Channel Depth Clearance Calculator
Determine if your boat can safely transit a channel at a given tide level. Account for draft, squat effect, and safety margin.
Results
Visualization
How It Works
NOAA charts show depths at Mean Lower Low Water (MLLW) — the average of the lowest daily tide. Actual depth = charted depth + current tide height. Squat effect causes a boat to sit deeper in shallow water at speed — reduce speed in shallow channels. The rule of thumb is to maintain at least 2 feet of under-keel clearance. Trim angle, waves, and soft bottoms all affect real-world clearance. Always check tide tables before transiting shallow areas.