Bringing the Book-2 ships into a Book-5 milieu

[Carlobrand]

One of my pet peeves for the longest time has been the disjunct between Book 2 ships and Book 5 ships, with the Book 2 ships on the one hand making no sense because of that odd power plant fuel rule and on the other hand being necessary because Book 5 has trouble making a profitable low-tech merchantman.

One convention I adopted was to allow import and export of ship parts, so that the shipyards can construct ships that would ordinarily be beyond their tech level. It means that a TL9 shipyard can built the 90% of the ship that is within its local tech and then import the power plant to finish the job, rather than try to sell something no one wants or lose the whole job to a world with better tech. The power plant tends to set the tech level of unarmored ships, since it varies in cost and size with tech level. Accompanying that, I limited civilian tech to TL13 and limited civilian weapons except sandcasters to TL7 (ostensibly to keep civilian ships from being targeted by privateers for their tech, since the neighboring polities don't have access to TL15 goodies and might be a bit less eager to take a prize if they had to bring it back to retrofit better weapons, and it keeps the civilian ships from having an edge over local governments).

The other involves creating a variant of the two most common Book-2 fusion plants. The only ships I cared to rescue from Book 2 were the Free Trader and the Subsidized Merchant; that simplified things since I didn't have to deal with the disparities found in the larger plants; a few others came along for the ride, but these were the focus. To accomplish my goal I calculated what a power plant would mass and cost if the ship were built using HG-80 maneuver and jump drives but had the same cost, cargo capacity, and so forth as the Book-2 ship, then I created such a plant. The result would be a ship that cost the same as the Book-2 version, with the same performance, but mounting a unique, lower cost but somewhat inferior power plant, the Book-2 plants burning a lot more fuel than their Book 5 counterparts. I took the name from a mention in the deckplan of the Far Trader in Supplement 7. The result is:

The Halonic Prime is a TL8 MCr4 7dT fusion plant common on low-tech worlds as an alternative to conventional fusion technology. The plant generates 500 Mw but consumes fuel at a rate 5 times greater than conventional fusion plants. The Halonic Prime is seen in the Free Trader, Scout/Courier, and Yacht.

The method produces one departure from canon, other than the plant itself: a Halonic Scout/Courier carries 8 weeks of power plant fuel and costs MCr28.53.

The Halonic Duplex is a TL8 MCr8, 9 dT fusion plant, likewise common on low tech worlds, that generates 1000 Mw but likewise consumes fuel at a rate 5 times greater than conventional fusion plants. The Halonic Duplex is found in the Far Trader, Subsidized Merchant, Safari Ship, Vargr Trader, and X-boat.

(This plant produces these departures from canon, other than the plant itself:

• A Duplex Far Trader costs MCr59.4.
• A Duplex Subsidized Merchant carries a 2-week supply of fuel instead of a 4-week supply. Most subsidized merchants take advantage of the extra space in the 50 dT drive compartment, adding a 10 dT auxiliary fuel tank there so the ship has 4 weeks plant fuel available.
• A Duplex Safari Ship has a 10-dT cargo capacity. Cost is MCr72.99.
• A Duplex Vargr Trader costs MCr58.59.

I did up a duplex x-boat but, since the Book-5 X-boat comes in at TL13, it wasn't worth it. The HG x-boat had 15 dTons to play with at MCr65.6 with a 28-day supply of power plant fuel, while the variant Duplex had 6 dTons to play with at MCr59.85 with a 10-day supply of power plant fuel.

 

[mike wightman]

There are a couple of other options.

1 - keep LBB2 ship construction apart from pp fuel, use the formula from HG for the pp fuel but set a minimum tonnage.
2 - reduce the cost of lower TL pp in HG so that low TL plants are big and cheap while high TL plants are smaller but more expensive,

 

[AnotherDilbert]

Even with the vastly cheaper special PP an LBB5 Free trader is not competitive, despite with larger payload:


LBB2 Free Trader, MCr 37:

FT-2211111-000000-00000-0       MCr 37,1         200 Dton
bearing                                            Crew=4
batteries                                            TL=9
            Pass=6 Low=20 Cargo=82 Fuel=30 EP=2 Agility=1

Single Occupancy    LBB2 design                    82        41,2
                                     USP    #     Dton       Cost
Hull, Streamlined      200 Dt          2          200            
Configuration       Cone               2                     10  
Scoops              Streamlined                                  

Jump Drive          A                  1    1      10        10  
Manoeuvre D         A                  1    1       1         4  
Power Plant         A                  1    1       4         8  
Fuel, #J, #weeks    J-1, 4 weeks            1      30            
                                                                 
Bridge                                      1      20         1  
Computer            m/1                1    1       1         2  
                                                                 
Staterooms                                 10      40         5  
Low Berths                                 20      10         1  
                                                                 
Cargo                                              82            
                                                                 
Empty hardpoint                             2       2         0,2
                                                                 
Nominal Cost        MCr 41,20            Sum:      82        41,2
Class Cost          MCr  4,53           Valid      ≥0          ≥0
Ship Cost           MCr 37,08                                    
                                                                 
                                                                 
Crew &               High     3        Crew          Bridge     1
Passengers            Mid     3           4       Engineers     1
                      Low    20                     Gunners     0
                 Extra SR     0      Frozen         Service     2
                                                                 
                                                                 
Estimated Economy of Ship     Standard                                     
       Ship price     Down Payment         Mortgage       Avg Filled
        MCr 37,08        kCr 7 416          kCr 155              80%
                                                                 
Expenses per jump                       Revenue                  
Bank                 Cr 74 160          High            Cr 24 000
Fuel                 Cr 15 000          Middle          Cr 19 200
Life Support         Cr 19 600          Low             Cr 16 000
Salaries             Cr  7 200          Cargo           Cr 64 000
Maintenance          Cr  1 483                                   
Berthing             Cr    200                                   
                                                                 
Summa               kCr    118                         kCr    123
                                                                 
     Income potential per jump     kCr 6                    
  Yearly yield on down payment      1,9%

LBB5 Hybrid Free Trader, MCr 46:

QN-2200011-000000-00000-0       MCr 45,8         200 Dton
bearing                                            Crew=4
batteries                                            TL=9
            Pass=6 Low=20 Cargo=90 Fuel=22 EP=0 Agility=0

Single Occupancy                                   90        57,2
                                     USP    #     Dton       Cost
Hull, Streamlined   Custom             2          200            
Configuration       Cone               2                     22  
Scoops              Streamlined                               0,2
                                                                 
Jump Drive                             1    1       4        16  
Manoeuvre D                            1    1       4         6  
Power Plant         Halonic Prime      1    1       7         4  
Fuel, #J, #weeks    J-1, 4 weeks            1      22            
                                                                 
Bridge                                      1      20         1  
Computer            m/1                1    1       1         2  
                                                                 
Staterooms                                 10      40         5  
Low Berths                                 20      10         1  
                                                                 
Cargo                                              90            
                                                                 
Empty hardpoint                             2       2            
                                                                 
Nominal Cost        MCr 57,20            Sum:      90        57,2
Class Cost          MCr 12,01           Valid      ≥0          ≥0
Ship Cost           MCr 45,76                                    
                                                                 
                                                                 
Crew &               High     3        Crew          Bridge     1
Passengers            Mid     3           4       Engineers     1
                      Low    20                     Gunners     0
                 Extra SR     0      Frozen         Service     2
                                                                 
                                                                 
Estimated Economy of Ship     Standard                                     
       Ship price     Down Payment         Mortgage       Avg Filled
        MCr 45,76        kCr 9 152          kCr 191              80%
                                                                 
Expenses per jump                       Revenue                  
Bank                 Cr 91 520          High            Cr 24 000
Fuel                 Cr 11 000          Middle          Cr 19 200
Life Support         Cr 19 600          Low             Cr 16 000
Salaries             Cr  7 200          Cargo           Cr 72 000
Maintenance          Cr  1 830                                   
Berthing             Cr    200                                   
                                                                 
Summa               kCr    131                         kCr    131
                                                                 
     Income potential per jump     kCr 0                    
  Yearly yield on down payment      0,0%

 

[mike wightman]

Yup, you really need to import the reduced cost standard hull as well.

 

[AnotherDilbert]

The Far Trader is superior with the special PP with lower price and larger payload:


LBB2 Far Trader, MCr 66, 48 Dton cargo:

FT-22212R1-000000-00000-0       MCr 65,8         200 Dton
bearing                                            Crew=4
batteries                                            TL=9
             Pass=6 Low=4 Cargo=48 Fuel=60 EP=4 Agility=1

Single Occupancy    LBB2 design                    48        73  
                                     USP    #     Dton       Cost
Hull, Streamlined   Custom             2          200            
Configuration       Cone               2                     22  
Scoops              Streamlined                                  
                                                                 
Jump Drive          B                  2    1      15        20  
Manoeuvre D         A                  1    1       1         4  
Power Plant         B                  2    1       7        16  
Fuel, #J, #weeks    J-2, 4 weeks            2      60            
                                                                 
Bridge                                      1      20         1  
Computer            m/1bis             R    1       1         4  
                                                                 
Staterooms                                 10      40         5  
Low Berths                                  4       2         0,2
                                                                 
Cargo                                              48            
                                                                 
Empty hardpoint                             2       2         0,2
                                                                 
Air/raft            4 Dton                  1       4         0,6
                                                                 
Nominal Cost        MCr 73,00            Sum:      48        73  
Class Cost          MCr  7,96           Valid      ≥0          ≥0
Ship Cost           MCr 65,76                                    
                                                                 
                                                                 
Crew &               High     3        Crew          Bridge     1
Passengers            Mid     3           4       Engineers     1
                      Low     4                     Gunners     0
                 Extra SR     0      Frozen         Service     2
                                                                 
                                                                 
Estimated Economy of Ship     Standard                                     
       Ship price     Down Payment         Mortgage       Avg Filled
        MCr 65,76       kCr 13 152          kCr 274              80%
                                                                 
Expenses per jump                       Revenue                  
Bank                Cr 131 520          High            Cr 24 000
Fuel                Cr  30 000          Middle          Cr 19 200
Life Support        Cr  18 000          Low             Cr  3 200
Salaries            Cr   7 200          Cargo           Cr 36 000
Maintenance         Cr   2 630                                   
Berthing            Cr     200                                   
                                                                 
Summa              kCr     190                         kCr     82
                                                                 
     Income potential per jump     kCr -107                    
  Yearly yield on down payment     -20,4%

LBB5 hybrid Far Trader, MCr 58, 60 Dton cargo:

FT-22212R1-000000-00000-0       MCr 57,6         200 Dton
bearing                                            Crew=4
batteries                                           TL=11
            Pass=6 Low=20 Cargo=60 Fuel=44 EP=4 Agility=1

Single Occupancy                                   60        71,8
                                     USP    #     Dton       Cost
Hull, Streamlined   Custom             2          200            
Configuration       Cone               2                     22  
Scoops              Streamlined                               0,2
                                                                 
Jump Drive                             2    1       6        24  
Manoeuvre D                            1    1       4         6  
Power Plant                            2    1       9         8  
Fuel, #J, #weeks    J-2, 4 weeks            2      44            
                                                                 
Bridge                                      1      20         1  
Computer            m/1bis             R    1       1         4  
                                                                 
Staterooms                                 10      40         5  
Low Berths                                 20      10         1  
                                                                 
Cargo                                              60            
                                                                 
Empty hardpoint                             2       2            
                                                                 
Air/raft            4 Dton                  1       4         0,6
                                                                 
Nominal Cost        MCr 71,80            Sum:      60        71,8
Class Cost          MCr 14,95           Valid      ≥0          ≥0
Ship Cost           MCr 57,56                                    
                                                                 
                                                                 
Crew &               High     3        Crew          Bridge     1
Passengers            Mid     3           4       Engineers     1
                      Low    20                     Gunners     0
                 Extra SR     0      Frozen         Service     2
                                                                 
                                                                 
Estimated Economy of Ship     Standard                                     
       Ship price     Down Payment         Mortgage       Avg Filled
        MCr 57,56       kCr 11 512          kCr 240              80%
                                                                 
Expenses per jump                       Revenue                  
Bank                Cr 115 120          High            Cr 24 000
Fuel                Cr  22 000          Middle          Cr 19 200
Life Support        Cr  19 600          Low             Cr 16 000
Salaries            Cr   7 200          Cargo           Cr 48 000
Maintenance         Cr   2 302                                   
Berthing            Cr     200                                   
                                                                 
Summa              kCr     166                         kCr    107
                                                                 
     Income potential per jump     kCr -59                    
  Yearly yield on down payment     -12,9%

 

[AnotherDilbert]

Sorry, I see no parity, just random tinkering with the system...

 

[AnotherDilbert]

Yup, you really need to import the reduced cost standard hull as well.

Agreed, you can't compare small LBB2 and LBB5 designs without taking standard hulls into consideration.

On the other hand LBB5 has a larger standard discount and fuel purifiers...

 

[AnotherDilbert]

Note: We can build reasonable low tech traders with LBB5, just use LBB2 drives, e.g.:

FT-2611111-000000-00000-0       MCr 37,8         200 Dton
bearing                                            Crew=4
batteries                                            TL=9
            Pass=6 Low=20 Cargo=82 Fuel=30 EP=2 Agility=1

Single Occupancy                                   82        47,2
                                     USP    #     Dton       Cost
Hull, Streamlined   Custom             2          200            
Configuration       Flattened Sphe     6                     16  
Scoops              Streamlined                               0,2
                                                                 
Jump Drive          A                  1    1      10        10  
Manoeuvre D         A                  1    1       1         4  
Power Plant         A                  1    1       4         8  
Fuel, #J, #weeks    J-1, 4 weeks            1      30            
                                                                 
Bridge                                      1      20         1  
Computer            m/1                1    1       1         2  
                                                                 
Staterooms                                 10      40         5  
Low Berths                                 20      10         1  
                                                                 
Cargo                                              82            
                                                                 
Empty hardpoint                             2       2            
                                                                 
Nominal Cost        MCr 47,20            Sum:      82        47,2
Class Cost          MCr  9,91           Valid      ≥0          ≥0
Ship Cost           MCr 37,76                                    
                                                                 
                                                                 
Crew &               High     3        Crew          Bridge     1
Passengers            Mid     3           4       Engineers     1
                      Low    20                     Gunners     0
                 Extra SR     0      Frozen         Service     2
                                                                 
                                                                 
Estimated Economy of Ship     Standard                                     
       Ship price     Down Payment         Mortgage       Avg Filled
        MCr 37,76        kCr 7 552          kCr 157              80%
                                                                 
Expenses per jump                       Revenue                  
Bank                 Cr 75 520          High            Cr 24 000
Fuel                 Cr 15 000          Middle          Cr 19 200
Life Support         Cr 19 600          Low             Cr 16 000
Salaries             Cr  7 200          Cargo           Cr 64 000
Maintenance          Cr  1 510                                   
Berthing             Cr    200                                   
                                                                 
Summa               kCr    119                         kCr    123
                                                                 
     Income potential per jump     kCr 4                    
  Yearly yield on down payment      1,4%

Yes, it is almost identical to the LBB2 Free Trader, but with a different configuration, we annoyingly need new deck plans.



We can increase profitability with a fuel purifier:

FT-2611111-000000-00000-0       MCr 37,8         200 Dton
bearing                                            Crew=4
batteries                                            TL=9
            Pass=6 Low=20 Cargo=73 Fuel=30 EP=2 Agility=1

Single Occupancy                                   73        47,2
                                     USP    #     Dton       Cost
Hull, Streamlined   Custom             2          200            
Configuration       Flattened Sphe     6                     16  
Scoops              Streamlined                               0,2
                                                                 
Jump Drive          A                  1    1      10        10  
Manoeuvre D         A                  1    1       1         4  
Power Plant         A                  1    1       4         8  
Fuel, #J, #weeks    J-1, 4 weeks            1      30            
Purifier                                    1       9         0,0
                                                                 
Bridge                                      1      20         1  
Computer            m/1                1    1       1         2  
                                                                 
Staterooms                                 10      40         5  
Low Berths                                 20      10         1  
                                                                 
Cargo                                              73            
                                                                 
Empty hardpoint                             2       2            
                                                                 
Nominal Cost        MCr 47,24            Sum:      73        47,2
Class Cost          MCr  9,92           Valid      ≥0          ≥0
Ship Cost           MCr 37,79                                    
                                                                 
                                                                 
Crew &               High     3        Crew          Bridge     1
Passengers            Mid     3           4       Engineers     1
                      Low    20                     Gunners     0
                 Extra SR     0      Frozen         Service     2
                                                                 
                                                                 
Estimated Economy of Ship     Standard                                     
       Ship price     Down Payment         Mortgage       Avg Filled
        MCr 37,79        kCr 7 558          kCr 157              80%
                                                                 
Expenses per jump                       Revenue                  
Bank                 Cr 75 584          High            Cr 24 000
Fuel                 Cr  3 000          Middle          Cr 19 200
Life Support         Cr 19 600          Low             Cr 16 000
Salaries             Cr  7 200          Cargo           Cr 56 000
Maintenance          Cr  1 512                                   
Berthing             Cr    200                                   
                                                                 
Summa               kCr    107                         kCr    115
                                                                 
     Income potential per jump     kCr 8                    
  Yearly yield on down payment      2,7%

And we don't have to misjump every year or two...

 

[creativehum]

that odd power plant fuel rule...

Is this about the 10Pn from the fuel requirements?

 

[boomslang]

Is this about the 10Pn from the fuel requirements?

Yeah; operationally, it's often much more fuel than smaller ships actually use in practice (cf. Beltstrike).

As per page 11 of the Belter's Handbook, a 100dt, Plant-2 Type S which "must" carry 20dt of fuel to support 4 weeks of power plant operations typically burns through less than 1 dton of fuel per week even if you constantly hotdog it around at 2Gs.

Plus, if you hack a Type S into a Type J, you are either breaking the Jump fuel requirement or the power fuel requirement. I always figure that 10Pn is a rule-of-thumb safety regulation, rather than a descriptive metric. At 30 dtons total, a Type J does in fact carry 10Pn in available fuel -- 20dt -- but operators often fly around on less, having burned a full 20 dtons to make a J-2 previously. The 30 dtons of fuel a Type J carries by default in integral tankage meets both the Jump fuel and power plant fuel guidelines, just not combined, so I figure the ship is granted its spaceworthiness certificate and allowed to operate from starports with 20dt to meet either requirement and 10dt left over to partially satisfy the other, as needed by the varying particulars of how it is operated.

Finally, there is the weird problem that -- for example -- a model A power plant "needs" 20dt of fuel to operate in a Type S, but the exact same drive only requires 10 dtons when installed in a Type A. The rule assumes the Model A power plant drives the same model A M-drive at the same output -- 200Gee-tons -- somehow twice as efficiently in the bigger ship, Beltstrike notwithstanding.

And in both cases, the power plant is apparently really only using ~.75 dtons of fuel a week, tops. The 20dt a Type S carries should be good for not merely 4 weeks, but more like 26 weeks -- half a year or so. (Which is not a big deal, since fuel for a Type S can often be had for free anyway.)

Hence the definite "oddnesss" of the rule...

 

[Grav_Moped]

Yeah; operationally, it's often much more fuel than smaller ships actually use in practice (cf. Beltstrike).

As per page 11 of the Belter's Handbook, a 100dt, Plant-2 Type S which "must" carry 20dt of fuel to support 4 weeks of power plant operations typically burns through less than 1 dton of fuel per week even if you constantly hotdog it around at 2Gs.

Plus, if you hack a Type S into a Type J, you are either breaking the Jump fuel requirement or the power fuel requirement. I always figure that 10Pn is a rule-of-thumb safety regulation, rather than a descriptive metric. At 30 dtons total, a Type J does in fact carry 10Pn in available fuel -- 20dt -- but operators often fly around on less, having burned a full 20 dtons to make a J-2 previously. The 30 dtons of fuel a Type J carries by default in integral tankage meets both the Jump fuel and power plant fuel guidelines, just not combined, so I figure the ship is granted its spaceworthiness certificate and allowed to operate from starports with 20dt to meet either requirement and 10dt left over to partially satisfy the other, as needed by the varying particulars of how it is operated.

Finally, there is the weird problem that -- for example -- a model A power plant "needs" 20dt of fuel to operate in a Type S, but the exact same drive only requires 10 dtons when installed in a Type A. The rule assumes the Model A power plant drives the same model A M-drive at the same output -- 200Gee-tons -- somehow twice as efficiently in the bigger ship, Beltstrike notwithstanding.

And in both cases, the power plant is apparently really only using ~.75 dtons of fuel a week, tops. The 20dt a Type S carries should be good for not merely 4 weeks, but more like 26 weeks -- half a year or so. (Which is not a big deal, since fuel for a Type S can often be had for free anyway.)

Hence the definite "oddnesss" of the rule...

Seems to me that the Beltstrike fuel consumption rules were built with High Guard ships in mind (at the very least, written so they wouldn't invalidate HG designs), which is why they look silly when applied to a converted Type S.

I still think the Type S has the extra fuel for Jump purposes (this is non-canon and requires some apparently dubious rules interpretations).

It can do a J1 and a J2 consecutively by only using the powerplant at Pn-2 during the week in J-2.

Or, it can do an emergency J-1 from just outside the 10D limit (and with Pn-2, do it in one HG turn instead of two), accept the misjump, and still have a chance of re-entering normal space with enough fuel to Jump to a self-rescue. ("So you're saying there's a chance?")

It's extremely high-risk, but the Type S is such a woefully poor combat platform that its odds of surviving a running battle to the 100D limit make a misjump the less-risky option...

 

[mike wightman]

Type A pp/md m-rating/fuel requirement 2g/20t in a 100t ship, 1g/10t in a 200t ship.

My explanation - the maneuver drive field (which encompasses the volume of the ship) reduces the inertial mass of the ship such that in a 100t ship the thrust component of the engine (fusion rocket) can achieve 2g. Put the same engine/machinery in a ship with twice the volume/mass and you can only achieve 1g so you use less 'fuel' reaction mass.

Note
1 the ships in Beltstrike are LBB2 designs, even the 5000t mining platform is described as having type W drives.
2 in original CT 77 the pp fuel was replaced every jump as well as the jump fuel, there was no four week duration.

 

[boomslang]

Seems to me that the Beltstrike fuel consumption rules were built with High Guard ships in mind (at the very least, written so they wouldn't invalidate HG designs), which is why they look silly when applied to a converted Type S.

I am not at all convinced of that explicitly as such. The Type J is included right there in the module; the only tacit acknowledgement of High Guard in Beltstrike is the mention that 5000-dton Type NS Mining Platforms get transported to the systems in which they are stationed by some sort of even bigger transport -- hence, Book 5 is assumed, necessary background chrome, but the adventure is clearly aimed at PCs with a Book 2 vessel -- by default, a Type A2 named Go For Broke.

I note that Beltstrike is intended as a Starter Traveller adventure (it says as much in the intro on page 2 of the Belter's Handbook); Book 5 is not mentioned anywhere in the entire module (and Book 6 is only mentioned once in passing).

The waters are further muddied by the idea that small craft are useable for prospecting (see dead-tree editions of JTAS, for example, from which Beltstrike was eventually drawn), and are, by the time of ST/BT/DT/TTB, pretty clearly using B5 fuel requirements (and power plant output calculations of EP to support weaponry and computer installations -- but that is a separate :CoW. The fuel consumption rates from Beltstrike are consistent with small craft operations as well, suggesting that the consumption rate(s) were informed by High Guard and then retconned into the Basic Traveller context of Beltstrike.

The (canonical, if we must use such a word) evidence therefore suggests that Book 2 ships in practice consume a fraction of the power plant fuel they are required to carry. (As I have mentioned elsewhere, I figure the overly-generous 10Pn requirement is so that planetary navies are not constantly tasked with diverting resources to rescue cheapskate traders who have shaved their costs so thin that, due to the vagaries of astrogation, they have run out of fuel and are now adrift and on batteries. You fly with less than 10Pn at your own risk, as it were.)

I see the fuel consumption rules in Beltstrike as a later attempt by GDW to establish some consistency between B2 and B5 ships by specifying in more detail how the former operate, in a manner consistent with how the latter do. So, not so much with B5 ships "in mind" as "in light of stuff we finally got around to looking closely at when we wrote HG2 that has implications for the entire OTU" I would venture.

Much like getting rid of "M-drives as energy weapons" when moving from HG1 to HG2, while retconning gravitics-based propulsion (to replace the original, terrifying idea of HEPlaR-based M-drives) into Basic Traveller so that PCs aren't setting entire ecosystems ablaze in fits of pique over inflated berthing fees, for example. B5 and B2 are clearly in conversation with each other, despite not being in harmony. But Beltstrike per se is pretty B5-agnostic.

 

[Grav_Moped]

Type A pp/md m-rating/fuel requirement 2g/20t in a 100t ship, 1g/10t in a 200t ship.

My explanation - the maneuver drive field (which encompasses the volume of the ship) reduces the inertial mass of the ship such that in a 100t ship the thrust component of the engine (fusion rocket) can achieve 2g. Put the same engine/machinery in a ship with twice the volume/mass and you can only achieve 1g so you use less 'fuel' reaction mass.

Sort of reasonable, but the fuel use should still be proportional to [mass (volume) * acceleration]. Then again, the rule is unreasonable (it's for game effect, not realism) so the handwave doesn't need to be reasonable either...

Note
1 the ships in Beltstrike are LBB2 designs, even the 5000t mining platform is described as having type W drives.
2 in original CT 77 the pp fuel was replaced every jump as well as the jump fuel, there was no four week duration.

That's a really high burn rate... which brings me to:

...
Much like getting rid of "M-drives as energy weapons" when moving from HG1 to HG2, while retconning gravitics-based propulsion (to replace the original, terrifying idea of HEPlaR-based M-drives) into Basic Traveller so that PCs aren't setting entire ecosystems ablaze in fits of pique over inflated berthing fees, for example.
...

The LBB2 maneuver drive always felt to me as though it was intended as an thrust-producing attachment to the power plant, especially in the '77 edition where only the maneuver drive needed a power plant.

Where the other drive letter tonnage formulae were "X*(ordinal value of drive letter)+Y= tons" (i.e. Jump: 5*letter+5=tons, Power: 3*letter+1=tons) maneuver drives were 2*letter minus 1=tons. The first two imply that those drives are made up of a constant-size component and a variable-size component that scales with output. The third implies that the maneuver drive has a variable-size component with a hole in the middle that's always 13.5m³ -- like a rocket nozzle!

 

[Carlobrand]

There are a couple of other options.

...2 - reduce the cost of lower TL pp in HG so that low TL plants are big and cheap while high TL plants are smaller but more expensive,

Considered that one once. Triggered a discussion where people pointed out that new tech was often less expensive than older tech, this computer I'm typing on being an example.

Yup, you really need to import the reduced cost standard hull as well.

Damn, forgot to mention that detail. That was an important point. Yes, we're also using the reduced cost standard hull where needed to reduce costs further. Thanks for reminding me.

I'm of two minds there. Option one is simplest: we rationalize it by saying we're recycling old hulls, pulling out all the innards and build the new ship inside of them. Ships whose designs are old enough and common enough that they show up in significant numbers for recycle serve as the basis for cut-rate hulls. I figured when Striker threw tank-armor hulls at me, I could make a bit of lemonade out of it by riding that for the standard hull rule.

Option 2 is a bit more complicated in that I'd need to adjust the Book-5 combat rules a bit, but it allows me to integrate Book 2 features a bit more effectively: the so-called "standard" hull is a seriously cheap hull adequate for space flight but not intended for combat. Canon descriptions of entry through the hull have you cutting through a hull of the same thickness as the inner bulkheads. I think we argued at one time for that to be equivalent to something like an inch thick steel. Book 2 combat made this the stuff that missiles could do multiple hits to, thin enough that power plant and jump drive hits are a possibility. So, the hull is a metal plate faced with ceramic heat tiles, mounted on a structure of girdering and backed with a thick section of a lightweight radiation-absorbing plastic, atop another metal plate, the whole sufficient to stop radiation and most micrometeor hits but no more difficult to penetrate than the typical bulkhead when attacked with personal energy weapons. Space combat weapons striking a ship equipped with a "standard" hull do not receive the +6 damage DM when using the High Guard combat rules and, in the unlikely event a "standard hull" comes under fire by a weapon with a rating of A+ (i.e. spinal mounts), that weapon receives a -6 to the damage roll (which means more than half the time the result will be a critical). And, no, they are not as hardy as the ships described in Adventure 12, Secret of the Ancients; they aren't intended for operations in deep water or deep in a gas giant atmosphere.

 

[Madmax]

Considered that one once. Triggered a discussion where people pointed out that new tech was often less expensive than older tech, this computer I'm typing on being an example.

That is certainly true when you are dealing with sales taking place at or near the manufacturing location.
However, if the point of sale is a significant distance from the manufacturing point, then the price is dominated by supply and demand considerations instead of cost to manufacture.

For an in game example (extreme case): imagine a tech 11 world (call it Farb) out in the middle of a rift. There is a jump 5 route that connects Farb to a region with more densely packed stars. Occasionally a J5 or J6 ship may pass through Farb, though not often. Farb can and does produce J2 ships used for reaching the handful of planets that are in range.
Back in the more densely populated region tech 15+ planets are fairly common, and tech 14 J2 ships are, on average, cheaper than tech 11 J2 ships of similar size and capability. However on Farb tech 14 J2 ships will cost many, many times more than an equivalent tech 11 J2 ship because there will be so very few of them, but everyone will want one.

 

[Condottiere]

Generally speaking, an entrepreneur will open up a factory locally, if demand is large enough and transport costs prohibitive.

There may be political factors both furthering and hindering such enterprises.

 

[mike wightman]

Is there therfore a gap in the market for some sort of manufactory ship?

Move you ship into a system and then send out subcraft and refineries to harvest raw materials from moons, asteroids and comets.

Your manufactory ship is basically a collection of makers that can turn out any product of any TL up to its own...

 

[Condottiere]

That's fifty kay starbux per tonne, default, before you start calculating in the other ship systems.

 

[Carlobrand]

That is certainly true when you are dealing with sales taking place at or near the manufacturing location.
However, if the point of sale is a significant distance from the manufacturing point, then the price is dominated by supply and demand considerations instead of cost to manufacture. ...

The more the item costs per unit volume, the less the significance of shipping costs in the equation. At a thousand credits per dTon per parsec, something with a base cost of 1 or 2 million credits per dTon can go quite a long way before the shipping costs reach more than a percent or so of the item cost. Whether you're talking about a multi-million credit power plant or a 4-dTon crate of 100-credit 1-liter Ultra-Gameboys from Rhylanor, shipping costs are not really all that significant at the far end of the market over distances within a sector. The real factor at that point is how much can a given world turn out, how much of that is going to be consumed locally before the export market gets its chance at them, and does a given import planet have a big enough population for anyone to bother serving that market. The four TL15 worlds account for 44% of the Imperial Marches GWP but only 14% of the Imperial Marches population, which implies a manufacturing base well able to serve the distant markets for high-value exports. Loop in the TL13-14 worlds and they account for 64% of GWP but 28.5% of pop.

As GURPS sees things, interstellar trade is only a tiny fraction of these megaworlds' GWP, but that still amounts to millions of megacredits annually. Fusion plants aren't shipping far enough within a sector for shipping costs to be a factor, and the output from the high-tech industrial worlds should be sufficient to meet at least the needs of shipbuilding. I'm still left with either arbitrarily lowering the cost of the lower tech plants without adequate explanation or introducing these alternate cheap-but-fuel-hungry plants that sorta could maybe serve to bring in a few of the Book 2 ships.

That's fifty kay starbux per tonne, default, before you start calculating in the other ship systems.

What's a starbux?