Machinery onboard ships require regular care and maintenance so that their working life and efficiency can be increased, and the cost of operation, which includes unnecessary breakdowns and spares, can be reduced. For different types of machinery and systems, different measuring tools, instruments and gauges are used on ship.
Measuring instruments and gauges are used to measure various parameters such as clearance, diameter, depth, ovality, trueness etc. These are important engineering parameters which describes the condition of the working machinery.
Popular mechanical gauges and tools used on ships are:
Ruler and scales: They are used to measure lengths and other geometrical parameters. They can be single steel plate or flexible tape type tool.
Callipers: They are normally of two types- inside and outside calliper. They are used to measure internal and external size (for e.g. diameter) of an object. It requires external scale to compare the measured value. Some callipers are provided with measuring scale. Other types are odd leg and divider calliper.
Vernire calliper: It is a precision tool used to measure a small distance with high accuracy. It has got two different jaws to measure outside and inside dimension of an object.It can be a scale, dial or digital type vernire calliper.
Micrometer: It is a fine precision tool which is used to measure small distances and is more accurate than the venire calliper. Another type is a large micrometer calliper which is used to measure large outside diameter or distance.
Feeler gauge: Feelers gauges are a bunch of fine thickened steel strips with marked thickness which are used to measure gap width or clearance between surface and bearings.
Telescopic feeler gauge: It is also known as tongue gauge and it consists of long feeler gauge inside a cover with tongue or curved edge. The long feeler strips protrude out of the cover so that it can be inserted in to remote places where feeler gauge access is not possible.
Poker gauge: This gauge is used to measure propeller stern shaft clearance, also known as propeller wear down.
Bridge gauge: Bridge gauges are used to measure the amount of wear of Main engine bearing. Normally the upper bearing keep is removed and clearance is measured with respect to journal. Feeler gauge can be used to complete the process.
Liner measurement tool: Liner measurement tool is a set of straight assembled rod with marked length in each set. It is used to measure the wear down or increase in the diameter of the engine liner.
American Wire Gauge: American wire gauge or AWG is a standard tool which is circular in shape and has various slots of different diameter in its circumference. It is used to measure cross section of an electric cable or wire.
Bore Gauge: A tool to accurately measure size of any hole is known as bore gauge, It can be a scale, dial or digital type instrument.
Depth gauge: A depth gauge is used to measure the depth of a slot, hole or any other surface of an object. It can be of scale, dial or digital type.
Angle plate or tool: It is a right angle plate or tool used to measure the true right angle of two objects joined together.
Flat plate: Flat plate is a précised flat surface used to measure flatness of an object when it is kept over the flat plate.
Dial Gauge: Dial gauge is utilised in different tools as stated above and can be separately used to measure the trueness of the circular object, jumping of an object etc.
Lead Wire: It is a conventional method to used soft lead wire or lead balls to measure the wear down or clearance between two mating surfaces. The lead wire or balls of fixed dimension is kept between two surfaces and both are tightened against each just as in normal condition. The increase in the width of the lead wire or ball will shoe the clearance or wear down.
These are some of the main tools that are used onboard ship. If you feel we have missed any important tool, then let us know and we will add it in the list.
You may also like to read- A List of Processes Used in the Marine Workshop of a Ship