Free
Ship Resistance Fundamentals
What actually slows a ship down in calm water — the five components of resistance, where each one comes from, and which of them you can influence from the bridge.
- Lessons
- 6
- Time
- about 40 minutes
- Who it's for
- Superintendents, performance analysts, and anyone who reads a noon report and wants to know what the numbers are describing.
- Assumed knowledge
- None. No equations are required to follow it, though a few appear where they earn their place.
Before weather, before fouling, before anything a voyage throws at a vessel, there is a floor: the resistance a hull meets in flat, still water. That floor is not one force but five, and they behave very differently. One of them scales with the cube of speed. One of them barely exists until the ship reaches a certain length-to-speed ratio, then punishes hard. One of them is present on a dead-calm day with no wind at all.
This short course walks through all five, in the order they matter. Each lesson is built on an article we have already published, so you can read the original at any point — the link is at the foot of every lesson.
By the end you should be able to look at a vessel's speed–power curve and say something specific about which resistance is responsible for the shape of it.