Most Efficient Ship by TL for Cargo to X Parsecs

[Proneutron]

Passenger costs are (cost of 4Td cargo+Cr1000 in life support+Cr1000 in financed cost of the stateroom) per passenger per two-week jump cycle. It is dependent on the opportunity cost of the cargo displaced by the 4Td stateroom.

(This is also the cost of one crew member's quarters and life support, excluding salary.)

High passage costs are (( 1.125[1] X cost of passenger) + Cr188[2]) per jump cycle.
Stewards cost (if counted separately from the above calculation) is (cost of passenger + Cr1500[3]) each.

Low passage costs are (cost of 0.5Td cargo + Cr100 in financed cost of low berth (2 weeks) + Cr100 per use).

Notes:
[1] This is the passenger's stateroom and life support, plus 1/8 of the steward's stateroom and life support since 1 steward supports 8 high passengers.
[2] This is half the monthly salary of a steward, divided by 8 high passengers
[3] This is half the monthly salary of a steward.

Great details. Thanks!

 

[mike wightman]

High passengers also take 1 ton off your cargo capacity - they get a baggage allowance of one ton.

 

[Grav_Moped]

Somewhere after that, I'll start looking at over-tanked ships doing back-to-back jumps as substitutes for higher-Jn ships, to address AD's subsector geography issues.

Just trying to establish the details of overtankers.

An overtanker is a low-Jn ship with extra jump fuel, used in place of a ship with Jn equal to the range of the overtanker (e.g. a Jump-1 ship with fuel to jump twice consecutively, substituting for a Jump-2 ship. The canon Type Y Yacht fits this category.

In a pure LBB2 context, the ship will have to be constructed with this fuel tankage originaly. With Beltstrike brought in, the extra tankage can be internal demountable tanks. With LBB5, it can be collapsible internal tanks.

The frequency of the "annual" maintenance will increase proportionately to the number of jumps performed. That is, the annual schedule is based on no more than 25 jumps per year; if a ship by design jumps more frequently than that, it will need two weeks maintenance downtime in a Class A or B Starport after 25 jumps. (PC ships doing the occasional gas-and-go quick turn between jumps shouldn't be penalized, but if they make a habit of this then start tracking it.)

I have a question about the fuel allocation rules.

Typical ships (with tankage for one maximum-range Jump) are required to have four weeks of power plant fuel. This should leave two weeks of power plant fuel in reserve after a flight to the 100D limit, a jump, and transit from the destination's 100D limit to the destination world.

The Type Y (which can jump twice) has four weeks of power plant fuel. This implies that after a flight with two consecutive jumps, it only has one week of power plant fuel in reserve at most.

So, here's the question: Does an overtanker need two weeks reserve fuel after finishing its series of consecutive jumps, or only one?


Also, is there a canon or generally-accepted term for what I'm calling "overtankers"?

 

[mike wightman]

I thought you said you were using the rules as written?

Annual maintenance has nothing to do with the number of jumps you perform per year according to the rules as written.

 

[AnotherDilbert]

High passengers also take 1 ton off your cargo capacity - they get a baggage allowance of one ton.

Yes, one ton, not one displacement ton, of baggage.

High Passage- ...
There is a baggage allowance of up to 1,000 kilograms. High passage costs Cr10,000.

 

[Grav_Moped]

I thought you said you were using the rules as written?

Annual maintenance has nothing to do with the number of jumps you perform per year according to the rules as written.

Rules as written also assume waiting a week between jumps. Do we assume Long(?) Traders (overtankers) wait a week in deep space to get their bearings before jumping again?

Because if we can abandon the "two jumps per month" standard practice, the mainline freighters won't wait a week between jumps. They'll have personnel at each world arranging for a full load of cargo to be standing by when they arrive, load up immediately, and leave. That brings a one-jump trip down to nine days instead of fourteen, so scheduled ships will be jumping 39 times per year (with 2 weeks off for maintenance) instead of 25.

 

[AnotherDilbert]

In a pure LBB2 context, the ship will have to be constructed with this fuel tankage originaly.

The Traveller Adventure uses TCS tankage in a LBB2 ship as a plot device. I think we can safely assume that is accepted by canon.

The frequency of the "annual" maintenance will increase proportionately to the number of jumps performed.

I wouldn't bother. We actually do maintenance on the jump drive after each jump (LBB5) plus annual maintenance of the entire ship (LBB2).

Typical ships (with tankage for one maximum-range Jump) are required to have four weeks of power plant fuel. This should leave two weeks of power plant fuel in reserve after a flight to the 100D limit, a jump, and transit from the destination's 100D limit to the destination world.

The Type Y (which can jump twice) has four weeks of power plant fuel. This implies that after a flight with two consecutive jumps, it only has one week of power plant fuel in reserve at most.

So, here's the question: Does an overtanker need two weeks reserve fuel after finishing its series of consecutive jumps, or only one?

No special rules, as the Yacht illustrates.

As we can add extra tankage easily as an aftermarket mod according to TCS, we don't need especially designed ships.

We can do three consecutive jumps on the basic four weeks of PP fuel, but then we have basically no margin for error. A nasty Referee will start to roll the dice...

Also, is there a canon or generally-accepted term for what I'm calling "overtankers"?

I have no better term, but it leads my mind to "tanker". How about "over-fuelled" or "multi-jumper" (bi-jumper, tri-jumper, ...)?

 

[AnotherDilbert]

Rules as written also assume waiting a week between jumps. Do we assume Long(?) Traders (overtankers) wait a week in deep space to get their bearings before jumping again?

Because of the delicacy of jump drives, most ships perform maintenance operations on their drives after every jump. It is possible for a ship to make another jump almost immediately (within an hour) after returning to normal space, but standard procedures call for at least a 16 hour wait to allow cursory drive checks and some recharging.

Non-commercial ships usually follow the same schedule of one week in jump and one week in a system. If haste is called for, a ship may refuel at a gas giant immediately, and re-jump right away. This allows the ship to make one jump per week, but makes no provision for cargo, passengers, or local stops.

Deep space layovers don't need a week.

A Gas giant refuel would still take a few days to a week to accelerate to the GG, skim, accelerate to 100D. A starport refuel is probably quicker, since worlds generally have smaller diameters than GGs.

Because if we can abandon the "two jumps per month" standard practice, the mainline freighters won't wait a week between jumps. They'll have personnel at each world arranging for a full load of cargo to be standing by when they arrive, load up immediately, and leave. That brings a one-jump trip down to nine days instead of fourteen, so scheduled ships will be jumping 39 times per year (with 2 weeks off for maintenance) instead of 25.

Yes, I consider that natural for mega-corp scheduled traffic.

One week in port is for Free Traders and adventurers.

 

[BRJN]

My operating concept to cross the Sirius Gap was to use inflatable tanks for the J1 tankage; the normal tanks are for J2. Spend 24 hrs in Sirius (which per ISW has _nothing_ in the way of facilities ... but neither Vilani nor Terran Navies are talking about secret bases) to ease calculations - in event of emergency the needed ship checks took an hour or so IIRC.

I used a kitbash of Traveller Book (mostly), High Guard (for cool features) and ISW (overrides the previous if mentioned) spacecraft construction rules.

 

[Grav_Moped]

The Traveller Adventure uses TCS tankage in a LBB2 ship as a plot device. I think we can safely assume that is accepted by canon.

I'm ok with that for now. Doesn't make much difference in the cost in any case.

I wouldn't bother. We actually do maintenance on the jump drive after each jump (LBB5) plus annual maintenance of the entire ship (LBB2).

The LBB5 phrasing looks like inspection and calibration rather than an incremental overhaul. It seems to be there to make sure that ships don't stop in a system without giving adversaries an opportunity to engage -- unless otherwise declared, at unspecified higher risk. Notably, it doesn't require starport facilities, which the annual overhaul does.

No special rules, as the Yacht illustrates.

I'm ok with that, but... If it can do two jumps with 4 weeks of fuel, why can't it (or any ship) do 1 jump with two weeks of fuel? And if that's the case, why is there a four-week minimum requirement? ("Because the rules say so" points to an in-universe policy decision rather than fuel consumption rates driven by the game's physics.)

As we can add extra tankage easily as an aftermarket mod according to TCS, we don't need especially designed ships.

I'm ok with that.

We can do three consecutive jumps on the basic four weeks of PP fuel, but then we have basically no margin for error. A nasty Referee will start to roll the dice...

Yes. Three weeks fuel burned during the jumps, with the remaining "week" being necessary to get to and from 100D. Main-line commercial ships won't cut their fuel requirements that close, and independents shouldn't.

And that comes back to the in-universe policy decision I mentioned. The 4-week requirement establishes a 2-week reserve beyond a normal 2-week jump cycle (out to 100D - jump - in from 100D, loiter for a week). The Type Y works because the 2-week fuel consumption is half the four-week consumption . It's legal because it's rated as Jump-1 -- on paper it has fuel for 1 jump and 3 months powerplant operation (and nobody could possibly imagine that the excess power plant fuel would be used for the Jump Drive). <Whistles innocently in Vilani>

The practical upshot is that ships will carry fuel for the intended mission (out to 100D - (jump - repeat as needed) - in from 100D) plus two weeks additional powerplant fuel as a safety reserve. PCs may forego the reserve; but as you note, that has its risks. Still, the 5Td of "safety" fuel are costing them Cr7,500 (Cr500/ton refined fuel, Cr5000 in lost cargo revenue*)...

As an (economically silly) example, a Type A Free Trader crossing a 3-parsec rift would carry demountable tanks holding 45 tons of fuel, for a total of 75 tons of fuel. 60 of that are jump fuel for the three jumps, 10 of it will be used by the Pn-1 power plant during the three jumps and the outbound and inbound normal-space legs, and the last 5 tons are the two-week safety reserve.

I have no better term, but it leads my mind to "tanker". How about "over-fuelled" or "multi-jumper" (bi-jumper, tri-jumper, ...)?

How about "Long Ships" as the category, and "Long" as the mission modifier? (E.g.: Long Trader, Long Liner). I see this as a parallel to the use of "Far" for ships with higher Jn than typical for their type (e.g.: Far Trader). Unless it's already used for something else?


* The J-1 ship is standing in for a J-3 ship that can do it in 1 jump so they get paid the same. (Or I could run the cost-per-ton-per-parsec numbers on a Type A with only 7 tons of useable cargo space left but honestly they're not making money on this trip anyhow...)

 

[Grav_Moped]

Deep space layovers don't need a week.

A Gas giant refuel would still take a few days to a week to accelerate to the GG, skim, accelerate to 100D. A starport refuel is probably quicker, since worlds generally have smaller diameters than GGs.

I didn't expect they would.

Yes, I consider that natural for mega-corp scheduled traffic.

One week in port is for Free Traders and adventurers.

Which is where I was going with that concept. The annual overhaul schedule is what Free Traders and adventurers deal with, in the same way that the trade mini-game is what Free Traders and adventurers deal with. It may not be meant to model periodic maintenance schedules of ships in mega-corp scheduled service, any more than the trade mini-game is intended to model the entire interstellar trade flows of a world. (In fairness, for isolated worlds it may actually be the planet's entire interstellar trade flow...)


During peacetime, military ships probably follow the two jumps per month paradigm. In wartime, annual maintenance is probably a moot point since battle damage repair is the priority. ("That meson hit trashed our Jump Drive, but hey -- at least we don't have to worry about overhauling it next month!")

 

[Grav_Moped]

My operating concept to cross the Sirius Gap was to use inflatable tanks for the J1 tankage; the normal tanks are for J2. Spend 24 hrs in Sirius (which per ISW has _nothing_ in the way of facilities ... but neither Vilani nor Terran Navies are talking about secret bases) to ease calculations - in event of emergency the needed ship checks took an hour or so IIRC.

I used a kitbash of Traveller Book (mostly), High Guard (for cool features) and ISW (overrides the previous if mentioned) spacecraft construction rules.

Seems consistent with the rules. Allow TCS power-down rules for the week of the Jump-1 segment and there should be a decent amount of fuel left over when exiting the second jump.

 

[AnotherDilbert]

And if that's the case, why is there a four-week minimum requirement?

The only thing I can think of off hand is that misjumps are variable time, so can take more than a week in jumpspace.

Three weeks fuel burned during the jumps, with the remaining "week" being necessary to get to and from 100D. Main-line commercial ships won't cut their fuel requirements that close, and independents shouldn't.

Getting to/from 100D only takes a few hours, in most cases.

A reasonable schedule for three weeks would be:
__0 h _ Fill up tanks just before departure.
__6 h _ Accelerate to 100D (~size 8 planet)
168 h _ First Jump
_16 h _ check jump drive, pump fuel into main tanks
168 h _ Second Jump
_16 h _ check jump drive, pump fuel into main tanks
168 h _ Third Jump
__6 h _ Accelerate from 100D to planet (~size 8 planet)
===========
548 h ≈ 22.8 days, leaving 5 days margin.

No problem normally, but if shit happens...

For a large LBB2 ship an extra weeks PP fuel will only cost a few Cr in cost per cargo, so no big deal.

How about "Long Ships" as the category, and "Long" as the mission modifier? (E.g.: Long Trader, Long Liner). I see this as a parallel to the use of "Far" for ships with higher Jn than typical for their type (e.g.: Far Trader). Unless it's already used for something else?

Sure, why not.

 

[AnotherDilbert]

Which is where I was going with that concept. The annual overhaul schedule is what Free Traders and adventurers deal with, in the same way that the trade mini-game is what Free Traders and adventurers deal with.

Sure, I just wouldn't bother. We're not putting any more operation time on the power plant or life support, since that is running all the time. The M-drive runs less. The hull would take fewer heat cycles from landings.


The cost of another weeks maintenance a year is just a few tens of Cr in cost per trip per ton. At least it will not discriminate any further against small ships.


Naval vessels in peacetime would probably hurry up and wait, for months...
Until the get a mission, then they would rush into place and loiter.
What I mean is, they would jump as fast as possible (good training), and then they would stay on station for months. Regular schedules are for merchantmen.

 

[boomslang]

The hull would take fewer heat cycles from landings.

With gravitic M-drives, hulls do not take heat stress from landings. Such ships may perform entry interface at subsonic speeds -- which is probably mandatory for noise abatement on well-populated planets.

 

[Proneutron]

With gravitic M-drives, hulls do not take heat stress from landings. Such ships may perform entry interface at subsonic speeds -- which is probably mandatory for noise abatement on well-populated planets.

Truth. With Trav ships no one would be doing orbital velocity reentries. Down Ports probably require ships hover in the trailing direction of the port and slowly come down to land. One would probably leave going to spinward (direction of planet rotation) and climb out.

 

[mike wightman]

Yes, one ton, not one displacement ton, of baggage.

But 1000kg is one displacement ton of cargo according to LBB2 trade rules

 

[mike wightman]

Rules as written also assume waiting a week between jumps. Do we assume Long(?) Traders (overtankers) wait a week in deep space to get their bearings before jumping again?

Because if we can abandon the "two jumps per month" standard practice, the mainline freighters won't wait a week between jumps. They'll have personnel at each world arranging for a full load of cargo to be standing by when they arrive, load up immediately, and leave. That brings a one-jump trip down to nine days instead of fourteen, so scheduled ships will be jumping 39 times per year (with 2 weeks off for maintenance) instead of 25.

Have you seen the GT concept of the LASH trade system?

Lighter Aboard Ship - basically the jump ship carries cargo modules that can be rapidly offloaded to port while being refuel and picking up cargo. passengers and possibly a replacement crew for the next destination so there is no week long wait between jumps.

 

[mike wightman]

How about "Long Ships" as the category, and "Long" as the mission modifier? (E.g.: Long Trader, Long Liner). I see this as a parallel to the use of "Far" for ships with higher Jn than typical for their type (e.g.: Far Trader). Unless it's already used for something else?

You mean like the canonical Tukera Long Liner? You can find it in The Traveller Adventure.

It is a 1000t jump 4 ship.

 

[Grav_Moped]

You mean like the canonical Tukera Long Liner? You can find it in The Traveller Adventure.

It is a 1000t jump 4 ship.

Ok, so it's taken. <sigh>