“Same Boat” is a little no-budget sci-fi comedy that walks that uneasy line between “deadpan” and “half-assed.”

It reaches for droll and dabbles in humanity. But the laughs are few and far between in this travelogue/cruise ship misadventure that seems more promising as the starting point for a remake.

In the future, time travel has been solved and time traveling assassins are sent back to this or that point from the past to prevent some calamity from visiting the planet by killing those most responsible for it.

“Results,” we are told in an opening credit, “have been mixed.”

Thus we find mop-topped James (director and co-writer Chris Roberti) and his apprentice Mot (Julia Schonberg) on a beach interrupting honeymooners. The killers whip out their little liquidation/mission-status gadgets — which look like ear thermometers — and commence to cleanse the future.

But but…”we work in TELEVISION!” the groom protests. Yes, it’s 1989 and the killers have come to snuff-out the inventors of “reality TV” and prevent the damage it does to civilization, culture, politics and the planet.

That’s as funny as this conceit gets, as the rest of the film is set on a cruise ship where an assignment goes terribly wrong.

Because Mot gets sea sick and is confined to her cabin. And James, who could take care of this on his own, no prob — is smitten by this flirtatious fellow passenger Lilly (Tonya Glanz).

She’s just heartlessly broken up with her dopey/needy boyfriend Rob (Evan Kaufman).  She, and it turns out James, have all this time to kill, all these buffets to gorge, shore trips to Key West and Cozumel to do and nobody to do them with.

Except each other. And there is, of course, a complication. Which you’ve already guessed.

The moral dilemma of the work of killing “nice people” is dismissed with a “They’re bad for humanity, not bad people. There’s a difference.”

No enough is made of James’ unique perspective — consoling the semi-suicidal Rob and others by urging them to enjoy “this golden age…the twilight of America!”

James knows.

The characters could be darker and more interesting, and the killers absolutely have to be more fanatically-committed to the mission for there to be a “journey” that they make towards redemption.

Nobody here has much of an arc. Lilly needs to be closer to beyond salvation for her journey to be engaging. She’s all, Key West? “It seems nice.”

“Yeah, until the oceans rise,” James prophesies. Which Lilly doesn’t buy.

Instead Roberti (pictured above being shady, an “officially-approved” still from the movie, if you can believe that) relies on cruise ship gags and supporting players to deliver the laughs.

The ribald, rude and randy crew, Rob in his manic post-breakup state, etc., put more effort into wringing a laugh from this than the leads.

The principals take their cue from the director-star, who is funny once or twice — a drunken karaoke duet on “House of the Rising Sun” — but mostly just a bland void around which the others and the movie revolve.

Funnier lines, more sharply-defined characters, higher stakes in the whole “Who lives/who dies?” game and darker twists would make “Same Boat” float instead of sink.

MPAA Rating: unrated, some violence, profanity, sexual situations

Cast: Chris Roberti, Tonya Glanz, Julia Schonberg, Evan Kaufman

Credits: Directed by Chris Roberti, script by Josh Itzowitz and Chris Roberti. A Dark Star (VOD, streaming April 7) release.

Running time: 1:23