Paid SpecialistCertificate

Added Resistance from Wind

The one added-resistance term you can compute from a ship's drawing, taught end to end: apparent wind, the coefficient that turns a superstructure into a force, the subtraction that makes it 'added', the Fujiwara regression and its traps, and what the number is worth once the anemometer has had its say.

Lessons
8
Quiz questions
72
Exercises
1 (10 min)
Calculators
1
Time
About 84 min
Price
€179+ VAT
Certificate
Graded final exam, then a PDF certificate with a number anyone can verify
Who it's for
Performance analysts, sea-trial engineers and anyone who corrects measured power for weather, and anyone who has to defend, or challenge, a wind correction someone else computed.
Assumed knowledge
Our course Ship Resistance Fundamentals, whose air-resistance lesson sets the calm-air baseline this course departs from. Comfort with vectors and a cosine is enough mathematics.
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 Added Weather Resistance 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. Resolve a reported true wind and the ship's own velocity into the apparent wind the hull feels, applying the checks that catch a reversed from/towards convention before it reaches a performance figure. Lesson 1
  2. Compute the longitudinal aerodynamic force from air density, apparent wind speed, transverse projected area and a wind-resistance coefficient, and convert the force into added shaft power. Lessons 2, 8
  3. Defend the two-term subtraction that makes the resistance "added": evaluate the still-air term correctly, predict the sign of the result, including when wind genuinely helps, and name the fouling-shaped bias created when the subtraction is omitted. Lesson 3
  4. Extract the eight geometric inputs a wind-resistance method needs from a general-arrangement drawing, and recompute the five that move when the draught changes. Lesson 4
  5. Evaluate the Fujiwara regression at any apparent-wind angle, auditing an implementation for the cross-flow and branch errors that survive head-wind testing, and choose defensibly between a wind-tunnel coefficient database and the parametric regression, stating the uncertainty the choice carries. Lessons 5, 6
  6. Correct a measured wind from anemometer height to the coefficient's reference height, choose defensibly between the ship's own sensor and a hindcast field, and quote a corrected power that has passed the 100 per cent guard rail, with its uncertainty ranked honestly. Lessons 7, 8

Wind is the added-resistance term everyone believes they understand and almost nobody computes correctly. It looks simple: the superstructure is a sail set backwards, so multiply an area by a dynamic pressure and be done. Then the details arrive. The wind the ship feels is not the wind the weather service reports. Half the answer depends on a coefficient that varies with angle in a way no intuition predicts. The ship's own motion generates a headwind that is already inside the calm-water baseline, so it has to be subtracted back out. And the instrument measuring it all sits in the most aerodynamically disturbed place on the vessel.

This course takes wind resistance at the depth its role deserves, because it is the correction applied most often, on the most records, in both sea trials and continuous monitoring. The physics first: dynamic pressure, frontal area, and what a wind-resistance coefficient actually is. Then the subtraction that defines the word added, and why getting it wrong biases every performance figure downstream in one direction. Then the geometry: the eight numbers that describe a ship to the wind, and the five of them that move with draught. Then the method itself: the Fujiwara regression, term by term, including the cross-flow term whose sign a plausible-looking rearrangement silently loses, and the smoothing the ITTC procedure and ISO 15016:2025 prescribe at beam wind. Then the measurement problem: anemometer height and position, the boundary-layer correction, and the choice between the ship's own sensor and a hindcast.

The opening lesson is free to read as a sample. By the end you should be able to compute a wind correction from a general-arrangement drawing, state its uncertainty honestly, and spot the sign errors that silently ruin other people's, from a wind direction read the wrong way round to a cross-flow term a rearrangement has quietly broken.

What the course covers

  1. True Wind and Apparent Wind: The Vector the Ship Actually Feels 8 min
  2. How a Superstructure Becomes a Force 9 min
  3. The Subtraction That Makes It 'Added' 9 min
  4. Reading the Superstructure: Eight Numbers Off the Drawing 8 min
  5. The Fujiwara Regression, Term by Term 9 min
  6. Measured Database or Parametric Regression: Choosing the Coefficient 9 min
  7. The Weakest Link: Anemometer, Height and Hindcast 9 min
  8. Spending the Number: Corrected Power and Its Guard Rails 23 min + exercise

€179 + VAT

€221.96 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 Added Weather Resistance 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 84 minutes in total), 72 quiz questions with explained answers, and 1 working Excel calculator: Wind resistance: coefficient and added power.

How much does it cost?

€179 plus VAT, paid once: €221.96 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 Added Weather Resistance 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?

1 lesson carries a required exercise, about 10 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, True Wind and Apparent Wind: The Vector the Ship Actually Feels, 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, whose air-resistance lesson sets the calm-air baseline this course departs from. Comfort with vectors and a cosine is enough mathematics.