I am trying to remember a scifi book (or maybe novella?), about which I remember a rather diverse set of things (so it's entirely possible I'm inadvertently melding more than one story here, or have gotten thing(s) incorrect):
- Main propulsion was 'grav pipes'. FTL jump drive, and I think for normal propulsion too? With increasing failure probability if you jumped too many times in quick succession.
- At one point someone was (illegally) using said grav pipes to... clean dust off of moss so it wouldn't die? With appropriately-'why-would-you-do-that' reactions from other people for using a starship drive for gardening in the middle of a war.
- We were fighting (in space) a seemingly-endless foe, who reacted to everything by sending exponentially-increasing waves. (I want to say 6-fold, with every ship carrying 6 of the next size down?)
- Said foe was actually essentially bluffing. Yes, they had the ships, but they were fighting a two-sided war and couldn't spare the ships from the other front.
- One weapon used was just essentially a spinning chunk of chain as a kinetic weapon.
- I want to say that spaceship combat was essentially carrier-based?
- At one point a chase ends in a pileup (multiple ships jumping the same FTL jump in sequence; the first ship couldn't get out of the way in time, which results in the second ship hitting the debris from the first ship, which results in more chaos, etc.)
- At one point a main character after experiencing a gravpipe failure during a fight ends up writing out calculations on the window to see how long they had to live.
- I want to say that the other front was essentially a static wall? This seems implausible however.
- I want to say the conclusion was essentially 'take out enough of the other front that said foe actually talked to us'?
I would have read it somewhere in the range of five-to-twenty years ago or so; I suspect it might be substantially older than that.