The Bridge, Ship Size, and Hull Size

[robject]

A recent discussion on the Safari Ship thread got into the weeds with ship size versus hull size, and how drop tankage affects bridge size, if at all.

It's a minor but interesting issue. Ought you to state the maximum external tankage your ship is designed to handle? I've never done that, but maybe I should?

I think how these three are related depends on the rule system you're using. Although, I would be surprised if there is not a consensus amongst all the various rules out there.

If I recall correctly, the ship's bridge is typically calculated last, even though it's usually just based on the hull tonnage. Meanwhile, drop tanks might be considered add-ons, rather than design-time considerations. As such, the bridge would presumably not need to "be large enough" to support oodles of drop tanks.

However, THAT is a subtle point that might be affected by the RULES you're using. Because, the order of ship design could potentially affect the "ship size" which might in turn affect the bridge allocation.

Book 2 is coy, since it doesn't tell us how to add drop tanks to its designs. (JTAS grafts High Guard drop tanks to Book 2 designs, implicitly assuming that it's OK to do so.)

Discuss with specific examples from rules systems.

 

[AnotherDilbert]

It's only an an issue in CT, as the bridge is a percentage in CT only.

 

[robject]

The problem doesn't emerge until your ship size totals greater than 1,000 tons, because 20 tons.

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High Guard 2 (1980) p27. Disposable fuel tanks may be added to the ship to increase its range. These L-Hyd Tanks are fitted to the outside of the ship, and drop away before jump. ... L-Hyd tanks are installed outside the hull, and increase the total tonnage of the ship; drives are reduced in their efficiency based on the total tonnage of the ship. With tanks retained, efficiency is decreased, and jump capability is reduced; when the tanks drop away, tonnage is reduced, and the drive efficiency is increased. ...

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This is in the FUEL section of ship design. Immediately following this paragraph is the next section:

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The Bridge: ... a bridge (designated as the main bridge or prime bridge) requires 2% of the ship's tonnage (minimum: 20 tons) at a cost of Cr5,000 per ton of ship. For example, a 100-ton ship must allocate 20 tons for the bridge at a cost of Cr500,OOO. A 1,000-ton ship must allocate 20 tons for the bridgeat a cost of MCr5. A 1,100-ton ship must allocate 22 tons for the bridge a t a cost of MCr5.5. The bridge contains all necessary equipment for the control of the ship with the exception of the computer.

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Okay this is what @mike wightman was saying. The Bridge depends on the ship's tonnage. "Ship tonnage" is not equal to "hull tonnage". In fact the earlier section on The Hull does not equate Hull Size to Ship Size.

 

[robject]

MegaTraveller. I won't try to unravel MegaTraveller's bridge rules. Suffice to say it's based on the number of control points or control stations required on the ship.

 

[robject]

Traveller 4th Edition

The bridge size in T4 (QSDS, SSDS, and FFS2) is completely a function of the number and roles of crew required for the ship. Drop tanks have absolutely nothing to do with it.

Fire, Fusion, and Steel 2 is the only book that talks about drop tanks. The bonus here is that drop tanks are apparently part of the design process, and therefore their tonnage is significant. This is a clarification that makes sense, even for previous editions of Traveller.

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(FFS2p16) Drop Tanks: Drop tanks are disposable exterior tanks ... The fuel from the drop tank is consumed in establishing the jump interface, and then the tanks are dropped away ... Drop tanks are designed as separate hulls... They are connected to the ship using a special type of grapple, built only to hold the tank and provide fuel couplings. ... Drop tanks increase the ship's mass and size, requiring jump and maneuver performance as well as signatures to be recalculated while they're installed.

Normally drop tank grapples are built into the ship when designed. ...

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Note two items: first, the ship's sensor signature is effected. No surprise there.

Second, "drop tank grapples are built into the ship when designed." This implies that the drop tank's maximum tonnage, plus or minus, is determined at the ship's design time. So by T4 the design system has caught up with the concept that ships are designed to specifications, and that includes drop tank tonnage.

However, this still does not affect bridge tonnage in T4, since there's no extra crew required to "operate" drop tanks.

 

[Condottiere]

Now that a new iteration of the ship design rules are out, I'm back on my quest to design the cheapest possible starship.

The thread does make me reflect whether the default bridge would costs half or a full megastarbux, since I've tinkered the performance down to one hundred twenty parsec tonnes.

Since hundred tonnes is the minimum volume, and fractions are irrelevant in range, maximum bang would be a one hundred twenty tonne volume.

Options would be a one hundred twenty tonne hull, one hundred plus twenty tonne attachment, fifty and two thirty five tonnes, and so on.

So if the primary hull is one hundred tonnes or less, am I paying for one one hundred tonnes, or two one hundred tonnes slots, which would cost be an extra half a million starbux.

One difference is, in Mongoose, the jump drive is switched off the moment you go down the rabbit hole.

In Classic, the jump drive continues to hum.

 

[AnotherDilbert]

LBB5'80 is not consistent and seems to use tonnage, hull tonnage, ship's tonnage, and tonnage of the ship somewhat haphazardly.

Example:

LBB5'80, p23 (design tables)
Formula indicates percentage of ship required for armor (a is desired armor factor).

LBB5'80, p29 (rules text)
The armor factor is the type of armor used; if no armor is selected, the armor factor in the USP is zero. The armor table indicates formulae for the computation of armor tonnage and cost, based on the factor selected. For example, the formula at tech level 9 is 4+4a (a is armor factor). On a 100-ton ship with an armor factor of 3, this formula indicates that the ship must allocate 16% (4+4x3), or 16 tons. Cost is MCr.3+.la per ton; the cost per ton is MCr.6 (.3+.1x3), or MCr9.6 (16 tons times MCr.6) total for the ship. The added value of armor on a ship may not exceed the ship's tech level.
When armor is used, the entire hull is armored.

Hull? Ship? Is there a difference?

As far as I can see the rules are written without consideration for corner cases, such as drop tanks, and the implications of drop tanks are described in the drop tank rule.

 

[AnotherDilbert]

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(FFS2p16) Drop Tanks: Drop tanks are disposable exterior tanks ... The fuel from the drop tank is consumed in establishing the jump interface, and then the tanks are dropped away ... Drop tanks are designed as separate hulls... They are connected to the ship using a special type of grapple, built only to hold the tank and provide fuel couplings. ... Drop tanks increase the ship's mass and size, requiring jump and maneuver performance as well as signatures to be recalculated while they're installed.

Normally drop tank grapples are built into the ship when designed. ...

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...
Second, "drop tank grapples are built into the ship when designed." This implies that the drop tank's maximum tonnage, plus or minus, is determined at the ship's design time.

You truncated that quote:

Normally drop tank grapples are built into the ship when designed. Adding a grapple to an existing ship increases the grapple mass and volume by 20%, to cover the extra reinforcing that has to be added, and increases the price by 25%.

You can add it at design time, or later to an existing ship. The rest of the ship itself does not change.

T4 allows external pods and keeps track of hull and total size separately.

 

[robject]

^ Thanks for that. Yes, I truncated because it started to get annoyingly messy, but you're right.

Ends up not mattering for T4 bridge-wise. It does show that ships can indeed be refitted, which we already know, but that doesn't invalidate the importance of design all things to a specification.

 

[McPerth]

For CT, in S9 we have two canon ships whose tonnage is variable. The Gazelle (page 17) and the Jump Ship (page 22).

The Gazelle is described as 300 dtons ship with additional 10 being used as drop tanks, but it has 4 hardpoints, so hinting the drop tanks are included in the ship design. At those low tonnages, bridge is not a problem (20 dton).

The Jump Ship has a variable tonnage according its cargo, from 5000 to 10000 dtons. While the efects on the jump performance are well described, the size of its bridge (taht would be 100 dtons if tonnage is 5000 and 200 dtons if 10000) is not described...

Personally, I designed a ship (using MgT1E rules) with variable tonnage: my Jump Frame and Barges Freighter, and I designed it as a 2000 dton ship, despite the jump frame itself being only 400 dtons, just to avoid this kind of problems. The bridge, repair drones, etc. were all calculated for a 2000 dtons ship (so being quite oversized when not at full cargo).

 

[robject]

For CT, in S9 we have two canon ships whose tonnage is variable. The Gazelle (page 17) and the Jump Ship (page 22).

Also the Ghalalk, if I recall?

 

[robject]

Traveller 5th Edition

Pretty much the same as Traveller 4 in philosophy. Extra hulls duct-taped to the main hull come up immediately after the main hull section, however, making it clearer that design to the specs includes all subhulls, including drop tanks.

Crew, on the other hand, completely depends on equipment installed into hulls, not the hulls themselves. Every 35 tons of equipment has a control panel, and each workstation manages one or more of those. And workstations, very roughly, require a crew member (or, one crew member per operational shift).

Since drop tanks are simply hulls, they have no special control requirements, thus they don't impact the bridge size.

 

[McPerth]

Also the Ghalalk, if I recall?

I'm araid I don't see any variable tonnage feature in the Ghalalk (page 30)

 

[Condottiere]

The Ghalalks got a revision, and if used as an example, would amplify that the bridge size and cost is dependent on the tonnage you actually control.

 

[robject]

Usage

All this is great, but in REAL LIFE, have people bothered to calculate bridge size based on drop tank inclusion? I mean since the beginning of Traveller.

For that matter, did this topic ever come up in the TML?? Because we had hard-core nerds there that vivisected the rules with verve.

 

[McPerth]

I did it in my own design, when considering it a 2000 dton ship that could be reduced to 400 by taking the barges out (some barges are fuel ones, so roughly equivalent to drop tanks, through not thought to be released before jump).

In fat, though I based it on the examples of the Tenders, where the Riders were included on its design, and considered any barge as a Rider equivalent, not even thinking about drop tanks...

 

[AnotherDilbert]

Usage

All this is great, but in REAL LIFE, have people bothered to calculate bridge size based on drop tank inclusion? I mean since the beginning of Traveller.

Note that Mike suggests that armour and basically all percentage based components should be based on hull + tanks.

Has anyone recalculated armour to cover the drop tanks, despite not covering the drop tanks?

Has anyone refitted a ship with a bigger bridge, when an external tanks was retrofitted?

I certainly haven't.

 

[robject]

Trawling the TML

Going through the TML, I see complaints about the magic hardpoint of course, as early as 1988. But, nothing about drop tanks affecting the bridge.

So @mike wightman's point is reasonable, but I believe usage has always been to ignore drop tankage re bridge size. Later rulesets implicitly support this, in that bridge size is about the ship's equipment.

 

[Condottiere]

Towing rules probably apply, whatever they are.

 

[Spinward Flow]

A starship bridge is 2% of a starship's (permanent) hull, with a minimum of 20 tons in CT.
Drop tanks get attached to a starship's hull, but the tanks themselves are NOT starship hull ... because the drop tanks are not permanent features. The drop tanks are "separate from" a ship's hull and are therefore not "starship hull material" themselves.

Adding/removing drop tanks are explicitly detailed as modifying drive performance (supported by the Gazelle USP change) ... but conspicuous by its absence is any mention of drop tanks modifying anything else (such as the 2% for bridge tonnage allocation).

LBB5'80 is not consistent and seems to use tonnage, hull tonnage, ship's tonnage, and tonnage of the ship somewhat haphazardly.

Mainly because the design paradigm of LBB2 (and therefore by extension, LBB5) was for "internal" bookkeeping of tonnage for hulls. The lack of "external" bookkeeping for tonnage outside of hulls (docking, towing, etc.) is something you won't miss if you never intended to use it, but it becomes glaringly obvious as soon as you introduce external loading factors such as drop tanks and cargo pods (or anything else that requires accounting for external tonnage, regardless of contents).

The whole external load capacity question is totally a blind spot in the CT ship design rules (mainly by turning a blind eye away from the problem and ignoring it) ... so the best a Referee can do is interpolate and infer their way to a solution.