The Xboat is a HG2 design

[robject]

So the Xboat is a High Guard 2 design.

There are mentions in 1979, but there is one detail I'm hanging this on:

High Guard 2 specifically calls out express boats as not having maneuver (p.22), but High Guard 1 does not mention them at all.

So the Xboat's design was presumably conceived after HG1 came out, and before HG2 came out. 1979-1980.

The 1977 Book 2 element, permitted specifically on p22, allows the jump drive to function without a power plant.

1979 - AD01 Kinunir - "Express Boat": library data, no specs.
1979 - Supp03 SpinMar - "Xboat": short library data, no specs.
1979 - JTAS No. 2 - mention of installing Jump-6 L-Hyd express boats in the Marches.


Traders & Gunboats specifically says:

PowerPlant: None. Jump drives carry power plant capacities and functions.

This is likely a use of the "custom-built" and "Book 2" drives clauses on page 22.

Going on the Traders & Gunboats deckplan (and I understand that deckplans are always suspect), I can guesstimate 5 tons for "message data banks" and 8 tons for "communications" equipment, leaving 7 tons of bridge space for control stations.

Xboat Designs

HG1                        HG2     T5
Vol   Component            Vol     Vol
----- ------------------ -----   -----
(100) Hull               (100)   (100)
   5  Jump-4               15*     18   (T5: self-powered jump drive)
   4  Power-4               *   
  44  Fuel                 40      40
   1  Computer              4       4 
   8  Staterooms            8      12   (T5: 2x suites)
  20  Bridge               20       8
  **  Message data banks   **       -
  **  Communications eq.   **      15   (T5: Deep-Space Communicator Barbette)
   1                        1       1   Cargo
----- ------------------ -----  -----
  17  TONS FREE            12       2

* '77 Book 2 drives allowed for HG2 only by p22.
** Classic Traveller uses bridge volume for communications and data banks, etc.

 

[robject]

The Traveller5 version uses my custom designed "Self-Powered" jump drive, which uses the idea of '77 Book 2 but is a little bit larger.

I also mount a communicator on a barbette hardpoint and give it the furthest range possible, thereby eating up most of the remaining free volume very nicely.

I note that Classic Traveller uses bridge tonnage to account for communications and data storage equipment.

 

[Spinward Flow]

You're still not reconciling an obvious problem.

The Express Network (Tenders and XBoats both!) relies on TL=10.
LBB5 (either version) Jump-4 drives require TL=13.

Star Peg vs Triangle Hole
Round 1
FIGHT!



It is not possible to build a J4 XBoat under LBB5 (either version) at TL=10 without resorting to use of LBB2 drives (specifically, LBB2.77) to get the job done.

AT BEST ... you're looking at a LBB5.79 design relying on LBB2.77 drives with no jump governor (so the jump drives consume 40 tons of fuel every time regardless of parsecs jumped) in order to meet the TL=10 requirement.

There is simply no other way to reconcile the issue of the Express Network being capable of Jump-4 since inception by Empress Arbellatra from 624 up through 1105 (some 480 years or so). For one thing, the Third Imperium only HAD TL=12 at the time the Express Network was founded in 624 and wouldn't have had enough TL=11-12 worlds scattered "here there and everywhere" in order to support the logistics demands of a far flung communications network spanning 20+ sectors of the Third Imperium.

Additionally, the canon sources have never referenced any kind of "upgrade" of the network from Jump-2 (Type-S Scout/Couriers to start with) to Jump-4 (XBoats) at some later date after the network got built out so as to allow enough time to pass for higher tech levels to come along and support a TL=13 J4 XBoat construction. Opportunities for such historical sourcing of info has been almost overwhelming ... and yet NONE of them make any reference or hint or even a head fake in this direction of "start with what you've got (Type-S) then streamline everything later into a better upgraded network (Type-X)" at any point.

Additionally, there are notable points of astrogation where 2 parsecs of range is simply DISQUALIFYING as being insufficient to the necessary distances involved (I'm thinking 3-4 parsec gaps between stars, such as the Abyss Rift in the Lanth subsector of the Spinward Marches as merely one example). There are simply too many 3-4 parsec gaps in the maps for a mere 2 parsec range to function properly/reliably as an initial build out phase for the Express Network.



Other versions of Traveller besides CT no doubt rely upon different rules and combinations ... but with CT, you're basically stuck with LBB2.77 drives exclusively.

 

[whulorigan]

I also mount a communicator on a barbette hardpoint and give it the furthest range possible, thereby eating up most of the remaining free volume very nicely.

Would a Commcaster in a Barbette be more useful for the X-Boat for coordinating comms traffic and data between itself and its Tenders?
(See T5.1 Book 2 p. 163 "Sensors in Missiles" sidebar, "Relay Mode" (toward bottom) - note about Commcasters and Communication).

 

[whulorigan]

There is simply no other way to reconcile the issue of the Express Network being capable of Jump-4 since inception by Empress Arbellatra from 624 up through 1105 (some 480 years or so). For one thing, the Third Imperium only HAD TL=12 at the time the Express Network was founded in 624 and wouldn't have had enough TL=11-12 worlds scattered "here there and everywhere" in order to support the logistics demands of a far flung communications network spanning 20+ sectors of the Third Imperium.

The Third Imperium had late TL-13 in 624.
The Imperium was TL-14 by the 700's.

 

[mike wightman]

And those are for the civilian rollout of those TLs. Agent of the Imperium shows that the Imperium had jump 5 TL14 ships in the 400s and TL15 jump 6 in the 700s.

 

[whartung]

I also mount a communicator on a barbette hardpoint and give it the furthest range possible, thereby eating up most of the remaining free volume very nicely.

"That? Why that's a 250MW Communication laser..."

 

[Spinward Flow]

The Third Imperium had late TL-13 in 624.
The Imperium was TL-14 by the 700's.

But how widely spread were those tech levels?
It's fine to say that TL=15 is "available" (for example) ... but then you look at places such as the Spinward Marches and there's only 4 TL=15 worlds in the entire sector in 1105 out of hundreds. It's a similar story in Verge sector where there's a scattering of TL=15 around the sector, but it is by no means "commonplace everywhere" and readily obtainable within 2 jumps of every star system.

The Express Network can't logistically support itself on the bleeding edge of technology like the Imperial Navy can.
The IISS Communications Office needs to be "low tech enough" in their operations requirements to be widely supportable throughout the length of breadth of the Third Imperium using local suppliers limited to local tech levels. That needs to be true both within the core sectors and out on the fringes in order to streamline operations through commonality of design so you have a unified system rather than a hi/lo patchwork mess.

 

[mike wightman]

Those are the TLs when the Imperium as a whole was considered to be TL13 or TL14.

The Imperium was TL12 in year 0, it achieved widespread TL13 by 300 and TL 14 by 700, and as I noted earlier cutting edge TL was significantly higher.

 

[robject]

The trickiness is in High Guard's own rules. The loophole... I am willing to bet 25 cents that that loophole was created precisely for the sake of the Xboat, and that the Xboat was one of the initial ships designed using HG2.

Custom-built drives must be produced and installed while observing restrictions as to tech level and interior space. It is possible to include standard drives (at standard prices) from Book 2 if they will otherwise meet the ship's requirements; such drives use fuel as indicated by the formulas in Book 2.

It was pointed out to me today that "Book 2" back then meant 1977 Book 2. That means the Xboat indeed doesn't have jump governors. Page 10, Traders & Gunboats, implies this:

Fuel tankage is forty tons, enough for one jump.

The X-boat network sheds light on the ship's ability to jump fewer than 4 parsecs. It still takes all 40 tons of fuel, of course.


It doesn't mean WE are constrained to 1977 Book 2. It does mean that we are free to use 1977 or 1981 Book 2 in HG2 where we want it.

 

[robject]

I'm gonna ask Marc. Inquiring minds want to know.

 

[whartung]

I'm gonna ask Marc. Inquiring minds want to know.

Doesn't he just stare at you, facepalm, sigh, and go "what the heck are you people blathering on about?"

 

[robject]

Doesn't he just stare at you, facepalm, sigh, and go "what the heck are you people blathering on about?"

LOL He's nicer than that, and he is a sort of Traveller geek too, but he does admit that many things are vague because they didn't -- and don't -- know.

 

[Grav_Moped]

... which is to be expected. We're still kicking this around forty years after they thought they were done with it (at least at first).

I mean, who expects to have to address four decades of play-testing?

 

[AnotherDilbert]

So the Xboat is a High Guard 2 design.
...
This is likely a use of the "custom-built" and "Book 2" drives clauses on page 22.

The Xboat is explicitly a LBB2 design:

The Xboat is not a "legal" HG'80 design:

Drives: Three types of drives are required for starships- maneuver drives, power plants, and jump drives. Non-starships may omit the jump drives. Some ships (such as express boats) omit the maneuver drives. All ships require power plants.

"Custom-built" drives are HG drives, "standard" drives are LBB2 drives:

Custom-built drives must be produced and installed while observing restrictions as to tech level and interior space. It is possible to include standard drives (at standard prices) from Book 2 if they will otherwise meet the ship's requirements; such drives use fuel as indicated by the formulas in Book 2.

Standard drives are not magical objects producing power from thin air.

Note that all ships require a power plant already in LBB2'77:

The Engineering Section: Each starship is fitted with a power plant (to provide internal power and power for the maneuver drive), a maneuver drive (for interplanetary travel), and a jump drive (for interstellar jumps). Each is essential to the definition of a starship.

Someone made an exception for the Xboat; it can't be designed under the standard rules, anymore than the Modular Cutter can.

 

[AnotherDilbert]

The size and cost of the data banks and comms are taken out of thin air:

Single Occupancy    LBB2 design                     1        78,5
                                     USP    #     Dton       Cost
Hull, Part Streaml  Custom             1          100           
Configuration       Sphere             5                     20 
                                                                
Jump Drive          B                  4    1      15        20 
Power Plant                                                     
Fuel, #J, #weeks    J-4, 0 weeks            4      40           
                                                                
Bridge                                      1      20         0,5
Computer            m/1bis             R    1       1         4 
Data&Comms                                  1      15        33 
                                                                
Staterooms                                  2       8         1 
                                                                
Cargo                                               1           
                                                                
Nominal Cost        MCr 78,50            Sum:       1        78,5
Class Cost          MCr  8,64           Valid      ≥0          ≥0
Ship Cost           MCr 70,65

Note that the XBoat has a m1/bis computer on S7 p9, but a m/4 on page 10...

 

[AnotherDilbert]

It was pointed out to me today that "Book 2" back then meant 1977 Book 2. That means the Xboat indeed doesn't have jump governors. Page 10, Traders & Gunboats, implies this:

S7, p9:


The Xboat lives in a grey zone between LBB2'77 and LBB2'81, and can't quite make it's mind up (as with the computer).

 

[Spinward Flow]

LBB5.80 incorporating LBB2.81 drives:

---

TL=10
Tonnage (custom hull): 100 tons
Configuration: 5 (Sphere, partial streamlining, MCr7)
Fuel Scoops: None
Armor: 0
Jump-B (code: 4, 15 tons, MCr20, TL: 9, Capacitor storage: 2 tons = 72 EP maximum)
Maneuver-NONE
Power Plant-B (code: 4, 7 tons, MCr16, TL: 9, EP: 4, Agility 0)
Total Drives: 15+7=22 tons
Fuel: 45 tons (4 parsecs = 40 tons) (3.5 days operations = 5 tons, 14 days powered down)
Bridge (20 tons, MCr0.5)
Computer: 4 (Code: 4, 4 tons, MCr30, TL: A, EP: 2)
Crew required: Pilot
Staterooms: 2 single occupancy (8 tons, MCr1)
Cargo: 1 ton

15+7+45+20+4+8+1 = 100 tons
7+20+16+0.5+30+1 = MCr74.5 base cost for single production

X-1540441-000000-00000-0

---

Power plant and computer only need to be run "at full power demand" briefly in order to initiate jump, so for probably about 1 hour, rather than continuously at all times for an entire month.

The rest of the time spent during jump there are no ship systems requiring EP other than the computer and the computer can be put into "power conservation mode" so as to only need to draw EP: 1 instead of EP: 2 in order to sustain computer functions while in jump space (functions at model/3 capacity for CPU/Storage).

With the computer needing less EP, the power plant can be powered down from code: 4 to code: 1 for the duration of time spent in jump space, extending the 3.5 days of power plant fuel endurance from 3.5 days out to 14 days in total. This reduction in power plant fuel requirement is only possible due to the organization of the Express Network standard operations involving Tender recovery of Express Boats after breakout from jump. The 14 days powered down endurance is sufficient for the needs of an Express Boat that could spend up to 3 days on ready standby waiting for authorization to jump outbound with communications, spend 7 days in jump and still have 3 days of power plant fuel endurance to await rendezvous and recovery by an Express Tender at the destination. Given the decidedly "non-standard" mission profile executed by Express Boats in coordination with Express Tender recovery standard procedures, the typical 28 day minimum power plant fuel endurance requirement was waived.

Although the B-drives used require only TL=9 to construct (and maintain) and the computer model/4 requires only TL=A to construct (and maintain), a society constructing Express Boat starships like these must first unlock the secrets of higher Jump capacities at TL=11 (J2), TL=12 (J3) and TL=13 (J4) before the LBB2.81 standard drives used can be "tuned/enabled" for Jump-2/3/4 performance. Until the requisite advancements in jump technology research are completed, understood, propogated and disseminated for incorporation into standard engineering practices, the Jump-B standard drive will be forced to operate at below theoretical maximum jump capacity ... although "unlocking/enabling" of higher performance at a later date for the "designed in growth margin" is perfectly possible.

---

So basically, the Express Boat requires a "house rule" (that makes sense, given the standard operational context) loophole in the power plant fuel formula as a matter of lateral thinking with regards to a reasonably defined specific context. Given that an Express Boat is just about as "non-combatant" as it gets in the field of starship design, the whole idea that the power plant and computer do not need to be running "full blast" continuously at all times makes perfect sense. Owing to the limitations of the mission profile, "full power" from the power plant and computer are only needed in short bursts that will usually only last for a few hours at most during each refueling cycle in coordination with Express Tender servicing, so a "power conservation mode" to extend the limited power plant fuel supply long enough to cover standard operations between bursts of full power consumption makes a lot of sense. However it is certainly a performance profile that cannot be usefully applied to almost any other class of starship as a matter of routine, so the reduced fuel endurance requirement for Express Boats is an explicit carve out exception to the general rule made possible by the explicit Express Tender recovery context.

Without a recovery by an Express Tender, crews (and passengers, if any) cannot expect to survive long without a fast rescue effort (within days of breakout from jump). Such is the price of offloading most of a starship's endurance margin onto a Tender operation (that will usually be there within the available margin of time).

 

[AnotherDilbert]

LBB5.80 incorporating LBB2.81 drives:

---

...
Fuel: 45 tons (4 parsecs = 40 tons) (3.5 days operations = 5 tons, 14 days powered down)

Very much house ruled, just like the power plant-less version:

At a minimum, ship fuel tankage must equal 0.1MJn+10Pn, where M is the tonnage of the ship, Jn is the ship's jump number, and Pn is the ship's power plant rating.

Just use a HG power plant with the LBB2 jump drive:

XB-1540441-000000-00000-0       MCr 75,2         100 Dton
bearing                                            Crew=1
batteries                                           TL=10
                           Cargo=1 Fuel=44 EP=4 Agility=0

Single Occupancy                                    1        94
                                     USP    #     Dton       Cost
Hull, Part Streaml  Custom             1          100          
Configuration       Sphere             5                      7
                                                               
Jump Drive          B                  4    1      15        20
Manoeuvre D                                                    
Power Plant                            4    1      12        36
Fuel, #J, #weeks    J-4, 4 weeks            4      44          
                                                               
Bridge                                      1      20         0,5
Computer            m/4                4    1       4        30
                                                               
Staterooms                                  1       4         0,5
                                                               
Cargo                                               1          
                                                               
Nominal Cost        MCr 94,00            Sum:       1        94
Class Cost          MCr 19,74           Valid      ≥0          ≥0
Ship Cost           MCr 75,20

 

[mike wightman]

Under your interpretation of the rules you have to include a maneuver drive in a LBB2 design, omitting a maneuver drive is not allowed since it says you have to install all three for a starship.
The fudge comes from:
"The installed power plant must be of a letter type at least equal to the drive letter of the installed maneuver drive"
so no maneuver drive, no power plant.