When two boats share the same hull type — in this case both the Zodiac Medline 500 2013 and the Zodiac Medline IV 2011 are deep vee designs with rigid inflatable construction — the buying decision usually comes down to a handful of practical questions: how many people are you putting on the water, how far do you trailer, and what does your tow vehicle weigh?
Size is the most obvious dividing line here. The Zodiac Medline IV 2011 measures 27,9 feet overall (2011), giving it roughly 11,5 additional feet of deck space compared to the Zodiac Medline 500 2013 at 16,4 feet (2013). Weight tells a clearer story for trailering families: the Zodiac Medline IV 2011 tips the scales at 3 527 lbs — 2 749 lbs less than the Zodiac Medline 500 2013 at 778 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 350 hp, the Zodiac Medline IV 2011 has a 310-hp advantage over the Zodiac Medline 500 2013's 40-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 IV 2011 carries 106 gallons versus 23 gallons in the Zodiac Medline 500 2013. 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 Medline 500 2013 is rated for 9 passengers, while the Zodiac Medline IV 2011 caps at 8. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Zodiac Medline 500 2013 could be the deciding factor.
At this size, power-to-weight ratio matters more than outright horsepower. The Zodiac Medline IV 2011 comes in at 10 lbs per hp versus 19 lbs per hp for the Zodiac Medline 500 2013. 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.
The Zodiac Medline IV 2011 has a documented top speed of 57 mph. Speed data wasn't available for the other model.
The Zodiac Medline 500 2013 is an inflatable design — lighter, easier to store, and quicker to launch from a beach or dock without a slipway. The Zodiac Medline IV 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 Medline 500 2013 if your priority is putting more people on the water — it handles 9 passengers and at 16,4 ft it has the deck room to back that rating up comfortably. The Zodiac Medline IV 2011 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 8 that costs less to run day-to-day.