Matching a tunnel Shallow Sport 15 ft. Classic 2010 against a flat Shallow Sport 18 ft. Sport 2011 means you're likely deciding between two genuinely different on-water experiences. Hull type shapes everything from ride quality and fuel burn to dock handling and resale trajectory.
Both boats share a closely matched power ceiling — 130 hp for the Shallow Sport 15 ft. Classic 2010 and 130 hp for the Shallow Sport 18 ft. Sport 2011. Real-world performance will come down more to which motor is actually bolted on, its load at the time, and whether it's a 4-stroke or 2-stroke setup.
For family outings this is probably the sharpest distinction between the two. The Shallow Sport 18 ft. Sport 2011 is rated for 5 passengers, while the Shallow Sport 15 ft. Classic 2010 caps at 3. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Shallow Sport 18 ft. Sport 2011 could be the deciding factor.
Bottom line: Choose the Shallow Sport 18 ft. Sport 2011 if your priority is putting more people on the water — it handles 5 passengers and at 18,0 ft it has the deck room to back that rating up comfortably. The Shallow Sport 15 ft. Classic 2010 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 3 that costs less to run day-to-day.