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Pykrete (wikipedia.org)
114 points by raldi on July 7, 2015 | hide | past | favorite | 41 comments

It plays a major role in Neal Stephenson's latest novel, SeveneveS.

Yes it does. And the book is mighty good as well.

The opinion about Seveneves varies quite a lot. I found it to be really bad and a great disappointment, and I am a huge Stephenson fan. Anathem being one of the best reads of my life. Seveneves is far from being a new Anathem.

I definitely liked it the least of all the Stephenson I've read. He spends lots of time talking about pykrete and bolides and orbital mechanics and robot swarms and space habitats, and in the end it doesn't feel like he spends very much time talking about people.

agreed - interesting story, but many small editing errors, and endless harping on about stuff that doesn't really do anything to drive the narrative forward left me disappointed.

I've never read Stephenson for the characters.

I like Anathem better, but Seveneves is interesting and worth my while.

Especially compared to Reamde. Now there was a turd.

Something like this shows up in Arthur C. Clarke's The Songs of Distant Earth.

In that book, the interstellar starship Magellan can reach a large fraction of lightspeed, thanks to its "quantum drive," but, at those speeds, interstellar gas and dust becomes a real problem that could damage the ship. The ship, therefore, has an ablative shield on its nose, made of ice. (This shield has to be replaced, which is why the Magellan stops off at the mostly-water world Thalassa en route to its final destination.) The shield is built of giant hexagonal tiles of ice, which contain seaweed as a strengthener; the resulting mixture is dubbed "icecrete" by some of the engineers. Clarke may have been alluding to pykrete here; I assume he'd have known about it.

Probably posted based on the earlier post today about Boston's snow problem: https://news.ycombinator.com/item?id=9842887

Basically, their snow is dirty enough that there's still a 12 foot pile of the stuff.

I think you're right.

Sorry for the tangent, but posting to HN seems a rather passive-aggressive way to show someone something. The submitter could have just linked it to the discussion they were having. Instead it's like OP is desperate for attention.

Or at least that's how it works on Imgur.

Thanks in part to the submitter, the Wikipedia article now exists:

  1. In that HN thread,  
  2. As its own item on HN, and  
  3. With a link between the two.
It has been exposed it to a wider audience than those who clicked the Boston snow thread.

Your "passive-aggressive" and "desperate for attention" comments are out of line. There are more than a few differences between HN and Imgur.

How the heck is it "passive-aggressive"? Who is being aggressed?

OP posted what they thought was an interesting link. Enough other people agreed to vote it onto the front page. Nothing nefarious going on.

Having not seen the "original" post, this didn't bother me at all :) I had no idea something like pykrete exists, or that it'd be used to build ships (of all things)

You're concluding too much, it could be just someone found it interesting and decided to share.

Actually, I did it for the karma.

Good plan. It worked! :)

I did find it interesting though.

Because building concrete ships has worked out so well in the past. The Selma developed a crack, nobody knew how to repair it, so she was scuttled. However she was too big to scuttle with other ships, so a specific spot had to be made.


A ship made of pykrete is probably a lot easier to scuttle than one made out of concrete. You just let it melt.

That can take forever in the arctic, as mentioned in the article...

Another one from WWI was the SS Atlantus. Although scrapped after 2 years service it was used successfully to transport troops back from the Euro theatre after the war. I remember seeing its 3-piece remains sitting in the waters off Cape May, NJ during a visit there as a little kid.

With concrete canoes, wonder if they ever experimented with Roman seawater concrete, which generates heat when it reacts with water. Heated hulls supposedly exhibit less friction which may give a slight edge in a race.

Regular Portland cement goes off under water too - it is exothermic as it reacts but it doesn't continue to generate heat. The "heated hull" would only be during the initial setting when the cement was weak and prone to cracking.

A heated hull riding on a bed of steam sounds like an interesting [and very high energy cost] engineering challenge though!

Cf. https://en.wikipedia.org/wiki/Cement

Mind game: posit construction of one of these cement canoes with Roman seawater cement (but with topology incorporating hollow cylinders in whatever is designated the stern). Data mining tidbit: 'For underwater structures, lime and volcanic ash were mixed to form mortar, and this mortar and volcanic tuff were packed into wooden forms. The seawater instantly triggered a hot chemical reaction. The lime was hydrated—incorporating water molecules into its structure—and reacted with the ash to cement the whole mixture together.” * Back to the canoe race. Once the flotation test is passed, incorporate sealed mortar canisters into cylinders and when race is underway expose mortar to sea water. Result: jet thrust for a time with residue morphing undetected (maybe) into the original primary construction material. Odds are you'd be disqualified but it might be a fun feasibility study.

*http://www.bloomberg.com/bw/articles/2013-06-14/ancient-roma... ... reaction reportedly reaches temperature approaching 900C.

I like the way you're thinking but I'm doubting you can generate any useful thrust from this.

> The Selma developed a crack, nobody knew how to repair it

Pykrete, however, appears to be repairable with seawater, a refrigeration unit, and a hose.

The concrete canoe community is doing rather well though. http://concretecanoe.org/

I thought this was some new python package.

Grab the name before someone else takes it!

We tried to make it with simulated Martian regolith at MDRS, but no go.

That's awesome, is there a list somewhere of the different experiments that have been done at MDRS?

http://mdrs.marssociety.org/crew-reports Sadly there's no list per se, this is the closest.

I have always particularly liked this scene, even if it is completely apocryphal:

"Next, he fired at the pykrete to give an idea of the resistance of that kind of ice to projectiles. The bullet ricocheted off the block, grazing the trouser leg of Admiral Ernest King and ending up in the wall."

So this would be a good way to prevent sea ice from melting? Just drop wood fiber into the artic ocean(near gjoa haven) sometime in late september, and then continue dropping wood fiber until february moving out in the direction of the aleutian islands.

There are far simpler things you can do to affect the global climate. See the "Risks and criticisms" for some reasons on why we may not want to.


There's a Mythbusters episode where they make a boat out of Pykrete, it's pretty awesome.

They used layered newspaper, right?

This would be a great link to submit to HN!

I was really hoping this was going to be a python package for manipulating the symbols in the Linear A and Linear B scripts. :-/

dream of a DOD contractor. Short term of service (thus launching a ship a replacement for it has to be started to be built immediately) with constant maintenance during it. Looking at the flight test results, i suspect that pykrete has made its way as a super secret core material inside composite pieces of F-35.

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