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Comment by WJW | Hacker News Reader

Interestingly ships get cut in half and reassembled "all the time". Certainly way more than people think.

See for example https://www.maritime-executive.com/article/photos-fincantier..., where an entire cruise ship was cut in half and an extra section was inserted into the middle before welding everything together again. I will also never forget the training ship of the Dutch Navy, which was shortened by cutting it into half and removing a section from the middle. Sadly this messed up the hydrodynamics fiercely and it was extremely seasickness inducing in even moderate seas. The ship certainly was effective as a training vessel though.

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The front 1/3rd of the Maersk Honam was burnt beyond repair in a fire in 2018. That included the bridge and accommodation block. They cut it off, took the rest of it back to the shipyard on a heavy lift ship, and built a new front...

https://en.wikipedia.org/wiki/Maersk_Honam

on fire: https://www.google.com/search?q=maersk+honam+fire&client=ubu...

here's some photos of it on the heavy lift ship: https://www.google.com/search?q=maersk+honam+heavy+lift&clie...

you could say the front fell off? https://www.youtube.com/watch?v=3m5qxZm_JqM

that's what happens when you make it from cardboard derivatives

I'm sure we can move the wreckage and other waste outside the environment.

I can't help but feel God playing jokes when you see a fire in the middle of an ocean

I had an old Datsun 180B that caught on fire in the pouring rain once, and I felt this way

That cruise ship example is wild. To do all that work (450,000 man hours) to just add 50 feet to the length of the ship... a 12% increase in passenger capacity. Obviously it must be cost effective but on face value it looks crazy.

My dad used to work for a ship servicing & repair shop ("Humber Ship Repairers"), now defunct. I remember them doing this to a Sally Line ferry. It was fascinating seeing the progress when we occasionally drove past the dry dock. Very little for a while as things were cut through internally, then suddenly one trip the thing was in two halves and the new middle was being put in place.

It does seem crazy. This bit in the article claims that a retrofit would be faster than building entirely new ships.

> The lengthening is a novel approach to adding vessel capacity as shipyard availability shrinks. With demand soaring, many cruise shipbuilders are booked into the early 2020s, and expedition/luxury lines are increasingly ordering newbuilds at yards that used to specialize in offshore vessels or yachts.

It seems crazy to think there is demand for new cruise ships, now.

The article quoted is from 2018

back of envelope:

450k man hours = 225 people full time, 1 year @ ~ 70k a year = 15m

They added 34 more suites * 2 people * $1000 per person per cruise week = 78000 more per trip

~200 trips to pay back the cost - not sure what the utilization of cruise ships is usually, but if they do 40 packed cruises a year, they're at a ~5 year ROI.

I guess I forgot the cost of the new section itself, but I'm going to guess all in, < 10 years ROI?

Don't forget the opportunity cost of the ship being out of commission during that work.

Though it is quite possible the ship was due for refit anyway.

They key thing here would be to factor in all of the costs for a new ship e.g.

- Design time

- building time

- "fit and finish" time etc

- cost for all of the above

It's very possible the cost (or even ROI) would be larger(longer) than your calculations.

I think it was more of they were already going to refurbish the ship. I doubt extending a brand new ship would make any sense.

if you have more passengers, you will also have more cost to service these passengers per trip.

The ship is a luxury cruise liner: the article, somewhere close to the bottom, says "Pricing for the 7-day cruise starts at $5,600 per person"

that 'starts" in the last part is kinda-important ... I took a look and they have 1 week cruises for $22,000

So, its really more like

34 more suites * 2 people * $5600 per person per cruise week = $380,000 more per trip at the low end

34 more suites * 2 people * $22000 per person per cruise week which is just over $1.4M more per trip at the high end

Assuming $15M from the 450k man-hours and $23M in materials for the retro-fit, (seriously over-estimating materials because I want the nice easy math that goes with a $38M total), it would be:

- 100 cruise-weeks or about 2 years to re-coup at the low end

- ~30 cruises (not cruise weeks, literally cruises ) to re-coup at the high end

Yeah, it’s surprisingly common. For years when getting the a CalMac ferry from Oban in Scotland you could spot that the MV Isle of Mull had been extended because they had to repaint the ship’s name. That was done to fix stability as all the steel was right at the thickest end of the specified tolerance resulting in the ship being heavier than intended.

I think the "surprising" or unintuitive part for me is that I wouldn't have thought that a join could be sufficiently strong.

However, in another thread recently, it was mentioned that large ships can't support their own weight without water anyway, so I guess that the strength needed is mainly just in tension?

> With demand soaring, many cruise shipbuilders are booked into the early 2020s...

That didn't work out so well for them.

Cruise lines seem to have survived just fine and are starting operations back up (for vaccinated passengers). And if you believe that all publicity is good publicity they should have no problems filling those ships

This is turning out to be an interesting business model - there are obviously the "pay us and we keep your money, but keep offering you future cruises till the pandemic is over"

Additionally they are now offering "single country cruises" - start in one country, sail from port to port in same country - which radically simplified the vaccination

It'd be nice if the US would ditch it's statutes from the late 19th century that make it illegal for foreign-flagged vessels from taking passengers from one US port to another.

This is why, for example, almost all Alaskan cruises sail from Vancouver.

Without those rules, what is to stop foreign vessels from replacing domestic passenger ships? The Staten Island ferry might just adopt a foreign flag and staff the ships according to foreign (ie cheap) labor laws.

What could be more American than that?

What domestic passenger ships?

There's a handful of cruise ships that are US flagged specifically for the Hawaii route. That's it.

If you're concerned about car ferries, you can make specific laws about them. Or better yet, New York state could, since that's in their jurisdiction.

It's a bit of a few different thigns. There are tons of ferries across the US and getting rid of that rule would require either rewriting the law to maintain the change for them or for every state along the coasts to do their own regulating. Then there's a desire to maintain some domestic shipping and ship building industry from a national security standpoint and from the goal of protecting the environment immediately around the US.

> Then there's a desire to maintain some domestic shipping and ship building industry from a national security standpoint and from the goal of protecting the environment immediately around the US.

This is the original purpose of the law, but it has failed completely and utterly. At some point you have to stand back and survey what the actual results of legislation are, as opposed to the intended results, and if those two aren't in any way congruent, scrap things and start over.

It only 'really failed' Puerto Rico.

Airlines have similar rules, yet I never see people grousing that you can't take an Air Malay flight from Chicago to LA.

The domestic ship building industry imploded. America is an economic empire built on maritime shipping with only one remaining commercial shipyard capable of producing large vessels, and it is being kept alive with government contracts.

That has everything to do with lower cost of labour overseas.

Without the requirement for US ships to go from one US port to another, the shipbuilding industry would still be dead, and you'd have a dead shipping industry with it. You would have foreign-flagged crews moving cargo with foreign-built ships, against which you'd have zero recourse, in the event of disaster.

A better law that more precisely addresses the various situations instead of depending on the verbiage chosen by the long dead.

>> verbiage chosen by the long dead.

Look at the average age of the people writing laws. I'd say that 90% or more of current law was created by people now "long dead".

Where would those foreign workers live? In the ship?

Yes. That is exactly how such things are done.

Hmm, I didn't think it was legal for foreign nationals to live (be resident) just offshore like that..

Such as all of those manning the cruise ships sailing out of US ports? Every large ship sitting in s US harbor has forgien workers living aboard.

I would have assumed cruise-ship workers would come on land for long port stays. And that larger cargo vessels wouldn't stay long. How long can you stay in one place before it counts as residency?

Syrian sailor stranded on abandoned cargo ship off Egyptian coast - BBC News Apr. 6, 2021

https://www.youtube.com/watch?v=OyU6NtwspLM

The Egyptians have told him he cannot leave the ship. He has been stuck as its "master" for over a year. These things happen in the world of international shipping. Human rights tend to disappear.

But wait, this isn't a standard thing - the cargo vessel wasn't intended to stay long?

The problem isn't so much the flag requirements as the other ones- especially the requirement that the ship must be built in the US.

The cruise line business is very cyclical so the companies hold really big piles of cash for when things get slow (like 2007-2008 financial crisis)

All the big companies had a couple billions each sitting around just for shit like this. They just fired most of the crew (they still need to have 100+ crew per ship to keep them in good condition) and anchored them waiting for better days.

With this reduction in costs they could easily wait out a year or two for business to come back.

Wendover Productions did an excellent video on the topic https://youtu.be/N4dOCfWlgBw

(including how they solved getting their tens of thousands of employees back home when planes were not flying really)

The USS George Washington was originally going to be an attack submarine, but instead they decided to lengthen it by 130 feet & make it a ballistic missile sub. [1]

[1] https://en.wikipedia.org/wiki/USS_George_Washington_(SSBN-59...

SSBN-626 and -635 were both ballistic missile submarines that were converted into training ships by going the other way and ripping out the missile compartment.

That's cool. I hadn't heard that before. Thanks for sharing.

Those changes were made without any actual cutting though: the decision was made early enough in the process that there was nothing to cut apart. They just put some different pieces together than originally planned.

Source: personal conversation with Dr. Gary Weir, US Naval History and Heritage Command.

Ford lengthened 50s-era freight ships used for hauling raw materials in the Ford River Rouge Complex an additional 120-feet in the 70s for increased capacity. [0]

Someone uploaded a TV special centered on the SS Byron D. Benson and its captain, in which he speaks to the lengthening and how it affected the ship. [1]

[0] https://en.wikipedia.org/wiki/SS_William_Clay_Ford

[1] https://www.youtube.com/watch?v=cFiF5LUsi1A

That cruise ship is a great example of a well designed extensible modular monolith.

They spent 450,000 man hours to extend the ship from 195m to 210m long. That is a 7% increase in length. That seems like a lot of work for a tiny bit of gain.

They will spend a lot more man-hours than that, since the 450.000 hours only included welding the ship back together. The article also mentioned that the operation represents about a 12% increase in passenger capacity, since it's mostly cabins and amenities rather than non-money generating stuff like engines or anchors. According to wikipedia passenger capacity went from 540 to 608 passengers.

So let's do the math: The article states that "Pricing for the 7-day cruise starts at $5,600 per person." Presumably some passengers will pay more, let's assume an average of 6k/passenger/week. Assuming 45 sailings weeks per year (the rest being relocations and maintenance periods), the 68 extra passengers will bring in slightly over 18 million USD per year in extra revenue. Wages in Italy are not that high, so even assuming all workers are welders making the maximum from http://www.salaryexplorer.com/salary-survey.php?loc=105&loct..., it would only be about 20 EUR/hour. That makes the price of the 450k manhours "only" 9m EUR, so it seems likely they'll make back the total price of the expansion quite quickly.

I've no particular knowledge in this case but presumably they would undertake such work at a time when the ship was due or nearly due a refit.

Your analysis doesn't include the engineering to make this possible, the materials and labor to create the new section, the fees associated with using the dry dock, the lost revenue while the ship was out of service...

I find it hard to believe they will make it back quickly.

Yes, I made a few shortcuts. But is it really so hard to believe that the shipping company made a much more detailed analysis beforehand and decided it was worth it? It's not like you just YOLO a cruise ship into drydock and find out it's too expensive halfway through the project.

(Insert joke about software engineering budget bloat here)

In software the losses would not matter, Softbank would be happy to throw more money into the bonfire

Is the volume increase what really counts.

And the fact that it is pure payload as well as two restaurants. 100% of the ship's length is much more than the payload area.

What strikes me about your comment is that you think that a cruise ship company and their army of consultants and engineers would not have done the required calculations to figure out that they would make substantial profit on this over the long term.

I didn't say that. I thought it was interesting enough to mention. My assumption before reading the link was that it would have been a much more substantial change.

It makes me wonder if the fixed cost of the operation was relatively small, or if there was an outside constraint that meant further lengthening was not possible or profitable.

The fixed cost is 10's of millions, but the big thing to focus on is that 7% of the length of the ship is a much larger fraction of payload and that there are also two more restaurants included.

I'd feel a lot more comfortable in a ship that's been cut apart and welded back together than I would in a submarine.

Is there some kind of standard sizing that makes this kind of thing possible?

They'll have the blueprints and the actual ship to measure and confirm against. I'd imagine most of these are heavily custom jobs.

Depends on the project; for the cruise ship it's a newly built section built specifically for that ship and the submarines they were both the same design so as long as you cut in the same place on both ships they should fit together plus or minus 2x the tolerances it was originally built with.

Note that ships in the same class are rarely actually identical. There was also quite a bit of time since they were both built, and the later vessel no doubt incorporated changes / improvements on the design.

And then you get into the really fun stuff, where what's on the plans, and what actually got built are usually at least a little different... and maybe the as-built documentation was not finished correctly either.

They also sag. A half of a ship isn't as rigid as an entire ship. It changes shape in all sorts of unpredictable ways. There is lots of lifting and pulling before the two hulls line up well enough to start welding them together.

In a dry dock though they’ll be better supported so the differential sagging will be much smaller. It’s how they were originally built as well.

The overall structure should be basically the same though and any changes should be documented on a government contract like this so future maintenance and upgrades can be planned and built by any contractors.

Steel ships are often built in prefabricated sections, either from front to back or bottom to top, which are then welded and bolted together.

https://en.wikipedia.org/wiki/Shipbuilding#/media/File:HMS_D...

https://en.wikipedia.org/wiki/Shipbuilding#Modern_shipbuildi...

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