SOUNDING IN METRES Reduced to Approximate LAT (=NAP+1dm) HEIGHTS IN METRES Mean Sea Level Vertical clearances above HAT. CHANGING FAIRWAYS Due to strong currents the fairways are changing continuously. Actual depth may differ from the charted soundings. The buoyage is adjusted accordingly. SPEED RESTRICTIONS In these waters restrictions for sailing with fast motorboats and waterskiing are in force. TIDAL STREAMS Attention is drawn to the strong tidal streams in these waters. For tidal streams and tidal information see: HP 33 Tidal heights and streams for coastal waters of the Netherlands and adjacent waters and HP 33D-NLTides published by the Netherlands Hydrographer.