Which of the following statements about Irish hydrographic surveying is correct?

The statement regarding historic data significantly impacting current chart accuracy is correct because historical data plays a critical role in ensuring the reliability and precision of nautical charts. Hydrographic surveys often incorporate data collected over extended periods, which helps in understanding changes in tides, seabed conditions, and navigational variances that could affect chart accuracy. Charting relies heavily on both present and past data to establish trends, validate present conditions, and provide a comprehensive view of navigational safety.

In hydrographic surveying, seasonal and environmental changes can alter water depths, seabed composition, and coastal configurations. Historic data allows surveyors to interpret these changes accurately and make necessary corrections to charts. This incorporation of past data can be especially important in regions where rapid geographic or climatic changes occur, thereby enhancing the reliability of navigational aids for mariners.

The other statements have limitations: the effects of climate change are ongoing and complex, meaning they cannot be fully accounted for in any single assessment. While current data is essential, it does not encompass all necessary historical contextual information. Additionally, while many hydrographic surveys may be voluntary, there are typically mandatory surveys that are conducted for safety and legal requirements.