Last cruise I did my 60D had the kit 18-135 on most of the time. Circular polarizer and a ND filter were used frequently.
I also took my 28 1.8 for low light shots, especially while on the ship. I also took my Canon G9 for beach days where I didn't want to lug my big camera around.
For bright light conditions my G9 does a great job. It is small and fits in my pocket or my wife's purse.
I love the convenience of the G9. It doesn't have the low light capabilities or the versatility of my 60D.
If it did, my big camera would stay home and just have a fun cruise.