Curious if anyone has ever been run over by a waterspout while on DP. What happened, did you hold your position, hit something, ESD transfers?
We got clobbered one night (we were tied to the rig with the anchor out). It was dark and the weather very mild, until suddenly, whack! We did not have any hazardous effect from it, but I’ve often worried that our DP system would never have fared as well, so I was hoping to hear some other experiences.
Hasn’t happened to me but certainly rapid changes in wind speed and direction have but not so bad that the model failed. As long as the model is good and the thrusters all have enough HP then shouldn’t be a problem except for a possible immediate excursion when the spout first hit. I can’t image that any DP model could withstand the insane changes in wind speed and direction of an intense waterspout however. I’d say the best thing if you saw it coming would be to pull out to a safe distance and go into manual joystick until they have all passed. I would not want to be right up under a platform when they were in the area. Of course with a very brief spike in wind, it might not make that big of a change to the model since it is always being averaged as a mean over a relatively long span of time. Anybody know what that span is? Why does the number 11 come to mind? Kongsberg also has “quick model” you could use but I don’t think you would want to right in the middle of the impact?
I would say that if you got caught by one completely unaware it would be your own damned fault for not keeping a close watch out the windows or on the radar. A waterspout makes one hell of a radar target!
Ironicly we had a water spout cross right over the stern of the boat one day in broad daylight. EFFing mate was sitting at the stern controls with his feet proped up never saw it coming. We were very lucky, we had divers in the water, one in the decompression chamber. The water spout barely grazed the stern of the boat at an angle coming down the starboard side. We were right under the GSF Artic 1 that shuld tell you how long ago it was. I was amazed no one saw it coming, it barely got the edge of the rig. One of the tenders saw it at the last minute and got everybody off the deck. We lost everything that was not welded down on the back deck. Nobody was hurt amazingly There were actually fish on the cat walks ontop of the rig when it passed. The DP system held good the boat never moved that I could tell. But it also happend so quick, I dont think anything would have had time to react. 45 seconds and it was gone.
Two months ago we had some fair sized squalls approach on radar at night. We saw a little hook echo in the smaller squall, and we were getting the ROV out of the water for maintenance anyway. Moved vessel 100 meters out from rig, about 400 ft total to wait while they passed. Winds went from 15 kts to 45 in a few minutes, vessel held pretty well, thrusters ramped up no major problem.
Wind slacked off slightly, but came up quickly from opposite side and built over next three minutes to a sustained 82 kts for over 2 minutes.(still have the screen shot )!
Sideways rain followed buy golf ball sized hail. At 55 kts we started losing bow and took over on stick, brought another generator on line and tried to make our way out of the 500 meter zone. Gone as soon as it started, guess well never know if it was all straight line winds, or a waterspout.
Pucker factor of 8-9, was glad Master had just relieved me at the console !
It was certainly a learning experience…
We got it at night (so much for your window theory). And while some modern boats may have radar displays at every station, our old junker was lucky to have one at the primary helm. This is a problem even for some modern boats. The ROV boat we work with routinely misses traffic on our project because their normally have the radar up in their doghouse. But then, ECO isn’t know for their greatness (unless you ask them - lol).
Our wind speed topped out at 96 knots, so clearly no model could respond to that. But the duration was short, less than a minute, so I was curious if it had happened to someone on station. Just wondering how the exit plan went and so fourth. We never stopped pumping dry bulk. The crane operator came on the radio, the poor guy was in the cab when it hit, and, predictably, said "what Fuuuuuu$% was that!?)
We got a call from the ECR last week saying that there was a waterspout just aft of the ship. We made an all page for everyone to seek shelter, there’s a waterspout! Well, as one might have guessed, the whole crew did just the opposite and ran outside to see. Fortunately, it was gone as soon as it started. We have some separation between the wind sensors on here. I would guess, haven’t seen one hit us, that the system would reject and vote out a sensor that spiked quickly and from a different (variable) location. There would be a potential for drive off from wind feed forward, but I’d bet it would be less than 10 meters… still enough to have some big problems! Think about the paperwork…