North Sea Wave Lab
Physics model · Aberdeen to Lerwick

North Sea
Wave Lab

A 125-metre ferry floats on a computer sea. The sea is built from the real forecast along the route, for any time you choose. Every moment, the computer works out how hard the water pushes up on 132 slices of the hull, and the ship rolls, pitches and rises in response. Nothing is pre-planned.

Aberdeenopen North SeaFair IsleLerwick
Time--:--
Roll0°
Pitch0°
Rise & fall0 m
Wave every0 s
Biggest wave0 m
Speed18 kn
Drag to look around · scroll or pinch to zoom

Time and sea

Loading…
Day
12:00
00:0006:0012:0018:0024:00
The ferry is
–waves
–waves come from
–wind
–sky

3.0 metres
0 m5 m10 m15 m20 m
Waves come from
Stabilisers

Weather

These switch on by themselves as the sea gets wilder. You can change them at any time.

With sound on, count the seconds between flash and thunder. Every 3 seconds means the strike was about 1 km away.

Sailors call it

Slight

Douglas sea state 3 of 9

A wave as tall as

a grown-up

Wave height here is the average of the biggest third of the waves. Some will be bigger.

Will the ferry sail?

Yes

Sailing as normal.

How do you feel?

Fine

Walking around is easy.

Meanwhile, in the café

You're looking forward through the café, with the window on the right. The room moves exactly as the ship in the big view does. The sea outside comes from the same computer sea.

The cup feels gravity and the ship's lurches. When the push along the table beats friction, it slides, and it can fall off. The lamp swings freely, so it always shows which way is really down.

0°roll right now
0°biggest roll, last 30 s
0cups spilled

Under the bonnet

What the computer works out

The sea is 32 waves added together
Each has its own length, speed and direction. Their sizes follow JONSWAP, a recipe scientists made from measuring real North Sea waves. Bigger seas get longer waves, and the crests get sharper.
Every slice of hull is pushed up
The hull is cut into 132 upright slices. Each is pushed up by the weight of the water it pushes aside. That's Archimedes' principle, worked out 120 times a second.
The ship fights back with its weight
This model ship weighs about 11,000 tonnes. Left alone, it would roll from side to side once every 12 seconds. When the waves arrive at the same rhythm, the rolling builds up.
Stabilisers add drag
Fins stick out from the hull under the water and resist the rolling. Switch them off to see the difference.

Experiments

Try this

  1. Press "Set to now" to see tonight's real sea. Then try 3 a.m. tomorrow. Will it be rougher or calmer?
  2. Set the waves to 5 metres from the side. Watch the roll number, then switch the stabilisers off. How big does the roll get?
  3. Change to "Straight ahead". Does the ship roll or pitch more now?
  4. Push the waves to 15 metres from straight ahead. Watch the front of the ship crash down and throw up spray.
  5. Watch "Biggest wave". How much bigger than the slider does it get?
  6. Go "On deck" in an 8 metre sea and watch the horizon.