# Physical oceanography: Waves

1. Jun 20, 2011

### starfire123

A former sea captain recounts a stormy night in Atlantic when he observed waves with wavelengths of a few metres passing his 51m long ship in less than 3s. Should you believe him?

How do we go about answering this question? I have no idea where to start from, well, we learnt about group velocity and phase speed of waves, but I don't know how to use them to answer the question?

2. Jun 20, 2011

### SteamKing

Staff Emeritus
Think about the vessel heading into the wave. If the vessel had some speed on it, would the observation about the waves make sense?

3. Jun 20, 2011

### starfire123

hm.. i think its possible? because waves can travel at a speed of 1m/s (assuming wavelength is 3m and period=3s?)

is tat the way to support the answer though? it seems too simple

4. Jun 20, 2011

### SteamKing

Staff Emeritus
Don't you know a formula for calculating the velocity of a deep water wave given the wavelength? Remember, deep water waves of a given wavelength all travel at a certain velocity relative to a fixed reference point. An observer on a vessel is not necessarily fixed in position relative to the wave motion.