Record low water at Lake Constance: what owners should check in their hull wording

Lake Constance, the large lake shared by Germany, Austria and Switzerland, is showing this autumn how quickly a familiar berth can become too shallow. At the Berlingen gauge on the western arm, the Untersee, the water fell in early October 2026 below the previous record low of January 1949, and on 13 October the joint lake report gave 2.50 metres above gauge zero at Konstanz and 2.54 metres at Bregenz. For owners whose sailing yacht or motor boat is still afloat, this is not just a weather story. It is a reason to check their hull wording and to know what it says about a grounding before it happens.

The gauge alone says little about any one berth. What matters is the depth in the approach channel, at the harbour entrance and under the keel, and in a shallow harbour that changes faster than the number on the gauge board. The lake report expects a further fall in the coming weeks, as precipitation in the mountains turns to snow and the glaciers release hardly any meltwater. Sailing yachts with a fixed keel and motor boats with a deep sterndrive or shaft are most exposed. Dinghies with a swing keel and trailer boats with a tilting outboard have more margin, though a propeller can still end up in the gravel.

Many hull wordings across Europe name grounding and stranding as examples of an accident to the vessel, and a grounding in an entrance that has silted up or dried out is exactly that case, subject to the deductible. Some go further and add a separate clause for the inspection after a reported grounding, because nobody can tell from the outside whether the keel bolts or the laminate at the keel root have suffered. Where such a clause exists, it is worth reading closely: whether the inspection is capped at a fixed amount, whether a deductible applies and what counts as reporting the grounding in time.

Not every hull contract lists accidents at all. Some cheaper policies cover only named perils, typically storm above a stated wind force, fire and explosion and theft of the whole boat. Under a wording like that a grounding is simply not an insured event, and neither is the inspection afterwards. An owner with a keel boat in shallow water this autumn should find out which kind of contract they hold before casting off, not after. Liability is a separate matter and the low water does not change it: if a boat damages another boat or a jetty while manoeuvring in a tight, shallow harbour, that is a third party claim like at any other water level.

Two limits belong in the picture. The first is the duty after a loss. Most wordings require prompt written notice of every claim and expect the owner to do what is reasonable to keep the damage small. A boat that has already touched bottom at its berth should be moved to a deeper spot or hauled out, rather than left to settle on the bottom night after night as the water keeps falling. The second limit is what a grounding is not. Wear and tear and poor maintenance are standard exclusions in hull wordings, and a propeller with old nicks does not become accident damage because the lake happens to be low.

Our view is that the record low is above all a reason to plan the autumn differently. Owners who intend to haul out anyway should ask the harbour or the winter storage yard now whether the crane or slipway can still be reached at the current level, and bring the date forward if in doubt. Owners staying afloat should ask the harbour master for the usable depth at their berth and in the entrance, not just the gauge reading. And after a grounding, report it even if nothing shows: keel damage that only appears at the spring lift is hard to link to a single day in October.