[3e] Stating a Refrigerated Cargo Hold

[Varyon]

Note that "$500 more per ton" for a Spaceships Cargo Hold works out to "$500 per ton," because Spaceships Cargo Holds are free - or, rather, their price is low enough compared to all the other components of a spaceship you can just ignore it. Power draw is presumably similar, low enough you don't need to account for it (just like you don't need to account for the power draw of the computer systems in the Control Room). For volume, the guideline from Payload (B74) is 1 cubic foot per 20 lb cargo space; I believe Spaceships vessels tend to have a density somewhere around that of water, which would instead be around 1 cubic foot per 60 lb cargo space (Spaceships stats assume all cargo holds, fuel tanks, etc are full).

EDIT: Forgot this was about 3e, which I assume means you're using Vehicles. I think the Environmental Control system from page 77 would cover most refrigeration needs.

[RyanW]

Originally Posted by Varyon

Power draw is presumably similar, low enough you don't need to account for it (just like you don't need to account for the power draw of the computer systems in the Control Room).

When you are already dumping reactor heat (thousands of degrees), dumping refrigerator heat (tens of degrees) is a fairly trivial addition.

[The Colonel]

I'm guessing the size of the refrigeration plant is going to make a difference as well - a TL6 reefership is going to have to dedicate significant amounts of machinery space to its plant, but that will fall off over time. I know people use individually temperature controlled shipping containers now, but doubt they have completely superseded the cooled hold. Come to think of it, TL is probably going to have a big effect on the cost isn't it?

Oh, by the way, found this:

http://www.ships-for-sale.com/

when I was down the GoogleHole over this ... did we know about this site? Some of the ships even have deck plans...

[GURPS Fox]

Originally Posted by Varyon

Note that "$500 more per ton" for a Spaceships Cargo Hold works out to "$500 per ton," because Spaceships Cargo Holds are free - or, rather, their price is low enough compared to all the other components of a spaceship you can just ignore it. Power draw is presumably similar, low enough you don't need to account for it (just like you don't need to account for the power draw of the computer systems in the Control Room). For volume, the guideline from Payload (B74) is 1 cubic foot per 20 lb cargo space; I believe Spaceships vessels tend to have a density somewhere around that of water, which would instead be around 1 cubic foot per 60 lb cargo space (Spaceships stats assume all cargo holds, fuel tanks, etc are full).

EDIT: Forgot this was about 3e, which I assume means you're using Vehicles. I think the Environmental Control system from page 77 would cover most refrigeration needs.

So use a combination of additional cost (and I've seen a reference to additional space) and use a modified version of the Enviro-Con energy consumption rules?

Originally Posted by RyanW

When you are already dumping reactor heat (thousands of degrees), dumping refrigerator heat (tens of degrees) is a fairly trivial addition.

True.

Originally Posted by The Colonel

I'm guessing the size of the refrigeration plant is going to make a difference as well - a TL6 reefership is going to have to dedicate significant amounts of machinery space to its plant, but that will fall off over time. I know people use individually temperature controlled shipping containers now, but doubt they have completely superseded the cooled hold. Come to think of it, TL is probably going to have a big effect on the cost isn't it?

Oh, by the way, found this:

http://www.ships-for-sale.com/

when I was down the GoogleHole over this ... did we know about this site? Some of the ships even have deck plans...

Interesting information... could help quite a bit.

[Anthony]

There's two reasons a refrigerated hold would be preferable to individually refrigerated containers:

1. The weight and cost of a refrigeration system should vary with the surface area of the container (roughly 2/3 power of volume), not the volume -- both insulation weight and the amount of heat leaking through (which determines required refrigeration power) are surface effects.
2. A refrigeration system produces waste heat that has to be dealt with. For something built into the ship, you just run ventilation from the inside to the outside of the ship. For containers, they either dump the heat into the interior of the hold, or they need specialized hookups to the ship's ventilation system so they can dump heat outside.

However, as far as Vehicles goes, given that Vehicles doesn't use different tank types for water and liquid hydrogen, I expect this is below the threshold of caring.

[Pursuivant]

I found an option for cargo containers from GURPS 3E Transhuman Space: Spacecraft of the Solar System which gives a cost of $500 per cargo space where a space is equal to approximately 300 cf, using a modular vehicle design system based on GURPS 3E Vehicles 2E.

Surprisingly, there isn't anything on specialty cargo holds in Vehicles 2E or its supplements.

The virtue of refrigerated holds is that they can be cooled to extremely low temperatures greatly increasing the number of cargoes a merchant ship can carry. Realistically, they'll also be heavily insulated which helps with soundproofing and damage control when firefighting. They might also have better ventilation and ventilation control and a more modular design with more bulkheads and doors between cargo hold sections and the nearest airlock.

IIRC, GURPS 3E Space 3E touches briefly on space merchant operations. GURPS Traveller Far Trader really gets into the details, but much of that information was cleaned up, consolidated and reprinted in GURPS 4E Spaceships 2.

[shadowjack]

(Oh, thank goodness, there's still a copy of the old GURPSnet archives up somewhere...)

I managed to find MA Lloyd's old "GURPS Vehicles 2nd edition Additions" files from 1998, which in chapter 01 suggests this:

*Refrigerated Cargo* (TL5): Some or all of a vehicle's cargo space can be
refrigerated. This uses up 2% of the space for insulation and refrigeration
coils, costs $1 per cf cooled and consumes 0.005 kW per cf.

Hope this helps!