I think that you might have emphasized the scene a bit more if the sun were somewhat more occluded. As it is, the brightness difference between the sun and the rest of the image is so large that my eyes keep going back to the sun, even though I know that there's nothing interesting in that part of the picture.
very calming composition and could benefit if the palm feathers were cloned out as they detract one's attention from the boat and the sun. This applies to the buoy behind the boat as well. You could also have fixed the 'horizon' where the hills meet the water as in seems to be slightly tilted. Still a very suggestive snapshot.
I like the composition of this, but feel that it would benefit from greater depth of field. It seems that the yacht is not quite as sharp as it could be.
Great idea to use the arch to frame your subject. More contrast between your main subject and the background would probably give the image more impact. The bright area of the sky is a bit distracting. A slightly different vantage point may have allowed you to minimize it. 6