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Comment by dten | Hacker News Reader

I found out yesterday that the port of LA has a free real-time dashboard (https://tower.portoptimizer.com/) so you can check the stats yourself. While it's interesting that next (week 19) shows a 35% drop YoY, the following week predicts a 25% increase from w19 and "only" 8.7% drop YoY.

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I think its: https://volumes.portoptimizer.com/ ?

That number for w20 will probably change. For example, when https://youtu.be/2GgcIuQ4X5k?t=324 was produced w20 was predicted to be up 0.84% YoY.

This site is obviously a "hostile and political act" by the Port of LA.

Turns out reality itself is a hostile and political concept if your political leadership is incompetent enough.

That's why there's such a strong push towards "alternative facts"

"Reality has a well-known liberal bias" - Stephen Colbert

Could it be similar to weather forecasts where the further out the forecast goes the more it relies on seasonal averages?

I think two weeks is pretty much the low end of transit time for a container from China to US, so I wouldn't expect needing much modeling within that window.

Ships can be rerouted while in transit. I bet it is extremely unusual for a container ship, but we do live in interesting times.

Cruising speed can also be modulated, easily within some ranges. You might speed up a little if you think you can land cargo before new tariffs, and you may slow if you think tariffs may be reduced if you land later. Staff costs for the vessel are relatively small, so as long as you don't go outside the range of speeds that are fuel efficient, there's flexibility.

Some of the tariff increases are so high that they effectively spoil the cargo; there's no point in bringing it through customs at those prices, and it typically won't make sense to ship it back, and it may not be possible to ship it elsewhere from the port either, so it is most likely to be destroyed at the port. Delaying to see if tariffs go down may be worthwhile for enough of the cargo that it makes sense to slow the whole boat.

Additionally, if demand for shipping is up, going faster allows for more supply, and if demand has slowed, going slower reduces supply.

The tariffs are based on departure not arrival date.

Do you have a source for this? Because from my own experience, and from everything I can find online, this is not true.

Tariffs are based on date of entry: https://www.vedderprice.com/remember-basic-import-rules-when... (see 'Rule 2')

That's easy enough to fake. How is US customs going to know when a German company's ship registered in the Philippines left a Chinese port?

I've very briefly worked with a team that was responsible for satellites that track ships and their AIS data, including trying to identify ships spoofing AIS though various means. (It was civilian, a university group, but I'm sure states have similar and more)

There is a pretty huge amount of ship and satellite tracking these days

Presumably by asking the Chinese authorities directly? We have near instantaneous global communication these days - that's how I'm conversing with you right now.

There's also AIS

https://www.marinetraffic.com/en/ais/home/

Of course enabled by the very tech you mention.

You’d just lie about which ship it was on.

While it's still in the shipping container with a GPS tracker on it?

It happens all the time but it’s more useful to think in terms of container flows getting rerouted. Container ships sail in fixed loops so have containers on board for multiple ports. It often happens that the order in which the ports are called (the rotation) is changed, or a particular port gets skipped all together. Reasons can be congestion, delays in previous ports, etc. etc. The line can choose to transship the cargo, so pick it up with a second ship to carry it to destination, have the customer pick it up in the new location (possibly with a rebate) or truck/rail it to the final destination themselves.

There was an interview with a shipping manager somewhere (probably the 3-hour documentary by Gamers Nexus?). They said absolutely have been rerouting container ships in transit.

But these ships are carrying containers for many different companies, right?

If some companies want the goods now and other companies need to hold off, how does that work?

Just whoever's shipping the most goods wins?

Most container ships aren’t enormous behemoths

The more reasonable sized ones and the specialized ones (especially the car ones) often service a single buyer at a time

Container ships did get rerouted when that ship got stuck in the Suez Canal.

But that’s “same port, different route” rerouting right? Here you would have to have “different port” rerouting (or some really weird weather making the Pacific intransitable”

Yeah I was wondering if those models try to smooth those bumps.

Week 9->10 2025 had a 35% drop too. And Week 9->10 2024 had a 45% drop and a 26% drop Week 16->17 2024.

Starting to wonder how significant this news really is?

That is Chinese New Year, it has always a very large drop. It's very impactful but expected and yearly.

My companies reporting needs to correct for it since the date shifts on western calendar and if would mess up all reporting otherwise, so yes, this is extremely significant.

Thank you for the details. I've no doubt that tariffs are having impacts. Was looking at that specific data and finding it hard to conclude with just that data. Does CNY also explain the Week 16->17 drop in 2024?

Chinese New Year falls between 21 January and 20 February. This would be somewhere between week 3 and week 8.

Some ISO 8601 week numbers for CNY:

2022 CNY fell on Feb 1 , which is Week 5

2023 CNY fell on Jan 22, which is Week 3

2024 CNY fell on Feb 10, which is Week 6

2025 CNY fell on Jan 29, which is Week 5

It’s sad that these posts of relevant facts - that are only presented as such, with no judgement - are being downvoted, apparently because they don’t supportive a narrative. One of the things I’ve always loved about Hacker News was how the community was so curious about truth. I guess all good things come to an end at some point.

I would love to have conversations with folks about the details and learn more about it. The CNY mention was helpful.

There's probably an effect of people who tried as hard as they could to get their goods loaded under the wire before the tariffs took effect, and so the following week would be less, but the following week would be closer to normal.

Predictions are based on historical data which isn’t relevant in this case.

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