Countries could have bilateral agreements on timing departure and arrival and from this calculating the average cruising speed (all other conditions taken into account, of course).
Now, there are still ways to cheat that, but my gut feeling is that cheating would be more expensive than just following the agreement.
It's hard to visualize, but a ship's engine speed is only one factor in its overall speed across an ocean, even with powerful engines, wind and especially current will improve or degrade a ship's overall speed as measured by satellite. So a naive port fee based on time of departure will not exactly work.
It's a roughly accurate measure though. If there's a storm that slows them down, it would be perfectly acceptable for them to burn more fuel to arrive in port on time.
I think you are wrong about this, there are so many variables and sea conditions can affect things, for example older engines and maintenance at sea. AIS data is also known to be wildly inaccurate.
Source: built an engine performance model at a maritime company.
Too easy to fake. Maybe instead base it off of fuel consumption. At the end of the day, they can't fake a full tank of gas -- Require it to be documented when they buy fuel and use that to approximate what they're using for a cross-seas voyage (giving appropriate margin so that in case of storm/emergency they can still make it, but perhaps tax them if they eat into buffer)
Actually laughing at this, you have no idea, the people onboard type in the engine data and usually they type the exact same thing as the last reading with some decimal points changed and 0 if they were stopped (even though ships use plenty of fuel even if stopped usually).
It's the ships speed relative to the water what causes any fuel consumption. For the purposes of saving fuel, if you don't know the water surface speed, you know nothing.
Precisely! You could be going slowly against the tide or current or weather and using loads more fuel - you ask anyone who has been at sea about weather and localised conditions that don't show up on satellites are common enough for me to believe the on ship reports.
Nearly all ships are registered to a country. By registering with a country you agree that the laws of that country apply. Those laws can include anything they country wants - including speed limits enforced by whatever means. In return the Navy of that country (and applied Navies of other countries) will help defend you from pirates and other military action.
There is such as thing as unregistered ships. They are called almost always pirates up to no good: most navys will sink them on sight. Most ports will not allow an unregistered ship.
The Paris MOU and Port State Inspection changed the status quo here forever.
If an Open Registry (the technical name for a "Flag of Convenience") doesn't enforce rules the Port States (mostly economically important countries with a coastline) care about that flag essentially labels you as likely non-compliant - and whether you are or not it's a world of pain because those Port States care.
So most of the famous Flags of Convenience cleaned their acts up. It just made too much financial sense.
You can try mumbling about how Port State Control isn't fair, but the people who think it is have guns and money and you don't. In this case (and many previously) this works in our favour.
Panama at least has close ties to the US. If they want to enforce laws they can call the US and get a large fleet to help. Panama also has the canal which is important to global shipping: if they want to they can refuse ships passage if they don't comply with whatever rules they want.
Of course the IF above is big. I don't know how to get Panama to care.
You place a fine if the ship arrives too soon at the destination. There are still ways to cheat the system, e.g. make an undocumented stop, but compliance should be the easiest way. Of course it would also increase the cost of shipping as you either need more ships to reach the same tonnes of goods per year and/or pay the captains more since they are at sea for longer.
Enforcement at destination countries is far too simplistic to assume. There are too many countries who just won't care, for example Somalia, Haiti, many in S.E. Asia, and many others where a bribe will suffice.
Then there are a lot of question marks regarding the jurisdiction of a destination country when the ship is flagged elsewhere. How or who enforces the penalty on this ship? And if such a penalty is applied, the ship owners simply change name and move to a different country's flag.
This is exactly the same problem with illegal fishing. Perpetrators are getting away with it because effective policing is not happening.
I agree. For example, it would also allow ships to make up time lost to rough weather by ignoring the speed limits later in the passage (which is probably not good for the environment).
I also don't know that a blanket speed limit makes sense for all ships. The longer the waterline length of a ship (for a given weight) the easier it is for it to make a given speed.
I feel like a better metric could be used, like fining vessels for trips which consume more than X tonnes of fuel for a ton of cargo where X is designed to be met only by building highly efficient ships or by existing ships operating at reduced speed.
The countries that care about regulations are typically also those who import and export most stuff. Once you're in a port you're subject to the local laws, so imposing a fine should be no legal hassle.
Only if it's convenient. Docking time slots are limited, fleeting, and expensive. If there's an open spot, and a ship ready to unload, it's going to get unloaded.
Reading Ian Urbina's Outlaw Ocean[1] was an eye opener regarding what activities happen in effectively un-policed international waters.
[1] https://www.theguardian.com/books/2019/oct/02/the-outlaw-oce...