# About the Seakeeping category

**URL:** <https://solarboats.discourse.group/t/about-the-seakeeping-category/10>\
**Category:** Seakeeping\
**Created:** [October 14, 2026, 6:07pm UTC](https://solarboats.discourse.group/t/about-the-seakeeping-category/10 "2026-10-14T18:07:14Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Sandith](https://sea2.discourse-cdn.com/flex042/user_avatar/solarboats.discourse.group/sandith/32/11_2.png) [@Sandith](https://solarboats.discourse.group/u/Sandith)\
**Post date:** [October 14, 2026, 6:07pm UTC](https://solarboats.discourse.group/t/about-the-seakeeping-category/10/1 "2026-10-14T18:07:14Z")

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Boat motions in waves: heave, pitch and roll, passenger comfort, operability limits, and what the conditions on your route mean for the design.

**What belongs here**

- Heave, pitch and roll: natural periods, response in waves (RAOs), and how hull form and loading change them
- Passenger comfort and motion sickness, especially for ferries and tourist boats
- Operability: what wave height or wind the boat can work in, and when to stop running
- Wave conditions on your route: backwaters, rivers, estuaries, coastal crossings
- Model tests, sea-trial measurements, and comparing them with predictions
- Slamming, green water and deck wetness on small craft

**What goes elsewhere**

- Static stability, GZ curves, heel criteria → _Hull & Stability_
- Added resistance and speed loss in waves → _Resistance & Propulsion_

**About the calculator’s Seakeeping module**  
It is under development and its results are **not yet reliable**. Checked against Ursell’s exact solution for a semicircular section, its added mass is off by 13–69% and its damping by up to 72%. The heave and pitch results carry that error, and roll is not reported at all. The module says so on screen. Until it is validated, use it for learning and rough comparison only, not for design decisions.

**Can you help validate it?** We are looking for published sectional added-mass and damping coefficients for real ship sections (for example Tasai’s or Vugts’ tables), or model-test or sea-trial motion data for small craft. If you have any, please post here.

**When asking a question, include:** vessel length, beam and draft, displacement, speed, and the wave conditions (height and period, or a description of the route). Without these, nobody can give a useful answer.