LASH Tender

[Pwyll]

heya alan

Originally posted by alanb:
</font><blockquote>quote:</font><hr />Originally posted by Pwyll:
really, the whole idea behind LASH (from my point of view) is to minimize the turnaround time to increase the profit margin. so what we want most here is more than 2 jumps per month.

Well, I don't think you can for the _lighters_. You can make more than 2 per month for the tenders/tugs, easily.

What you are trying to do is haul the same amount of cargo with fewer ships. As a result, you have to consider the economics of the whole system, rather than of its individual components.

Alan B </font>[/QUOTE]right, the lighters (or cargo pods, or whathaveyou) aren't making the jumps. its the tenders/LASH vehicles that jump. and we're trying to make them jump more often. using the same framework of trade rules, the desire is to increase the rate at which trade is transacted.

i do not understand that last sentence, "As a result, you have to consider the economics of the whole system, rather than of its individual components"

 

[alanb]

Originally posted by Pwyll:
i do not understand that last sentence, "As a result, you have to consider the economics of the whole system, rather than of its individual components"

The lighters are more or less self-propelled, non-jump capable cargo pods.

They are carried through jump space by the tugs/tenders - hence "lighters ABOARD ship".

Their operational cycle is:
Undock from a tender.
Go to a world, sublight.
Go through normal cargo unload/reload cycle.
Go to where next tender will be.
Dock with tender.
Be carried thru jump space by tender.

The tender's operation cycle is:
Launch carried lighters.
Dock with new lighters.
Jump.

(Ignoring maintenance checks, fuelling, etc.)

A single lighter will be carried by different tenders at various times. A single tender will carry different lighters at different times.

There is therefore a system of lighters and tenders. It works more or less on the basis of a schedule. "A tender will be here at this time. A lighter will be waiting."

Ideally, the overall _system_ will be more profitable than a conventional ship _fleet_ hauling the same amount of cargo/operating over the same period of time.

Alan B

 

[Pwyll]

Originally posted by alanb:

There is therefore a system of lighters and tenders. It works more or less on the basis of a schedule. "A tender will be here at this time. A lighter will be waiting."

Ideally, the overall _system_ will be more profitable than a conventional ship _fleet_ hauling the same amount of cargo/operating over the same period of time.

Alan B

nods, support is key to decreasing that turnaround time. we want to move our cargo at a rate greater than one jump per 14 days.

so why do you think we ought allow 14 days per jump for moving our cargo? that is the value we are trying so hard to reduce. i assure you, duplicating personnel and equipment will not of itself increase our profit margin.

 

[The Oz]

Originally posted by alanb:OK, without checking your maths, there are two problems here.

First, when/how does the tug refuel? Wouldn't it be better if the lighter brings a fuel load to it?

This ship works in settled, high-pop systems (the only ones with enough trade to need such a ship) and so the tug's fuel is brought by tanker shuttles (which is why I had refined fuel costing Cr1000/ton for the LASH tug).

Second, three jumps a month seems unreasonable for the lighters. They are the ones that will be spending all the time in normal space, after all.

They have to travel to a world, undergo customs checks, offload and load cargo, refuel, and travel back out to the pickup point in between every jump they make.

I would suggest that two jumps a month would be more likely.Alan B

Two jumps/month for the lighters will reduce their profit considerably, but not eliminate it. It'll cost them 10-11 jumps/year.

OTOH, if the tug can still make the 33 jumps/year, it could cut the "carriage fee" it charges the lighters and still make money, and that would increase the lighter's profit.

In another approach, GT:FAR TRADER says that LASH ships save enough time to make 4 additional jumps a year. This sounds like a schedule that both tug and lighters can make, and would keep both parts of the system nicely profitable.

 

[alanb]

Originally posted by Pwyll:
so why do you think we ought allow 14 days per jump for moving our cargo? that is the value we are trying so hard to reduce. i assure you, duplicating personnel and equipment will not of itself increase our profit margin.

The problem is that you _can't_ compress that 14 days (much).

It takes _most_ of the 14 days to get your cargo loaded, travel out to the rendezvous with the tug/tender, dock, travel through jumpspace, undock, travel to the new world, and unload. This is time that can't be compressed.

Of course, you will save a bit by being able to load cargoes that your on planet factors will have booked beforehand (more infrastructure!), but the actual physical travel time is constant. That's from the point of view of the actual cargo and/or lighter.

The saving isn't here. The saving is in what the tender is doing. The _tender_ is doing more jumps. It is carrying more cargo in a given period of time.

Alan B

 

[Pwyll]

LASH assumptions...

our tender by definition must be jump-capable. by book 2 page 16, this requires it to have a pilot, navigator and medic on the crew. it must be equipped with jump drive, power plant, bridge, and computer.

from paragraph 3, page 17 of HG: "Any jump, regardless of number, takes approximately one week (150 to 175 hours);"
a simple average yields 168 hours per jump, im sure we all realize. since the time spent in jumpspace is not exact, the location of the ship's emergence will be no more precise. so there will be significant maneuvering involved with any transfer of mass. our LASH-style system thus requires pilot, bridge, maneuver drive and power plant on at least one of the lighter or tender.
even if we have lighters and support (like fuel and relief crew) waiting in space to transfer cargo (swap lighters) and replenish the ship (fuel, life support, crew), there will still be the need to approach and match trajectory first. perhaps one 20 minute book 2 space combat turn under the right circumstances would be enough, but since i figure the Earth moves over 2.5 million km per day, the inherent imprecision in jump space emergence indicates an approach time of several hours.
i used 1,000,000 km as an average figure for distance from port to jump point (100 planetary diameters).
from book 2, page 10, Typical Travel Times gives a 1g vessel 333 minutes for 1,000,000 km. so to travel from jump point to port (or vice versa), i haven't the math to make a good estimate, but 6 hours would seem to be a fair minimum. maximum might be a few hours more. so it seems to me as though there will be an approach time of perhaps 6 to 8 hours regardless of whether we support the tender from space or from the ground. of the two, ground facilties will be all-around more cost-effective most of the time.

from paragraph 4, page 17 of HG: "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."
i presume it takes one hour to charge up for a jump, during which time the drive may not be inspected. 15 hours would be the minimum time in which a standard inspection may be accomplished, and thus 16 hours may be considered as our minimal turnaround time between jumps for the tender. i presume the personnel involved in the inspection will fully occupied, and the ship may not maneuver. perhaps there would be a risk of misjump if the inspection is not accomplished. though LBBs do not specify it, a 16 hour turnaround might require rolls for success. instead of the malfunctions specified in book 2, drives that fail inspection might only need minor adjustments performed by the crew, requiring extra time before jump-readiness. applying differing degrees of severity to drive malfunctions might be fun.

presumably, customs inspection and drive inspection could be accomplished concurrently, proximity to customs officials permitting.

LASH evaluations...


7 days per jump - 50 jumps/year - no time to inspect drives or transfer cargo, not useful.
8 days per jump - 43 jumps/year - 24 hour turnaround time. cutting it very close, but it seems possible with the correct design and support.
9 days per jump - 39 jumps/year - 48 hour turnaround time. should be achievable by more designs.
10 days per jump - 35 jumps/year - 72 hour turnaround time.
11 days per jump - 31 jumps/year - 96 hour turnaround time.
12 days per jump - 29 jumps/year - 120 hour turnaround time.
13 days per jump - 27 jumps/year - 144 hour turnaround time.
14 days per jump - 25 jumps/year - 168 hour turnaround time.

 

[Anthony]

Frankly, as long as you have warehouses, set schedules, and cargo factors, a turnaround of 10 days for a liner is practical, and a turnaround of 8 days for a LASH liner doesn't seem odd either.

 

[Pwyll]

Originally posted by alanb:

The problem is that you _can't_ compress that 14 days (much).

i'll get back to this below

Originally posted by alanb:

The saving isn't here. The saving is in what the tender is doing. The _tender_ is doing more jumps. It is carrying more cargo in a given period of time.

i agree that tender jumping more often increases our savings. i managed to get the cost of transporting a lighter down to less than 600 per ton in this manner. that figure was not, however, low enough to make the lighters economically viable (imo, of course)

Originally posted by alanb:

Of course, you will save a bit by being able to load cargoes that your on planet factors will have booked beforehand (more infrastructure!)

imo, you are underestimating how much of affect this can have. it means we transport MORE cargo. yes, one particular shipment will take the same subjective time, but decreasing turnaround time increases the number of shipments sent.

i found reducing the amount of equipment involved as much as possible also had a major affect on our profits. not to mention reducing capital investment

 

[aramis]

consider a 4 lighter, two ship system.

Tenders numbered 1 & 2
Lighters lettered a-d

Day Hm Far JSp
0 1ab 2cd –
1-7 b d 1a2c
8-A 2bc 1ad -
B-H c a 1d2b
J-L 1cd 2ab

20 days, ALL FOUR lighter jumped.

Mind you, that's 2 jumps per lighter per 20 days.

Any larger spread, managed right, gains this syystem benefit, that a signle tender system can not make.

Now, for maximum turnaround, the jump-fuel plus two weeks PP fuel is carried by the LIGHTER, not the tender, using the lighter as a non-disposed drop tank. The tender carries NO J fuel itself, and has storage for 4 (or even 6) weeks of PP Fuel, and then you have NO need for colliers.

It does increase the deisgn costs under HG, as it's not a DT, but a modular design...

 

[Pwyll]

Originally posted by Aramis:
consider a 4 lighter, two ship system.

now yer talkin

all of this is intended as a network.

we can have as many lighters or cargo pods at each world as are needed.

we can also run as many tenders as local interstellar economy will support.

the efficiency is amazing, isn't it? potentially almost twice as much use of the jump equipment

 

[Pwyll]

Originally posted by Aramis:
Now, for maximum turnaround, the jump-fuel plus two weeks PP fuel is carried by the LIGHTER, not the tender, using the lighter as a non-disposed drop tank.

sweet

 

[The Oz]

Originally posted by Aramis:

Now, for maximum turnaround, the jump-fuel plus two weeks PP fuel is carried by the LIGHTER, not the tender, using the lighter as a non-disposed drop tank. The tender carries NO J fuel itself, and has storage for 4 (or even 6) weeks of PP Fuel, and then you have NO need for colliers.

I'm not sure I understand what benefit you think is being gained here. Carrying an (empty) fuel lighter through jump just reduces the amount of paying cargo carried through jump. Why reduce the payload in this way? If you have a fuel tanker come and refuel the tender while it is picking up the new lighters for the next jump, you save the same turnaround time, and you don't end up carrying an empty fuel lighter through jump.

I also don't see the need for so much powerplant fuel in the tender. The tender has to come into normal space at the end of every jump. Since you have to pick up new jump fuel at that time, why not pick up new powerplant fuel at the same time? Carrying extra fuel through jump costs you space you can use for other functions.

In the LASH concept, the ideas are to concentrate all the jump-related components (jump drive and fuel for jump) onto one hull, so that the carried vessels can dedicate all available volume to cargo, and to reduce turnaround time by keeping the jump tender outside the 100D limit while the "self-propelled cargo bays" come and go. Anything that alters this reduces the viability of the concept. Your idea cuts the cargo space carried through jump and doesn't really cut turnaround time.

 

[Pwyll]

Originally posted by The Oz:
Why reduce the payload in this way?

that is a very good point

 

[Pwyll]

departures from LASH design

when i created my first LASH design, its lack of financial viability surprised me.


cargo pods vs lighters

as i analyzed the LASH-style system i was struck by the amount of equipment duplication. a lighter must have a bridge, power plant, maneuver drive and crew, just like the tender. (i designed a maneuverless tender, but it looked too much like a clay pigeon) so for my 100 ton tender system, i removed as much equipment as possible, leaving the "lighter" basically an empty hull with some electronics in it (the extra bridge cost by tonnage). this had a tremendous impact on the cost, actually making the tender/pod combo competitive with a free trader (at the same yearly jump rate of 25)

ground vs space

once i realized that we were going to have to spend several hours maneuvering to swap cargo even if the lighters/pods and refueling shuttle are waiting at the jump point, i decided support the system from the ground to eliminate the need for support vessels. it still costs an extra 6 (or so) hours to reach the jump point while outbound, so the choice was between ~6 hours maneuver time for space-based support, or ~12 hours maneuver time for ground-based support. if it meant the difference between 8-day turnaround and 9-day turnaround, perhaps it would be desireable to support the cargo transfer in space.

hull size

standard 100 ton hulls only cost 2 MCr as opposed to .1 MCr/ton for custom (20 MCr MINIMUM!), so i wanted take advantage of this savings as well.

other costs

berthing, taxes and similar fees...
also, we need at least:
a factor/broker
a large port-side warehouse
an office space of some sort with staff
some relief crew
some ground crew
some extra pods for our clients who do not invest in pods of their own.
a source of fuel
and unless i've missed something, that's about it. not a whole lot, really. the economics resemble a free trader with a yearly jump rate of 43 instead of 25, with a tender that is basically a scout.

the only drawback i see is the large amount of ship crew employed, particularly pilots.

 

[aramis]

Originally posted by The Oz:
</font><blockquote>quote:</font><hr />Originally posted by Aramis:

Now, for maximum turnaround, the jump-fuel plus two weeks PP fuel is carried by the LIGHTER, not the tender, using the lighter as a non-disposed drop tank. The tender carries NO J fuel itself, and has storage for 4 (or even 6) weeks of PP Fuel, and then you have NO need for colliers.

I'm not sure I understand what benefit you think is being gained here. </font>[/QUOTE]base cost for tonnage of craft is not that much.

By using a jump core with accomodations, bridge, and main jump computer (remembering that a Model X is required to calculate for JX), Jump drive, and sensor kit, and a modular designed overall craft, with the lighters as detatchable modules, which carry a model 1, the jump fuel, a maneuver drive, PP, and cargo only, the lighters BECOME the main ship maneuver drive, and the tender provides all the long term support needs EXCEPT fuel and maneuver drives. (It has an onboard PP reserve for LS purposes in a pinch.)

by carefully following the model, a 9 day jump schedule could be used ASSUMING:
a: you can pre-arrange for a certain jump entry-exit point (within a day)
b: the lighters have enough guts to get from nominal point to actual point within 1 day
c: you never bring the tender within 100 diameters (which by the way, according to COACC and some other spots, means they never enter world customs authority!).
d: as soon as the module-lighters are docked, you can jump; being designed as modules, rather than as carried craft, they need not pump the fuel into tanks aboard the tender, so the fuel is immediately useful, and since the tender is not coming in, an immediate jump may be possible.


THe only problems are annual maintenance, crew fatigue, and misjump chances and effects. Under CT, this can be nearly nil chance of misjump (IE, Ref's House Rules & wild hairs only!).

 

[The Oz]

Aramis:

Check me to see if I understand you correctly.

Your jump tender would have only bridge, jump drive (sufficent for tender plus all lighters to have jump-1), powerplant (size determined as with jump drive), computer (big enough to allow maximum jump when carrying minimum load), and crew quarters.

Each lighter would then have a bridge, maneuver drive and powerplant, crew quarters (minimal?), their own powerplant fuel, plus enough extra fuel to provide jump fuel for the combination of jump tender and that lighter. Everything else would be cargo.

Is this what you have in mind?

 

[aramis]

Originally posted by The Oz:
Aramis:

Check me to see if I understand you correctly.

Your jump tender would have only bridge, jump drive (sufficent for tender plus all lighters to have jump-1), powerplant (size determined as with jump drive), computer (big enough to allow maximum jump when carrying minimum load), and crew quarters.

Each lighter would then have a bridge, maneuver drive and powerplant, crew quarters (minimal?), their own powerplant fuel, plus enough extra fuel to provide jump fuel for the combination of jump tender and that lighter. Everything else would be cargo.

Is this what you have in mind?

not minimal quarters, but NO quarters on the lighters at all. just workstations. (Actually, I'd use the 1/2 ton seats for the crew other than the 2 free seats specified in HG.)

And, if the combined tonnage is less than 1000 Tons, you don't even put a bridge upon the tender....

since the JDrive and computer are the major expense units, and the "modular config" volume losses come from the core, not the lighter, the lighter is a bridge, a model 1, a PP1, and an MD1, plus cargo, seats for the engineers, and fuel.

The core has the PP4 J4 Model/4 plus staterooms, and PPfuel for the PP4. If you wanted a spinal mount, it would go in the core, along with the Model/9 to get those to hit DM's.

If I were setting it up myself, I'd go with fuel and cargo only lighter, with a "lift tender" at each station, and a "Jump Tender" travelling.

So, now, the three module model
rough numbers... All TL 13, Bk 5 designs. Costs not figured. Remember, the idea is maximumcargo throughput.

cargo pod: 800 Td; 500 Td fuel, 300 Td Cargo
Passenger Pod: 800 Td, 500 TD Fuel, 60 Td Cargo, 240 Td LSR, 55 high passengers, 5 stewards

Cargo pod Lifter: 1000 Td
(880 Td pod, 20 Td Bridge, 20Td PP, 10 Td PPFuel, 20 Td MD1, 1 Td computer model 1, 46 Td 23 SSR, 3 hp with turrets.)

Jump Liner 1200 Td 24 Td bridge, 60 Td J4, 96 Td pp4, 48 Td PP Fuel, 4td Model 4, 80 Td 20 LSR, 8 hardpoints w/fc.
Crew: CO, 1O, 2Plt, 1 Cmp Off, 3 ratings (Steward, medic, and radioman?), 2 Engr, 3 maintenance. Total = 13

Note: since we get three lighters per month, we actually have 60 Td of PP fuel available per month...

for each station, we need 1 lifter per 2 jumpers. We could probably do one per 3, but that means maintaining the schedule....
for each link, we need 2 jumpers and 4 pods.

 

[aramis]

additional thought: at J2, as a baseline, rather than the L4 long-liner, the numbers are WAY better for the Jump frame.

J2 Jump Frame. 370.6MCr
1100Td Hull MCr55 Dispersed Structure
880 Td pod 0MCr
22 Td bridge MCr 5.5
1 Td Model 1bis MCr4
44 Td PP2 MCr132
33 Td J2 MCr132
22 Td PPF MCr0
64 Td 16 LSR MCr8
4 Td 4 ELB 0.4
22 M 1G MCr33
7 Td HP & FC. MCr0.7

Likewise, pod only needs 170 Td of fuel (160 JF, 10 for PP), for 630 Td of cargo.

Assuming Close Structure and Box to be sysnonmus, the carggo pod costs a mere hull cost of MCr 48 in either long-line version or short hop version. Note that a short hop frame can get 2J2 from a long-haul pod.

SO, for a J2 system... 1+nodes lifters. 2 x legs jump frames, 4 x legs pods...

 

[Pwyll]

looks great

hows the economic analysis look?

 

[mike wightman]

Speaking of which, I have finally completed mine and the only way I can find to make book 2 LASH bulk hauling profitable is to be subsidised by a government or mega-corp.
The problem is the number of lighters needed, a minimum of three full tenders worth IMHO, plus the fuel ship.
As an aside, any merchant line would be economically negigent if they didn't invest in their own fuel refinery equipment.
I am now investigating your cargo pod idea but on a much larger scale.
A 1000t jump ship carrying a 1500t cargo pod with normal space 1000t tugs waiting at each end of the jump. Should give the same turnaround time as the LASH system. Give the tugs collapsible fuel tanks and they can carry the fuel to the jump ship.