IMH Takes to the Skies

In the northeast, IMH is working with state agencies and university students to document coastal archaeological sites in tidal environments, and coastal sites that have become exposed as a result of storms.

Not to be confused with Autonomous Underwater Vehicle (AUV), IMH recently volunteered its DJI Phantom 3 Professional, an Unmanned Aerial Vehicle (UAV), aka “drone”, to document shipwrecks exposed following offshore hurricanes and heavy beach erosion on Salisbury and Seabrook Beach in Massachusetts and New Hampshire:

http://www.newburyportnews.com/news/local_news/remnants-of-centuries-old-shipwreck-wash-ashore-at-salisbury-beach/article_7d6e2781-d7a5-5235-9f80-223908847145.html

http://www.seacoastonline.com/article/20151105/NEWS/151109434

State agencies such as the Massachusetts Board of Underwater Archaeology, the New Hampshire Division of Historical Resources, and Maine Historic Preservation Commission, occasionally receive notification from the public of exposed shipwrecks and coastal prehistoric sites, but almost always lack the resources and manpower to conduct site visits and gather information that can be used to document exposed archaeological sites, and inform decision-making and support preservation efforts. Here is where IMH (and UAVs) can play an important role in supporting the documentation and preservation of maritime heritage.

Case in point, in October-November 2015, following hurricanes Joaquin and Kate, beachgoers reported to state agencies that large shipwreck fragments were exposed or had washed up on Salisbury and Seabrook Beach. The agencies then contacted me and asked if I could make a site visit and evaluation. My response was, of course! After a short 20 minute drive from home, I was able to quickly deploy the UAV and document the wreckage within 15 minutes. The Phantom 3 has an on-board Global Positioning System (GPS) that provides excellent location data for the UAV, but not necessarily the subject matter of the image (i.e., the wreckage). Therefore, I also collected Ground Control Points (GCPs) using a sub-decimeter GPS, which allowed me to correctly orient and scale the wreck debris. After a few perspective shots to provide context, a close-up overhead shot, and about an hour of post-processing on the computer back at the office, “Voila!” – the result was a high-resolution, accurate site plan, allowing for direct measurement from the photograph:

The imagery not only provided documentation for posterity, but also supported decision-making for those government agencies charged with the protection and conservation of maritime heritage in the following ways:

  1. Determined that the wreckage was squarely in the jurisdiction of Massachusetts, and not in New Hampshire, as originally reported.
  2. The debris was clearly a large fragment that was disarticulated (or dislodged) from a shipwreck site as a result of recent storm, tidal, and wave activity, and was not in situ (in its original location), or representative of a shipwreck site.
  3. Provided site formation process insights, in that within two days the wreckage had migrated some 300 feet south from its original reported location, and had broken off from what was once a much larger hull fragment.
  4. Allowed state agencies to record site location information into cultural resource databases, make decisions about the historical significance and conservation potential of the reported finds, and alerted coastal resource managers of the presence of heritage and shipwreck sites in the area.
  5. Confirmed that UAVs offer a cost effective, rapid response, and accurate means of documenting maritime heritage sites.

There were no identifying marks or historical artifacts to indicate which ship the wreckage is associated with, but it is generally thought that the fragment is from the wreck of Jennie M. Carter, a three-masted schooner that beached in a storm in 1894 en route from Rockland, Maine to New York with a cargo of stone. The wreck fragment appears to be coincident with 19th-century schooner construction, so this wreckage is perhaps associated with Jennie M. Carter, but could not be confirmed. Any future survey work, such as wood species and dendrochronology sampling could support further vessel identification and dates of ship construction or repair.

Based on the aerial imagery provided by IMH, the decision at the state level was ultimately to not recover the debris or conduct any further investigation of the wreckage. There is generally little appetite for or availability of public funds to document and conserve artifacts of this nature, and therefore the “do-nothing” response at the local, state and federal levels, beyond basic recordation is perhaps appropriate but also not surprising. However, when responsibly and safely deployed, the UAV is certainly one tool that can be used effectively by organizations such as IMH to raise awareness of and document and preserve maritime heritage in a way that also supports, encourages, and engages our government and citizens to do the same.

In 2016, IMH will be using its UAV to document maritime heritage from an entirely new perspective. I will be taking to the skies to photograph a variety of maritime archaeological sites and built-heritage sites throughout New England. Check back to the IMH website for updates on IMH’s UAV work!

revised plan, autumn 2015

It was disappointing to cancel our big fall projects up the Potomac, but we can focus on the Lord Dunmore project instead.  It would be very valuable to Maryland and IMH to find and prove a vessel that was scuttled by Dunmore in the summer of 1776.  That would be the first underwater site dating from the Revolution found in Maryland.  Historical records say between eight and 23 vessels were burned, so we are looking for stone ballast piles and associated debris.

The site is convenient to Tall Timbers and does not present the logistical constraints the Potomac projects posed.  It can be done in stages on weekends, and it offers good ancillary training in boat handling, sidescan operation, and magnetometer operation once we get that puppy to work.

Depths are 10 to 20 feet.  The bottom is hard, and visibility is unusually good by Potomac standards.

Prior scans by Azulmar, LAMP, and IMH with sonar and magnetometer covered about half the target area and disclosed several dozen protruding objects that need to be mapped and assessed, and at least 23 isolated magnetic anomalies that need to be refined, found, and assessed — plus two linear magnetic targets hundreds of yards long.  Those probably are underwater cables, perhaps left from the US Navy torpedo test station that operated in the area from 1941 to 1959, or electrical cables that once powered a lighted aid to navigation.  That speculation needs to be proved or disproved.

So, the revised plan for autumn is to dive and map the Dunmore site every weekend the weather allows, starting this Sunday, 20 September.  (Saturday 19 is out.)  Most weekdays are available too, if we have divers.  The standard plan will be to meet at Tall Timbers at 0830, load up, get underway by 0900, arrive on site and start diving by 1015, secure at 1600, and dock at Tall Timbers at 1715.  Two tanks should be enough.  Roper will carry spare tanks with yoke fittings.  We will anchor or live-boat, depending on location, conditions, and manning.  Mapping will be done by sonar, offsets, and trilateration.  Bring a tape, slate, and lunch, and confirm with me by email or phone (302-222-4721) the day before you come.

Autumn 2015 work

We have five projects scheduled for this autumn after our workboat Roper comes home from LAMP at St Augustine:

7-10 September:  help the Naval History & Heritage Command evaluate a portable sonar system;

11-18 September:  assess 19 sites in the Potomac River in transit to Widewater VA;

19 September – 19 October:  assess about a dozen WWI wooden steamship hulls at Widewater;

20-26 October:  assess a possible Civil War site near Quantico VA; and

2-24 November:  assess features that might be related to vessels scuttled by Lord Dunmore in July and August 1776.

If you would like more information on these projects, and especially if you would like to participate, please click the “contact” button on our homepage.