fitted and is tied around the lips of the spurling pipe as well as the chain. No empty spaces should be found.
Cement mixture is prepared and the entire cover is covered with this mixture.
A chain stopper as shown below may be of various designs, but all serve the same purpose to hold the cable.
The cable is passed through the stopper with the holding bar lifted up by the counterweight on top. There is a pin to hold the bar in this position.
Once the decision has been taken to hold the cable, the safety locking pin is removed and the bar is eased down on top of the cable. Note that the default position of the holding bar is to arrest the cable, only a effort is required to keep it up.
Once the bar is placed over the cable the cable may have to be adjusted a little to ensure that the flat part of the cable falls in the holding area and not the vertical section, the safety locking pin is now introduced to prevent the bar from jumping u[ in case the cable slip from the brake.
Once the lacking pin is in position the brake can be released and the stopper would do the work of holding the cable.
Masts and Sampson posts
Bilge and ballast piping system of a cargo ship
The following shows a bilge and ballast line diagram of a general cargo ship.
The bilges are all fitted with non return valves so that not water may be inadvertently be pumped into the holds.
The bilges are serviced by a bilge pump which incorporates a strainer and this should be checked before starting the pump.
The strum box fitted in the holds is to be kept clean and the perforations are to be checked that they are not closed due to muck and rust.
Same with the mud boxes in the ER fitted into the system.
Arrangement of a fire main
Capacity of fire pumps
The capacity of the fire pumps is stated in SOLAS but need not exceed 25m3 per hour
Arrangements of fire pumps and of fire mains
Ships shall be provided with independently driven fire pumps as follows:
Passenger ships of 4,000 tons gross tonnage and upwards at least three
Passenger ships of less than 4,000 gross tonnage and cargo ships of 1,000 tons gross tonnage and upwards at least two
Cargo ships of less than 1,000 tons gross tonnage to the satisfaction of the Administration
Sanitary, ballast, bilge or general service pumps may be accepted as fire pumps, provided that they are not normally used for pumping oil and that if they are subject to occasional duty for the transfer or pumping of oil fuel, suitable change-over arrangements are fitted.
The arrangement of sea connections, fire pumps and their sources of power shall be such as to ensure that:
In passenger ships of 1,000 gross tonnage and upwards, in the event of a fire in any one compartment all the fire pumps will not be put out of action.
In cargo ships of 2,000 gross tonnage and upwards, if a fire in any one compartment could put all the pumps out of action there shall be an alternative means consisting of a fixed independently driven emergency pump which shall be capable of supplying two jets of water to the satisfaction of the Administration. The pump and its location shall comply with the following requirements:
The capacity of the pump shall not be less than 40% of the total capacity of the fire pumps required by this regulation and in any case not less than 25 m3/h.
Number and position of hydrants
The number and position of hydrants shall be such that at least two jets of water not emanating from the same hydrant, one of which shall be from a single length of hose, may reach any part of the ship normally accessible to the passengers or crew while the ship is being navigated and any part of any cargo space when empty, any ro-ro cargo space or any special category space in which latter case the two jets shall reach any part of such space, each from a single length of hose. Furthermore, such hydrants shall be positioned near the accesses to the protected spaces.
Pipes and hydrants
Mainly galvanised steel pipes are used and during repairs no doublers or such part renewals are allowed change is flange to flange renewal.
The arrangement of pipes and hydrants are to be such as to avoid the possibility of freezing.
On cargo ships where deck cargo may be carried, the positions of the hydrants are to be such that they are always readily accessible and the pipes are to be arranged, as far as practicable, to avoid risk of damage by such cargo.
A valve is to be fitted at each fire hydrant so that any fire-hose may be removed while the fire pump is at work.
The above figure shows a typical fire mains line. Note that the emergency fire pump is located away from the machinery space as per rules.
Isolation valves are provided so that any system being damaged the other system may be used for example the port system and the starboard system.
In the machinery space a separate pump (Fire and GS pump) is also coupled, this is generally used when washing decks, and as an emergency measure while the fire pump is being overhauled.
Sounding pipes covers come with varied designs. That shown below is a sunken cap type generally the cap is made of brass. The justification being that of the two thread and cap assembly the thread of the brass is to wear out first and that of the deck pad. The renewal of the brass cap being inexpensive and convenient rather than the deck pad which entails hot work.
The metal cap (not sunken) type of covers have a chain attached to them to prevent their being washed overboard.
Air pipes to ballast tanks or fuel oil tanks
The above figure shows a design of air pipe cover.
In normal condition the ball remains at the bottom of the air pipe head and the tank breathes in and out through the vent.
However in the event that the air pipe is submerged then the ball floats up and closes the opening at the top thus preventing any water from entering the tank.
Sea spray and rain is prevented from entering the tank by the design of the head. It is totally enclosed and a rectangular plate, which leaves a small gap between the mesh and itself, allowing the breathing of the tank.
Fittings and lashings for the carriage of containers on deck
In the figure above the containers on deck are loaded on top of shoes which are welded on top of the deck as well on top of the hatch covers.
Twistlocks are fitted on the shoes and the containers placed on the twistlocks. Hinged eyes are welded on deck to secure the container rod lashings.