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VBRP/LCMM Diving Crew August 2000

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Accumulating sediments have long since covered and concealed the battle debris that settled to the floor of Valcour Bay.  Its flat, featureless surface provides no visible indication of what lies beneath. 

Land-based archaeological surveys typically involve the physical removal of large quantities of sediment to discover what lies in distinct areas of study.  This approach isn’t feasible with the study of a vast, underwater battleground like that at Valcour.  This is because the work of the VBRP divers is limited by their supply of compressed air and their visibility of the site.  At the 40’ plus depths that we’re working, a standard tank of compressed air lasts an average of 45 minutes.  Once the divers disturb the sediment, it soon becomes suspended in the water column and the distance they’re able to see is reduced to mere inches.  The VBRP team would need to develop an unconventional approach.

A vast array of weapons complimented the British and American fleets during this eighteenth century battle.  Among them were cannon, mortars, swivel guns, muskets, swords and bayonets.  By the battle’s end, many of these objects and large quantities of shot had sunk to the bottom of the bay.  Since these objects consist mainly of iron and other metals, submersible, hand-held metal detectors offered a cost-effective and efficient means of locating them.    The detectors are capable of locating metallic objects, buried under several feet of sediment.

The survey team’s principal investigators chose to rely on a thorough and systematic method to search the project’s 50’ grids.  They decided to employ the parallel-track search pattern; it’s an overlapping, back-and-forth pattern.  Search and rescue teams often refer to this method as “mowing the lawn”.  It provides thorough coverage when there’s the potential for locating targets anywhere within a search area.  Since the team didn’t know if other artifacts existed or where they would find them, this method was our best option for conducting the survey.

Now the challenge for the team’s principal investigators was to develop a means to deploy the parallel-track pattern within the 50’ grids.  On a good day, underwater visibility is only about 20’ in the bay; how could divers consistently and accurately find their way across the grid’s 50’ expanse?

The team found their answer with the PVC grid posts that they had used to form the grid system.  By cutting channels in the tops of the grid posts, attaching tape measures to them and using triangulation, the divers were able to precisely determine where each corner of the grids should lie.  They found that the thick layers of clay in the bay’s floor held the posts extremely well.  It didn’t seem to matter how much the diver’s pulled on the tape measures; the posts didn’t budge.  The solution was simple – more posts!

Once a grid is selected for survey.  A series of posts are placed at precise intervals along the grid’s north and south borders.  We refer to these posts as transect posts.  Lines are strung between corresponding posts on each side that guide the divers as they traverse the grid.  The posts and the lines form a physical model of the parallel-track pattern.  The system allows the divers to concentrate on their metal detection and prevents them from becoming disoriented.  As with the survey map, I won’t go into to the minute details of the system; but a schematic is posted below for those who wish to study it.  This is the same schematic we provide to new survey divers when introducing them to the survey’s methodology.        

Continued here: Survey Documentation

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Other links about Valcour Island and the Battle of Valcour within
The Lake Champlain and Lake George Historical Site

The Battle of Lake Champlain: The American Revolution on Lake Champlain

• The Battle of Valcour on Lake Champlain

• Valcour Island- Scene of The Battle of Lake Champlain, October 11 1776

• Vessels involved in the Battle of Lake Champlain- October 11 1776

• Arnold's Bay- Panton, Vermont

Download a copy of The Lake Champlain Maritime Museum's Official VBRP Cannon Raising Commemoration Program- Click HERE.
 

IMPORTANT NOTE: Artifacts on the bottom of the lake are the property of the People of the States of New York and/or Vermont by law. It is illegal to remove or damage them under State Law(s) without the appropriate clearances and permits. Removing them and transferring them across state lines violates Federal law & makes one liable to Federal prosecution.