Hacker News Reader

Comment by nickhalfasleep | Hacker News Reader

I wonder if a series of small robotic tugboats could take turns hauling a container ship across oceans. As their battery wears down, another swaps in place. They could recharge at nearby fixed solar/wind floating platforms, or undersea cable recharge points.

View on HN

I think you underestimate the distances involved. It'll be impossible to maintain the infrastructure. How are you going to get these people there? Additionally, You will need an enormous number of tugs. It's' not like there are clearly marked highways or anything. The area to be covered is going to be huge. What are they going to do in bad weather? Then, who is going to coordinate all of this? How do the tugs know where to go and when? If the weather is bad and there is no fresh tug available the ship will go down. Let's not even talk about how inefficient and slow this will be.

The forces of nature these ships work against are nothing to sneeze at. This stuff is not at all trivial.

The idea is clever because it does not require retrofitting the existing fleet, and it works because it can be done incrementally.

You can for example start with 1 tug boat that would shave off 200km of fuel usage.

No, it's not "clever." It's ridiculously uninformed. Tugboats are far less efficient than the ship running under its own power to start with. Add to that you now have a fleet of tugboats and their associated crews (robotic tugboats are nice in concept; not so great as a reality in 2022) sitting idle/travelling to meet a ship/recharging/etc. And more vehicles that require ongoing maintenance whether or not they're in use.

A clever idea would be supported by data that shows how it can be effective. This is just an off the cuff suggestion by someone who's thought about the problem for 30 seconds.

As a generality, towing a substantial ship - even in light seas - is a far more problematic and labor-intensive task than having it run under its own power. Also slower and less energy-efficient.

Like others have said, tugging seems to be highly impractical. If you'd really, really, really want to try anyways, you might perhaps habe an easier time with electric ships that are fully capable of going alone, just without enough battery for the whole way. And that can be take-extended on the go by a relay of battery boats supplying electric power via cable instead of some very high number of Newtons (battery boats would only carry enough engine to self-supply). But close formation in heavy weather would still be so hard that it might in fact be easier to "simply" make them all submarines... (yellow, presumably)

But we shouldn't start juggling around absurd amounts of batteries as long as we don't even utilize low hanging fruit like equipping all those cargo haulers with mighty propulsion kites. That's basically a solved problem, just not happening because the refinery waste ships are conveniently incinerating is still too cheap. Particularly as long as we still burning fossils for electricity on land. Ship engines operate much to optimal load than ICE car engines designed for a market that demands excessive peak power for short bursts of acceleration. The carbon break-even point for ships would require much cleaner electricity than that for cars. Cars are an absolute outlier because their cruise load is so much lower than their advertised power and ICE engines are almost comically inefficient at low load fractions.

That would be a recipe for disaster. Towing sucks in any kind of heavy sea state, and swapping tow cables from one vessel to another is even worse.

For river shipping it might work, there tugs are commonly used and rivers have power close the entire distance. You need the ability to swap tugs, more often, but that isn't hard to build.

I wonder if you could skip the batteries and just put in overhead catenary like trains have. Tugs mostly have to follow the same paths anyway.

Tugs may follow broadly the same paths, but there's a big difference between along same channel, adjusting for wind and current differences and running on rails. An overhead catenary system suspended over a river sounds like it'd be a nightmare to build and maintain anyway.

for river shipping it would be better to have a train like traction system. It could be only placed on the one side of the river when you go upstream. Batteries would do the job for docking and going downstream. Similar to https://www.electronicdesign.com/markets/automotive/article/...

There's a reason this (tow-path boats) fell out of fashion 100+ years ago.

A bit like stage coaches swapping horses at each inn along the way.

I don’t think tugs though can operate in anything above fairly calm waters.

Reply on news.ycombinator.com