Danger to navigation is a significant hazard found during a survey that is uncharted or charted wrongly, such as a wreck, rock or shoal shallower than shown in water used by shipping. It is reported to the charting authority within days, with position, least depth and supporting images, so a warning or chart update can go out without waiting for the final survey.
New 5.2 shoal in the approach where the chart says 8, write it up as a DtoN tonight.
Report first and refine later: a DtoN with a slightly conservative depth is worth far more than a perfect figure that arrives with the final survey.
Also heard as
- danger to navigation
- DTON
Related terms
Notice to Mariners
An official bulletin of chart corrections and navigational warnings, issued regularly to keep charts current.
Least depth
The shallowest depth over a wreck, rock or other feature, which is the value that gets charted.
Wreck
The remains of a sunken vessel, charted as a hazard or a feature depending on its depth and size.
Shoal
A seabed area shallower than its surroundings that can endanger vessels; as a verb, to become shallower.