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

From: "Charles Taylor" <nerik@?????????.?????.??.uk>
To: <SPELLJAMMER-L@??????.???????.com>
Sent: Saturday, October 06, 2007 6:29 PM
Subject: Re: [SPELLJAMMER] Are Attached files ok?


David Shepheard <david_shepheard@???????.com> wrote:

<snip>
>>> There are three sets of corrected dimensions; 1 using 1 ton = 100 cubic
>>> yards, one using 50 cubic yards, and one using the Hackjammer 
>>> measurement
>>> of 1 ton = 1000 cubic feet.
>>
>> You realise that you are describing units of volume. While tons are 
>> actually
>> units of weight.
>>
>> Volume = tonnage - measured by the amount of usable space within a ship.
>>
>> Weight = tons - measured by the amount of water displaced when a ship is 
>> in
>> water.
>
>Well, in Spelljammer, a 'ton' was originally 100 cubic yards (although
>there has been some debate about this).

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*.

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.

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).

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).

>> I would be interested to see what sort of numbers you get if you tried to
>> calculate the relative size of ships based on the amount of weight each
>> design would have.
>
>Hmm.. I've actually done a bit of reaserch trying to find out if there
>was a simple relationship between ship size and weight for a given
>design of ship - but I couldn't find a lot of info on the subject (so
>far) - and I can't find the notes that I did take ATM.

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".

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.

>> (Actually, given the fact that ships can be measuered using volume or
>> weight, there is one thing that makes me side with the volume argument - 
>> the
>> "Stronger Materials" rules on page 44 of CoAS. These rules say that you 
>> can
>> change a wood ship into a metal ship, without manouverabity, hull points 
>> or
>> AR being effected. Only saving throws change. If SJ tons were based on
>> weight then tons *would* change when a wooden ship was transformed into a
>> bronze ship.)
>
>However, the War Captain's Guide changed that: Bith AR and MC were
>both dependent on hull material, while Hackjammer has hull points
>dependent on hull material as well.

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.

>> Could this not be turned into an table and put into a Beyond the Moons
>> article on the subject? I'd love to see how 100 cubic yards and 50 cubic
>> yards alter the spectrum of ship sizes. I'm assuming that large and small
>> ships would be affected differently.
>
>
>I'll contact Static and see about getting the table posted on BtM. In
>the meantime, do you want me to send you a copy?

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.

>> I'm also assuming that the Hackjammer ton would have a different effect 
>> on
>> large and small ship sizes. I'm pretty sure that Adam, Paul and Rian 
>> changed
>> this for a reason, so it might be worth asking them what they wanted to
>> achive with their change.
>
>Well, Hackjammer uses 1,000 cubic feet for a ton, which is a 10' × 10'
>× 10' cube - which could make estimating the volume of some designs
>easier.

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.

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.
** = I'd suggest that "cargo tonnage" should be based on groundling 
measurements of groundling ships, as something like a galleon should have 
stats in "groundling" RPG sources.
*** = (I'm not entirely keen on this name.) The total weight of the ship 
will be dependend on the materials, so a brass hammership should have more 
tons of mass than a wooden hammership. This statistic could be useful when 
working out how much damage a ship causes when it crashes.

The extreme situation that could illustrate the different types of tons, 
would be to get a ship hull that displaces a large air envelope, but doesn't 
have large ram-like features (I'd suggest an Elven Armada for this metal 
exercise as the neogi ship has a ram). Replace the existing material 
(ceramic) for something really heavy (such as solid gold). Fill up all the 
cargo spaces with more heavy material (such as lead). And then use a high 
level helmsman on a Major Helm to ram the ship into the Rock of Bral at full 
tactical speed (10 hexes). I'd argue that it should do a lot more crashing 
damage than a conventional Elven Armarda.

Mind you, I might be wrong looking at ships without rams. The additional 
cargo capacity of this ship, might actually be in an area that splits open 
easily and does less damage. It could be argued that a ram should be solid 
as the mass within it forms a built in "cargo" designed to inflict more 
damage on an enemy ship.

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.

"Pay no attention to the kender behind the curtain."
David "Big Mac" Shepheard
Virtual Eclipse Role Playing Club
http://uk.groups.yahoo.com/group/virtualeclipselrp/links/d20_system_001071937434/Spelljammer_001071430476
http://www32.brinkster.com/virtualeclipse/