RYA Day Skipper Tides Does the tide go below Chart Datum?

Title Idea: Can the Tide Go BELOW Chart Datum? | RYA Day Skipper Navigation Explained Description: Ever wondered if the tide can actually drop lower than the numbers shown on your chart? In this RYA Day Skipper navigation tutorial, we explore the rare phenomenon of negative tidal heights and what it means for your boat's safety. Chart Datum is typically defined as the level below which the sea surface "seldom falls," but as a skipper, you need to be prepared for those rare occasions when it does! ⚓ In this video, we cover: ✅ What is Chart Datum? – Understanding the reference point for all chart soundings and tidal tables. ✅ Negative Tides Explained – A real-world example from 2020 where the tide dropped 0.5 meters BELOW Chart Datum. ✅ Calculating Actual Depth – Learn why a 10m sounding on your chart might only be 9.5m of actual water during a negative tide. ✅ Visual Impact – See what happens when piers at Canary Wharf sit directly on the mud due to extreme low water. ✅ Chart Plotter Accuracy – Why your GPS might show you "in the water" when you’re actually standing on dry land during these rare events. Understanding tides is a core part of the RYA Day Skipper theory and Essential Navigation courses. Whether you are sailing in the Solent, the Thames, or anywhere else in the world, knowing how to calculate your actual depth of water is vital to avoid running aground. [00:00] Intro: What is Chart Datum? [00:11] Definition: The level below which the sea surface "seldom falls." [00:24] The Science of Tides: The gravitational bulge of the sun and moon. [00:41] Tidal Cycles: Low tide to high tide (approximately 6 hours). [01:16] Measuring Tidal Heights: How depths are recorded on charts. [01:33] Calculating Depth: Example of a 10m sounding vs. a -0.5m tide. [01:51] Visual Proof: Canary Wharf pier sitting on the mud. [02:10] Locations: Footage of the Thames at Tower Bridge showing low water levels. [02:35] Navigation Tech: Why chart plotters show your position differently during negative tides. [02:52] Conclusion: Summary of this rare tidal occasion. Watch the full City Sailing tutorial here: 👉    • RYA Day Skipper Tides Does the tide go bel...   Subscribe for more RYA Sailing Tutorials: [Insert Channel Link] #Sailing #Navigation #RYA #DaySkipper #Tides #ChartDatum #SailingTutorial #CitySailing #MaritimeSafety #BoatLife #LearnToSail