When planning offshore operations, it’s important to understand how waves behave — not just how big they are, but where they come from and how they interact. That’s where 2D wave spectra come in.
✅ What is a 2D Wave Spectrum?
Think of the ocean surface as being made up of many waves coming from different directions and with different sizes. A 2D wave spectrum is a detailed map showing:
Wave height (energy)
Wave direction
Wave frequency (how fast the waves occur)
It’s called "2D" because it maps energy by both direction and frequency.
🎯 Why does it matter?
For offshore operations, knowing the full picture of wave conditions is critical. A simple wave height number (like "3 meters significant wave height") doesn't tell the whole story.
The 2D spectrum helps answer key questions:
Are the biggest waves coming from the side or the front of the vessel?
Are there multiple wave systems at once (e.g. swell from one direction, wind waves from another)?
Will the combination of waves cause excessive vessel motions?
This deeper understanding improves planning and safety.
🚢How ODST Uses 2D Wave Spectra
In ODST, the 2D wave spectrum is visualized to help teams make better decisions. It supports:
Accurate vessel motion and product response predictions
Go/No-Go decisions based on actual sea state
Deeper understanding of real sea state conditions
The tool combines this high-resolution wave data with vessel and product response characteristics to predict responses 5–7 days ahead.
How to Read the Plot
There are two ways to view 2D wave spectra in ODST.
Polar plots:
The direction shows where the waves are coming from
The colors represent wave period (Tp) — warmer colors = higher periods
The wave height (Hs) increases from center to edge
You might see multiple energy peaks, showing different wave systems present at once.
The below example spectrum has swell waves coming from south-west and wind waves coming from north-east.
Time plots:
There are two different time plots visualised in ODST; one displaying direction and one displaying wave period. Both plots have time on the horizontal axis and significant wave height represented by color. The vertical axes represents direction and wave period respectively.
Significance and Dominant Directions:
By analyzing the spectrum, it's possible to identify the significant wave height, which is the average height of the highest one-third of waves. Additionally, the dominant wave directions, where most of the energy is concentrated, can be determined.
Swell and Wind Waves:
The spectrum helps differentiate between swell waves (longer period waves generated by distant storms) and wind waves (shorter period waves generated locally by wind).
💡 Summary
A 2D wave spectrum gives a much richer picture of sea conditions than a single wave height number.
It’s a key part of smarter offshore planning.
In ODST, this data is used to make operations safer, more efficient, and easier to manage.