farmerben

On the Mississippi river the towboats do not stop to refuel. Tender boats come out and refuel them with diesel in motion. I wonder to what degree you could do the same thing on batteries? The big towboats use about 10,000 kW of power.

Given that weight is a big issue and the square cube law. This could be a partial solution for ships.

What is the difference between crushed glass and sand? Can you use them interchangeably in concrete? If you were to spread crushed glass on the environment, would that be worse than spreading sand?

Another idea. What about using wood? Very little wood is "wasted" at saw mills, but more of it goes into fuel than engineered products. The engineered wood products require process heat after all. Anyway when you saw lumber anywhere from 25-50% of it ends up as wood chips and they will oxidize eventually one way or another.

Do staircases work in Martian or Lunar gravity? So do you want much larger steps to leap up to, or are staircases governed by the flexibility of the average person and need to be the same size?

i made it to lvl 8. not easy

Don't waste my time on another LEO station if it doesn't have a centrifuge.

It looks like they had plenty of extra fuel, albeit the mission was unloaded.

The top fins on starship took reentry damage. Good thing they are steel.

Competitors should be designing payloads right now. Think about how cheap the next Mars rovers will be. It's time to go find some lava tubes.

I guess it would be bad to sweep dust out an airlock, future collision hazard and all that.

Given the shortage on nuclear development on land, I see no reason to prioritize it on the water. Everything on boats break much more often due to the constant wave motion. Actually dirty maritime fuels reduce global warming due to the aerosol effect. https://www.livescience.com/planet-earth/climate-change/cutting-pollution-from-the-shipping-industry-accidentally-increased-global-warming-study-suggests

The chances of a nuclear accident are too high for this sort of thing. Meanwhile an electrical propulsion system that takes up less volume than an ICE is not necessarily better. What matters is the weight and the amount of extra water displaced. The engine rooms on conventional ships are huge and mostly empty space. Shipping containers are typically loaded to 25 tones or less. On US roads that is about the maximum weight without special permits. That's about half full with lithium batteries. Cargo ships also like to load the heaviest containers at the bottom and empties on top.

I'm not sure what tools. I've picked up tidbits like they used sharkskin for sandpaper. The red boats above I think are modern replicas of boats that were built in the late 17 or early 1800s. Even if you assume metal axes and metal chisels, it's still pretty impressive. For that matter the totem poles of the pacific northwest are impressive carvings if you wanted to make one without metal tools. One source I read said Europeans used to lash hull planks together with leather until the Vikings invented the technology of nailing planks to the hull. The Romans appear to have used mortise and tenon (peg or biscuit) joinery to bond planks edge to edge. Anyhow that is an astonishing number of skilled man hours that go into building a ship, akin to building a temple. The Viking clinker method sped things up considerably. Metal axes and knives were the first things traded by early Spanish explorers. One preferred method for introducing yourself was to hang a tomahawk in a tree some distance from a village. The next time you return sit still under that tree with a blanket full of trade goods. Indigenous cultures almost universally understood and wanted to trade.

Back to modern times, the material most suitable for building multihulls today is aluminum. Your other choices are carbon fiber, steel, fiberglass, wood, etc. Aluminum alloy is much cheaper than carbon and much more corrosion resistant than steel. What we need is robots who perform the function of the English wheel, weld, and so on.

Polynesians did piece together their hulls sometimes with intricate joinery to bond the bow and sterns, and side planks to raise the freeboard. They were lashed together and the seams were stuffed with breadfruit tree bark, which seems to have been good watertight caulking. Dovetail joinery and wooden pegs they knew of also. Some of the master woodworking was a closely guarded secret held by certain lineages.

Lots of chemistry in this video about separating alloys from lunar dust.

The Scottish guy is dependent on shore power just not every day. If I were Fletcher Christian, I'd learn the Polynesian technology for boat building rather than try to make metal nails and so on. A 30m catamaran with over 2m of freeboard sounds totally plausible to me using traditional methods.

https://en.wikipedia.org/wiki/Kamehameha_I King Kamehameha built ships matching your description around 1790.

And a pacific proa gives you the longest boat for the mass. The hull speed of a boat is determined by the square root of its length. In the Marshall Islands they are very popular but typically rather small. The biggest ships the Hawaiians traditionally used seem to have been catamarans.

https://proafile.com/multihull-boats/article/the-camel-a-sailing-cargo-proa

Bad for reefs. How much horsepower does that thing have?

There is a lot of interest in making maritime propulsion green. I've been looking at sailboats. Most yachts have a sail area to displacement ratio of 10-20m2 per ton. If you scale that up, it doesn't work for anything like a modern cargo ship. There are some videos out there about Magnus effect sails and inflatable sails. Nobody really breaks down the performance of these devices. I suspect they motor sail all the time and get maybe an extra 1/2 a knot of speed boost under ideal conditions. The Magnus device is powered so it's really a question of air propellers vs underwater propellers. I love sailboats, but they are mostly just expensive toys. Back in ye old days sailing cargo ships were all we had, but they were terribly slow by modern standards. The idea that you could use solar alone, also doesn't really scale. I suspect methane and hydrogen to become prominent as maritime fuels before they make it into other transportation sectors.

https://en.wikipedia.org/wiki/DC-to-DC_converter I understand Impedance in LC circuits. The only complicated part is the switching mechanism. I'd like to plug one into an oscilloscope and see what the output really looks like. It is surely not a flat voltage on the load.