Can someone please explain to me the plot of "Lost Voyage"?

I saw it a few nights ago and felt like i'd only watched half a movie! Can someone please explain what I was missing?

 

Never seen it, but this link might help you?

They have user reviews at the bottom and official plot summaries (link on sidebar)


Amazing.

 

Okay, now I've come to the conclusion that the reason that I didn't understand it is because there is no plot . . .
These quotes are from two reviews linked to on the page you showed me . . .

A drearily bad movie sounds like a rather weird description. But it really describes Lost Voyage quite well. The plot is a ripoff of Event Horizon through and through . . . In addition to a complete lack of originality the acting is beyond belief bad. The characters act in completely illogical fashion in getting themselves killed. So much so that towards the end I was cheering for the ship, demons, ghosts, or whatever the bad guy(s) were, is, are, uh, whatever to bump the remaining survivors off. Avoid at all costs. The scariest thing about this movie is you will not be able to get those two of your life back you wasted on Lost Voyage.

And . . .

. . . [Lost] Voyage is a mess of a movie that draws its plot details from past ghost movies yet fails to combine them in any coherent fashion. In fact, the ghosts themselves seem an afterthought--we'll occasionally see a spectral figure or a door slammed by an unknown force, but it's never to a point. Voyage is also confused about what the ghosts want--a couple of characters are murdered . . . for no reason that's ever explained to us, and yet others are permitted to live with little otherworldly interference. Judd Nelson's character, a paranormal researcher haunted by losing his parents on the ship when it disappeared, seems to be in danger at no point during the movie. Nelson, who really doesn't give a bad performance, is saddled with a ridiculous plotline that has his dead(?) father requesting he come to the ship to retrieve . . . well, it's not worth mentioning. If any of The Lost Voyage was supposed to be uplifting, it missed by a wide margin.