Floating containers - ever seen one?

[LittleSister]

This reminds me of reading somewhere of a US sailer / writer who calculated that the chances of a collision between a yacht and a ship on (IIRC) the west coast of the USA were negligible, and promulgated the view that it was effectively quite safe for single-handers to sleep underway there.

He was later himself in such a collision, but lived to tell the tale and revised his view.

I don't know the details or how reliable his maths were.

 

[RolyGate]

Where do you get your information from?
These people seem to think otherwise... https://www.billiebox.co.uk/facts-about-shipping-containers/

I remember calculating how fast one would sink and was surprised just how long it would take. Its not the air that needs to get out, but the amount of water that needs to get in through some very small holes that takes the time.

No - I have no info. This is what I'm asking. I heard about 4 a day go over the side, worldwide. But I've sailed tens of thousands of miles including a 3 year cruise from the North Sea to the Indian Ocean etc. and never seen one - so that is what I'm asking, in order to check the validity of my opinion.

Thanks.

 

[RolyGate]

Aha, yes, I've seen all kinds of floating junk too - some of which would certainly rip the rudder off a regular boat hitting it.

Never heard of a box washed up so that is of interest - thanks.

 

[RolyGate]

OK, thanks - interesting.

Bad news to hit that at night.

 

[RolyGate]

OK - thanks.

We have box ship crew in our sailing club, and they say there are never enough clips and chains to secure them with; and since there is no real penalty, it is inevitable that boxes are lost.

I would imagine they go over the side in F10 or above, especially on the shelf where the waves are bad. Biscay, north Spain, places like that. Surprising more don't come off in the Western Approaches though, it's grim out there sometimes.

 

[RolyGate]

Ah now that strikes home. On a trip Az back in to Fal I was hammering downwind and saw a mass of large floating buoys roped together. Lucky to miss that.

A container would have been real bad news to hit flat out.

 

[RolyGate]

Thanks.

 

[RolyGate]

Aha - excellent.

Thanks.

 

[RolyGate]

Very good info - thanks.

 

[RolyGate]

Thank you.

 

[RolyGate]

Celutex insulation boards?

Yes, that's true. But PIR boards are actually not closed cell foam, and they waterlog easily. In boats we install them wrapped in plastic or they will eventually get too damp to work, at least up north anywhere. If you leave a Cellutex or Kingspan board out in the rain, eventually it will weigh 10kg not the 1.5kg it started as.

The foil-foil boards are better than the fibreglass tissue version, which are a nightmare for various reasons. Don't get those

 

[Lon nan Gruagach]

Not sure I concur with your maths...

So if there is 1 40ft container in 400,000 square miles that means there is a rectangle 40ft x 8ft in the 400,000 sq.mi.

400,000 square miles is equivalent to a rectangle 1 mile wide and 400,000 miles long.

Thats 400,000 x 5280 = 2112 million feet long and 5280 feet wide.

If you were to cover that width with a grid 8 feet wide you can fit 660 x 8 foot wide rectangles into that width and nearly 53 million 40 foot long rectangles into the distance. a 400k sq.mi area covered in a grid 40ft x 8ft would have 34848 million 40 x 8ft rectangles. Your container in theory occupies just one of those.

Your 160,000 vessels of unknown size in that 400,000 sq.mi area at any one time. Some will be bigger than one 40 x 8ft rectangle. Others will be smaller. I don't know what the average is but lets say 80ft x 16ft (so 4 rectangles) would be average. So 640,000 of your rectangles are covered by a boat. 1 by a container. And 34,847,359,999 are uncovered. If we assume your odds of hitting a container happen every time you move into a new rectangle, that you can never hit another boat, and that another boat can not be in the same rectangle as a container then you have a 1 in 34,847,360,000 chance that your next rectangle move will result in a collision. A collision for a ship is probably low risk. But for a yacht travelling at 6kts is serious. 6kts means covering 36456feet per hour. So you transition through 911 rectangles per hour (assuming you move along the long length of the rectangle). So any any hour of sailing you have a 911 in 34,847,360,000 chance of hitting a container. so 1 in 38 million chance per hour of sailing. If we estimate the average boat sails say 8 hours on Sat and 8 hrs on Sunday, 2 weekends a month, for 6 months of the year (192 hrs a year), and the average sailor sails for 40 years. So ~ 8000 hours in a life time. I *think* that gets you to a 1 in 5000 chance that you enter the same "rectangle" as a container in your lifetime if you kept sailing in that some 400,000 square miles and the container never sank or was replaced by another.

I realise thats all rather arbitrary and there is a lot of guess work in there, and it has been a while since I did any probability maths so I may have it wrong too. There will likely be other factors at play:

- are more lost in oceans than coastal?
- are more lost in winter?
- how many are lost attached to hulls that are lost vs how many are loose containers?
- tide dynamics - you tend to sail with currents if you can - the box will move with currents too...
- if a ship hits it - does it the sink?
- a container is >8ft tall. if you sail in 'shallow' waters it would likely get stuck on something at some point.

Interesting and quite involved maths there...
My thumb in the wind calculation was to consider the area swept by a boats in a day. That way all you need is distance travelled times width (averages of course).
On the big side theres a Batillus class supertanker they can cover about 17 square miles a day. Chance of hitting a box 1:23,500
On the titchy side you might have 20' day sailer doing 5kts for 8 hours which would do just 0.06 square miles. chance: 1:6,600,000

But the chance of any collisions = 1 - chance of no collisions
if an average boat is 100' beam and does 8kts all day
chance for an average boat (yeah no considerations of distribution of vessel size at all ) = 1:80,000 ish
so....
chance of not hitting a box = 1 - 1/80,000
chance of every boat not hitting a box = (1-1/80,000)^160,000
chance of at least one boat hitting a box per day = 1-(1-80,000)^160,000 = 0.86
odds like that are worth a punt with real money.

 

[RolyGate]

Thank you.

 

[RolyGate]

Man, the reply system on this board is, um, hard to get right. Must change my view to Threaded, or something.

Here's a YBW article:
https://www.yachtingworld.com/news/...the-danger-to-sailors-real-or-imagined-107508

Some interesting stuff in there:
1. The leading expert on this topic says it is impossible for lost boxes to float below the surface, and that they must always project above the surface, or sink.

Since there are numerous reports in this thread of boxes floating just below the surface, I think it fair to say that 'expert opinion' on this topic is not reliable.

2. In one study, 20% of boxes were overweight. More than 50% were loaded incorrectly, in the wrong place.

Looks like there are some inconsistencies between the theory and reality, here. But nobody cares, anyway - certainly not the trade. The box ship crew in my sailing club confirm that there are never enough clips and chains for the load, and nobody cares.

 

[Wansworth]

Loads of veggie oil plastic bottles turning up on Galician coast these days,the container must have opened

 

[Daydream believer]

Not sure I concur with your maths...

So if there is 1 40ft container in 400,000 square miles that means there is a rectangle 40ft x 8ft in the 400,000 sq.mi.

400,000 square miles is equivalent to a rectangle 1 mile wide and 400,000 miles long.

Thats 400,000 x 5280 = 2112 million feet long and 5280 feet wide.

If you were to cover that width with a grid 8 feet wide you can fit 660 x 8 foot wide rectangles into that width and nearly 53 million 40 foot long rectangles into the distance. a 400k sq.mi area covered in a grid 40ft x 8ft would have 34848 million 40 x 8ft rectangles. Your container in theory occupies just one of those.

Your 160,000 vessels of unknown size in that 400,000 sq.mi area at any one time. Some will be bigger than one 40 x 8ft rectangle. Others will be smaller. I don't know what the average is but lets say 80ft x 16ft (so 4 rectangles) would be average. So 640,000 of your rectangles are covered by a boat. 1 by a container. And 34,847,359,999 are uncovered. If we assume your odds of hitting a container happen every time you move into a new rectangle, that you can never hit another boat, and that another boat can not be in the same rectangle as a container then you have a 1 in 34,847,360,000 chance that your next rectangle move will result in a collision. A collision for a ship is probably low risk. But for a yacht travelling at 6kts is serious. 6kts means covering 36456feet per hour. So you transition through 911 rectangles per hour (assuming you move along the long length of the rectangle). So any any hour of sailing you have a 911 in 34,847,360,000 chance of hitting a container. so 1 in 38 million chance per hour of sailing. If we estimate the average boat sails say 8 hours on Sat and 8 hrs on Sunday, 2 weekends a month, for 6 months of the year (192 hrs a year), and the average sailor sails for 40 years. So ~ 8000 hours in a life time. I *think* that gets you to a 1 in 5000 chance that you enter the same "rectangle" as a container in your lifetime if you kept sailing in that some 400,000 square miles and the container never sank or was replaced by another.

I realise thats all rather arbitrary and there is a lot of guess work in there, and it has been a while since I did any probability maths so I may have it wrong too. There will likely be other factors at play:

- are more lost in oceans than coastal?
- are more lost in winter?
- how many are lost attached to hulls that are lost vs how many are loose containers?
- tide dynamics - you tend to sail with currents if you can - the box will move with currents too...
- if a ship hits it - does it the sink?
- a container is >8ft tall. if you sail in 'shallow' waters it would likely get stuck on something at some point.

If I have read that correctly you have worked out how many rectangles a yacht will cover in a certain time.
However, i do not think that you have calculated how many rectangles the container will have covered in the same time whilst traveling in a 1 knot tide.( pretty average for the world, if you apply wind as well, I would have thought)

So if your calcs were based on a yacht doing 6 knots you have to divide that by another 6 for the container doing 1 kt because the container is covering a greater area per hour than just one rectangle ( think of the old pac man game & how hard it is to get past them)
So the chances are 6 times less than you have stated- the container is whizzing about within the danger area whilst the yacht is sailing towards it.

Alternatively, as the yacht moves so the container moves so the figures have to be re calculated for every rectangle occupied by each, so it may be argued that in fact the chances actually are 36(or whatever) times less than you have suggested.Simply because the container is 6(or whatever) times more likely to have moved out of the way . The fig 6 based on the yacht going 6 times faster than the container

Another issue with the calculation.
If the yacht hits the container, the rectangle could well become an bigger rectangle, as it can be hit on either end of the container & on either the port or starboard side of the yacht, depending on what action the helmsman takes.Ie adding the beam of the boat to each end of the container
If that is the case then should the rectangles all be taken as 70ft ones not 40 ft ones- for a 15 ft beam boat -because that is the danger area?

Really interesting subject that you have raised & I would love a statistician to comment
(Our college lecturer used to say that there were - lies, damned lies & statistics!!)

 

[Lon nan Gruagach]

If I have read that correctly you have worked out how many rectangles a yacht will cover in a certain time.
However, i do not think that you have calculated how many rectangles the container will have covered in the same time whilst traveling in a 1 knot tide.( pretty average for the world, if you apply wind as well, I would have thought)

So if your calcs were based on a yacht doing 6 knots you have to divide that by another 6 for the container doing 1 kt because the container is covering a greater area per hour than just one rectangle ( think of the old pac man game & how hard it is to get past them)
So the chances are 6 times less than you have stated- the container is whizzing about within the danger area whilst the yacht is sailing towards it.

Alternatively, as the yacht moves so the container moves so the figures have to be re calculated for every rectangle occupied by each, so it may be argued that in fact the chances actually are 36(or whatever) times less than you have suggested.Simply because the container is 6(or whatever) times more likely to have moved out of the way . The fig 6 based on the yacht going 6 times faster than the container

Another issue with the calculation.
If the yacht hits the container, the rectangle could well become an bigger rectangle, as it can be hit on either end of the container & on either the port or starboard side of the yacht, depending on what action the helmsman takes.Ie adding the beam of the boat to each end of the container
If that is the case then should the rectangles all be taken as 70ft ones not 40 ft ones- for a 15 ft beam boat -because that is the danger area?

Really interesting subject that you have raised & I would love a statistician to comment
(Our college lecturer used to say that there were - lies, damned lies & statistics!!)

The chance of a container moving out of the way is pretty much identical to the chance of one moving into the way. Thinking more of relative speed and location will help un-twist your melon on that bit

 

[webcraft]

http://znoy8.co.uk/photos/tank.html

- W

 

[Mister E]

Mr Swain does not claim to have hit one yet.
So the chances of hitting one must be very low. After all he claims to have hit just about everything else??

 

[Kukri]

Man, the reply system on this board is, um, hard to get right. Must change my view to Threaded, or something.

Here's a YBW article:
https://www.yachtingworld.com/news/...the-danger-to-sailors-real-or-imagined-107508

Some interesting stuff in there:
1. The leading expert on this topic says it is impossible for lost boxes to float below the surface, and that they must always project above the surface, or sink.

Since there are numerous reports in this thread of boxes floating just below the surface, I think it fair to say that 'expert opinion' on this topic is not reliable.

2. In one study, 20% of boxes were overweight. More than 50% were loaded incorrectly, in the wrong place.

Looks like there are some inconsistencies between the theory and reality, here. But nobody cares, anyway - certainly not the trade. The box ship crew in my sailing club confirm that there are never enough clips and chains for the load, and nobody cares.

“”Clips” and “chains”?

I have no idea who you have been talking to, but certainly not container ship crew.