Re: Tons, tons and more tons - Was: Are Attached files ok?

In message <BAY135-DAV9F9E6D07CF281AA54E4059AA40@???.gbl>
          David Shepheard <david_shepheard@???????.com> wrote:


[snip]

>>
> 
> You are not stating the full facts here. Page 28 of Concordance of Arcane
> Space (CoAS) states that an ocean ton of displacement is different from a
> spacial ton. It then defines a spacial ton as 100 cubic yards of
> *atmosphere*.

While page 26 of the same book simply states that a ton is 100 cubic 
yards. I said it was a matter of debate ;-), see below.
> 
> A "spacial ton" is a measurement of the ship's *air*. Page 7 of CoAS has an
> illustration called "Extent of the air envelope" and I'd say that the
> majority of the air is outside the ship itself.
> 
> So if you are taking it as 100 cubic tons of *ship* capacity, you are not
> doing it right. A spacial ton refers to the air envelope and doesn't really
> tell you anything about the cargo capacity of the ship itself.
> 
> The only way that the internal volume would be equal to the "spacial tons",
> would be if you were doing the Mystaraspace thing and making airtight ships
> that work like submarines. But that would only apply while those ships
> stayed inside Mystaraspace. As soon as they went to another crystal sphere
> they would be able to attract an air envelope and their "spacial tons" would
> shoot up when they flew into the atmosphere of a planet.
> 
> Interestingly the rules on page 7 of CoAS say that the  envelope has "an
> all-around depth equal to the cross-sectionional diameter of that body"
> (i.e. the air envelope size is three times the hight, width and depth of the
> ship). While the description of the Elven Man-o-War on page 32 contridicts
> this by suggesting that the wings brush the edges of the air envelope.
> 

Ok, so we have most of the 'volume' outside the ship. That implies the 
air volume is 27 times the volume of the ship (3^3) - the listed 
figures are out - but they are not out by that much! Added to Page 26 
of the Concordance of Arcane Space, where each ton of ship size is 
listed as 50 tons of cargo - so a ship can carry 13.5 times its own 
hull volume in cargo! I'm sorry, but I can't make this work in three 
dimensions ;-)

If we base the atmostpheric volume on the ships overall dimensions 
(including masts etc.) - it gets even worse!

> The rule on page 7 implies that adding a longer ram to the front of a ship,
> or attaching outriggers, *would* increase your air supply. And looking at
> that from the reverse direction, it would also imply that ships with
> features like that would have lower cargo capacity than other ships of the
> same "spacial tonnage".
> 
> The "Air Quality" section of CoAS has 1 ton of air being enough air to
> remain fresh when breathed by 1 person for 16 weeks. So you should actually
> be able to calculate how much air volume a standard D&D character breathes.
> (I think this may be where people were debating things.)
> 
>>In the real world, the volumes of ships were also given in 'tons' but
>>these were 100 cubic feet.
> 
> As I've said recently there are tons of volume and tons of weight. Both come
> from the same source. According to Wikipedia, "tonnage" was a tax on "tuns"
> (casks) of wine (that weighed about 2,240 pounds and contained about 252
> gallons of wine).

Correct, and why I use quote marks a lot - It would have been a lot 
simpler if they had just rated ships by weight (or, even better, 
mass).
> 
> What you are referring to is "Gross Registered Tonnage". I'm not entirely
> sure how old that measurement is. However, I think it would be more
> appropriate to use that sort of "ton" to calculate cargo taxes charged on
> sailing ships (and spelljamming ships visiting groundling worlds).

Its old, IIRC 'tonnages' were often estimated - there is a formula 
Tons = (Keel Length - 0.6 × Beam) × Beam ^2/188 - I think - to 
determine 'tonnage' based on keel length and Beam (interestingly 
enough, these are frequently the only measurements were given for 
Spelljamming ships) - This formula assumes a tubby, merchantman or 
cargo ship - there was also a 'Thames Tonnage' formula: Tons = (Keel 
Length - Beam) × Beam ^2/188 for yachts - which would work better for 
more streamlined ships. I may be mis-remembering both formulae though.
> 

[snip]

> 
> I don't think there should be any relationship between the two types of
> tons. It *should* be possible for one person to max out the cargo capacity
> of a hull design. And it should be possible for another person to max out
> the air carrying capacity of a hull design. Ships like tradesmen should have
> more "cargo tons" per "spelljamming ton" and ships with long unusable
> features (like the ram on a Squidship) should have less "cargo tons" per
> "spelljamming ton".

Well, a 'simple' estimate could be surface area × hull thickness + 
deck area × deck thickness. Two ships could look very similar and be 
made of the same material, but if one has decks and hull twice as 
thick as the other, it will weigh twice as much.

In other words, the bust we could manage for weights would be to 
assume a 'standard' hull thickness (perhaps a proportion of ship 
length) for each hull material, and increase it if the hull is 
thickened (extra armour) or reduce it if it is thinned (stripped for 
more manoeuvrability). We would probably be doing little better than a 
good guess (are there any nautical engineers here?).
> 
> I think that if you could calculate both types of tons and plot them on a
> graph, you should be able to work out a theoretical maximum and minimum for
> pushing the air envelope above the cargo capacity.
> 

[snip]

> 
> The War Captain's Companion sounds like a sensible way to do things as a
> theoretical solid lead Squidship should have a different AR and MC than a
> wooden ship. I'd argue that the thing would fall apart.
> 
> I'm not so sure we need to discuss Hackjammer at all as the authors are all
> on the SJML. We can just ask them for a detailed explanation of how they
> have done any things that are not identical to Spelljammer.
> 

[snip]

> 
> Good luck getting this on BtM. I don't want a copy at the moment, as I am
> very busy and have a big backlog of other stuff I haven't looked at.
> However, I would like to see this later.
> 
Well, I'm still working on it ATM - mostly trying to see if the mass 
of data I've accumulated is telling me anything useful!

[snip]

>>
> 
> Do you remember off-hand if the HackJammer ton relates to internal cargo
> capacity or air envelope size? If HackJammer tons are ship cargo capacity,
> they could actually be used *alongside* Spelljammer tons instead of
> replacing them.

Fortunately, I have the book here: 1 HJ ton is equivalent to a 10' × 
10' × 10' cube. 1 ton means enough air for 1 man-sized creature for 4 
months.

>From calculating the volumes of their ships, at least the easy to 
calculate ones, like the beholder doomship (a cone) does tend to match 
the ships volume assuming 1 ton is a 10' cube.

Beholder Doomship: cone 200' long by 40' diameter or 20' radius.
Cone volume is pi/3 × height × radius².
So, thats pi/3 × 200 × 20² = pi/3 × 200 × 400 = pi/3 × 80,000 = pi × 
26,666 2/3 = 83,775.8 cubic feet.

Divide by 10×10×10 to get volume in HJ tons = 83.78 tones.

Actual listed tonnage = 80 tons - which is close enough.
> 
> We could even go the full distance and give three types of tons for every
> ship:
> 
> * A "spacial tonnage" that tells us the amount of air in a ship's air
> envelope and therefore its crew capacity*,
> * A "cargo tonnage" that tells us the amount of cargo a ship can carry** and
> * A "mass tonnage" that tells us the total weight of the ship***
> 
> * = The relationship between "spacial tonnage" and total ship length, height
> and width is why I always ask if people have used mast heights or ram
> lengths when calculating ship volumes. Maybe I didn't get the importance of
> this across before.

Thats one of the reasons I'm posting this spreadsheet - I've included 
estimated (or scaled or diagrams where possible) mast and/or wing 
lengths to produce a set of 'overall' dimensions, as well as the hull 
dimensions.


[snip]

> 
> 
> Given that we have three meanings for tons, I think it might be worth
> finding alternative terms that can be used instead of the word ton. Or if we
> really don't want to do that, we should at least use the word in
> co-ordination with a second word that clarifies the sort of ton we are
> talking about.

I agree about this - but I don't have any good ideas at the moment!
> 
> "Pay no attention to the kender behind the curtain."
> David "Big Mac" Shepheard

[snip]

-- 
Charles
When you said he was acting odd, you did not specify "Miniature 
Spacetime Singularity" odd!