The power of the sea at St Bees

 We went to St Bees. We had seen TV coverage of the tidal surge earlier in the week. The grass above the promenade was covered in stones and debris. All of the life belt holders had been knocked flat. I did some calculations of the force of the wind hitting me in a December blog post. The theory says that the rate of change of momentum of the water hitting the life belt holder is the same as the force of the water. The assumption made is that the water stops dead. The theory is on the earlier post. I estimate that the life belt holder is 75 cm square. I'll estimate that the sea is doing 10 mph, which is 4.4 metres per second. The volume of water stopped in one second = area x speed. Change in momentum = mass x speed = density x volume x speed = density x area x speed squared. I get 11kN which is the equivalent of 1 metric tonne hitting the red board. If I could remember the bending moment theory I learned at university, I could calculate the minimum force from the fact that the steel bent at the bottom and thus tell you the minimum speed of the sea water. Trouble is that even a bit of Internet research isn't bringing it back quickly enough.

 

We are fond of the café and it has taken a bit of a pounding too. The banks below it don't look too secure.