Forest Green
ACCESS: USAP
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- 11 June 2019
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Anchor dragging isn't at all like driving with the handbrake on. A better analogy would be that anchoring a ship is like parking on a hilly dirt track.Inadvertent LOL. It's like driving a car with the handbrake on.
Inadvertent LOL. It's like driving a car with the handbrake on.
A competent driver would leave the car in gear on a hill, equally cars with worn tyres don't pass MOTs. Additionally, if that car does slide down the hill into a bus stop queue, guess who's going to prison.Anchor dragging isn't at all like driving with the handbrake on. A better analogy would be that anchoring a ship is like parking on a hilly dirt track.
Your car will probably be where you left it, but if your tyres are worn, the hill is steep, and there's a rainstorm coming... well, that's what insurance is for.
The guy who dropped the anchor can't remember or something? How convenient. A prison sentence on them and a fine on the operators will help their memories.Really isn't according to people in the know. Ships are mostly driven on autopilot (not called an autopilot but I forget the exact term) from waypoint to waypoint. That 'autopilot' automatically compensates for seas, wind, current to get itself to the next waypoint. Dragging an anchor just becomes another element that the pilot compensates for, and because there's typically no indicator on the bridge that an anchor is down (no really), they can just motor along, dragging an anchor, and only being slowed down by a couple of knots.
View: https://www.youtube.com/watch?v=GWkKnyEu_Bc
It's an analogy.A competent driver would leave the car in gear on a hill, equally cars with worn tyres don't pass MOTs. Additionally, if that car does slide down the hill into a bus stop queue, guess who's going to prison.
You'd think there'd be a warning that the anchor is deployed on newer ships, possibly even an interlock. But someone on the crew should realise if they're even slightly competent. If not, they shouldn't be at sea.It's an analogy.
Anchors don't hold on the seabed 100% of the time. Usually it's fine. But sometimes the environmental loads are higher than the cable alone can resist, and the anchor drags. It's a thing that happens, and isn't really avoidable except by not anchoring.
Yes, if the anchor is undersized or inappropriate for the conditions (not all anchors work equally well on all seabeds) there's a problem. Not knowing the anchor is down is also a problem. But the anchor dragging isn't, in itself, a problem - provided the crew responds appropriately before anything gets broken.
First off, how do you determine if the anchor is down? You'll pay out different amounts of cable in different depths of water, so you can't use that. And you lower the anchor to the waterline while still making way, so you can't just check if the anchor is in it's housing. So you're left withYou'd think there'd be a warning that the anchor is deployed on newer ships, possibly even an interlock. But someone on the crew should realise if they're even slightly competent. If not, they shouldn't be at sea.
How do you judge if your car is going to miss a wall when reversing. Safety margins apply.First off, how do you determine if the anchor is down? You'll pay out different amounts of cable in different depths of water, so you can't use that. And you lower the anchor to the waterline while still making way, so you can't just check if the anchor is in it's housing. So you're left with
Don't have the anchor down near cables.Secondly, you need to start the engine before you bring the anchor in. Otherwise you'll drift. And if the anchor is dragging due to weather or poor holding – which is a thing that happens – you'll need to start the engines promptly to regain control.
Which leaves you with a system that fundamentally relies on recording that the ship is at anchor, and acting accordingly. And that opens the door to human error. There should be processes to mitigate that. Not having those processes is one of the things that will get a ship banned from port or detained. But with an awful lot of ships out there, and intense commercial pressure to cut costs to the absolute minimum, human error will still happen from time to time.
First off, you tantalizingly end your top paragraph with "So you're left with" - pray tell exactly WHAT???First off, how do you determine if the anchor is down? You'll pay out different amounts of cable in different depths of water, so you can't use that. And you lower the anchor to the waterline while still making way, so you can't just check if the anchor is in it's housing. So you're left with
Or don't put cables near roadsteads. Unfortunately they have been. Look up a chart for a busy port: you're likely to find a 'no anchoring' area. Very often that's because of cables.Don't have the anchor down near cables.
I belive the second paragraph was inserted later - you're left with procedural controls as described in the final paragraph.First off, you tantalizingly end your top paragraph with "So you're left with" - pray tell exactly WHAT???
At least until the sensor, or the cable connecting it to the ship, is destroyed by the marine environment. Which would most likely occur the first time the anchor was deployed and recovered.Second, both anchor contact with the sea floor and presence or absence of the anchor in/from its housing can be reliably determined with dedicated in situ sensors
Not necessarily. The article identifies three possibilities. This one is interesting, because it's intermediate between 'cables attacked' and 'things get broken at sea':
Dozens of miles? No, of course the crew would notice that. Although an anchor can drag for several miles while the crew is busy trying to do something about it, depending on conditions.The idea that an anchor would drag for dozen of nautical miles without a crew noticing is ridiculous. Please stop. You are making this forum a fool for newcomers.
Guys, again, listen to someone who knows, that's why I linked to Sal Mercogliano's vid in the first place. Systems on ships don't necessarily work how you think they do, or how you think they should.Really isn't according to people in the know. Ships are mostly driven on autopilot (not called an autopilot but I forget the exact term) from waypoint to waypoint. That 'autopilot' automatically compensates for seas, wind, current to get itself to the next waypoint. Dragging an anchor just becomes another element that the pilot compensates for, and because there's typically no indicator on the bridge that an anchor is down (no really), they can just motor along, dragging an anchor, and only being slowed down by a couple of knots.
View: https://www.youtube.com/watch?v=GWkKnyEu_Bc