Τhe Shipwreck (Navagio) of Zakynthos: Decay & Preservation. A First Approach

The Mediterranean Sea has numerous shipwrecks which are
exposed to various environmental conditions similari to Navagio
in Zakynthos such as in Gytheio- Peloponnese...


Introduction
The Mediterranean Sea has numerous shipwrecks which are exposed to various environmental conditions similari to Navagio in Zakynthos such as in Gytheio-Peloponnese etc. The particular shipwreck in Zakynthos is a unique specimen of ship on a coast, in contradiction with the majority of shipwrecks with metal or wooden core that were discovered underwater.
Specifically, Navagio or Shipwreck (Figure 1), which casted away in 1980, is an exposed cove, sometimes re-ferred to as «Smugglers Cove», on the coast of Zakynthos, in the Ionian Islands of Greece. Navagio beach was originally known as Agios Georgios.
Ιt is located to the northwest of the island Zakynthos (    Archaeologist Dr. D. Kourkoumel is confirmed three shipwrecks, (in 1.260 to 1.800 m. depth), that was named Poseidon 1, 2 and 3.
Poseidon 1 and 2 are placed chronologically in the 3 rd century A.D., during the Roman period. Ceramic, marble and metallic findings were collected, some of them may be parts of their core. Poseidon 3 is probably from the 17 th -18 th century and the main part of its core is saved, such as ceramic artifacts and various objects. These Finally, in Gytheio (Peloponnese-Greece) in the Selinitsa beach (the locals name this particular spot of the beach "Valtaki") a shipwreck was found on the coast (1981), ( Figure 5). At first, the ship "Dimitrios" was abandoned by its crew in the port of Gytheio, even though the ship was private property, the owners left it there.
Through the time the shipwreck moved in its current position on the coast and became a tourist attrac-tion. The bottom of the ship is placed inside the sea, covered by sand with the main core standing out of the water such if it was its original place. Even though the similarities with the "Navagio" in Zakynthos are ap-parent, their placement is different, since "Dimitrios" shipwreck is partly underwater [5].

Surveying Documentation: A Step Before Preservation
Before any action could be taken, thorough documentation and extensive study should be made in order to define the exact position, its actual form, the stability, the materials and the damage of the object. The Surveying Documentation of cultural heritage objects serves as a tool to make information accessible to those (research experts or any interested persons) who cannot investigate the object itself. Furtherome, the main problems of Navagio during documentation are: a) The object is not accessible to researchers. Actually, according to the latest law (FEK 907/15.03.2019) the beach is not accessible to anyone taking into consideration the recent earthquake and the fallen of a large rock. All the boats are just approaching the coast but not the ship.
b) The object is too large or too complicated to study and it would be too time-consuming to execute an own investigation.  Cultural heritage recording and documentation comprises a wide field of objects, disciplines, and technolo-gies. Because of those large diversities, every project is different. This makes the task difficult. Co-operation be-tween different scientific and professional disciplines is necessary. On the other hand, these requirements make it very challenging and rewarding to work in this field.

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Even in primer scientific studies, recorded shipwrecks needed multi-professional teams to achieve a com-plete survey, a noticeable example of the late '60s is the Kyrenia Ancient Greek Ship in Cyprus ( Figure 6). The excavation was conducted by Susan Womer Katzev and Michael Katzev, where a 54 member team from differ-ent fields recorded the shipwreck using stereo photos, manual triangulation and multiple surveying methods to collect as much information as possible. Navagio Shipwreck may be more approachable than the Kyrenia shipwreck, but the fact that they are unique specimens from different eras make them important findings that need extent research and multiple scientific approaches [7].

General preservation state
During the short autopsy, observation was taken not only for the main construction materials of the ship such as metal and wood but also for the entire future stability of the ship taking into consideration the extreme changes of the environmental conditions where it acts as a suppressor in further future preservation of the ship.
Strong or weak Northwest winds and falling temperatures in the winter months, as well as increased temperature (over 36°C) and humidity levels (over 68%) during the summer and winter months, create a fur-ther instability in the preservation of both inorganic (metal, paints) and organic (wood) exposed construction materials of the Shipwreck. During winter the ship suffers from mechanical & chemical decay coming from the sand, salts, and water ( Figure 7). The strong north-west winds and the wave accelerate the deterioration of the metal surface. Furthermore, the see salt -spray increase the chemical decay with the metal parts but also with the remain paints (pigments) where they have been applied to the outer shell of the ship. Furthermore, mechanical decay is also caused from the everyday vandalism of the tourists (scratches, paints, stickers, sprays, etc.), (Figure 8) during the summer period and also the entrance of many tourists inside the ship. The recommendation is if it is possible in the future to measure continuously the RH levels and the UV radiation which the ship is exposed giving further information for the future level of the deterioration.

Iron corrosion
Iron consist to be the main construction material of Navagio.
Metal identification through physicochemical analysis is an important and necessary step, as it gives a specific direction for the preservation statue as and conservation process in order to choose appropriate materials and methodology. The use of the stereoscope is a very useful detailed observation instrument, particularly for a first verification of the alloy components. The procedure was nondestructive and was done with Stereo Microscope Leica® M205FA (160x), with fixed focus 7,8x, on all shots [8].
The purpose of the analysis with Xray fluorescence spectroscopy is quantitative and qualitative documenta-tion of the ship. The  (Table 1). Finally, the basic chemical element of the metallic part of the ship is Fe (60.22%). The corrosion mechanism of the Shipwreck in Zakynthos is described below [9][10][11]: When the iron is eroded, the iron dissolution reaction (the anodic half-reaction is Fe → Fe 2+ + 2e -) occurs at the interface between the metal and the corrosion products.
In aqueous solutions with a pH higher than 4, this half-reaction is offset by the reduction of dissolved oxygen (the cathodic half- When the iron is exposed to the air and allowed the acidic solution FeCl 2 is compacted, the corrosion products are hydrolyzed and there is a high amount of oxygen: Fe 2+ ions in the solution react with oxygen and water and take the form of ferrous corrosion products (III) and new compounds: FeOOH is solid and can cause physical damage to the object The second step is the oxidation of FeCl 2 to FeOOH and the subsequent appearance of HCl: This process is called acid regeneration cycle. What is to be understood is that chlorine ions produce a soluble iron salt [9][10][11].
It is also recognized active iron corrosion on the surface of the ship, which is the result of the formation of iron chloride (II), which has the following characteristics:   Furthermore, Akaganeite is formed by the presence of high concentrations of chlorine ions and only when the iron object is exposed to the air. Its presence indicates that the object is heavily contaminated with chlorides. Red-brown corrosion products at points of surface rupture are usually Akaganeite (β-FeOOH). It is a specific type of oxide with a structure stabilized by chlorides.
Furthermore, up to the external corroded layer, some areas of pigments with green, red, blue and light blue colors are totally corroded [9][10][11], (Figure 11).

Figure 11:
The corrosion levels of the pigments on the metallic surface using Optical Microscopy.
To sum up, the shipwreck as marine iron usually exhibits a stratigraphic structure of corrosion products. The outer layer is a mixture of iron corrosion products, such as goethite, and foreign materials such as small stones, sand, and soil and fish shells deposits.
Below this, there is another layer of iron corrosion products in a lower oxidation state, usually magnetite, on the remaining metal.
Up to the external corroded layer, some areas of pigments exist with green, red, blue and light blue colors. The most of the pigments corroded and in many areas pigments completely are lost.

Wood decay
Only a very few parts compared to its total volume (Figure 12), like the planks as a floor on the bridge, the lower parts of the deck's metal floors as a support to the beams and the rudder on the bow outside of the ship are made of wood ( Figure 13A&B).  Wood is a reliable material for use in an environment close to the sea since it is neither polymerized nor anodized, but it must also be a special hardwood in order to be resistant to specific conditions. In the case of the Navagio wreck, wooden parts constitute a very less percentage of the entire ship, so they can be made from any kind of wood, even a soft one, therefore more susceptible and sensitive. This is obvious by the microscopic cellular structure that has been made by a very small piece of wood that was lying by the ship and was Wood has a variable structure and properties, making it particularly sensitive to the prevailing environmental conditions.
Especially softwoods contain alternate layers of earlywood, which has a low density, and latewood, which has a density three times greater. This structure, therefore, has the disadvantage of alternate weak and strong layers, making it a very vulnerable material and in constant dependence with the environmental changes. The wreck has been exposed for over thirty years on a beach with weather conditions extremely changing, not only over the years but also during the day. Every winter the sea covers the entire ship for a few months, while in the summer the water subsides exposing it to direct sunlight and causing abrupt drying and wide-spreading mustiness while making it even softer. This means that the wreck is exposed to two very different environments causing significant damage to the wooden parts of the ship, although surprisingly well preserved, compared to the metal parts. This is due to the fact that the wooden elements are in places protected by the direct contact with the sun and the sand, but mainly they are hardly accessible by the tourists.
This shows the necessity of interrupting this interactivity of tourists with the ship, which causes the most significant damage. A unique example of management in a similar situation is the Cavtat Shipwreck in Croatia, which is one of the first underwater sites that are presented to the public, through the deployment of protective cages. The public can visit the site, but not interact with the findings unless they are authorized, researchers. Even though the Navagio Shipwreck is on the coast, the containment of the site from the public is of the essence in order to preserve the ship, [12].
Wood is hygroscopic, so it absorbs or eliminates moisture in order to balance with the surrounding environment. It also exhibits anisotropy and heterogeneity, that is, a difference in density and hardness in various directions. So moisture affects its physical strength, elasticity, and dimensional change. The effect of temperature is catalytic in several types of damage. In a very warm environment, it is dried and weakened, while the high temperature in a high relative humidity environment enhances the hydrolysis processes of wear, causing extensive deteriorations.  The problem of wood degradation due to marine organisms [13], occurs when the water recedes in the summer months, as sufficient oxygen allows them to survive and retreat to the wood.
These are the fungi that are usually above the waterline ( Figure   14B), while worms that attack mainly the sunken wood do not cause damage as the ship is exposed beyond a marine environment for longer time. Contaminants that form suspended particles, sulfur dioxide, nitrogen, ozone, hydrogen sulfide, chlorides cause degradation of wood fibers, reduce mechanical strength, and chemical erosion. Wind action carries sand grains whose friction and impact cause erosion and aesthetic pollution (Figure15A). Salts from the sea cause separation of wood fibers (Figure15B).
The knots, the various cracks and all the imperfections of the wood, cause pressure and movement. Some spots have extensive loss of paint and varnish, while elsewhere the wood is completely exposed. Light has weakened the cellular structure of the wood and has broken the lignin bonds. Especially at the deck where the ultraviolet radiation of the sun is direct.
Finally, the most important damage that the wooden elements of the ship have suffered from are the metallic points with which they come in contact, but also the nails used for their joining ( Figure   16). Extensive oxidation causes enormous mechanical pressures and therefore cracks and deformations, as well as coloring [14].

Conclusion
Preserving a unique cultural item such as Navagio, through its significant historic resources gives a community its unique character. Furthermore, that navagio is exposed and suffer every year from the extreme changes of the environmental conditions. Many experts believe that the ship will eroded and lost its stability totally at the near future.
Τaking into consideration the first documentation attempt, the dilemmas for the preservation of the Navagio are crusial and complex. The stability of Navagio is a complex issue which different experties should be considered. The overal preservation state of the Navagio is very poor and further preservation plan should be immediatelly drawn. Furthermore, the full documentation & conservation of the Shipwreck (Navagio) of Zakynthos will provide and preserve a global tourism spot for the island and generally for Greece. Therefore, the owners and the public insitutions in Zakynthos which they are responsible for Navagio should consider that the future preservation of the Shipwreck (Navagio) of Zakynthos are beneficial to the community in many ways. The Shipwreck will attract more visitors in the future seeking heritage tourism opportunities. Finally, from a sociological point of view the community of Zakynthos will benefit when citizens preserve history and mutual concern for the protection of the shipwreck.