Hi Amina,
One thing that most people discover rather quickly about making photos on small boats is that it is often difficult to move backwards enough to get everything into a photo. For that reason, people can often look rather cropped… like in this instance.
Because your subject is also really close to the camera, it is also difficult to get a reasonable depth-of-field into the image. Depth-of-field is the term used to describe how much of the picture is in focus – from the closest to the furthest away parts of the picture. As we can see in this photograph, your friend is in focus but the fishing rod and background are both out of focus… this is what we might describe as a narrow, or shallow depth of field.
One option in this instance is to use a wider lens. I notice that you made this photograph using an 18-55mm lens on your Nikon D3100, but the photo itself is captured at the 22mm lens setting.
If you had set the lens to the 18mm setting, that slightly wider perspective might have got more of your friend into the picture. Something else that happens when you use a wider lens is that the depth-of-field naturally increases.
To get more depth of field, another option you could have tried would be to close down your aperture a couple of stops, from f8 to f16.
Closing down the aperture increases depth of field but it also reduces the amount of light entering the camera. To compensate for this, I would increase the ISO from 100 to 400. The exposure remains the same, but about now you will notice that the background is starting to come more into focus.
One last trick you can try when you're making a photograph like this is not actually to look through the camera, but to hold the camera out at arms length over the side of the boat while aiming it at your friends. This technique takes some practice but it is actually a technique that gets used by reportage photographers a lot.
Hope this is a help!
Cheers, Anthony