Terry Mixon
Emperor Mongoose
Following up on the info in the Farcebook post, it seems this has been explicitly legal since High Guard 2022 Update came out, as the X-Boat does the same thing.
Using High Efficiency Batteries for Jump Drives
- Thread starter Sageryne
- Start date
Arkathan
Emperor Mongoose
There are two reasons to make a J1 ship at 100 tons:
You are at a TL 9 shipyard
-or-
You don't have enough room to squeeze 20 power points for jumping out of somewhere... but since the 100 ton hull (lights, computer, life support) draws 20 points of power, you'd need a drone ship in order to hit that wall.
Thus TL 9 or prototypes is the only case
Condottiere
Emperor Mongoose
There's only one reason to make hundred tonne starships.
Anything lower, and the chances of misjumping increase.
Anything lower, and the chances of misjumping increase.
AndrewW
Emperor Mongoose
This ship uses a battery in the 2nd edition High Guard as well, so early.
For most ships, at least civilian ones, the J-drive and the M-Drive have comparable ratings and, thus, draw comparable power. So you aren't saving anything by doing this 'trick'. Because they are just moving the same power from one drive to the other. If your J-Drive is higher rated than your M-Drive, I guess you get some benefit from it.
Terry Mixon
Emperor Mongoose
I picked a random ship from Traders and Gunboats to get a glimpse at how they are designing ships. With everything entered (though they didn't allocate everything so that it fit with the right amount of cargo space left over and even double stacking the crew, they don't all fit) the ship is powered to do everything, coming in only 2 power points short of meeting all needs--including jump--simultaneously. So, the official designs--based on admittedly one ship--seem to not be saving any space by shorting the power plant.
Adding batteries sufficient for the jump and backing off on the power plant released almost 9 tons for use. I'd gain an additional 3 tons if I eschewed the batteries and just backed the power plant back.
Sageryne
Cosmic Mongoose
With almost all of the ships I design, I assume that the manoeuvre drive and the jump drive won't be both drawing power at once (assuming that power to the manoeuvre drives is cut one second before the jump drives are engaged). I don't believe there is a requirement to power both concurrently.
Although it doesn't affect the calculations, personally, I always divide the power plant into two or three equally sized units spaced around the ship. That way if one is taken out, there are other reactors can provide at least partial power. The rules to not require one large power plant, and there is not benefit to having one big one. The same goes for the manoeuvre drives.
Although it doesn't affect the calculations, personally, I always divide the power plant into two or three equally sized units spaced around the ship. That way if one is taken out, there are other reactors can provide at least partial power. The rules to not require one large power plant, and there is not benefit to having one big one. The same goes for the manoeuvre drives.
Yeah, there's approximately zero use case for simultaneously accelerating and jumping. It used to be standard design for that power switch to be the case. I guess the new standard is different or people think the M-drive is like the accelerator in your car and you slow down/stop if you turn it off. Which is obviously not the case in any meaningful sense in space.
Terry Mixon
Emperor Mongoose
Understood. My personal view is that the batteries make a good backup to the power plant. Not needed in most situations, but no one wants to be short power to jump out as the pirates are bearing down and dealing damage that might drop the power plant. Call it inexpensive insurance.
I would point out that while the X-Boat uses batteries instead of a POWER PLANT for the purposes of making a jump, it does still need jump fuel. Essentially what CT and High Guard are saying is that the Jump Drive batteries are enough (or have been increased enough) to cover jump drive power requirements and life support for one for a week.
Annic Nova is an edge case, but I believe it's still accumulating hydrogen and storing it as jump fuel?
The need to have both M-Drive and J-Drive powered at the same time is purely tactical. About the only time I could see it being desirable is if the ship is under threat and needs to get to 100D (or 10D!) without any delay. Even then, there are often other systems that can be taken offline or not used (weapons, life support temporarily if everyone is suited up, G-Compensation if the crew can cope etc), and the power plant put into Montgomery Scott mode, if you have to. Military ships will often be ABLE to do it by simply not firing all their guns.
Annic Nova is an edge case, but I believe it's still accumulating hydrogen and storing it as jump fuel?
The need to have both M-Drive and J-Drive powered at the same time is purely tactical. About the only time I could see it being desirable is if the ship is under threat and needs to get to 100D (or 10D!) without any delay. Even then, there are often other systems that can be taken offline or not used (weapons, life support temporarily if everyone is suited up, G-Compensation if the crew can cope etc), and the power plant put into Montgomery Scott mode, if you have to. Military ships will often be ABLE to do it by simply not firing all their guns.
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Terry Mixon
Emperor Mongoose
No one is saying it doesn't need the fuel. At least I think not. It still has a power plant and can manage just fine in jump space. I'll have to plug it into a spreadsheet to be sure, but I believe the 20 point power plant will handle that. The batteries are solely to power the jump (40 power points).
EDIT: I just entered the Express Boat into the spreadsheet and the 20 power points generated by the power plant is what is required for the ship minus jumping.
As a side note, TL8 power on a TL13 craft? Really?
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EccentRick
Banded Mongoose
Somewhere I have a copy of an independent? adventure I picked up at DriveThruRPG centering around a mis-jump on a ship that cut that switchover a hair to fine.
Yes, that's the actual intent of the batteries: to have a reservoir of power if you lose part of your power plant to malfunction or battle damage. But that's batteries on top of your power plant, not instead of.
Arkathan
Emperor Mongoose
That's better than the TL12 power plant that they keep insisting on installing in the TL 10 Shuttle. At least they got the TL 9 passenger shuttle right, where TL is concerned.
I don't recall it being possible to jump with battery power in CT. I think Mongoose Traveller is the only version that allows it. Marc has always been super restrictive about what can and can't power jump drives, with assorted contorted rationales for making Chemical and Fission power plants ineligible.
How the Annic Nova works depends on which edition of the game. But it never collected hydrogen fuel.
Terry Mixon
Emperor Mongoose
I see your point, but even with the power plant scaled back to not cover jump and that power going to batteries, most ships still have the option of rolling back main power and using the power plant or going with batteries.
Still, your point is well taken. Almost no ships use batteries at all, so pulling power from the power plant and putting it to batteries isn't really a change, just a chance to save tonnage while getting the same result.
EDIT: To your credit, I was struggling to remember why I thought it was a great idea after your rebuttal, and the above was what popped into my head. If most ships had full power plus batteries, it wouldn't be a good deal. If they are providing the same power when needed (like when jump rolls around) and saving valuable tonnage, it seems like a no brainer.
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Yes. As far as I am aware, you can provide the power for jump with any source of power you want in Mongoose Traveller. Chemical, mechanical, fission, fusion, anti matter, batteries, etc.
Ships should have emergency power, batteries, or other such things. But that level of complexity is normally ignored. The option exists in MgT2e but it's rarely used.
There was one edition of Traveller that built ships that way. T:NE or T4, I don't recall off the top of my head.
Ships should have emergency power, batteries, or other such things. But that level of complexity is normally ignored. The option exists in MgT2e but it's rarely used.
There was one edition of Traveller that built ships that way. T:NE or T4, I don't recall off the top of my head.
Terry Mixon
Emperor Mongoose
There are restrictions on power sources in Mongoose Traveller.
And then in the batteries section:
I'd imagine the bolded part is the justification for using batteries to power jump, so long as the right kind of power plant generated the hot dogs, er, power. It's the justification I was using, anyway.
EccentRick
Banded Mongoose
Supposedly the lower TL helps cut costs over the large number in use, the arguable "explanation" of the inherited lack of M-drive. It's been a minute since I looked, but I got the impression everything on it was as low TL as possible.
I want to think that a Budget TL9 M1 allowing X-boats to get to the tender/station means you need fewer hulls than requiring the tender to chase all the boats. If you make the messenger-scout run basic systems at half-power while the M-drive is engaged, you don't even need to get a bigger power plant.
I'd imagine the bolded part is the justification for using batteries to power jump, so long as the right kind of power plant generated the hot dogs, er, power. It's the justification I was using, anyway.
Sure, but it is a flatly nonsensical statement
Power from a fusion plant is not different in kind from power from a fission plant or a gas turbine. 
The half-arsed explanation for why fusion plants can power jump in other editions is that they "overclock" and produce orders of magnitude more power for the short time necessary to produce a jump bubble.
Batteries obviously don't do that. Even assuming future tech batteries merge with capacitors to provide the best of both. Once you let batteries power jump, you don't have any legitimate argument for disallowing fission plants from doing so.
