[QUOTE=Radiocheck;131969]This formula comes very close to our SOP on o ~50,000 DWT tanker. I allow a bit more chain when expecting heavy weather but, the fair condition conclusion seems right on for my ship. I am assuming decent holding ground. We work very hard in heavy winds when light. The bow gets trucking and pops the anchor. Extra chain early prevents ass ache. I’ve had little success stopping dragging by slipping more chain. We usually need to pick up and reset once she gets moving. We usually schedule this maneuver for 0200 when it’s raining sideways at 35 degrees. We attempt the maneuver at least three times to be sure we’ve gotten it right. We then pick it up and slow steam until the weather passes. Greater than force six… We’re going for a cruise. Screw the office.[/QUOTE]
We jack around pretty hard sometime, it starts at a little over 20 kts and increases as the wind increases. . The paper calls it horsing. At 35 kts it gets bad and we have to watch the position closely. F-7 is maybe and she’s not going to stay put in F-8.
Current is a factor as well, She sometime really charges around with a current and wind, running up towards the anchor then putting the wind almost abeam and going for a run like a dog on a chain chasing a cat. I guesstimate that 1 kt of current is equivalent to 10 kts of wind.
I’ve had the same experience as you with dragging, once they start going it’s all over, the big ones anyway. .The linked paper has some good info on how much sea room is needed to recover the anchor and how much speed and room is required to regain control. Takes a lot of acreage.
I can’t low speed steam until we make some technical changes , that’s a big problem. Sometimes I drift which sucks but sometime I’ve got no choice but to run.
I did get in a pickle one time and couldn’t leave, I called a couple of tugs and they held the bow into the wind and she stayed put ifn 50+ kts but it was exhausting work. Lucky it was only a few hours. The paper talks about using the bow thruster, I can cut down on the jacking a little with judicious use of the thruster but you don’t gain that much,