hello Jacoolo,
welcome aboard

here are a few suggestions from my side (for your next round of renderings!):
- next time, get the water modeled! it should not be too hard to find a tutorial for i.e. Blender (free) to get you the water modeled, even though you are not into modeling. the water currently looks flat and not very real!
- this might also help you to work with caustics. at least, I would give it a try to get some "life" to that front surface of the boat ! if everything fails, put some reflections in in Photoshop ! that surface needs life !!!
- bring in some light from the front !!!
I know your light source comes from behind (which is in this case probably questionable ...) but your objects are very hard to read, as they are too dark and dull from the front. (i.e. the Cruiser model at the right hand side!). I am a product designer and the first ideas are always done as hand renderings and hand sketches. I have a rough light setup in my mind, when I start sketching, but I when I do not get my point across with this setup and the shape can not be understood, I add an additional light source. this is a product rendering and the product is the main player here and as Bob Ross used to say : "This is your own little world, you can do whatever you want ...!"

Play with the lighting to make the scene look more realistic.
- play with your passes !!
as it looks like at the moment, there is very little post processing done to the images. at least mix the ambient occlusion pass in in Photoshop !!
IMHO the new AO pass of Keyshot (since version 7), does not do a very good job, as it is too "flat". I always create a second scene and add my own AO material, dim the light and let it render out as a seperate rendering and mix it later in PS (Photostudio)
I would highly suggest to go through this course from the godfather himself for the next time!! it costs a dime and a bit for your time and will transport your images to next galaxy
http://esbenoxholm.dk/keyshot-video-course/- as for your interior shots:
play a bit with field of depth (as in the real photographs like i.e. the bedroom from the 360 model (the pillows i.e. are not in focus...). this will take away from a too clean look !
which brings me to the next point: try to bring a bit of "grunge" to your scenes ! you are doing a very good job already with the velvet seat material (in fact I would even reduce it a tiny bit there ...), but this in comparison to the rest of your scene, makes the rest look too clean, almost steril!
in general though, I would say, the interior scenes a nice, well chosen and would only need a bit of touch up !
the model shots I would re-think a little for the next time in terms of the overall setup !
I hope I do not come across too critical: you have a wonderful subject to render but a very hard one as well !!!
please take my words as suggestions and not as critics!
this is for sure as challenging as a car render and with everthing going on around it (reflections, caustics, spray of water etc.) maybe even harder !
so your playing in the premier league with your renderings, which is a hard start!
I would assume, that you not really familiar with Photoshop, but I can only suggest to dig deeper into it, as for this field, it is crucial!
Again, there are a lot of tutorial videos around, also on the Keyshot page, but the tutorials from Esben Oxholm would be my first choice here!
keep on practising, you will develop an eye for this with time and this is already a very good start !
cheers
designgestalt