|
I am indebted to the Staff of the Northern Lighthouse
Board for the following detailed information on recent
developments at the Lighthouse.
Work commenced on automation in the late 1990s. Unfortunately
during reconstruction work an incident occurred resulting
in a fire which caused considerable damage, not only to
the kitchen, watchroom and lightroom, but to the upper courses
of the tower itself. This delayed the project by an extended
period until the damage could be repaired.
|
|
|
|
The Lightroom showing
the damaged
panes of glass
|
The kitchen, immediately
below the lightroom, where the keepers kept watch
|
The pictures above show some of the damage to the kitchen
and lightroom floor. The triangular shapes seen in the lightroom
photograph are the blackened glass panels through which
the light can normally be seen. Many of these panels had
to be replaced after the fire.
|
The photograph to the right shows the type of scaffolding
used to repair the masonry after the fire. The stonework
inside the kitchen had splintered due to the intense
heat of the fire and this caused cracks to appear
in the external walls, which had to be injected with
a special compound to strengthen the tower and keep
out the water.
A normal scaffold is built from the ground up, but
this cannot be used at the Bell Rock because the tide
covers the rock during high water and would wash the
scaffold away. The name given to this special type
of scaffolding is called "cantilever". It
is supported by the building itself. The rock is submerged
twice a day to a depth of several metres. Some days
the rock is never seen above the surface of the sea
at all, due to the time of year, the general state
of tides and weather conditions.
|
|
The automation of the Bell Rock was finally completed in
1998. The technology available at this time required the
use of a hybrid system. This system used electricity to
provide power for the Emergency Lanterns and to rotate the
main light's lens; also acetylene gas to provide a suitable
light source for the main light.
The main light consisted of a "Third Order" lens
(a lens approximately 700mm in diameter, which magnifies
the gas mantle light source) shown in the photograph below.
|
|
|
|
The "Third
Order" lens
|
The Gearless Pedestal
|
The lens is rotated using a machine called a "Gearless
Pedestal". This is a very low-speed electric motor
which does not require a gearbox and therefore has a limited
number of moving parts to maintain. This machine does not
require a great deal of power and only uses about a thirtieth
of the power used by a normal 60watt household lamp.
Batteries are used to provide the power required by the
pedestal and these are charged using solar panels, which
convert daylight into electricty.
The photograph above shows the Gearless Pedestal and the
mechanical device, which changed the gas mantles if one
stopped operating. This actual mantle changer can be seen
in the Signal Tower Museum, Arbroath.
The white panels seen in the background of this photo are
some of the solar panels used to charge the batteries.
The solar panels installed in the lightroom - from the front.
An extension was built onto the balcony to accommodate
12 further solar panels to enable the batteries to be charged.
Even with all the additional panels it was thought to be
insufficient charge to operate the system in the depths
of winter, so in consequence a diesel generator was installed
to cope with any deficit during the winter period. The generator
is primarily intended to be used to provide lighting and
power for visiting personnel.
A device called a "photo electric cell" senses
daylight and when it starts to get dark this device sends
a signal to the control system to turn on the light. There
is a small pilot light (similar to the pilot in a gas central
heating boiler) which is always lit inside the gas mantle.
The control system then opens up the main gas valve and
allows the mantle to operate normally.
Should any of this system fail it will switch itself off
and switch on the emergency lanterns which are mounted externally
on the balcony. These will provide a light that can be seen
at a nominal range of 11 miles (approximately 15 kilometres).
The operation of all the equipment in the lighthouse is
monitored and the information is sent by radio to Fife Ness
Lighthouse (near Crail in Fife) and is then transferred
via a telephone line to the Board's headquarters in Edinburgh.
The decision to refurbish the station was taken primarily
to discontinue the use of acetylene gas. This is a highly
flammable gas, which is time consuming to replace, dangerous
to transport and is not environmentally friendly.
Due to advances in battery and lamp technology it was now
possible to remove the gas and replace it with a safer alternative.
The existing kitchen was retained (renewed after the fire)
as were the existing bedrooms when the lighthouse was still
manned. A new toilet area was constructed to allow for the
installation of generators, fuel and water tanks.
Due to the location and the physical constraints of this
site, the optimum amount of solar panels could not be accommodated.
Therefore to make up for any deficits, diesel generators
have been installed and these are used to charge the batteries,
and also to provide domestic lighting and heating for maintenance
visits.
The new light uses the existing "Gearless Pedestal"
which has been modified to remove the pipework for the gas
and the mantle changer equipment. The existing lens has
been re-used with a new electric light source. This new
lamp uses 35 watts, about one half of the power used by
a 60 watt household lamp. A new higher power battery system
was required for this lamp but because of advances in technology
the batteries were now much smaller than the old ones and
more batteries could be accommodated in the existing floor
space.
The existing solar panels were re-used as they were still
serviceable, even after 13 years exposed to the elements.
The lighthouse tender is required to deliver fuel to the
lighthouse as and when required. This is generally carried
out once per year.
The Entrance Level is extremely small and has a mezzanine
floor, which accommodates the Break Tanks for water and
fuel. These Break Tanks have been installed for the purpose
of reducing the height that the tender's portable pumps
have to pump fuel and water, when storing the station.
The water and fuel break tanks have a capacity of approximately
450 litres each. Fuel and water is pumped from the rock
level (during periods of low water) to each of the separate
tanks. This in turn is transferred via internal pumping
system to tanks located on the balcony. There are four fuel
tanks and four water tanks on the balcony, each with a capacity
of 600 litres. The water tanks provide the station with
water for domestic use ie washing etc.
The fuel tanks are used to supply a further two tanks in
the engine room. These tanks have two purposes: to reduce
the pressure of fuel applied to the engines (which provide
generated power for the station) and to provide increased
storage capacity for fuel. Each tank has a capacity of 350
litres.
The Engine Room contains the two Lister diesel generators,
each of which has a rated output of 10 kW. Each generator
is programmed to do a single start "Health Run"
of one hour each week to maintain the engine in good condition.
In addition the engine is always on standby to charge the
batteries should the voltage fall below its nominal 24V
level. Or when requested by the Optic System, a charging
run can take place for a period of 5 hours. Power for domestic
use is available from each generator.
All equipment is supplied from the new battery system and
even with the advances in technology it was not thought
that the system would run completely supplied by power from
the sun. As generators were required for lighting and power
for maintenance personnel, these generators can be used
to charge the batteries in the event that the batteries
are in danger of running down. The generators will use approximately
180 gallons (approximately 800 litres) of fuel per annum.
This figure does not include use by maintenance personnel,
therefore extra storage capacity was built in to allow for
this use.
The existing helipad was installed in the 1970s and has
provided sterling service during this period despite the
ravages of tide and weather over 30 years. The helipad and
walkway are now showing signs of their age, wear and tear.
A new helipad and walkway are planned and will be installed
within a year or so. Designs or drawings are not available
at the present time, but there follows a couple of photographs
of the existing structure.
The walkway and helipad as repaired in 1987
The helipad in the spring of 1988 after one winter.
Several of the handrail uprights have been damaged and some
are missing.
Sadly today the helipad and walkway are badly damaged in
places and several repairs have been carried out to address
this damage.
|
