A good sketch often provides a large amount of information about a site in the early stages, as it is more readily interpreted than a set of bare measurements. Some form of sketch is essential before further work can be planned as the size and shape of the site need to be known.

For assessing a site the sketch can be as detailed as you wish but should aim to give an overview rather than concentrating on one part in detail. It is important to establish the size and orientation of the site as a minimum. The position of any large features such as guns or anchors should be recorded as these can give a clue to the type and size of the ship or to sort out bow from stern on a wreck. The pattern of artefacts gives clues to how ship sank can give clues to show if ship has been salvaged or disturbed by trawlers. Information about the type and shape of the seabed is also useful at this stage as it can be used when planning control point networks or deciding the techniques to use for future work.

The sketch should show:

Any photographs and video of the site are very useful for planning even without accurate positions for them.

If the sketch was drawn underwater on plastic film then it can be copied on to paper by hand, using a photocopier or using a scanner. If the sketch has enough information to provide the starting point for the main site plan then this can be drawn on paper or on a computer.