So Shailene Woodley wakes up. There is blood on her face and on her clothes, and she is up to her waist in water.

We take in the surroundings. She is inside the cabin of a boat, and she panics, thinking it might be sinking.

She searches for a way back onto the deck, yelling, “Richard! Richard!” … And thus begins “Adrift” — all 100 or so minutes of it.

Written by Honolulu’s Kandell brothers and based on a memoir from 1983 — uh-oh, there goes all the suspense, doesn’t it? Dead people don’t write memoirs, do they? — “Adrift” tells the story of Tami Oldman, a young woman who, in 1983, went sailing with her boyfriend, intending to sail from Tahiti to San Diego.

It didn’t go well. They got caught in a Category 5 hurricane; the inexperienced Oldman had to navigate solo using a sextant, hoping to reach Hawaii.

It should come as no surprise that the opening scene of “Adrift” is followed by a flashback. In this case, we go back in time to find out how she got on that boat. The assumption here is that we’re curious. Turns out, Tami is a free spirit. She works for a time, then travels, works for a time, then travels some more. When we meet her, she’s in Tahiti. That’s where Richard meets her, too.

A good rule of thumb about lost at sea movies. The good ones make you worry about the people and wonder if they’ll ever get off that boat. With the bad ones, you also worry — about whether you’ll ever get off that boat. Just tossing that out there.

Soon “Adrift” reveals its narrative strategy — the old back and forth. So we get scenes of Tami and the injured Richard (Sam Claflin) on the boat, drifting and worrying. And these scenes are interspersed with other scenes showing Tami and Richard’s courtship. Over a bottle of white wine, they discover a shared passion for sailing and adventure. The screenplay’s goal is to make us care about these people and care about the relationship, so that we can have a more passionate investment in their survival.

One problem. It doesn’t look like all that great a relationship. It’s hard to know if it’s the writing or a bad choice of the actor, but as Richard, Claflin acts like something of a weenie. He simpers around Woodley like he’s afraid she’s going to hit him over the head with a rolled up newspaper. Indeed, the movie’s only real suspense is whether the boating accident or the movie itself will end up being the worst thing that ever happened to Richard.

So that’s what we’re dealing with here. Scenes of the lovers adrift, in which we worry more about our rescue than theirs, and courtship scenes involving people that we might wish well, in the abstract, but really don’t want to be around.

It’s not a good movie for Woodley. During those early scenes, in which she’s screaming and frantic, you may find yourself thinking exactly the wrong things. Things like, “I wonder how many people are on the set.” And “How far is the camera from her?” And “This is borderline funny.” And finally, “I just don’t believe her.” No, there’s no pleasure in saying that. Woodley has been first rate in everything she’s been in, particularly the “Divergent” series. But there’s something about her performance here that feels like the sincere and dutiful dispersal of medicine.

Here’s a thought: Sharks might have livened things up. Two or three? Half a dozen?