Could a boat made from granite float?

[michaelm]

I am reading The One Tree still, and I keep wondering about whether or not the concept of a granite boat is workable.

The masts are my biggest problem as I think they would add too much weight high above the waterline, and would not be flexible enough in strong winds.

However, without the masts, I don't see why not. Just wondered if anyone had given it any thought, or better still - know of any precendents that show that something like that is possible.

[wayfriend]

I would think it's possible. They make ships out of steel, which is about 7.9 g/cm³ - granite is about 2.7 g/cm³, far lighter. So six-inch granite walls would be about the same weight as two-inch steel walls. The weight of granite masts would be offset by the weight of a granite keel, as was explained in TOT.

In the end, only two things matter - is the weight of the water displaced greater than the weight of what displaced it, and is the center of gravity below the water-line?

Another thing going for it is the size of the ship. When you double the length of a ship, you increase the volume displaced by a factor of eight (2 cubed). However, you increase the surface area - which is how much wall there is - by a factor of four (2 squared). So, assuming the walls are the same thickness regardless, the bigger the ship, the more buoyant it is, and so the more it can carry. And giant ships are VERY big.

See also: Concrete Ships

[michaelm]

Has there ever been an example of a ship made from stone though (other than the Chronicles)?

[Frostheart Grueburn]

Has there ever been an example of a ship made from stone though (other than the Chronicles)?

Norse mythology, in a tale called Bárðar saga Snæfellsáss. A giant sitting in a stone boat.

[wayfriend]

Has there ever been an example of a ship made from stone though (other than the Chronicles)?

I had that link to boats made of steel-reinforced concrete.

Data on stone boats is hard to find in google because the term is used for lots of things that aren't actual boats.

This is a "Marble Boat" ... that doesn't really float.

[wayfriend]

Aha! The Maen Vag is made of granite and actually floats!



www.youtube.com/watch?v=wc8Wqj1x08s

[TheFallen]

To expand on WF's concrete ships, these were actually pretty large.

As impossible as it seems, the ocean once carried a fleet of ships built mostly of concrete. Concrete, a mixture of sand and gravel bonded together with a cement to form a solid, heavy mass similar to stone, seems an unlikely substance to be used in ship construction. Wood, which floats, seems a better medium for building vessels and indeed was the preferred material for ship building for thousands of years. Steel became the standard material for large vessels by the end of the 19th century because it was very strong for its weight.

During the First World War, though, steel was in short supply, yet ships had to be built. Ship builders took the idea a Norwegian inventor had patented a few years before in 1912 to use concrete instead of steel for the ship's hull. As strange as it seems, a ship of concrete will float as long as the weight of water it displaces is more than its own weight. It is a matter of density.

The density of an object is the mass of an object divided by the volume. To float, the ship must be less dense than the same amount of water. A solid, cube of concrete (and for that matter steel) is more dense than the same cube of water and will sink like a stone. When the concrete is formed into the shape of a ship, though, with much of the interior empty air, the ship's total volume includes the air. Air is less dense than water. Since the total ship is a combination of air and concrete, the density for the whole ship becomes less than the water, allowing it to float.

Should the ship spring a leak and fill with water forcing the air out, the density of the ship will become greater than that of the water, causing it to sink.

In 1917 and 1918 British builders constructed barges, tugs and fishing boats using concrete. The Americans were more ambitious, commissioning a fleet of 12 ocean-going concrete freighters costing 50 million dollars.

The concrete ships that were built followed the design of steel ships of that era, but required much thicker hulls to get the same amount of strength that the steel gave. A newly-developed form of concrete that included portland cement was used because it was relatively light (Only 120 pounds per cubic foot). Even so, the ships were much heavier than steel ships. The ship builders also found that concrete was much more difficult to manipulate than steel, making the ships more difficult to construct.

The first of these ships finished was the Polias which was launched from the Liberty Company Shipyard of Wilmington, North Carolina in 1918. It was 250 feet long with a draft of 22 feet and a beam of 45 feet. The walls of the hull were six inches thick. She required only one-third of the steel necessary for a regular freighter.

While these ships actually worked, many sailors referred to them as "floating tombstones" and did not like to serve on them. Still, some of them were used to transport troops back from Europe at the end of the First World War. Soon after the war when steel was more abundant, the concrete ships quickly became too expensive to operate. Their heavy hulls needed too much fuel to push them around and the ships became obsolete. One was turned into a casino, and another a restaurant.

In 1926 what was to become the most famous of the fleet, the Atlantus, was bought to be used as part of a dock on a proposed ferry line to be run from Cape May, New Jersey, to Cape Henlopen, Delaware. While the ship was moored near the site awaiting its fate, a storm hit the region. The ship broke loose and grounded off of Sunset beach, Cape May. Stuck fast in the sand, all attempts to move it failed. The ruins of the vessel remain there even today and have been viewed by generations of visitors. It is a reminder about a time almost a century ago when concrete ships plied the seas.

Link

[Vraith]

Too many problems with actual stone [as opposed to pouring concrete].
big enough slabs, grinding them into shape [or chiseling], tons...literally...of waste, rare to find, hard to transport, hard to bind together.
Stone is also very brittle compared to other materials.
Building it thin enough to ride high makes it extremely fragile...building it thick enough to manage impacts makes even small waves a swamp-threat.
Totally impractical/inefficient for so many reasons.
But it's definitely possible.

There exists some craftsman [or did exist] who demonstrated the principle:
toy/sculpture-size boats carved out of solid chunks of marble and jade that float.
I did a quick search, didn't find...but I know they exist. Saw some show a decade or two ago where they hired a modern sculptor to show the audience how it was done...

[michaelm]

I guess that's the beauty of fantasy writing - you don't need to get the reader to suspend belief, you just change the rules so that the seemingly impossible parts of creating that kind of boat are explained by the rules that govern the Land.

The concrete boat concept rings a bell though. I seem to recall being on vacation or traveling somewhere and hearing about there being one somewhere nearby. I'll have to rack my brains to try to remember where that was.

[wayfriend]

I guess that's the beauty of fantasy writing - you don't need to get the reader to suspend belief, you just change the rules so that the seemingly impossible parts of creating that kind of boat are explained by the rules that govern the Land.

Yes. The Giant's of Home had a variety of granite that had "the slight but necessary flexibility of bone". Which addresses Vraith's concerns. But which does not actually exist.

[DrPaul]

I guess that's the beauty of fantasy writing - you don't need to get the reader to suspend belief, you just change the rules so that the seemingly impossible parts of creating that kind of boat are explained by the rules that govern the Land.

Well, quite. Trell can use Earthpower and rhadamaerl lore to put shattered stone pots back together. Samadhi can use his lore and the powers of the Illearth Stone and Staff of Law to raise stone zombies. Pitchwife can use pitch and his lore to effect repairs to stonework that would be impossible in our reality. Building fine stone ships would have been a very exciting challenge for a people whose two favourite "elements" were Stone and Sea, but given that the Giants of Home would have been able to draw on their native skill with stonework, their native skill in shipbuilding, and the lore they would have gathered in their travels, it would not have been insurmountable.

[sgt.null]

www.concreteships.org/history/

[shadowbinding shoe]

Too many problems with actual stone [as opposed to pouring concrete].
big enough slabs, grinding them into shape [or chiseling], tons...literally...of waste, rare to find, hard to transport, hard to bind together.
Stone is also very brittle compared to other materials.
Building it thin enough to ride high makes it extremely fragile...building it thick enough to manage impacts makes even small waves a swamp-threat.
Totally impractical/inefficient for so many reasons.
But it's definitely possible.

Pure concrete is brittle but reinforced concrete which is made by implanting steel rods (and usually gravel as well) negates this problem. The reinforcing material gives the necessary tnsile strength and ductility to the concrete. That's how stone buildings and bridges are built. Otherwise they wouldn't be able to withstand earthquakes or other stresses. The main problem with stone ships appears to be their weight. They have thicker hulls because stone is weaker than steel and when you sail such a ship you wastes more money on fuel.

From a Land perspective iron appears to be a precious rare material so it would be very constly to build a steel ship and might even tempt other nations to try to capture such ships to smelt them into iron weapons. Also, considering the Giants' proportions, building giant wooden ships could turn lands into deserts and I think there might be problems making a keel for such a big ship.

[DrPaul]

From a Land perspective iron appears to be a precious rare material so it would be very constly to build a steel ship and might even tempt other nations to try to capture such ships to smelt them into iron weapons. Also, considering the Giants' proportions, building giant wooden ships could turn lands into deserts and I think there might be problems making a keel for such a big ship.

In the First Chronicles we find that the people of the Land are able to do all sorts of things with stone and wood that are done with metals in our world. Nonetheless we see metals being used for various purposes - the krill, the staves of ur-viles and Waynhim, presumably the swords and armour of warriors in the Warward. Certainly the original sword of The First and the one she takes from Brathairain are metal. Also the leader of the Swordmainnir is titled "the Ironhand". I don't think we can assume that iron is necessarily rare in either the Land or in other parts of the world of the Chronicles.

The real problem with building a steel ship is that it would require an industrial economy, and all of the cultures in the Chronicles are pre-industrial - and, of course, magical.

[Avatar]

Aha! The Maen Vag is made of granite and actually floats!



www.youtube.com/watch?v=wc8Wqj1x08s

That's awesome.

--A

[Harbinger]

As long as the boat is designed to displace more lbs of water than the boat weighs, it will float. Eureka! I have found it.

[sgt.null]

Will It Float?

[Rod]

I am reading The One Tree still, and I keep wondering about whether or not the concept of a granite boat is workable.

Hello,

Weren't the Giantships described being big as castles?
Which implies they were immense, and likely beyond the imagination of Linden Avery.
On the other hand, Revelstone was big as a castle and of course built by Giants, which also Covenant found difficult to fathom.

No, I'm inclined to believe the Giantship was merely a manifestation of Linden Avery's dream. Unfortunately corrupted by a raver.

(Brathairealm was also big as a castle.)

_________

[DrPaul]

Revelstone was much bigger than a castle. Even the tower and other structures around the two gates would have been as big as actual castles in our world. It was a rock-delved city, and in the days of the Old Lords would probably have accommodated many more people than we see in the Chronicles. If the depiction in the maps of the wedge of the Westron Mountains that contains Revelstone is anywhere near accurate, it would have been at least several miles/kilometres long on each side.

[DrPaul]

I am reading The One Tree still, and I keep wondering about whether or not the concept of a granite boat is workable.

Hello,

Weren't the Giantships described being big as castles?
Which implies they were immense, and likely beyond the imagination of Linden Avery.
On the other hand, Revelstone was big as a castle and of course built by Giants, which also Covenant found difficult to fathom.

No, I'm inclined to believe the Giantship was merely a manifestation of Linden Avery's dream. Unfortunately corrupted by a raver.

(Brathairealm was also big as a castle.)

_________

Well, we know that Starfare's Gem was able to accommodate a crew of 40 Giants quite comfortably, and still have room to spare for four Haruchai, two humans and Vain. This suggests that in order to get some idea of the size of Starfare's Gem, we should start from a vessel familiar to us capable of carrying a working crew of about 50 in comfortable conditions (i.e. not the cramped conditions on which people have often sailed in working ships, but at the same time not in cruise ship staterooms). Having established the dimensions of such a vessel, we would then need to multiply all of its dimensions by two, to take account of the difference in size between Giants and ordinary humans.

The term "dromond" in our reality refers to any particularly large medieval ship. The problem with that is that medieval ships in our history had medieval relations between the commanders and the poor bastards who worked on the ships, whereas the Giants have much freer and more equal relations with each other and between the captain and crew, which would extend to things like more living space for the crew, less cramped working conditions, better meals, etc.

Perhaps the best line of comparison is to think of Starfare's Gem as similar to a three-masted tall ship in our reality. ThePicton Castle en.wikipedia.org/wiki/Picton_Castle_(ship)could be a reasonable approximation. Now multiply all of that ship's dimensions by two for the reasons already mentioned and we get a length of 110 metres (about 360 feet) for Starfare's Gem. This is about half the length of the two 30,000 tonne sea-going ships I have travelled on (the P&O cruise ship Arcadia and the Spirit of Tasmania). However, we would then need to make further allowance for the generosity and egalitarianism of the Giants, which would bring Starfare's Gem to roughly the same size as a cruise ship in our world, but nothing beyond the imagination or comprehension of a modern American like Linden Avery.