The following non-statutory criteria were adopted by the ACHWS and Department for Culture, Media and Sport and are used for assessing the importance of wrecks or the sites of wrecks, and for considering whether designation as a restricted area under the terms of the Protection of Wrecks Act 1973 is appropriate.
Wreck sites may be comprised of the remains of vessels, their accoutrements, armaments, cargo, and other associated objects or deposits. Restricted areas may include that area of the sea bed around the wreck site considered appropriate by the Secretary of State to ensure its protection. Wrecks or wreck sites may be considered to merit designation if they contribute or appear likely to contribute significantly to the understanding of the past on account of their historical, archaeological, or artistic importance. Such significance may be assessed on the basis of the following criteria (which are not presented in any order of ranking). The criteria should not be regarded as definitive, and wrecks or wreck sites need not satisfy all the criteria in order to qualify for designation. Rather the criteria are indicators which contribute to a wider judgement based on the individual circumstances of each case.
Period
The historic interest of all types of wreck which characterise a category or period should be considered, and the selection of sites for protection should include wrecks which illustrate important aspects of social, political, economic, cultural, military, maritime, and technological history. In identifying sites to be protected, regard will be had to the currency of any particular wreck type (the length of time over which any particular vessel type was constructed and used or any cargo type transported) and its representativeness (whether the vessel or cargo type was one of few or many types representative of that period).
Rarity
There are some wreck categories which, in certain periods, are so scarce that all surviving examples that still retain some archaeological potential should be preserved. The age of a vessel is often closely linked to its rarity. The older a vessel is, for example, the fewer comparable vessels are likely to survive either in use as wrecks, and the more likely it is to have historical interest. The loss of one example of a rare type of site is more significant than the loss of one example of a very numerous class of site. In general, however, a selection for protection must be made which portrays the typical and commonplace, as well as the rare. This process should take account of all aspects of the situation and distribution of a particular type of wreck in a regional, national or international context.
Documentation
The significance of a wreck may be enhanced by close historic association with documented important historical events or people, or by the supporting evidence of contemporary records or representations. Historical records are generally only relevant to monuments of recent date, although it is important to recognise that some types of recent vessel may not be served by any historical records. The range of contemporary records that might be expected for a particular type of vessel needs to be considered so that the value of any known records which relate to it can be assessed. The importance of a wreck may also be enhanced by the existence of records of previous archaeological recording or survey work.
Group value
The value of a single wreck may be greatly enhanced by its co-location with other similar vessels (for example at the site of a battle) or by its association with other contemporary features such as port facilities or defensive sites. Association with vessels of other periods (for example on long-standing navigation hazards) may also enhance the value of a site. In some cases it is prefereable to protect the complete group of archaeological remains, rather than to protect isolated features within the group.
Survival / Condition
The degree of survival of a wreck is a particularly important consideration. In general, early wrecks are less likely to survive well than later examples, and in assessing the survival of any site it is important to consider the likely normal degree of survival of vessels of that date or type. Assessments of survival should consider the degree of intactness of a wreck, the likelihood of the preservation of constructional and technological detail and the current condition of the remains.
Fragility / Vulnerability
Highly important archaeological evidence from some wrecks can be destroyed by the selective or uncontrolled removal of material, by unsympathetic treatment, by works or development or by natural processes. Some vessel types are likely to be more fragile than others and the presence of commercially valuable objects within a wreck may make it particularly vulnerable. Vulnerable sites of this type would particularly benefit from protective designation.
Diversity
The importance of wrecked vessels can reflect the interest in their architectural design, decoration and craftsmanship, or their technological innovation or virtuosity, as well as their representativity. Consideration should be given both to the diversity of forms in which a particular vessel type may survive and to the diversity of surviving features. Some vessel types may be represented in the surviving record by a wide variety of building types and techniques which may be chronologically, regionally, or culturally conditioned. The sample of protected sites should reflect this wide variety of forms. In addition, some wrecks may be identified as being of importance because they possess a combination of high quality surviving features or, occasionally, because they preserve a single important attribute.
Potential
On occasion, the nature of archaeological remains cannot be specified precisely but it still may be possible to document reasons anticipating their existence and importance and so to demonstrate the justification for identifying a site for protection. For example, each type of site may provide a slightly different range of contexts for the preservation of archaeological and palaeoenvironmental evidence, and the environment of a site may provide strong indications of its likely level of survival. Sites may also be significant in terms of their potential to provide information on site formation and decay.