Overtonnage and Undertonnage - Discussion

[AnotherDilbert]

As far as I understand it is selected as the naval architect designs the ship. The cargo hold is specified to be a certain size.

If you don't like it, buy a ship of another class?

 

[Condottiere]

Configuration, especially if it involves containers.

 

[robject]

This bugs me a bit. Is it implying that the choice is per trip, or made at purchase by selecting the stretch option?

This is at design time. Marc footnoted his worked-out designs thoroughly, following his thought process as he went. That footnote is in the context of ship design: most ship captains will take an ungainly ship if it means profitability goes up.

The footnotes are how I came around to AnotherDilbert's take on how a ship accommodates high passengers. Without them, I'd not be convinced.

 

[robject]

My argument: Pods (small craft) are external (not included in the hull), overtonnage is internal (included in the hull). Two different things. External pods affect drive performance, overtonnage affects agility and stability.

I guess my argument is that all performance metrics account the Ship at time of use. So drop tanks don't just affect the Gazelle's jump performance, but also agility and stability in an atmosphere, if they're still grappled at the time.

So we have falsifiable arguments -- presumably, we can figure out what the rules say. Or if they say. Offhand I don't remember any particular passage that supports my argument.

 

[AnotherDilbert]

RAW is a bit murky...

B2, p51-52:
Overtonnage and Undertonnage. It is impractical to begin with hulls in less than multiples of 100 tons (for example, a 343-ton hull is not available as a starting point, although it may be a final result). Conversely, fine tuning in the final design is possible by attaching appropriate tonnage Pods or Subhulls.
In the final design, the Hull may be more or less than the initial design tonnage. Slight undertonnage (49 or fewer tons under design hull tonnage) positively impacts performance by increasing Agility (+1 per 25 tons under). Slight overtonnage (49 or fewer tons over design tonnage) negatively impacts performance by decreasing Agility (- 1 per 25 tons over). Gross overtonnage (50 or more tons) requires rounding the Hull Identifier to the next higher size.

B2, p70:
PODS AND BARGES
Pods and Barges are detachable ship components. Adding a Pod or Barge to a parent Hull increases the total tonnage for a ship, which potentially decreases the performance of its drives. Detaching a Pod or Barge from a Parent Hull de- creases the total tonnage for a ship, potentially increasing its performance.

B2, p117:
Renormalization
When the volume of a ship changes (by dropping drop tanks, changing the number of cargo pods, or adding or removing riders) the performance of the ship may change.
1. Note the jump drive code.
2. Determine the new tonnage.
3. Create new Drive Potential from Drive Potential-1

Opportunities
Some opportunities involving renormalization include:
Drop Tanks. The ship carries a substantial quantity of fuel (jump fuel) in tanks which can be jettisoned. When jet- tisoned, the ship no longer counts its fuel drop tanks against its tonnage for Jump purposes. For example, a 400-ton Close Escort has Jump Drive-H (potential=4), Maneuver Drive-H (potential= 4), and two 50-ton drop tanks and a 76-ton internal tank. In normal operations, it can do Jump-4 and 4G.
If it jettisons the drop tanks, it becomes a 300-ton ship (Jump potential-5 and 5G).
...

That's about it, I think.

 

[robject]

That reminds me -- I note that the Airframe hull has a built-in Agility+1. This means, for instance, that an overtonnage Airframe is Agility+0 -- a potentially viable option for merchants.

 

[robject]

I think everyone can agree that "hull" technically refers to the ship sans pods and the like. Using "hull" to mean everything the ship drags around is sloppy and incorrect (but it happens).


Also: more than half of the archetypal ship designs are more than just a hull. So how these extras affect the ship is potentially important.

Archetypes that aren't just a hull include:

* Subsidized Merchant (dorsal Launch)
* Gazelle (drop tanks)
* Subsidized Liner... I guess! Its ventral launch looks half-in, half-out.
* Safari Ship: its Launch looks at least partly out.
* Mercenary Cruiser: its modular cutters are partly (half?) out.
* Lab Ship: its boat is for all practical purposes "grappled", in a way.

What about the Patrol Cruiser? FASA's Lurushaar Kilaalum has them internal. (ACS 2 B3)

And the Yacht? Is its boat in a hangar? (example: FASA's Lady of Shallott has an internal boat) (ACS 2 B3)

 

[AnotherDilbert]

A ship can have several Hulls. We can designate one the Main Hull, to which we attach other Subhulls and Pods. We can attach them with detachable grapples or with permanent connectors.

A ship with a 400 Dt main hull, a 100 Dt Subhull, and a 20 Dt Pod all connected with permanent connectors is effectively a single 520 Dt hull.

 

[Grav_Moped]

What about the Patrol Cruiser? FASA's Lurushaar Kilaalum has them internal. (ACS 2 B3)

According to the deck plans, but not the cover illustration. The deck plans do not match the illustration.

Doesn't affect your point, but I've just spent a few weeks on this and thought it worth mentioning.

 

[AnotherDilbert]

LBB2 didn't care about such petty details. Formally there was no such thing as externally connected small craft:

LBB2'81, p15:
Ship's Vehicles: A ship may have one or more subordinate vehicles specified as part of the ship's equipment, and tonnage may be devoted to the permanent stowage or hangarage of the vehicles. The vehicles list indicates those vehicles and small craft commonly available
....
Small craft are covered later in this chapter. When carried on a ship, tonnage sufficient to hold them must be allocated.

It was a simpler time.

Archetypes that aren't just a hull include:

* Subsidized Merchant (dorsal Launch)

Mechanically it made no difference in LBB2. It was a 400 Dt ship including the Launch (whether internal or external). Now we would call it a 380 Dt hull with an external 20 Dt Launch, for a total of 400 Dt.


The Gazelle is different, it's a LBB5 design, the drop tanks are explicitly external, not part of the hull. Dropping them changes drive performance.

 

[robject]

LBB2 didn't care about such petty details. Formally there was no such thing as externally connected small craft:

Right. They were there, but below the threshold of Book 2.

 

[robject]

A ship can have several Hulls. We can designate one the Main Hull, to which we attach other Subhulls and Pods. We can attach them with detachable grapples or with permanent connectors.

A ship with a 400 Dt main hull, a 100 Dt Subhull, and a 20 Dt Pod all connected with permanent connectors is effectively a single 520 Dt hull.

Of course you're right. A catamaran hull can be a 400t main hull and a connected 400t subhull.

In the context of this discussion, though, does "hull" mean the initial starting volume when design begins, the volume of the ship at time of use, or the bits of the final design that aren't detachable, or something else?

 

[robject]

Actually the definition of Overtonnage isn't murky at all:

Overtonnage - the amount by which a Hull is more than the initial design tonnage. T5 B2 p52.


My problem is: Attached Items seem to affect Overtonnage, contrary to the above statement.

This thought seems to be supported by Marc's ship design. Flawed though the design clearly is, his intent flies in the face of p52.

 

[AnotherDilbert]

In the context of this discussion, though, does "hull" mean the initial starting volume when design begins, the volume of the ship at time of use, or the bits of the final design that aren't detachable, or something else?

Yes...

B2 uses the term planned tonnage or design tonnage, as opposed to resulting tonnage. Basically:
Design tonnage + overtonnage = resulting tonnage.

Drive performance is calculated on design tonnage.
Resulting tonnage is the final tonnage of the ship.

Simple example:
The Beowulf uses a hull of 200 Dt (design tonnage). Drive performance is calculated for 200 Dt.
It stuffs enough components (222 Dt) into the hull to get an overtonnage of 22 Dt. Resulting tonnage is 222 Dt.

 

[robject]

Right. So the discussion is, I think, about tonnage at time of use.

Marc's example shows Attached Items affecting Overtonnage, even though the rules don't mention it. He is deliberate and expresses the intent clearly by example, but not by rule.

So then, if Attached Items don't affect Overtonnage, then what is Marc doing?

1. He made a mistake.
2. This is an earlier (5.09?) design that has been superseded by 5.10.
3. He didn't write the rule clearly enough.
4. Something else?

Perhaps "hull" as used in the rules is not just the main hull, or the hull with its undetachable connected components, but the entire conglomeration. The text on Overtonnage and Undertonnage can support this. The performance rules (accel and jump) certainly support this, particularly the At Time Of Use bit.

 

[AnotherDilbert]

Overtonnage - the amount by which a Hull is more than the initial design tonnage. T5 B2 p52.

Yes, agreed.

My problem is: Attached Items seem to affect Overtonnage, contrary to the above statement.

This thought seems to be supported by Marc's ship design. Flawed though the design clearly is, his intent flies in the face of p52.

Hence murky...

This thought seems to be supported by Marc's ship design. Flawed though the design clearly is, his intent flies in the face of p52.

Are the ships designed by MWM or someone else? I kind of assumed someone else helped him with that given the confused state of some of the designs.

 

[AnotherDilbert]

Less simple example:
The Gazelle uses a main hull of 300 Dt + 100 Dt subhull = 400 Dt (design tonnage). Base Drive performance is calculated for 400 Dt.
Hypothetically it stuffs enough components (322 Dt) into the main hull to get an overtonnage of 22 Dt. Resulting tonnage is 422 Dt (with the tank), overtonnage is 22 Dt, regardless of the tank is carried or dropped.


Note it is a 400 Dt ship with a 300 Dt main hull (code C):

 

[AnotherDilbert]

And if you swallowed that, you should be able to swallow this:

A "random" ship uses a main hull of 400 Dt + 20 Dt pod = 420 Dt (design tonnage). Drive performance is calculated for 420 Dt.
Hypothetically it stuffs enough components (422 Dt) into the main hull to get an overtonnage of 22 Dt. Resulting tonnage is 442 Dt (with the pod), overtonnage is 22 Dt, regardless of the pod is carried or not.

See, it's the same logic?

 

[robject]

OK good, now we've got traction.

First -- Marc did the designs himself. I saw the deckplan in 2017, and saw the design draft in 2019. Naturally I didn't see the overtonnage issue.

The Gazelle uses a main hull of 300 Dt + 100 Dt subhull = 400 Dt (design tonnage). Base Drive performance is calculated for 400 Dt.
Hypothetically it stuffs enough components (322 Dt) into the main hull to get an overtonnage of 22 Dt. Resulting tonnage is 422 Dt (with the tank), overtonnage is 22 Dt, regardless of the tank is carried or dropped.


Note it is a 400 Dt ship with a 300 Dt main hull (code C):

By the way, Marc's QSP for the Gazelle is incorrect. LOL!

Hull. Hull ID (total tonnage). T5 B2 p93.

What the heck does "total tonnage" mean? Here it is:

Adding a Pod or Barge to a parent Hull increases the total tonnage for a ship, which potentially decreases the performance of its drives. T5 B2 p70.

And the rules specifically deals with that, where added subhull stuff can cause an increase in the ship's base hull (regardless of detachability).

A "random" ship uses a main hull of 400 Dt + 20 Dt pod = 420 Dt (design tonnage). Drive performance is calculated for 420 Dt.
Hypothetically it stuffs enough components (422 Dt) into the main hull to get an overtonnage of 22 Dt. Resulting tonnage is 442 Dt (with the pod), overtonnage is 22 Dt, regardless of the pod is carried or not.

LOL! I see overtonnage as 42 tons, because the drives are pushing 42 tons over their rating. That seems to be what Overtonnage is for: performance calculations.


So I'll introduce the term "total tonnage" which is used in key places in T5, and seems to mean "everything attached to the ship".

 

[AnotherDilbert]

Marc's example shows Attached Items affecting Overtonnage, even though the rules don't mention it. He is deliberate and expresses the intent clearly by example, but not by rule.

So then, if Attached Items don't affect Overtonnage, then what is Marc doing?

1. He made a mistake.
2. This is an earlier (5.09?) design that has been superseded by 5.10.
3. He didn't write the rule clearly enough.
4. Something else?

Not a throwback to T5.09, it had the same rules, but no examples.

Maybe he made a mistake, he changed his mind over time, or he has a slightly fuzzy idea in his head that he has failed to put down on paper clearly?


But, agreed, if the Daring-class example is correct, then I (and the rules) are incorrect. About a lot of things...


Just possibly, small attached items don't affect design tonnage but is counted as overtonnage? At least if the designer feels like it?