Author Archives: hunterbrendel

Site Delineation with an Underwater Metal Detector

by Hunter Brendel, Master of Maritime Archaeology student

It is a certain fact that all field archaeologists are aware of – equipment does not always behave the way you want it to. Yet when it doesn’t, the opportunity for “McGuiverism” is there. During the Flinders 2013 field school at Port MacDonnell, we had certain technical issues with the magnetometer we were using. Luckily for us, the staff came prepared with underwater metal detectors. By using metal detectors, we were able to conduct transect surveys to delineate a possible shipwreck site on shore (Figure 1). Students used the metal detectors to detect pings that were then marked on a survey plan.

Figure 1. Myself (left) and fellow student Chelsea Colwell-Pasch (right) conducting a metal detector survey on shore during the 2013 Flinders University Maritime Archaeology field school.

Figure 1. Myself (left) and fellow student Chelsea Colwell-Pasch (right) conducting a metal detector survey on shore during the 2013 Flinders University Maritime Archaeology field school.

Later on, we used the same transect method to delineate our shipwreck, Hawthorn, which was located approximately 10 meters off shore. Since the wreck was in the surf, we students were able to replicate the transect survey techniques used on land by snorkeling and marking pings on a Mylar survey plan slate. All we needed to do was give a thumbs up every time we heard a ping, and our dive buddy was there to mark where the ping came from. Two other students held down the transect line and moved it every time we cleared a lap. Simple enough, yet effective in practice.

The Lighthouse Archeological Maritime Program (LAMP) devised a similar strategy for their 2014 Storm Wreck field season after experiencing magnetometer issues themselves. Brian McNamara, a fellow 2013 Flinders field school student and LAMP archaeologist, devised a plan to use a metal detector to delineate the Storm Wreck site. Only this time was different. Site conditions such as an eight meter depth of the site, poor visibility (really poor visibility), and chance for swells were unlike those we experienced in South Australia. Not to mention it had to be done on SCUBA.

So we hit the drawing board and came up with a plan to delineate the Storm Wreck site by using an underwater metal detector. I was to carry out the trial run by delineating a 10×10 meter area south of the Storm Wreck site (Figure 2). Listed are the materials we needed to SCUBA with to effectively carry out the underwater detector survey:

  1. A ten meter polypropylene transect line with every meter marked with a zip tie. At the five meter mark was a looped zip tie.
  2. Two fiberglass rods.
  3. Measuring tape.
  4. Down line with a diver flag attached to a buoy.
  5. A mushroom anchor to hold the down line and western end of the transect line.
  6. A weight belt and weights to hold the the eastern end of the transect line.
  7. Underwater metal detector.
  8. Mylar slate and pencils (lots of pencils) for a survey plan.
  9. SCUBA gear, cylinder, compass, etc.

First, my student dive buddy and I brought with us a mushroom anchor and down line with a diver flag attached to a buoy. Then we swam to a screw anchor that held southern end of the baseline in place. At the screw anchor, my student dive buddy held the middle loop of the polypropylene transect line in place. I swam east, end of the transect line in-hand, to stretch out the transect line, which I tied to the weight belt so that it was secure. I inserted one of the fiberglass rods through the weight belt as a reference marker. Using my compass, I ensured that the line was on an east-west, or 180 degree, bearing. I swam back to my dive buddy, stretched out the other half of the transect line, secured it to the mushroom anchor, and used my compass to make sure the east-west bearing was still accurate. I then planted the other fiberglass rod through the mushroom anchor.

Now the survey could start.

My dive buddy and I swam east-west along the ten meter transect line with the underwater metal detector in hand. Covering two meters to north and south of the transect line with the metal detector, we would pick up pings and then mark their location on the Mylar survey plan slate. As the designated metal detector holder (aka “Wielder of Truth”), I would tap my dive buddy’s mask every time I heard a ping and my dive buddy would mark its location on the slate. After we cleared the ten meter transect line, we would measure and move the line two meters south and repeat the survey. When five survey tracts were completed, we would have covered a 10×10 meter area south of the site.

Believe it or not, the metal detector survey to delineate the Storm Wreck was a resounding success. All students and supervisors had an opportunity to conduct the survey around the northern, eastern, western, and southern periphery of the Storm Wreck site. LAMP staff hope to superimpose the results of the survey on an up-to-date site plan of the wreck. Piece of cake.

Figure 2. “Trust me, I’m an archaeologist.”

Figure 2. “Trust me, I’m an archaeologist.”

Opening an Offshore Maritime Site for Continued Excavation

By Hunter Brendel, Master of Maritime Archaeology student

The Lighthouse Archaeological Maritime Program (LAMP) 2014 Field School, in which I am participating, is a continuation of the total excavation of the Storm Wreck, an eighteenth-century American revolutionary war shipwreck off the coast of St. Augustine, Florida. Most field schools I am familiar with are usually shore dives of sites that entail pre-disturbance assessments. This field school is different. Work on site began in 2009 and has already covered five field seasons of surveying, researching, and excavating approximately 30 1×1 square meter units. This field season continues work from previous seasons.

The Storm Wreck lies approximately a kilometer off the coast in about nine meters of water, so access to the site requires the use of a research vessel. The LAMP research vessel, Roper, is moored over the site to provide surface support to archaeological divers and houses two water dredges that are used to excavate the site. There is a catch, however, as mooring directly on site risks disturbing the site and the archaeologists working on it. The vessel also needs to be soundly anchored to protect it from the elements, such as ocean swells, wind, and the risk of suddenly-turning weather (the shipwreck is named the Storm Wreck, after all).

In order to moor Roper over the Storm Wreck so that archaeological work may be safely conducted, the staff at LAMP have devised a three-point mooring system. Three permanent anchors are located north, east, and west of site. These anchors have individual mooring lines attached to them that are located by divers, raised, and tied to a fixed point over the Storm Wreck site. The lines are then attached to a buoy and submerged over site with the buoy acting as a down line for the divers once they commence work.

When I first arrived in St. Augustine a week before the field school started, my initial task was to help locate the mooring lines and open the site for work the next week. A fellow supervisor and I joked that finding the mooring lines was like opening the curtains on the first act of a play—the 2014 LAMP Field School—with the Storm Wreck site being the stage.

Finding the mooring lines in low visibility is not as simple as diving down to the lines and raising them. First, you have to find them by feeling the area. To do so, LAMP developed a method of circle search that allows both divers to swim around the search area. In a traditional circle search, one diver holds down the zero end of a measuring tape in a fixed position while the other diver searches with the other end of the tape on a 360 degree axis. LAMP’s method of a circle search, however, allows both divers to search by holding down the zero end of the tape with a t-probe and mushroom anchor. This frees up the diver (the finder) who would usually hold down the zero end, allowing him or her to search the length of the tape while the other diver (the navigator) rotates around a 360 degree axis on a northern bearing. When the full circle is complete, the navigator extends the length of the tape another five meters while the finder continues to swim the length of the tape (Figure 1).

Using GPS coordinates, Roper placed my dive buddy and me over where one of the anchors was supposed to be. Diving down, we had three principal tools with which to conduct our circle survey: a t-probe, a mushroom anchor, and a measuring tape. Using the mushroom anchor, which also served to hold our down line, we drove the t-probe and measuring tape into the seabed. My dive buddy, who was in the navigator role, extended the tape out to a length of five meters and with a compass conducted a full 360 degree axis sweep on a northern bearing. My role was finder.

Figure 1. A sketch showing how LAMP conducts circle searches with a pair of divers. The circle displayed is the search area. One diver (the navigator) holds the end of the tape at a distance of five meters and rotates on a northern 360 degree axis. When the circle is completed, the navigator extends the tape five more meters to expand the search area until the objective is found. The other diver (the finder) searches both sides of the tape as the measuring tape is rotated and extended. Sketch by Hunter Brendel.


As the navigator rotated around the axis, I searched up and down the measuring tape, which was held in place by the t-probe and mushroom anchor. Usually after the circle is completed, the navigator would extend the tape another five meters and widen our search area. Fortunately, before the first lap was done, I felt a snag in the measuring tape. Tracing the kink in the tape, I felt the mooring line blocking its path. We had found our anchor.

After lifting the mooring lines for all three anchors, we tied them together with a buoy and down line secured by a screw anchor only two meters from the Storm Wreck. The LAMP 2014 Field School was officially opened.

Whenever Roper finds the site by GPS, we locate the buoy that holds the mooring lines, untie them, and fix the three lines to the bow and aft of the stern. To release tension on the lines, LAMP uses pelican hooks for a safer and more secure hold (Figure 2). Then the real work begins!


Figure 2. One of the three-point mooring lines secured aft of the stern of Roper. To reduce tension on the line, a pelican hook is used. This technique of using a pelican hook was adopted by LAMP from local shrimp trawlers. Photo by Hunter Brendel courtesy of LAMP.

Maritime Archaeology by Braille

by Hunter Brendel, Master of Maritime Archaeology student

As I sit on the edge of a 1×1 square meter unit, all I can hear is the methodical sound of my own breathing through my regulator. The water dredge is operating in full force with my student dive buddy wrestling the dredge (I’ve dubbed it ‘the hydra’ as a term of endearment) and digging down into the darkness of history. Looking to the right, I spot a school of Atlantic spadefish within reach, curiously hovering over a neighboring unit to the west. They scatter when a fellow supervisor emerges from the unit, giving me the “okay” dive signal as he descends back into the darkness. Following a travel line, I swim around the unit into another one a couple of meters south of my position to scope out an artefact that is already plotted on the site plan I have engraved into my memory. I gingerly reach down into the unit with my right hand, feeling the artefact a meter down through the pitch blackness. It is then I realize I am touching history, an eighteenth-century cannon lost to the bottom of the ocean long ago. This scenario gives me flashbacks to a terrestrial field school I participated in a couple of years ago—only the dredge is our trowel and hand signals are our primary means of communication. This is all done with less than a meter of visibility.

It’s difficult to describe the surreal experience of excavating underwater in low visibility, but archaeology by braille is a task that requires all five senses to be fully functional. The site I am fortunate enough to be working on is known as the Storm Wreck, a British loyalist revolutionary shipwreck discovered off the coast of St. Augustine, Florida in 2009 by an American non-profit underwater archaeology organization, the Lighthouse Archaeological Maritime Program (LAMP). Since then, LAMP has dedicated a field school each summer to excavating the Storm Wreck by bringing in students and volunteers from around the world to work on the project.

Currently, we are in the throes of the 2014 field school, and I couldn’t be more excited about the work we have done and what we have yet to accomplish. The field school extends the full month of June, so I am blogging my experiences on certain aspects of the project as a directed study and to inform the public on how Flinders Maritime Archaeology students conduct archaeology outside of the crystal clear waters of South Australia.

This blog post focuses on what I consider to be the primary environmental difference between my previous experiences on maritime archaeology sites in South Australia to that of Florida’s northeastern Atlantic coast. The Flinders 2013 field school that I participated in near Port MacDonnell was focused on two sites that had diving conditions of relatively clear visibility. We students were able to document the sites by taking photos with cameras in underwater housings and sketching archaeological features on Mylar. On the Storm Wreck, however, site documentation by photography is nearly impossible unless the visibility is unusually good. In order to work on the site, I’ve had to memorize the site plan, trust my instincts, and follow travel lines to get where I want to be.


Figure 1. Students during the 2013 Flinders University Archaeology Field School near Port MacDonnell, South Australia.


Figure 2. A diver during the Storm Wreck 2009 field season installs a screw anchor to mark an anomaly. This photo was taken on what is considered to be a good visibility day. Photo courtesy of LAMP.

Even if visibility is excellent on the Storm Wreck site, by the end of the day it is nonexistent because of water dredges silting the site. To train students and supervisors to be ready for site conditions, LAMP staff devised an obstacle course in a freshwater dive shop pool that was riddled with obstacles such as barrels, wheelbarrows, and tangled line. The goal of finishing the course was to descend a down line, retrieve a flashlight, follow a travel line through the assortment of obstacles, clip the flashlight on the end down line, and ascend to the surface. Furthermore, the diver was further challenged by LAMP staff and supervisors by blacking out his or her dive mask with electrical tape. The course was to be completed without vision and taught the diver to trust his or her instincts and the travel line. Divers were also clipped to the bottom of the pool by bungee cords at certain points of the course to teach them how to comfortably unsnag themselves. At one point in the course, divers were to take off their BC (buoyancy compensator) and put it back on.

Since I was new to the project, I went through the course myself and nothing could have prepared me better, other than actually being on site, to navigate the Storm Wreck. I had a blast doing the course, as did all of the other divers, and I hope to see similar training on low visibility maritime archaeology projects in the future. Now to get back in the field!

Figure 3. A student is challenged to follow a travel line with his or her blacked out mask during the LAMP 2014 field school obstacle course. Photo courtesy of LAMP.