1. A look at how ships are made
At the ship builders
This lesson is designed to highlight the role of physics and design and technology principles to the real world by illustrating the processes involved in designing and making ships.
A look at how ships are made

2. Session outline The development of shipping
The physics, design and technology principles
behind ship building
How ships are made
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We will begin by looking at how shipping has developed from a historical perspective
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before moving on to discuss the physics, design and technology principles behind ship building
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Finally we will discuss how ships are made, illustrating how science and technology apply to the real world and why this is of importance to us all.

3. In the beginning…
Ships were made from hollowed out tree trunks and were called ‘dug outs’
As humans made better tools, they were able to build better ships, powering them through the water with oars and paddles
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As early as the Stone Age (2.5 million years ago – 2,500BC) humans built the first ships were made by hollowing out tree-trunks using stone tools and fire. They were called dug outs.
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As humans made better tools they were able to cover a frame with planks of wood, moving through the water using oars or paddles made out of wood.

4. The development of shipping
Sails allowed for wind power to propel ships forward
Oak was the best wood for making ships
With oak shortages, iron brackets were used
Later more iron was used and steam engines were added to drive paddles and propellers
The first iron ship was build be Brunel in 1839 – The Great Britain
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When bigger ships were made, sails were put on them so that wind power could be used to move ships through the water.
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Ships were made out of oak, and sometimes it could take as many as 1000 oak trees to make one ship! Click three
With the shortages of oak that followed and the increase in price of this building material, iron brackets were used in addition to save on wood.
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Gradually more iron was used and steam engines put in place of sails to drive ships forward using paddles and propellers.
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In 1839 the first ship was built entirely of iron by a man named Brunel. This ship was called The Great Britain
During the Industrial Revolution the internal combustion engine replaced the steam engine on all ships, making it possible for ships to travel further in a shorter time period than ever before.
There are two scientific principles to address when building ships. The first is looking at how and why ships float. The second is looking at how ships are able to move forward. Let’s address both in turn…

5. Why do iron ships float? Archimedes Principle
“An object in a fluid experiences an upward force equal to the weight of the fluid displaced by the object”
We can appreciate why wooden ships might float, as the material itself is quite light, especially when cut up into thin strips, but iron is a very heavy material (i.e. it exerts great force). So how does a ship made of iron, or any other metal for that matter, float?
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Archimedes, one of the great Greek Philosophers of his time, can help us understand this. He famously stated that:

6. Archimedes in practice:
Explains why iron ships float!
Ball: displaced water weighs less than the ball - SINKS
Hull: displaced water weight is the same as the
hull weight – FLOATS
Hull
But what does this mean in practice?
Lets take a look. I am about to show you two objects falling when I click my mouse. Before they hit the water you need to tell me whether each will sink or float. The two objects are made out of iron. Exactly the same masses just different volumes. What is going to happen. Why?
Click one
GO!
Why do you think this happened?
To the ball?
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Read from slide
To the hull of a ship?
Click three
Click four
This explains why huge iron ships that weight thousands of tonnes can float on water, because they displace as much water as their weight (force) of exerts.
Ball

7. The maths behind the theory: It’s all about densityV D
Density = Mass
Volume
Calculating mass:
In g
Calculating volume: (cm3)
Length x Height x Width
And it is all to do with density
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Our mathematical equation is density = mass over volume. The greater the volume the mass of an object is spread over, the more likely an object is to float! This is really important for ship builders and designers to understand as it helps them work out the minimum size and maximum weight of a ship.
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This is our magic triangle which helps us work out the calculation if any one of the variables is missing.
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To calculate the mass of an object, all we have to do is weigh it in g.
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To calculate the volume of an object, all we have to do is times the length of an object by the height and then the width.
What unit do you think density would be measured in? g/cm3
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We know if an object will float or not based on the outcome of this calculation. The golden rule to remember is that if an object has a density of <1g/cm3 it will float in water! If any greater it will sink. h
Golden Rule: If something has a density
of <1g/cm3 it will float in water! w l

8. Driving ships forward Chemical energy Heat energy Fuel Engine Oxygen
Combustion
HC’s + O2  CO2 + H20
Propeller shaft
Oxygen
Work done
Kinetic energy
Now let’s take a look at how the energy required to propel ships forward is created, tracking how energy is transferred from one form to another as we go.
Click one
For marine engines we generally start off with a fossil fuel, which in this case is oil. A ‘fuel’ is any substance which contains stored chemical energy that can be burned to release heat energy. How do you fossil fuels are created? (ask pupils)
(encourage pupils to say that the suns energy was absorbed by marine plants millions of years ago via the process of photosynthesis. As these plants, and the animals that ate them, died they fell to the seabed and got buried in mud and sand, forming fossils. More layers of mud and sand squashed the fossils, heating them under pressure which formed the crude oil we use today).
What form of energy do you think oil stores? (encourage pupils to say chemical) – Click two
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Oxygen is added to the fuel to start a chemical reaction inside the ships engine. (Ask pupils to name this chemical reaction. Encourage them to say combustion)
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It is important to understand that burning fuel does not make energy, it changes the energy stored inside the fuel from one form to another.
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To make ships move, chemical energy stored in the fuel is released as heat energy by combustion. This heat energy is used to heat water which produces steam and drives turbines that subsequently rotate a propeller shaft. (Ask pupils what form of energy they think the heat energy has been transferred to by turning the propeller shaft. Encourage pupils to say kinetic or mechanical energy).
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The propeller shaft is attached to a propeller, which spins with the rotation of the propeller shaft providing work in the form of thrust which drives ships forward!
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This image shows a simplified version of a marine engine, with the propeller in place.
Driving ships
forward
Thrust

9. Modelling propulsion You will need: A small box (e.g. a match box)
Two wooden sticks (e.g. matches)
A thick strip of card
An elastic band
A tray of water
1 – Fix two wooden sticks in a box like this
2 – Stretch an elastic band over them
We can see how kinetic energy will generate propulsion in water by using a few simple bits of equipment (this is an optional experiment which is useful to illustrate how stored kinetic energy can generate propulsion. This can be done as a whole class activity or run at the front by the teacher).
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Fix two wooden sticks in a box like this
Click two
Stretch an elastic band over them
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Place a thick strip of card, which will be your paddle, inside the elastic band as the picture shows
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Wind up the paddle and place in water
(ask pupils what they observe and ask pupils what kinds of energy are being transferred. They should say chemical [pupils using energy to wind up the boat, symbolising fuel on a ship] to elastic [the winding of the elastic band, symbolising rotation of the propeller shaft – although on a ship this would be kinetic] to kinetic energy, in the turning of the paddle which propels the box through the water).
3 – Place your paddle (thick strip of card) inside the elastic band
4 – Wind up the paddle and place in water

10. The tender and drawings from the naval architect
Plans are drawn before ships are built by a naval architect
Plans are taken to the shipping company, where they may be changed
When both parties agree a test model is built, usually from wood or wax
Now that we understand the theory behind how and why ships work (remind pupils that ship building is all to do with applying the principles of physics and design and technology), including how they float and propel through the water, let’s continue our story of how ships are made.
It is worth noting that no ships are built unless they have been ordered because of the sheer amount of time and money it takes to build them.
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When a shipping company wants a new ship, a few shipbuilding firms put in a tender. A tender is the price which the builders think the ship will cost.
At the ship yard where the ship is to be built, plans are drawn by a naval architect. A naval architect, just like a normal architect, draws plans and measurements that look a bit like blue prints (pictured), but for ships instead of buildings.
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The plans are taken to the shipping company, where they may be changed.
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Once both the shipping company and the ship yard have agreed on the plans, a test model of the ship is made. It is vital that the measurements and scaling the naval architect decides on is exact. Just a cm off and the ship that is made as a result may be unfit for use and a huge waste of money.

11. Testing the model Use a piece of equipment known as a ‘towing tank’
Measures the resistance and stability of the model ship so that the final ship will be seaworthy
Engines and propellers are also fixed to the model to decide the best ones for the final ship
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The model ship is tested using a piece of equipment known as a towing tank
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The towing tank measures resistance and stability of the model ship by towing it through a long channel of water. In the towing tank, sea conditions can be simulated e.g. waves to ensure that the final ship will be seaworthy.
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Engines and propellers are also fixed to the model to decide the best ones for the final ship
Towing tank at Newcastle University

12. Advanced Technology Points of instability in red
Some towing tanks have special pieces of software built in that can identify specific areas of weakness or instability on a ship. This computer generated output shows the exact points of instability (in red) of the keel (bottom) of a ship. This is very important to ensure the final ship is seaworthy and will be stable in the water.
Points of instability
in red

13. The mould loft
A full sized drawing of the ship is made in a huge room called the mould loft
Loftsman use a knife to cut out the lines of the ship
Makes templates out of wood, which are needed to be cut steel sheets to build the keel and the hull of the ship
Click one
When the testing of the model has been done, workers at the ship yard make a full-sized drawing of the ship. This is done in a huge room called the mould loft.
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The floor is made of wood and is painted black. On this floor the loftsman use a knife to cut the lines of the ship based on finalised drawings from the naval architect. These lines show up white on the dark floor.
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The loftsman then makes templates of these shapes out of wood, which are used to cut the steel for the hull.

14. The time of steel and building of the keel
Today ships are made of steel
Ships are often built by laying the ‘keel’ on a slope, with a river at the bottom for launch
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Iron ships remained popular in ship building until the early 1900s, but the main problem was that a hull made of iron quickly corroded in the surrounding seawater, and ships had to regularly be dry docked (taken out of the water) and repaired even if the hull was protected with paint. This is because iron reacts with seawater to produce iron oxide (rust) which is brittle and can damage the ship. Even the smallest chip in the paint work would result in the spread of rust.
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Today ships are made from steel, an alloy of iron and carbon which is more hard wearing and resistant to rusting than iron alone. However ships still need to be painted and dry docked once in a while for repair.
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The start of ship building begins with the bottom of the ship or the ‘keel’ from the templates made at the mould room. The keel is often built on a slope, which ends in a river for launching. Large sections of the ship are made in other parts of the shipyard, which are then lifted into place by cranes.
Iron becomes iron oxide (rust)
Building of the keel using steel

15. Cutting of the hull
The templates built by the Loftsman for the hull are taken to the plater’s shop
Platers cut steel plates to size
Two pieces of steel tend to be cut at any one time
Steel plates are painted very well and evenly to prevent rust and create a streamline finish
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The templates built by the Loftsman for the hull are taken to the Plater’s shop
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Here, people cut large steel plates to size using either a shearing machine or a very hot flame.
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When cutting steel for the hull, two plates tend to be cut at the same time (ask pupils why they think this is). This is because every ship has two sides, and by cutting two plates simultaneously there is a greater chance that the final hull will be symmetrical
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Once cut, steel plates are painted very well and evenly to prevent rusting and also to create a smooth and streamline finish to the ships’ hull to reduce the likelihood of drag.

16. The steel frame Steel plates for the hull are fitted to a steel frame
The steel frame is made by frame turners
Sometimes bars are made red hot before being bent into shape
Use long handled hammers to bent the hot bars
Some machines apply enough pressure to bent steel frames cold!
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The steel plates for the hull cut by the platers are fitted to a steel frame
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The steel frame is made from thick steel by people called frame turners. The turners need to bend the steel bars into different shapes.
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Sometimes the bars are made red-hot before they are bent be turners as it makes them much easier to bend (ask pupils why they think this is. Encourage pupils to think about what happens to a substance which is heated, i.e. it receives more energy which breaks bonds and makes the substance more fluid as the particles have the energy to move further apart).
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Long handled hammers are used to bend the red hot bars. (Ask pupils why long handled hammers are used. Encourage pupils to think about pivots and levers. The longer the lever, the greater the turning force about a pivot. Because the handle to the hammer is longer, it takes less effort to produce a load and bend the hot bars into shape).
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More recent technology means that bars can be bent cold. This is a lot less time consuming than hot bending.

17. Riveting the hull
The steel plates and frame bars need to be joined together to make the hull watertight
Used to be riveted together
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All the plates and frame bars have to be joined together to make the hull of the ship watertight. The plates are bent on huge machines.
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A few years ago plates on most ships were riveted together. Each plate had holes along the edges and plates were overlapped with pieces of metal, called rivets, placed in each hole.
The rivets were put in hot and other workers hammered the ends over to seal the hull.

18. Nowadays we use welding
Nowadays plates are electronically welded together
Hot sparks melt metal strips and the welders run the metal into cracks
When the metal cools, the plates are joined together
Better than using rivets because less steel is used and therefore it costs less to build your ship!
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Today plates on most ships are electronically welded together. One electric wire is fixed to the plate. The other wire leads to a strip of metal in the welding tool. The welders point the tool at the cracks between plates
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Where hot sparks melt the metal strips and the welders run the metal into the cracks
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When the metal cools, the plates are joined together and the hull is watertight
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Less steel is used on welded ships as the steel does not need to overlap, unlike on riveted ships. This makes the ships lighter and cheaper.

19. Fixing the propeller
When the hull is ready, the propeller, rudder and stabilisers are fitted
A hole is cut in the stern and a propeller shaft put through, which will eventually be attached to the engine
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Once the ships’ hull is ready, propellers are added. Some ships have more than one propeller and each may have between four and six blades depending on the requirements of the vessel i.e. what job it is going on to do. Rudders are added, which are used to steer the ship, and stabilisers also fixed to help prevent the ship from capsizing in waves out at sea.
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The propeller is installed by cutting a hole through the stern (back) of the ship. A propeller shaft is inserted, which the propeller is hung on, which will eventually connect to the ships’ engine.
Ship stabilisers

20. Making the engine
In another part of the shipyard, engines have been made. They are the most important part of the ship as they need to be reliable, powerful, not to costly to run and not too heavy.
Engineers work out the best kind of engines for each ship. Nowadays these are all oil diesel engines. They burn oil to heat water in boilers to make steam which drives turbines attached to the propeller shaft. This is attached to propeller(s) which drives the ship forward. We saw this earlier on in the presentation (remind pupils of the energy transfer processes in generating thrust).
Finished engines are too large and heavy to be moved into the ship in one piece. They have to be moved in parts and reassembled once inside the ship. The engines of ships are not fitted normally until the ship has been launched.

21. The Launch!
The keel blocks are finally knocked out and the ship slides down into a river. The ship is towed using tug boats to stop the ship from drifting.
A well known lady is usually asked to mark the launch of the ship by naming it and smashing a bottle of champagne against the ships bow (front). This is for good luck!
The boat is towed to a quarry or area of coast where the engine is finally assembled, the boat is kitted out with all the mod cons and the ship is finally ready for use!

22. Safety on ships: the load line
Samuel Plimsoll
Least dense TF F
If it is a merchant ship being launched, the only thing left to do is to make sure the ship is safe when it is loaded with whatever it is going to carry.
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This is done using a technique known as the load line, which used to be called the Plimsoll line after its founded Samuel Plimsoll who was a Merchant Shipping MP.
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The load line is used to ensure the ship has enough freeboard and sufficient reserve buoyancy and stability to remain upright during voyage. The load line makes it very easy to see whether a ship has been over or under loaded and indicate the safe depths at which ships may be loaded.
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The load line is actually different on ships depending on the type of water they are sailing in. The density of water changes depending on its salinity (how salty it is) and its temperature. The warmer and less salty the water, the less dense it will be (ask pupils why they think this is. Encourage pupils to say because salt water has a greater molecular mass than fresh water, it will be heavier. Because heat energy causes particles to expand and move further apart, the density of warmer water will be less than cooler water)
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Ships will float very well in cold, salty water (such as that in the North Atlantic in winter time, which is what WNA stands for), because the surrounding water is very dense, providing greater up thrust from the surrounding water which pushes up against the weight (as a force) exerted by the ship). As such, the safe load line is on the bottom of the ship.
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In contrast, ships will not float well in very warm, freshwater (such as freshwater in the tropics), because the surrounding water is not very dense, providing less up thrust from the surrounding water to push up against the weight (as a force) exerted by the ship). As such, the safe load line is on the top of the ship.
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In between these two extremes we have Freshwater (F), Tropical seawater (T), Summer (S), and Winter (W)
L R, as shown in the picture (middle bottom) stands for Lloyds register. This is the British society which exists to certify the seaworthiness of merchant ships of one hundred tons or more. T S W
Most dense
WNA

23. British shipping earns the UK economy £162 per second!*
The take home message: shipping is of great importance to our everyday lives
Employs 250,000 in the UK
Generates £37 billion to UK economy per year
The fishing industry provides us with a good source of protein for
our diets
Cargo shipping provides us with 95% of the products we use on a
day-to-day basis
Shipping is of importance to us all
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In the UK in particular, shipping employs 250,000 people in the UK,
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and is the second biggest earning industry after agriculture generating a massive £37 billion to the UK economy per year, that’s £162 per second (shown in the did you know box).
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As well as economic benefits, the shipping industry also provides social benefits as well, including a source of protein in our diets
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and the delivery of over 95% of the products we use on a day-to-day basis right to our doorsteps! (ask pupils to check the labels on their clothes and report on where it was made. Ask pupils how they think it reached shops where they bought it).
If we didn’t understand the physics, design and technology principles behind maritime transport such as shipping, the world would be a very different place!
British shipping earns the UK economy £162 per second!*
*SeaVision UK
Did you know?

24. Plenary activity: Measure the load line of your own ships!
Step 1 – Using your marker pen, draw as accurately as possible a 3D outline of a ship onto your block of foam
FRONT (bow)
BACK (Stern)
Step 2 – Cut out your ship shape using the hack saws and safety rulers provided
This is an optional activity that enables pupils to design, make and measure the load line of their own ships. All instructions on where to secure blocks of foam and tools required are provided in the Teacher’s Notes. Alternatively, half cut plastic bottles or something similar could be used. The load line of the same ship could be tested in different variations of hot, cold, salty and fresh water to illustrate the principles of density by collecting data for their own ship.
A plenary activity sheet is also supplied in the plenary activity folder of this resource and should be printed and handed to pupils in groups.
Click one, two and three read instructions from slide
Step 3 – To make your cargo hold, draw a box using your marker pen and score around it using a Stanley knife and safety ruler. Score across the box too. Using a flathead screwdriver, tease the pieces of foam out until you have a cargo hold. Sand the whole design down to a smooth finish and decorate using waterproof marker pens.