story identification - Sci-fi Novel about human starship fighting alien starships with FTL "warp bubble" missiles?

Plot Details/Summary

I remember this one as being an entertaining, if somewhat run-of-the-mill, "galactic war" type story. The story takes place aboard a Terran military starship (a destroyer by definition, IIRC) assigned to patrol and defense duties of a human-colonized star system. Many of the supporting themes and plot devices were common sci-fi tropes, almost to the point of cliché. The ship is an old, obsolescent vessel guarding a backwater system no one particularly cares about at HQ. Nothing really ever happens here, but the fleet has to send something out to protect them, so they send this lone, aging vessel. I remember a line about the ship smelling of old plastic or something like that. It's generally understood that if there was a serious incursion by whatever alien race Man is at war with, the ship probably wouldn't be up to the task.

Likewise, the crew isn't exactly top notch, either. They are demoralized, with personality conflicts and egos clashing frequently. I recall a scene where an officer aboard the ship, in an attempt to dominate, or possibly "send a message" to an troublesome junior officer, beats the other man in the showers. I recall a line about the senior officer reversing the ions in the climate controls in the room in order to agitate the situation, and something about kicking the other man in the stomach with his bare foot.

What is a bit unusual about the story is the weaponry they use in combat. The ship has an array of energy weapons - there is a line about banks of lasers, masers, and phasers (it's not a Trek novel). But the only weapon they actually use in combat against enemy vessels are the FTL-capable missiles I mentioned in the title.

FTL travel is possible in this universe by the creation of a warp "bubble" that surrounds a starship. This energy bubble allows for tremendous speeds - I think the human ship can travel up to 180 times the speed of light with their FTL drives. The alien vessels also use this method of FTL travel. The danger with this "bubble" is that if one warp bubble intersects another warp bubble, there is a tremendous release of destructive energy. Thus, the primary weapon for fighting a starship is a FTL missile that generates its own warp bubble. If you can intersect the enemy vessel's bubble with a missile's bubble, it's game over, so to speak. The only real defense is to intercept the enemy's missiles with your own FTL missiles.

At some point, an alien vessel does come to the backwater system, and suddenly the crew of the old starship have a serious challenge before them. I am very fuzzy on how the conflict plays out. I believe there are several engagements prior to the final one. It may play out a bit like the old WW2 movie The Enemy Below or the derivative TOS Trek episode "Balance of Terror." Except that I don't think we ever get the alien perspective in this story.

The climax of the novel comes with the final battle between the Terran ship and the alien one. Salvos of missiles are fired, with several tense moments. Eventually, the humans manage to get one of their missiles through and hit the alien's warp field. The alien ship is utterly destroyed and the Terran crew are buoyed by their victory. Hard feelings and defeat are forgotten in this moment of triumph. Something like that.

Timeframe of Publication

I'd guess the novel came out in the 1970s or 1980s. Probably not any later than that.

Answer

The time frame does not match, and yet this strongly reminds me of David Gerrold's Star Wolf series. Checking your hints, they're all panning out. This seems to be "Star Hunt", by David Gerrold. It can be found on Google Books.

As @user14111 observed, the original version of Star Hunt was published with the title Yesterday's Children (and a different ending) in 1972, which matches your memories.

In the prequel to Voyage of the Star Wolf, the starship Roger Burlingame is obsolete as it drifts through space on the brink of collapse. Yet, as its demoralized crew hopes for reassignment and its weary captain counts the days before his promotion to a desk job, a fanatical first officer named Korie refuses to succumb to apathy. He believes he has seen the enemy — no more than a blip on a screen — and he's sure he can defeat them.

Korie knows he will need these men — even if they hate him — to hold the Burlingame together until the final confrontation. But as they drift ever deeper into space, following quarry that may be only a figment of their first officer's imagination, the crew of the Burlingame must decide whether Korie is a savior or a madman — whether he is leading them to glory or certain annihilation.

The Burlingame is a destroyer, and it is old. The smell of old plastic is referred to in several places.

His nose no longer notices the familiar odors of old plastic and stale sweat

The FTL propulsion is a warp bubble, and the missiles work as you described:

The missiles are equipped with warp fields of their own - short-lived units whose main purpose is to home in on an enemy ship and disrupt his warp by overlapping their own warps onto his. If the missile is on target, the enemy's stasis-field generators will be overloaded; both the warp and the ship within it will be destroyed.

I also found the shower scene and the "climate reversing" episode:

He reverses the polarity of the ion generator. The positive ions will make the room feel stuffy, cramped.