This isn't a dream to interpret, or an interpretation of a dream, but rather a general thought on what dreams are. This could well help interpret some peoples dreams, so I thought this was the best place for it.
I believe that dreams are a like a kind of compression of data which you have experienced in your recent past. Like if you compress a file on the computer to save space, sleeping allows your brain to compress the information you've taken in. The information is then unzipped, restored, when you wish to remember it.
When waking, you are presented with the raw data which you have dealt with, and your mind rationalises this by placing you in related situations which you can conciously understand.
This means that a dream you have, say about ships, could be due to the fact that you recently have been on a ship, or have seen a ship in life or on the tv. Or it could be because you have been involved with water.
Not everything, of course will exactly correlate: you could have dreampt about a ship because your recent past included oceans (a nature doc about whales for example) and upon waking, your mind attempted to rationalise the situation and placed you on a ship.
Sometimes, a hotch potch of different ideas might combine and create a hybred which actually has nothing to do with your life, or while dealing with memories you brush against an old one, reviving it.
This is why I believe that we generally have a mixture of pertanent and completly random imagery in our dreams. If we are concerned or stressed about something, our interpretation of our memories will focus on that. But sometimes a giant floating bannana is just a giant floating bannana.