Matching a inflatable rigid Zodiac Cadet RIB 310 2011 against a deep vee Zodiac Pro Open 550 2013 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.
Size is the most obvious dividing line here. The Zodiac Pro Open 550 2013 measures 18,1 feet overall (2013), giving it roughly 7,9 additional feet of deck space compared to the Zodiac Cadet RIB 310 2011 at 10,2 feet (2011). At 143 lbs and 97 lbs respectively, both sit in a similar weight class — either should pair comfortably with most mid-size SUVs and half-ton trucks, though always confirm your specific tow rating with the motor added.
The power gap is worth calling out. Rated to 120 hp, the Zodiac Pro Open 550 2013 has a 105-hp advantage over the Zodiac Cadet RIB 310 2011's 15-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load.
For family outings this is probably the sharpest distinction between the two. The Zodiac Pro Open 550 2013 is rated for 11 passengers, while the Zodiac Cadet RIB 310 2011 caps at 4. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Zodiac Pro Open 550 2013 could be the deciding factor.
At this size, power-to-weight ratio matters more than outright horsepower. The Zodiac Pro Open 550 2013 comes in at 1 lbs per hp versus 10 lbs per hp for the Zodiac Cadet RIB 310 2011. The lower the ratio the more explosive the acceleration — meaningful on a short RIB where bursts of speed, quick planing, and agility in surf or tight waterways define the experience.
Top speed is rated at 45 mph for the Zodiac Pro Open 550 2013 and 24 mph for the Zodiac Cadet RIB 310 2011.
The Zodiac Pro Open 550 2013 is an inflatable design — lighter, easier to store, and quicker to launch from a beach or dock without a slipway. The Zodiac Cadet RIB 310 2011 is a rigid hull, which typically offers a more confident ride in chop and easier maintenance over the long term.
Bottom line: Choose the Zodiac Pro Open 550 2013 if your priority is putting more people on the water — it handles 11 passengers and at 18,1 ft it has the deck room to back that rating up comfortably. The Zodiac Cadet RIB 310 2011 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 4 that costs less to run day-to-day.