When a chart is referenced to RH 2000, the current sea level is all you need to keep track of in order to calculate the actual depth, provided that the current sea level is also related to RH 2000. The intention is that all sea level data should eventually use RH 2000 as reference level. Today, however, the current sea level is frequently stated in relation to the current year's mean sea level (MSL). The difference between RH 2000 and the mean sea level will still be about or less than 1dm for the next 10 years. In addition, should you be in need of a more precise translation to the current depth, it is possible to acquire information about this year's average sea level in relation to RH 2000.
Example: A shoal in the chart is shown with a depth of 2.9 m and the current sea level in the area is -17 cm. This means that, in order to be on the safe side, one should not assume that the current depth on the shoal is more than about 2.7m (2.9m - 0.17m = 2.73m), see diagram to the left below.
Moreover, taking into account the average sea level for the year (2014 in the diagram to the right below), which is for example +6.3cm in RH 2000 , the conversion would be (in meters) 2.9m - 0.17m + 0.063m ≈ 2.8m.
Click on the images to see them in a larger version.
See adjacent links for information and data about current sea level and this year's average sea level. There is also further information on height systems in general and RH 2000 in particular.