Did I forget to mention 'El Hurricane'?*
NB: I have delayed posting this because I didn’t want to worry my fainter-hearted readers but now that I have been home for a few weeks and am making a point of avoiding the River Cam I think it’s safe to assume that it won’t happen again. This entry was written 5/4/07 0932 GMT, i.e. in between the last two entries, but I decided not to post it then.
Hello blogwatchers. Well, I think it’s fair to say that tonight I have had an eye-opening experience of the power of nature.
We knew the winds were going to get up a bit as we headed out to the shelf break, but I definitely didn’t expect what was to follow. To whit: Violent Storm- and even Hurricane-force winds averaging over 60 knots (70 miles per hour) for 12 hours and gusting to over 80 knots (90 mph) during that period, massive swell, waves breaking over the stern and sides, and vibrations shuddering through the ship in tune to the sounds of flexing metal.
The view from the bridge last night was terrifying to a land-lubber like me. One moment we were pointing upwards into the sky, the next downwards into a flaming great big hole in the ocean, with everything else obscured by the wall of water crashing forward in our direction. Looking upward at tonnes of water as you steam downwards towards it is a disquieting experience when you are on the bridge, usually a good 20 metres above the waterline. The wind was so strong that the caps of each wave were vapourised and hurled towards us, freezing in the air and then pummelling the windows with frightening force. Venturing around the innards of the ship was like driving over hump-backed bridges in different directions every few seconds. While making coffee I could feel the floor of the officer’s bar flexing beneath my feet.
Funnily enough, the ship didn’t move about a huge amount more than in some of the not-quite-so-rough seas we experienced before. That was because the officers on the bridge kept the ship pointing permanently into the wind and waves, above other considerations, so that the stronger prow does all the wave-breaking and protects the weaker parts of the ship, like my cabin, from the force of the water. The ship has to be directed so that she is more stable and rocks back and forth (pitching) rather than from side to side (rolling); the larger length of the ship compared to its width averages out the effect of the waves a bit more. They had to put 3 megawatts of power into the drive-shaft to keep her heading at 3 knots into the waves, when in a calm sea 3MW would keep the ship steaming at a good 12 knots. Visibility was extremely limited and we were fortunate that there was no ice, land, or shallow uncharted waters around so that we could steam directly into the waves.
The ship is designed to withstand such forces, but the experience was extremely hair-raising nonetheless. I have to admit that I genuinely thought the game was up when the ship nose-dived at night into a few particularly big holes, as it seemed that when a few tonnes of water were dumped on the fo’c’sle that the elemental forces of nature simply must be too strong for any ship. Watching from the UIC as the waves rolled past and then broke over the aft deck was more frightening than any experience I have had before or any I wish to ever see again! Even a few experienced seafarers on board said that it was pretty rough, though most snorted with amusement at my lily-livered proclamations of fear.
Most importantly, I think we are going to have to re-think the surface boundary conditions in our model. And we didn’t get any CTDs done, in case you were wondering. Even the trusty salinometers were refusing to cooperate…
In the rest of this post I decided to show you some mildly scary pictures and videos, which underestimate the force of the waves because they were taken in the daytime when the wind had dropped (see graph). I found that it is impossible to capture rough seas in still photos. I can assure you that the night was a fair bit worse than this, particularly because no-one could see what was coming next. After the pictures I have also done a little weather analysis for the anoraks out there.
Here is some footage that 3rd Officer Douglas took from the bridge in the morning (thanks Douglas). He was driving the ship with the other hand. You get the general impression from the starting point of the video:
Here are some pictures of the ship (displacement approx. 6000 tonnes) being tossed around in the waves like a cat in a washing machine. I have tried to take pictures on a consecutive peak-and-trough pair so that you can see the motion but, well, you get the idea....
View from the bridge:
Looking backwards from the bridge:
View from the UIC:
Waves menacing the aft deck:
Firstly, here was the weather forecast. If you don't know how to read a pressure chart then an introduction is given here. Basically the closer together the pressure contours are, the higher the wind speeds will be. If you can't tell the contours apart from each other, you are stuffed!
Next, I have plotted the wind speed and atmospheric pressure. Note that the wind speed is highest when the pressure drops. I was on watch from about 23:00 GMT on 4/12/07 until about 11:00 GMT on 5/12/07.
Here is the Beaufort Scale, which is used to measure wind force. As you will notice the winds were officially Violent Storm force on average rather than Hurricane force, but I can assure you that it was scary!
And here is an alternative scale that I prefer, courtesy of Mark Brandon. Note the psychological scale, and it only goes up to 10 on the Beaufort scale! However, it is designed for fishing smacks rather than big robust ships like the JCR.
- Most of us didn't mention this on our blogs until safely home for fear of scaring the relatives, but not Karel. Her blog is in Spanish though, so the secret was safe until she referred to 'El Hurricane'...