The A1 (Arade 1) Shipwreck

 

Introduction


The shipwreck designated A1 by CNANS / GEO team in 2001 was found near the area where the shipwreck Arade 1 was sighted for a short period in 1970, during the dredging works described in the Volume 1 - The Site - of this report.  It was partially excavated and recorded during that summer's field season.

The account of the captain of the Dutch dredge Mark suggested that in 1970 the Arade 1 vessel was exposed on the embankment created by the dredge and, while projecting beyond the embankment and full of sediment, shattered when touched by the dredge.  It may have broke into two parts.  The projecting part slid along the embankment and may have been immediately buried by the falling sediment, since it was not observed in 1970.

A reconstruction of the bottom of the river in this area shows a steep embankment with a slope around 1/2 in 1970, after the dredging operations (Fig.1), and a much smoother slope in 1997, when the latest cartography of this area was made (Fig.2).  We must keep in mind, however, that the slope created by the dredge during its work was 1/6, much steeper than the 1/2 slope found after the Autumn of 1970, when the cartography was made.

Should the projecting half of the Arade 1 shipwreck be in a somehow cohesive form, it was certainly covered by several meters of sediment in 1970.

 

Fig. 1 - Bottom at the Arade 1 site in 1970 (Pedro Caleja CNANS).

Fig. 2 - Bottom at the Arade 1 site in 1997 (Pedro caleja CNANS).

 

As for the upper half of the Arade 1 shipwreck, it was reported covered with a thin layer of sediment - between 50 cm and 1 m - a few weeks after the visit of the CPAS team.[1]

One of the two tasks of the INA / Texas A&M University team was to assess whether or not the A1 ship was the Arade 1 of 1970, and if so, how much of it was preserved.  The other was to carry out a full recording of its hull.

 
 

The A1 Hull


As mentioned above, in 2001 part of the A1 hull structure was exposed and recorded at a 1/1 scale.  Most of the ship's hull was drawn on 1 x 1 m plexiglas slates, in horizontal projection.  The drawings obtained were then assembled in larger sheets of transparent plastic and then reduced over a grid into a 1/10 scale drawing.

However, to save valuable time, the portion of the hull over the keel axis was recorded directly over a sheet of plastic nailed to the structure (Fig. 3).

 

Fig. 3 - Preliminary recording on plastic sheet in 2001 (Photo: CNANS).

 

A series of pictures - excellent, when the general visibility is considered - were taken by Portuguese Navy Capt. Augusto Salgado, who is at the same time a navy officer, a historian, a skilled photographer, and a long time friend and collaborator of CNANS.

As it was uncovered during the 2001 field season, the A1 hull remains comprised part of a keel, one post, 18 frames, four ceiling strakes, two hull strakes on port side, and eight on starboard side.  The hull was clearly broken around amidships, and only half was preserved.

In order to answer the first two questions stated above, regarding the possible identification of A1 as the Arade 1 shipwreck of 1970, and the evaluation of the extent of the hull remains preserved, the 2002 field season was developed in three phases:

  • The first phase consisted of a rather quick cleaning operation, which entailed the removal of the layer of sandbags and plastic cover that protected the hull remains during the winter, and a repair of the 10 x 10 m square that had been positioned around the area in 2001.  This square was marked by a series of iron spikes tagged according to its position on the perimeter, and connected by a nylon cable and a red and white tape.  As in the previous year, these spikes proved to be very useful, given the low visibility of the site - inside the river mouth - for the orientation of the divers.  On the second phase of the work the spikes mentioned above were used as datum points to position the hull and artifacts lying within the 10 x 10 m square where the excavation was carried out.
  • The second phase consisted of the positioning of all archaeological features inside the 100 m2 area.  The mapping was performed at a 1:10 scale with the help of the WEB computer program.  The positioning of the hull was not difficult once we established a number of points that could be accurately positioned on the 2001 drawing, and identified in the shipwreck in situ, such as treenails and iron bolt concretions.  The extremities of the timbers were damaged during the winter by wood boring worms in spite of all the protection measures taken by CNANS before closing the field season in September 2001.  In fact, several octopuses - at least four! - found their way under the plastic cover that protected the shipwreck, and established themselves in the spaces between the sandbags that covered the whole wooden structure.  This action allowed the entrance of numerous mollusks and worms to the area between the timber upper surfaces and the plastic cover, and promoted a not negligible destruction of the upper surfaces and extremities of the timbers.
  • The third phase consisted of the verification of all measurements of the existing 1/10 scale hull drawing on an enlarged scale (1/5), the positioning of the hull in relation to the datum points set in the previous year, and the excavation of four trenches around the hull structure (Figs. 4 and 5).
 

Fig. 4 - The 100 m2 area after positioning the hull.

 

During this field season it was possible to identify the A1 ship as the Arade1 shipwreck of 1970 without any doubts, and it was demonstrated that the second half - the projecting half described by the captain of the dredge Mark - remains preserved, buried in the sediment nearby.  The portion of the hull excavated and partially recorded in 2001 was tentatively identified as the bow of this vessel, because of the gentle curvature of the post, and because no remains of any steering device - rudder, gudgeons or pintles - were found anywhere nearby.

 

Fig. 5 - The 100 m2 area with the position of the trenches.

 

Around July 15, once the first part of this third phase was finished - the verification of scantlings and fastening holes - the TAMU / INA team started the excavation of the four trenches defined within the 100 m2 working area (Fig. 5).

Trenches 1, 2 and 4 yielded a small number of artifacts, some rigging elements, a few loose timbers, and unidentified concretions.  These have greatly contributed to the understanding of the site, and suggest a late 16th century date for the A1 shipwreck.  The most interesting find occurred however on trench 3, where a second portion of this hull, showing a clear fracture area, plunged at a 45º degree slope into the sediments.

The portion of the hull found in trench 3 was recorded in a sketchy way for lack of time, and covered with sediment to be studied as soon as the full recording of the portion of the hull already exposed is completed.

However, this discovery contributed decisively to the identification of A1 as the Arade 1 shipwreck, mostly due to the details preserved, such as the filler pieces photographed in 1970 (see Volume 1 of this report - The Site).

 
 

Stratigraphy


The stratigraphy found along these four trenches was the same described by the 2001 team while exposing the hull:

Layer 1 - a first layer of fine, dust-like sediment, with a clayish consistency, dark brown color, and littered with seashells and ceramic shards.  This was presumably deposited very recently, certainly after the construction of the jetties that have closed the Arade estuary from the sea environment.  This layer was 5 to 10 cm thick.

Layer 2 - bellow layer 1 was dark clay, from dark-grey to black, presumably also deposited after the construction of the jetties, when the current speed was drastically reduced in this area.  It showed an impressive amount of live worms and mollusks, undoubtedly responsible for the degradation of the hull timbers during the period between the summers of 2001 and 2002.  Layer 2 is also littered with ceramic shards of diverse proveniences, as observed throughout the whole estuary area.  This layer was between 10 and 30 cm thick.

Layer 3 - under layer 2 was a layer of white sand with little organic material.  The thickness of this layer was impossible to determine.  Potshards in this layer may be associated with the shipwreck.  We have excavated 0.80 to 1.20 m into it.

Layer 4 - this layer was only touched in trench 4 and consists of white limestone round rocks.  It is not known if this layer is a geologic stratum, or if it is just a ballast pile.  It should be noted that no ballast was found in 2001 over the A1 hull, nor reported in the 1970 survey.

 

Fig. 6 - Plan of the hull remains after the 2002 field season.

 

Fig.  7 - Scheme of the stratigraphy in the Arade 1 excavation area.

 
 

Trenches


Trench 1

Trench 1 was excavated to a depth of around 50 cm along the southeast side of the iron gun found on the eastern corner of the 10 x 10 m square (Fig.5). 

The artifacts found in this trench are described in the Volume 3 of this report.  They consisted mainly of potshards of various proveniences, as it is frequent in the Arade estuary, and included a few fragments of a Spanish olive jar.

 

Trench 2

Trench 2 was dug to northwest of the iron gun and extended to west, in the direction of the presumed bow of the vessel.  This trench was extended to the west in order to fully expose a loose ship timber (A1-10) whose tip was found within its primary area.

 

Fig.8 - Timber A1-10 (photo: Alberto Machado).

 

Fig. 9 - Olive jar A1-30.

 

In this trench two large concretions were found, as well as a large number of potshards of different natures, and a complete Spanish olive jar.  Shards of at least one other olive jar were found in the area where this trench joined trench 1, under the muzzle of the iron gun, and concreted to the large concretion, which received number A1-12 (see Volume 3 - Artifacts).

 

Trench 3

Trench 3 was dug across the fracture zone.  As mentioned above, the second half of the ship's hull was uncovered, slightly displaced laterally, and heavily inclined along what seems to have been the 1970 embankment.

A few potshards - again of many different types - were found at several levels, between the shattered timbers.

 

Fig. 10 - Buried portion of the hull found in trench 3.

 

Trench 4

Trench 4 was dug along the west side - port side - of the hull remains.  Below layer 2 appeared a number of heavily eroded hull planks, displaced and lacking preserved seams.

Below these planks was found a long timber (A1-36) of roughly square section - possibly of pinewood - that showed no fastening holes (Fig. 11).  Under this timber there were three deadeyes and remains of rope (Fig. 12).

In the lower strata of layer 3 a few potshards were found, immediately above layer 4.

 

Fig. 11 - Timber A1-36, found partially under the port side of the hull (photo: Alberto Machado).

 

Three heart blocks - in Portuguese sapatas dentadas - were found immediately below timber A1-36, laying over archaeological layer no. 4, together with remains of rope (Figs. 6 and 12).

 

Fig. 12 - Heart block A1-94 (photo: Filipe Castro).

 

Citation Information:
Filipe Castro, ShipLab Report 5 - Arade 1 / 2002 Field Season, Vol. 2, 2002, World Wide Web, URL, http://nautarch.tamu.edu/shiplab/, Nautical Archaeology Program, Texas A&M University.

 
       

 


[1] Dra. Margarida Farrajota personal communication.