On a more productive note, from me that is, just a couple of further observations:
1. Working in 32bit is fine, but for display purposes, such as on here, 8bit is more than enough....15M for a file is a tad overkill.
2. Fairly obvious...hopefully.
3. When compositing images one thing is often overlooked, and that's blending with the background.
If you look closely at the BG you'll not see any sharp transitions in colour, everything blends together. When you add your elements you also need to blend them with the BG, the collar on your shirt and the end of your sleeve are good examples of how they are very sharp in comparison to the BG.(Or check out the oar in the above image...see how sharp it is compared to the sea?)
As a side note check out the 'solid' patches of blue colour on the back of your shirt.....would you see that in an untouched photo?
You can tackle this in several ways depending on when you remember to do it..LOL.
When masking you can add a 'feather' edge to the mask, this will have the effect of blending into the BG...or...
If you prefer to keep a sharp edge until you're done you can then, on a new layer and with 'Blur Tool' set to 'This Layer and Below' gently go around all the edges with the 'Blur Tool' and a small, soft brush.
It may not sound like much but sometimes its the little things that make a big difference.
Regards.
MrTom.