Marine & Navigation

Tide Window Planner

Estimate passable tidal windows around high tide for draft-limited transits.

Last validated: 2026-02-14

Tide Window Planner estimates how long draft-limited transit is likely available around high tide using charted depth, vessel draft, safety margin, and high/low tide heights. It is useful for bar crossings, marina entrances, and shallow-channel planning when timing is critical. The model treats the tide cycle as a semidiurnal sinusoid, so it is best for first-pass planning rather than final pilotage decisions. Use local tide tables and real-time observations before committing to transit.

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Input Pattern

Enter values in the left panel, keep units explicit, run the calculation, then copy or share the result. Invalid fields are highlighted immediately.

Tide Window Inputs

Estimate transit window around high tide using a semidiurnal sinusoid approximation.

Result

Required depth: 3.000 m

Required tide above datum: 0.900 m

Clearance at low tide: -0.300 m

Clearance at high tide: 2.500 m

Window available: Yes

Estimated window duration: 9.78 h

Around high tide: ±4.89 h

How to use this tool

Enter charted depth, vessel draft, and desired safety margin.
Add high and low tide heights for the expected cycle and run the calculation.
Use the estimated window duration and ±hours around high tide as planning guidance.

Worked Example

Auto-generated from the tool's current default or entered inputs.

Example Inputs

High tide m: 3.4
Low tide m: 0.6
Charted depth m: 2.1
Vessel draft m: 2.4
Safety margin m: 0.6
Required depth m: 3.0
Required tide m: 0.8999999999999999
Low tide clearance m: -0.2999999999999998

Expected Outputs

High tide m: 3.4
Low tide m: 0.6
Charted depth m: 2.1
Vessel draft m: 2.4

Interpretation

High tide m is 3.4. Use this as a decision input, not as a standalone conclusion.
Low tide m is 0.6. Use this as a decision input, not as a standalone conclusion.
Charted depth m is 2.1. Use this as a decision input, not as a standalone conclusion.
Cross-check the result against one alternate input set to validate sensitivity.

Scenario Compare (A vs B)

Use this to compare two input sets and quantify change in key outputs.

Scenario A

High tide m

Low tide m

Charted depth m

Vessel draft m

Safety margin m

Required depth m

Required tide m

Low tide clearance m

Scenario B

High tide m

Low tide m

Charted depth m

Vessel draft m

Safety margin m

Required depth m

Required tide m

Low tide clearance m

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Tide Window Planner

Input Pattern

Tide Window Inputs

Result

How to use this tool

Worked Example

Example Inputs

Expected Outputs

Interpretation

Scenario Compare (A vs B)

Scenario A

Scenario B

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