Balmoral is a traditionally built ship with a steel hull. The first
ships used wood, then in the 19th Century iron was the new material, as
used by Brunel in the Great Britain further down the Docks, although
Balmoral is actually moored over the place where Brunel's first ship, the
Great Western was built and launched! In the early part of the 20th
Century, steel became available. This was a form of iron with
additional chemicals that made it more flexible, much less brittle and
easier to work.
RIVETS AND WELDING
Originally iron ships were held together with rivets. These were plugs
inserted through matching holes in the plates and formers. They were
red hot when put in. This caused them to expand slightly and red hot
metal is softer than cold, so they were easier to form. The rivets
were heated up next to the ship, inserted into the holes with tongs and
and were hammered flat on the inside of the hull where they poked through,
so that as they cooled and contracted, the sheets of iron were pulled
together. This gave a very strong and watertight joint, but it was
slow and time consuming to put together and incredibly noisy as all the
rivets had to be hammered flat with a machine or in the early days, a man
with a sledge hammer !
As the 20th Century progressed, steel was used rather than iron, and this
was much better for building because it could be formed and was also
stronger for a given thickness, although it did rust much faster,
particularly in salt water ! The other great advantage was that steel
could be welded together. This involves using a very high electric
current to melt a stick that is pulled over a joint between two pieces of
steel. The intense heat melts the stick and softens the metal on
either side of the joint so that they all fuse together and form a
continuous waterproof join that is as strong as the surrounding material.
Although mistrusted at first as some ships had brittle welds that cracked
and cause the hulls to fall apart in rough seas, this was eventually
resolved and welding became the standard way to build ships. It was
cheaper, faster and used fewer men. It did produce a great deal of
poisonous fumes and intense light that could damage people's eyes, but once
these issues were controlled it soon became used for all ship building.
Balmoral is almost unique in that she uses a mixture of riveting and
welding. She was built at a time when shipyards were changing over to
welding but some ship owners still preferred the traditional rivets.
Balmoral thus has a riveted lower hull and welded upper sections. Over the
years as new hull pieces have been added to replace rusty sections, the new
parts have been welded into place, so she is something of a mix and match
these days, but there is still a lot of riveted metal in the ship and it is
easy to spot.
This is an example of welding. Each steel plate has been joined by
melting a welding rod into the surface, which leaves a tell tale bump with a
series of ridges ( called a weave ). This is done by moving the rod
slightly so that that the molten metal is mixed together and makes a
Here is a mixture of welding and riveting. The hull plates are
welded together and the weave of the join can be seen, while the rivets show
up as small regular rounded bumps and secure the frames that give the ship
its shape and strength, to the hull. This is a rare way of putting a
ship together but is incredibly strong if time consuming.
BILGES & BULKHEADS
Under the floor of the officer's quarters you can look into the very bottom
of the ship, known as the bilge. This is the area where the keel is
located. The keel is a very strong girder structure that is the first
part of a traditional ship to be assembled, and everything is built up from
it. In Balmoral's case it is clearly visible as a series of girders
and steel plates running along the centre line. Running out a right angles
are the ribs which form the curve of the sides and run upwards to the deck.
They are the formers to which the steel plates of the hull are welded or
riveted and Balmoral has one every 600 mm, which makes her hull extremely
strong. Additionally a ships engines are extremely heavy and these are
mounted directly to the keel of the ship which has a specially designed
section. The keel
is shown in blue on the diagram and the engines are clearly mounted
on the raised section so that their weight is distributed evenly to the hull
of the ship. If they were mounted on the plating that forms the skin of the
ship they would break through and tear a huge hole in the bottom !
This is the bilge area under the officers quarters. You can see the
centre keel section with the stringers either side and the riveted plates
giving strength to the bottom of the hull. At the furthest end of the
compartment is the bulkhead.
Most ships have dirty water and muck in this area. Balmoral was
extremely well built and is looked after by dedicated volunteers. Her
bilges are dry, clean and even painted as this photograph shows.
Another very important feature of the construction are the bulkheads
shown in yellow.
These are watertight barriers that turn the bilge area and lower part of the
hull as far up as the main deck into watertight boxes. These are
designed so that if the hull is damaged and begins to leak water, the
flooding will remain in a compartment and although the ship will float
lower, it will not sink. The other use of the bulkheads is to maintain
stability. If too much water enters the bottom of the ship, its centre
of gravity will begin to rise and eventually it will roll over. Thus
the bulkhead has two functions - it stops the ship sinking and also keeps it
stable in the event of an accident. There are no watertight doors on
Balmoral ! The bulkheads are completely sealed and the only way to get
from one compartment to the next is by climbing up a stairway ( companionway
on a ship ) and down another one into the next compartment. In this
way the water can't leak from one to another !
The lower lounge/bar area is another watertight compartment. You would
never know, but the top of the stairs are fixed to the top of the watertight
bulkhead that separates this section from the engine room compartment.
When a ship is built, there are always more bulkhead s at the bow and stern
than in the middle. This is because most accidents result in damage to
the ends, for instance if it runs aground, it will usually hit bow first.
Thus there is a small sealed area at the very front( forepeak ), a
collision bulkhead that is designed to withstand a major crash, and behind
that are regularly spaced bulkheads for the rest of the length,
followed by a smaller one at the rear that contains the steering and usually
an auxiliary generator.
............... and as a final photograph of rivets, here is the
boiler and part of the hull of a wrecked ship, the 'SS Staghound' that
was built in the 1890's, bombed and sunk during the Second World War,
salvaged and then grounded and finally blown up to test explosive charges!
Rivets are very strong indeed !