Paid PractitionerCertificate

Shallow-Water Effects

What the seabed does to a ship once it is close enough to matter: squat, bank effect, the critical-speed wall, the canal that sends a ship's own waves back at it, and the muddy bottom that is not where the chart says. The physics first, then the numbers, then what they do to a performance analysis that was calibrated in deep water.

Lessons
8
Quiz questions
72
Exercises
3 (26 min)
Calculators
1
Time
About 105 min
Price
€209+ VAT
Certificate
Graded final exam, then a PDF certificate with a number anyone can verify
Who it's for
Performance analysts and superintendents whose ships trade through estuaries, canals and coastal approaches; masters, pilots and voyage planners who want the physics behind the speed limits and the under-keel clearance rules; and anyone who has watched a power-speed deviation appear on a river leg and wondered whether the hull or the river was to blame.
Assumed knowledge
Our course Ship Resistance Fundamentals for the calm-water components every effect here distorts. Nothing harder than a square root and a cosine is needed; the depth Froude number does most of the work.
Taught by

Christos Papandreou

CEO & Founder, Blue Autonomy

  • Naval architect and marine engineer, National Technical University of Athens
  • 15 years of experience in fleet performance and operational data
  • Chief Scientific Officer, NEMO, previously DeepSea Technologies, StormGeo, Athenian Sea Carriers, PwC

Part of the Vessel Performance Analyst II: The Hull in Service specialisation.

What you will be able to do

By the end of the course. Each outcome names the lessons that deliver it, and the final exam samples every one of them.

  1. Explain why a nearby seabed changes a hull's resistance physics rather than merely limiting speed (continuity forces the return flow through a smaller section; the acceleration drives the pressure drop, friction rise, squat and altered waves), and size any situation with the two governing numbers (depth-to-draught ratio and depth Froude number), including the deep-water criteria (h > 3·√(B·T), h > 2.75·V²/g) that define when depth can be ignored. Lesson 1
  2. Predict squat with the ICORELS and Barrass estimators, state what each assumes (open water versus confined channel, and why their spread is a geometry question rather than noise), explain the speed-squared scaling and bow-versus-stern trim by hull fullness, and defend squat as a resistance problem as well as a clearance problem. Lesson 2
  3. Explain bank effect and passing-ship interaction as one asymmetric pressure field (bow cushion, stern suction, the V² scaling with clearance and depth, why the kick-ahead works, why overtaking is worse than meeting, and how the two effects stack), and identify the drift-and-helm-induced drag they leave in a performance record. Lesson 3
  4. Derive the shallow-water wave-speed ceiling √(g·h) from the dispersion relation, place a ship in the subcritical, transcritical or supercritical regime and describe the resistance hump; apply the Schlichting–Lackenby speed-loss method knowing its assumptions and why the 2020s trial standards replaced it; and compute a canal's blockage ratio, return flow, drawdown and Schijf limiting speed, explaining why canal legs are structurally different data. Lessons 4, 5
  5. Explain dead water as critical speed on a hidden density interface (reduced gravity, internal-wave speeds of a knot or two), describe fluid mud and the PIANC nautical-bottom concept (a consequence-based definition applied through a ~1,200 kg/m³ density proxy) with the two-bottom echo-sounder ambiguity, and classify muddy approaches as a third data category to flag and exclude. Lesson 6
  6. Size the false speed loss a deep-water baseline reports on shallow-water records, explain why the artefact is one-signed and accumulates into a fake fouling trend (and where it hides in draught bins), apply the four defences in order (carry the depth, filter on the deep-water criteria, classify confined waterways, compare like geometry with like). Then spend the physics on decisions: transit speed from Frh and the squat budget, a component-by-component under-keel clearance budget, the propeller/engine/steering consequences, and charter-party language that keeps confined legs out of a speed-and-consumption claim. Lessons 7, 8

Every speed-power curve a ship owns was drawn for water that is, for all practical purposes, bottomless. The model basin is deep, the sea trial is run in deep water by rule, and the reference curve in a monitoring system inherits that assumption without ever stating it. Then the ship enters a river approach, a canal, a shelf sea twenty metres deep, and the assumption quietly fails. The hull does not know it has entered a different regime. The performance analysis does not know either, which is the problem.

Shallow water does not simply limit speed. It changes the physics. Water that used to pass freely under and around the hull now has to squeeze through a gap, and the squeeze shows up as five distinct effects that the standard weather corrections do not contain: the ship sinks and trims as the pressure under her falls (squat); a nearby bank turns that pressure field asymmetric and tries to turn her across the channel (bank effect); the waves she makes find a speed ceiling at the square root of gravity times depth, and her resistance climbs a wall as she approaches it (critical speed); in a canal her own wave system reflects off the banks and the water alongside physically drops (confined-water wave deformation); and over a fluid-mud bottom the seabed itself stops being a fixed surface (mud and dead water).

This course takes each of the five in turn, building the one parameter that organises all of them, the depth Froude number, and the one that measures how close the bottom really is, the depth-to-draught ratio. Each effect gets its mechanism, its scaling laws, the published estimation methods with their honest limits, and a worked number on a ship you will come to know well. Then the course turns to what these effects do in practice: why a deep-water baseline fed shallow-water records reports a fouled hull that is not fouled; how a trial standard corrects for depth and why that correction was rewritten in 2025; and how speed, under-keel clearance and the charter party should be decided once the physics is understood.

The opening lesson is free to read as a sample. By the end you should be able to look at a power-speed deviation on a coastal leg and say, with a number beside it, how much of it the seabed wrote.

What the course covers

  1. The Seabed Joins the Flow 9 min
  2. Squat: The Ship Pulls Itself Down 18 min + exercise
  3. Bank Effect and the Passing Ship 9 min
  4. Critical Speed: The Wave That Cannot Outrun the Ship 21 min + exercise
  5. The Canal: Blockage, Return Flow and Drawdown 10 min
  6. Mud, Fluid Mud and Dead Water 10 min
  7. When Geometry Masquerades as Fouling 18 min + exercise
  8. Spending the Number: Speed, Clearance and the Contract 10 min

€209 + VAT

€259.16 including 24% VAT, which is what an individual in the EU pays. Outside the EU no VAT is added. A company in another EU country pays the net price once its VAT number is confirmed in VIES, the EU's register; a company in Greece pays the 24%. Checkout shows the total before you pay.

Paid once, for one person, for as long as the Academy runs: every lesson, the Excel workbook, the final examination and the certificate. Part of the Vessel Performance Analyst II: The Hull in Service specialisation, which costs less than its courses bought one at a time.

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All prices · Refunds: 7 days, unless you have started

Common questions

What exactly is included?

8 lessons (about 105 minutes in total), 72 quiz questions with explained answers, and 1 working Excel calculator: Shallow-water transit calculator.

How much does it cost?

€209 plus VAT, paid once: €259.16 with 24% VAT, which is what an individual in the EU pays; outside the EU no VAT is added, and a company in another EU country with a VAT number valid in VIES pays the net price. That buys every lesson, the Excel workbook, the final examination and the certificate, for one person, for as long as the Academy runs. The course is also part of the Vessel Performance Analyst II: The Hull in Service specialisation, which costs less than its courses bought one at a time. Everything else is on the pricing page.

Is there work to do, or is it only reading?

3 lessons carry a required exercise, about 26 minutes of hands-on work in total. You download that lesson's Excel workbook, follow the numbered steps against the numbers the lesson states, then change one input and watch the answer move. The exercises are where the method stops being something you have read and becomes something you can run; the stated course time includes them.

Do I get a certificate?

Yes. The course ends with a graded final exam, marked on our server rather than in your browser: you see your score and which questions you got wrong, but not the answers, because the questions are drawn from a pool. Pass it and you get a PDF certificate in your name, with a certificate number on it.

That number is the point. Anyone you show the certificate to can check it themselves at academy.blueautonomy.gr/verify, with no account and no email to us: the page states the name, the course and the date we issued it. A certificate nobody can verify is a decorated PDF, and we would rather issue one that stands up.

Can I preview the course?

Yes: the first lesson, The Seabed Joins the Flow, is free to read in full. It is a real lesson, not a trailer: same depth, same quiz.

Do I need prior knowledge?

Our course Ship Resistance Fundamentals for the calm-water components every effect here distorts. Nothing harder than a square root and a cosine is needed; the depth Froude number does most of the work.