Download The Savannah River Walking-beam Coastal Underwater

Coastal Underwater Archaeology Field Station
Georgia Department of Natural Resources
Skidaway Institute of Oceanography
10 Ocean Science Circle
Savannah, GA 31411
(912) 598-3346
___________________________________________________
Field Brief No. 08-10
Filed by: Christopher P. McCabe, Deputy State Archaeologist
20 October 2008
The Savannah River Walking-beam
In the late 1700s, steam technology emerged as a
growing force in maritime transportation. The
machinery’s early design originated in England’s
mining industry, where engineers applied the energy
derived from pressure cylinders and pistons to pump
water from flooded quarries and coal shafts. As marine
steam engines evolved, shipbuilders expanded upon
this straightforward principle through the use of a
“walking-beam”, a diamond-shaped iron framework
that see-sawed on a central pivot transferring power
from the piston to the vessel’s paddlewheels (Figure 1).
Throughout the 1800s, vertical walking-beams were
distinctly visible on steamboats along countless coastal
maritime trade routes, until ultimately being replaced
by more advanced steam engine designs (Figure 2).
Today, only two historic walking-beam steamboats
remain afloat.
Figure 1. Profile diagram of a
walking-beam steam engine.
Figure 2: A painting of the steamboat Enoch Dean by James Bard (1815-1897).
The vessel’s walking-beam is located just behind the stack above the word “Enoch” (detail).
1
In August 2008, while conducting a visual inspection of the Savannah River shoreline
associated with the city of Savannah’s river-walk extension project, underwater
archaeologist Chris McCabe discovered several pieces of a large iron walking-beam on
the water’s edge. Construction workers had recently uncovered the objects while
preparing the site for the new walkway (Figure 3).
Figure 3: Aerial image of Savannah, GA with the
walking-beam find location identified in red.
At present, the Savannah River walking-beam does not appear to be associated with any
particular vessel or shipwreck, but is more likely linked to a former shipyard, foundry, or
riverboat landing known to have once occupied the site (Figure 4).
Figure 4: A detail image of Savannah in 1871 and the waterfront near where the walkingbeam was found (note that both underway steamboats utilized walking-beam designs).
2
There are four major disarticulated pieces associated with the Savannah River walkingbeam. Preliminary observations show the main diamond-shaped framework to have an
overall length of approximately 15' 6" (4.72m) and a width of 6' 8" (2.03m). It is made up
of solid iron square bars approximately 4"x4" (10cm x 10cm) which approach 6" (15cm)
square at each end, with 4" (10cm) long "pins" extending outward on each side. The
central pivot piece is heavily concreted, but appears to be approximately 2’ (61cm) wide
at its widest point. The combined weight of the walking-beam is estimated to be in excess
of 3,500 lbs (1,588kg). The entire structure exhibits moderate levels of surface corrosion
and shellfish concretions indicating that it was intermittently buried in the shifting
sedimentation of the tidal river (Figure 5).
Figure 5: Pieces of the Savannah River walking-beam at the river-walk construction site.
As construction on the surrounding site continued and initial attempts to establish the
proper context of the walking-beam proved elusive, archaeologists at the Georgia Coastal
Underwater Archaeology Field Station (GCUAFS) decided that the iron objects needed
to be promptly relocated in order to save them. The Skidaway Institute of Oceanography
offered assistance to help move and temporarily house the hefty yet fragile artifacts. On
14 October, workers from TIC-The Industrial Company used a large commercial crane to
maneuver the individual pieces of the walking-beam onto thick rubber supports on the
back of a Skidaway Institute flatbed truck (Figure 6).
Figure 6: Construction workers from TIC load the walking-beam frame onto a SkIO truck.
3
Once back at the Skidaway Institute’s Priest Landing facility, Norman Thomas, Harry
Carter, and Chris McCabe carefully offloaded the walking-beam using straps rigged to a
backhoe, and positioned the pieces into a wet-storage tank where they will be thoroughly
cleaned, inspected, and documented. GCUAFS archeologists are hopeful that adequate
financial support can be obtained in order to properly conserve and repair the walkingbeam for eventual public interpretation and display in a suitable maritime setting. It truly
requires the efforts of a dedicated team of individuals to help keep Georgia’s maritime
heritage alive for future generations to study and enjoy. Special thanks go to:
♦ Georgia Southern University’s Applied Coastal Research Laboratory
♦ The Skidaway Institute of Oceanography: Marc Mascolo, Chuck Hartman,
Norman Thomas, Harry Carter, and Jay Fripp
♦ TIC - The Industrial Company: John Maher, "Bubba" Brockman, and the rest of
their skilled crew.
References:
The Mariner’s Museum
1991 The Mariner’s Museum Exhibitions and Collections, Newport News, VA. The
Model Collection, Marine Walking Beam Engine On-line:
http://www.mariner.org/exhibitions/highlights/model_walkingbeamengine.php
S.S. City of Milwaukee
n.d. S.S. City of Milwaukee - National Historic Landmark, Manistee, MI. Links, The
Carferries of the Great Lakes, Great Lakes Carferry Steam Engines, Triple Expansion
Steam Engines, Diagram of walking beam engine on-line:
http://www.carferries.com/triple/page15.jpg
"Birds Eye View of the City of Savannah, Georgia 1871. A. Ruger, St Louis, MO.
4