Gridirons and Bargebeds
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Thames Discovery ProgrammeGridirons and Bargebeds
Uploaded by
Thames Discovery Programmethames discovery programme
Gridirons,
foreshore factsheet number three bargebeds
and hards
Gridirons, bargebeds and hards are a related group of structures found on the foreshore. They all
provided a stable working surfaces on which vessels could be grounded at high tides. The three
types await close definition, and more research is needed into both the archaeological examples
and historical records. That's where you come in!
Bargebed
beach deposits
Surface of rammed
sealing bargebed
chalk
Quay
Timber
revetment
Foreshore
Gridiron at Custom House showing timbers forming level structure on which the vessel would be grounded; chalk
bargebed at Rotherhithe; section drawing of bargebed showing typical construction
Gridiron
The term 'gridiron' (sometimes referred to as a 'block') refers to a usually fairly ad hoc structure
built to allow a vessel to be repaired or broken up. The vessel is grounded on the gridiron, which
normally consists of long timbers laid perpendicular to the river forming a rough 'grid'. The vessel is
thus supported on the timbers, allowing work to be carried out at low tide.The Gridiron may be
slightly raised in order to make the platform level and possibly to allow work beneath the hull of the
vessel. Gridirons were usually constructed level, as opposed to slipways which would slope into the
river to allow the vessel to be launched.
The gridirons were often built of re-used ships timbers and can provide a valuable source of
information on the type of ships that were broken up in a specific location. Additional material such
as nails or scattered ships' timbers may be found in association with the gridiron and may be related
to the repair/breaking process.
Bargebed
A 'Bargebed' is another type of working surface. The term usually refer to a level platform adjacent
to a wharf, jetty or river wall on which barges or other vessels could be grounded in order to be
loaded and unloaded. Bargebeds were an expensive and usually well-constructed piece of
foreshore engineering that may be linked to a specific on-shore building or industry
Bargebeds were usually constructed by initially building a substantial pile and plank revetment
parallel to the river wall, behind which rubble and solid material was dumped to form the level
platform on which the vessels would sit. This dumped material may contain artefacts which can date
the structure, and also seal earlier foreshore deposits that may have been eroded away elsewhere.
These dumps were normally capped by a hard, rammed stone working surface, often of chalk
rubble or stone blocks. The gridiron surface may have been scoured out by later activities and may
be exposed in section. If badly damaged, the stone surface can be entirely eroded away, leaving
just the timber revetment.
Recording issues:
Is the structure level, or sloping?
Bargebeds are usually sited adjacent to the river wall for loading/unloading. How near is the
structure to access points, to cranes or to quays?
Is there any evidence for ship breaking or repairing around the structure? e.g. ship timbers
or nails?
What material is the structure made of? How was it constructed? How much care was taken
in its construction? Has it been repaired or extended?
Is the structure shown on old maps? Can you use historic maps to date structures/activity?
Can the structure be related to an adjacent building or industry? Common examples include
breweries, wharehouses or breaker's yards named on maps.
A 'hard' is a term sometimes used to describe a bargebed, although it may refer to a less specific
area where the foreshore had been consolidated. The hard may be made from rammed stone, re-
used architectural fragments, or even fragments of hulked vessels.
Slipways were used to launch boats which had been repaired, they can be confused with gridirons
as they are often also made from parallel ships timbers, although they normally slope down the
foreshore to allow the boat to be launched at lower tide.
Themes for research
All the structures are designed to allow the vessel to settle in a stable position, this may indicate they
were solely for flat bottomed vessels, however props may have been used to support keeled craft,
especially on gridirons. Are the functions of the structures different, or are they different approaches
to the same problem?
Some bargebeds were large and presumably expensive structures, especially when specifically
built for an industry such as a brewery, whereas gridirons appear to be simpler, cheaper solutions to
a similar problem. Detailed study of the structures, their date, and the associated foreshore and
land structures and buildings will hopefully lead to a better understanding of the forms, development
and function of the structures.
Local studies
All these structures may be indicated on historic or Ordnance Survey maps which may also show
additional structures such as wharehouses, shipyards, quays, wharves, jetties and cranes that may
be related to the function of the structure. They may also be shown in illustrations of the river.
Further information
Search for photos of gridirons, bargebeds, hards and slipways at the Thames Discovery
Programme Flickr page: http://www.flickr.com/photos/thamesdiscovery/tags/
this factsheet has been generously funded by the Barbara Whatmore Trust