🔍 Key Concepts

• Chart datum used for soundings in Long Island Sound / Connecticut River approaches • Meaning of extreme low water vs mean lower low water (MLLW) • How and why you apply a correction to charted soundings in unusually low water

💭 Think About

• Ask yourself: If the water level is lower than the chart datum, will the real depth be more or less than the charted sounding? Should the correction sign be plus or minus? • Think about the area near Saybrook: Is it known for especially large low-water departures that would require a small correction, a moderate one, or a relatively large one for safe under-keel clearance? • Consider which option best represents a realistic maximum departure from normal tides in that specific area during extreme conditions.

✅ Before You Answer

• Verify which vertical datum NOAA charts use for soundings in this region (e.g., MLLW) and what "extreme low water" means relative to that datum. • Check whether the correction should be added or subtracted from charted soundings when the water level is lower than normal. • Compare the numerical sizes: is a 1 ft, 2 ft, or 3.5 ft change more consistent with a stated maximum correction for extreme low water in that specific locality?