Gauge Kaub is on the Rhine at kilometre 546, on the km 541–566 stretch. The GlW is 77 cm and the fairway depth maintained below it (TuGlW) is 190 cm; after deducting 30 cm of safety margin the official rule of thumb comes out at Kaub +83. In practice Kaub +100 is used here, +17 cm against the official rule. At high water Marke I is at 460 cm and Marke II — above which the waterway closes — at 640 cm. This gauge has 4 forecast sources: the 4-day forecast from Elwis (green), the 2-day forecast from the Hochwasserzentrale Rheinland-Pfalz (red), the 14-day forecast from the BAfG (yellow) and the 6-week forecast from the BAfG (blue, set the time range to 6 weeks to see it). Upstream lies Bingen, downstream Koblenz.
Kaub
Kaub is the most famous bottleneck on the Rhine. The shallows here consist of rock and gravel. However, what exactly counts as the real bottleneck depends on the water level. At low water, the Kaub section is seen as the actual bottleneck, while at average water levels it is Oestrich. This is because the river in the Oestrich section is wide and needs more 'water' to raise the level by x cm than in the narrow Kaub section. The bad spots include the Geisenrücken fairway (though this has improved since they started milling off the rocks), the Jungferngrund, where mainly downstream traffic runs the risk of grounding if they take the bend too tight. A similar shallow is located opposite the Bacheracher Wert on the corner (Wirbeley/below Hotel Rheingold), where downstream traffic should also steer well clear of the red buoy. The biggest bottleneck that cannot be bypassed is at Lorch, where a shallow of rocks extends across the full width of the fairway. However, this shallow is located in the section where the GlW of Oestrich is valid (and so Oestrich (or Bingen) must also be used here to calculate the current depth/permissible draught), see also the bottleneck profile. See also the depth charts of the Dutch and German Rhine branches on pdf v20-08-2026.