Matching a deep vee Zodiac Medline II 2010 against a inflatable rigid Zodiac Pro Open 550 2010 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.
On paper these two are close siblings in the size department — Zodiac Medline II 2010 at 19,7 ft versus Zodiac Pro Open 550 2010 at 18,1 ft. Weight tells a clearer story for trailering families: the Zodiac Medline II 2010 tips the scales at 1 521 lbs — 639 lbs more than the Zodiac Pro Open 550 2010 at 882 lbs. That difference is meaningful if you're working within a half-ton or three-quarter-ton truck's tow rating, especially once you factor in a motor, gear, and fuel.
The power gap is worth calling out. Rated to 150 hp, the Zodiac Medline II 2010 has a 30-hp advantage over the Zodiac Pro Open 550 2010's 120-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Fuel capacity breaks the other way: the Zodiac Medline II 2010 carries 58 gallons versus 22 gallons in the Zodiac Pro Open 550 2010. On a lake day that's negligible, but for coastal cruising or long reservoir runs the extra range matters.
For family outings this is probably the sharpest distinction between the two. The Zodiac Pro Open 550 2010 is rated for 11 passengers, while the Zodiac Medline II 2010 caps at 5. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Zodiac Pro Open 550 2010 could be the deciding factor.
Bottom line: Choose the Zodiac Pro Open 550 2010 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 Medline II 2010 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 5 that costs less to run day-to-day.