Author Archives: bennettkurt

Maritime archaeologist, you say? You just strap on a tank and mask don’t you?

Introduction

When I asked my mum and dad to picture a maritime archaeologist, they immediately described a diver fluttering about underwater searching for lost relics on the seafloor (Figure 1). To those in the know, the archaeologist/diver would resemble something quite different; an individual meticulously excavating and recording a submerged archaeological site. But can the definition of a maritime archaeologist be as simple as a diver that straps a tank (or two) to their back?  Before any work underwater is carried out, the type of diving apparatus that will be used must be taken into consideration. Without the diving component archaeology cannot be conducted underwater. I will discuss the different types of diving equipment necessary to carry out a pre-disturbance survey and excavation in an occupational setting, but will limit the topic to standard compressed air diving. Other diving classifications such as NITROX and mixed-gas diving can be used, but are limited to trained professionals and the offshore oil and gas industry. The most common type of diving in maritime archaeology is compressed air diving.

Figure 1. A SCUBA diver fluttering about underwater (author)

Figure 1. A SCUBA diver fluttering about underwater (author)

Diving apparatus: SCUBA & SSBA

What is the difference between SCUBA (Self Contained Underwater Breathing Apparatus) and SSBA (Surface Supply Breathing Apparatus)? Apart from both acronyms containing the words ‘Breathing Apparatus’, the difference lies with the first two words, ‘Self Contained’ and ‘Surface Supply’. SCUBA is a self-contained unit in which the diver relies on a tank to deliver compressed air through a mouthpiece (Figure 2). Commercially developed in the 1950s by Jacques-Yves Cousteau and Emile Gagnan, SCUBA allowed people to explore the underwater world and by doing so, paved the way for maritime archaeology to develop into the discipline it is today (Green 1994: 2–4; Hosty and Stuart 2001: 5; Muckelroy 1978: 10–22).

Figure 2. Left, A maritime archaeologist using SCUBA; Right, SSBA diver entering the water. Notice attached air hose (Images courtesy of Donald A. Frey, Tufan Turanli, and Maddy Fowler)

Figure 2. Left, A maritime archaeologist using SCUBA; Right, SSBA diver entering the water. Notice attached air hose (Images courtesy of Donald A. Frey, Tufan Turanli, and Maddy Fowler)

SSBA is also a compressed air system, but exhibits slightly different features (Figure 2). The diver receives air from the surface from either a bank of compressed air tanks or an air compressor. The air is usually breathed through an AGA mask, band mask, or hard hat (Figure 3). A hard hat is a solid, one-piece helmet, usually associated with underwater construction. It provides head protection for the diver from falling debris. A band mask is made up of a solid face plate similar to the hard hat, but has a soft neoprene hood. An AGA mask is a full face mask secured to the diver’s head with a series of straps. SSBA can trace its origins back to early 19th century hard hat diving, and was an essential element of what is regarded as the first maritime archaeology survey—an investigation of crannogs in Loch Ness, Scotland in 1908 (Muckelroy 1978: 10, 12).

Different diving masks

Figure 3. Left Diver wearing a Gorski hard hat; Centre A band mask with soft neoprene hood; Right Diver wearing an Aga mask (Images courtesy of Rhiannon Phillips, Submarine Manufacturing and Products, and Maddy Fowler)

Which diving apparatus for what underwater method?

Different diving equipment will have advantages and disadvantages, depending on the type and extent of tasks that need to be performed. From my experience, SCUBA provides the freedom to cover a large area, as would be needed to conduct a pre-disturbance survey. The objective of a pre-disturbance survey is to survey and record a site as it appears on the seabed (Green 2004: 88; Tripathi 2005: 6). For more information on pre-disturbance survey methods see Lauren Davison’s blog post.

A diver with a ‘Self Contained’ breathing unit is free to travel as far as they want, subject to certain physiological and environmental restrictions. These include the strength of currents and amount of compressed air available. SSBA, by contrast, is restricted by the length of the equipment’s umbilical (which contains the air hose, communications link, etc.). Planning helps, but it is difficult to know how much umbilical is needed when the extent of the site is unknown. Other considerations for occupational diving include:

  • Environmental conditions (visibility, entrapment, water temperature, underwater terrain)
  • Hyperbaric/physiological (depth, frequency, duration, prior fitness)
  • Associated activity (manual handling, boat handling, dive platforms)
  • Other (dangerous marine animals, shipping movements)

Unfortunately, not all forms of diving equipment are affordable and/or available. In instances where only SCUBA equipment is available, the archaeology fieldwork plan will need to be adjusted to correspond to SCUBA’s limitations. Some of these limitations include the number of divers needed to conduct fieldwork, dive duration, and surface intervals between dives.

SSBA is used if the equipment is available and/or required under Australia’s Occupational Diving Standard (AS/NZS2299.1). This standard requires the use of SSBA when a dive project includes the use of surface machinery that is not under direct control of one or more divers, such as the water dredge or airlift. Both the water dredge and airlift are designed to remove spoil from the area of excavation and deposit it away from the site. Both have their advantages and disadvantages; for a discussion of this topic see Green (2004), and for more details about underwater excavation methods see Marc Brown’s blog post.

Maritime archaeology projects within Australia that involve commercial interests and the use of equipment such as dredges must utilise SSBA (Figure 4). Maritime archaeologists must hold an accreditation with the Australian Diver Accreditation Scheme (ADAS) to dive using SSBA. SSBA must also be used where participating divers undergo physical exertion. Projects reliant on SSBA must consider such factors as the use of a compressor, length of SSBA umbilicals, available bottom time, and the need for fuel and qualified personnel (a team of five is required for a two person SSBA dive team).

During each diving day both SSBA and SCUBA equipment must be set up, broken down, and tested on a daily basis. The equipment must also be maintained, usually on an annual basis. This is costly in terms of time and money, particularly for projects that are operating on a tight schedule and budget. Ultimately, both SCUBA and SSBA enable maritime archaeologists to undertake any underwater task, provided it meets occupational standards.

Figure 4. ADAS Part 2 divers excavating with a dredge (Image courtesy of Andy Viduka).

Figure 4. ADAS Part 2 divers excavating with a dredge (Image courtesy of Andy Viduka)

Conclusion

Before commencing archaeological investigations underwater, it is important to consider the apparatus best suited for the job and whether it complies with occupational standards. Because every site is different, dive equipment and planning will undoubtedly vary. Limited access to diving equipment may force a project to work with what is available and plan diving operations accordingly. With these factors in mind, the question remains: is a maritime archaeologist simply a mask and a tank? The answer is no, as there is a lot more to conducting maritime archaeology than just fluttering about underwater.

References

Akal, Tuncay

2008      Surveillance and Protection of Underwater Archaeological Sites: Sea Guard. Protecting Underwater Archaeology, Press Room. Electronic document, http://www.acoustics.org/press/155th/akal.htm, accessed 15 October 2013.

Green, Jeremy

2004      Maritime Archaeology: A Technical Handbook, Second Edition. Elsevier Academic Press, USA.

Hosty, Kieran and Iain Stuart

1994      Maritime Archaeology over the last twenty years. In Maritime Archaeology in Australia: A Reader, edited by Mark Staniforth and Michael Hyde, pp.5-12. Southern Archaeology, South Australia.

Muckelroy, Keith

1978      Maritime Archaeology. Cambridge University Press, Cambridge.

Submarine Manufacturing and Products

Kirby Morgan 18B Band Mask. Electronic document, http://www.smp-ltd.co.uk/product/productid/193/productname/Kirby-Morgan-18B-Band-Masks/, accessed 3 October 2013.

Tripathi, Alok

2005      Marine Archaeology (Recent Advances). Agam Kala Prakashan, India.

Finding A Shipwreck You Can’t See: Detection and Survey Methods from Hinchinbrook Island

By Kurt Bennett

I have just finished a week-long field practicum in tropical Queensland. The field practicum took place on Hinchinbrook Island between the 7th and 14th of July. Five students (including myself) from Flinders University helped the Heritage Branch of the Department of Environment and Heritage Protection (QLD) locate possible shipwreck sites. Multiple survey methods were employed to locate cultural material buried beneath the sand. This blog will focus on one site that was investigated during the field practicum. It is located on the north end of North Shepherd Bay (Figure 1).

Figure 1: Location of the ‘possible’ shipwreck and our campsite (Google 2013).

Figure 1: Location of the ‘possible’ shipwreck and our campsite (Google 2013).

Queensland Parks Service observed timbers in North Shepherd Bay after Cyclone Yasi, in 2011, removed sand from the beaches on the eastern side of Hinchinbrook Island. The GPS (Global Positioning System) coordinates were taken and passed on to Paddy Waterson, Senior Heritage Officer at the Heritage Branch. The pictures taken by Parks resembled possible ships timbers. On Monday the 8th July and Friday the 12th 2013, the GPS points were visited. The GPS points were located approximately 3.6 kilometres (km) from our campsite (South Macushla) along a walking track. The walking track finished on the southern end of North Ramsey Bay and required a 1.6 km walk along the beach to the approximate area. No cultural remains were visible upon arrival and therefore certain archaeological methods were needed to locate the previously seen cultural material. The following will discuss the methods employed in order to find the cultural material and determine what remains on the beach.

The first step was a mixture of two methods using both a GPS and a metal detector. The aim was to locate the original marks with the GPS and establish a central point for what was originally witnessed. A 20 metre (m) square was placed around the central GPS point, marking an area to be metal detected. The metal detector, Excalibur II, was set to exclude non-ferrous metals. This enabled the metal detector to detect iron concentrations. The metal detection was systematically executed, with the user following an east-west pattern every one metre along the 20 m grid. Every ‘hit’ was marked with a pin flag and measurements taken using the baseline offset method (Figure 2).

Figure 2: Metal detector hits with baseline. Photo facing NE, North Shepherd Bay (Kurt Bennett, 8 July 2013).

Figure 2: Metal detector hits with baseline. Photo facing NE, North Shepherd Bay (Kurt Bennett, 8 July 2013).

Once the designated area had been covered and all the hits were marked, the next step was to probe the points of interest (hits). This was to determine whether solid material was buried beneath the sand. Both metal and wood were detected, with metal being distinguishable from wood due to the vibrations and the sudden jolt felt by the probe, as opposed to the stickiness felt with waterlogged wood. The probing also indicated the depth of cultural material. The wood and metal was located at a depth of approximately 30 centimetres (cm) below the sediment surface. The sand proved to be a challenge to probe as it was wet and compacted due to being located in the intertidal area.

Once the probing indicated there was material below the beach surface, a 1 m square was placed around the GPS point; this also proved to be a concentration of iron from the metal detection survey. The trench was then excavated with shovel and trowel until material was found. Timber was uncovered, which was possibly a ship’s timber with an iron brace and a treenail (Figure 3). Photographs and measurements were taken of the timber. The trench could not be excavated any deeper than 30cm due to water seepage caused by the intertidal zone. Therefore only the top face of the timber and iron brace was seen, with the rest left submerged in watery sand. The trench also uncovered rocks that were thought to be metal when detected by the probe. This posed a challenge when trying to distinguish between metal and rock, as the rock had the same reaction as metal when probed.

This became more evident when the site was revisited on Friday the 8th.  Photographs were taken of the uncovered timber and the trench was backfilled. Our investigation was limited due to the tide and daylight dictating the time we could spend at the beach. The trench could not have been dug if the tide was in and therefore the site had to be visited during low tide. This left the team approximately four hours to investigate the site. Not to mention we had to be back at camp by nightfall for health and safety reasons. Apparently dusk is the time that crocodiles come out to feed, and that is definitely not the way I planned on finishing my field practicum.

Figure 3: One metre square excavated showing ships timber, North Shepherd Bay. Timber being measured by Flinders students (Kurt Bennett, 8 July 2013).

Figure 3: One metre square excavated showing ship’s timber, North Shepherd Bay. Timber being measured by Flinders students (Kurt Bennett, 8 July 2013).

North Shepherd Bay was revisited on Friday the 12th and this time the aim was to establish the full extent of the site. Again the metal detector was employed and this time we extended our square to 20 m north south of Monday’s metal detection area. To our disappointment the hits did not resemble the shape of a ship’s hull, but more a scatter of debris. This was still exciting, as it could still resemble a wrecking event. The only way to find out was to dig and dig we did!

Several holes were dug, with the longest being over four metres in length (Figure 4). This trench was a continuation from the previous ship timbers. Two additional timbers were uncovered and what appeared to be the beach substrate with a rocky base. It proved to be a little frustrating, since we set out to find a shipwreck. The timbers uncovered were measured and detailed drawings were produced, providing an accurate recording of what had been found. The lengths of the two timber were approximately 1.5 m. The rest of the metal detector hits uncovered a mixture of items that may have washed in over time, including a chain block and pulley, and buried car batteries. The metal detection survey was extended a further 250 metres, walking south along the beach, but it had to be cut short due to daylight running out.

Figure 4: Red arrows indicating points of interest dug for material. Photo facing SE, North Shepherd Bay (Kurt Bennett, 12 July 2013).

Figure 4: Red arrows indicating points of interest dug for material. Photo facing SE, North Shepherd Bay (Kurt Bennett, 12 July 2013).

The aim of visiting North Shepherd Bay was to investigate the known GPS marks. The timbers uncovered and seen after the cyclone may be a result of washed up material, possibly from a shipwreck in another location, or they could be the last remaining pieces of a shipwreck. The methods employed were systematically executed to try and determine if a shipwreck lay beneath the sand, however our thorough searching and non-stop digging proved it was a beach littered with cultural material that could span a whole century. The methods mentioned above will provide a basic plan for any archaeologist wishing to investigate buried shipwrecks on a beach.