When two boats share the same hull type — in this case both the Achilles RS-116 2013 and the Achilles SU-18 2011 are inflatable non rigid designs with 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 Achilles SU-18 2011 measures 18,0 feet overall (2011), giving it roughly 6,5 additional feet of deck space compared to the Achilles RS-116 2013 at 11,5 feet (2013). At 75 lbs and 44 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 Achilles SU-18 2011 tops out at 90 hp. Engine specs for the Achilles RS-116 2013 aren't listed — confirm with a dealer before selecting an outboard.
For family outings this is probably the sharpest distinction between the two. The Achilles SU-18 2011 is rated for 11 passengers, while the Achilles RS-116 2013 caps at 6. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Achilles SU-18 2011 could be the deciding factor.
Both are inflatable designs, which means they pack down for compact storage, can be carried in a bag, and are dramatically lighter than equivalent rigid hulls. The trade-off is setup time and the need to monitor tube pressure regularly. Tube diameter differs: 17 in. (43 cm) on the Achilles RS-116 2013 vs 24 in. (60 cm) on the Achilles SU-18 2011 — larger tubes generally mean more buoyancy and a drier, more stable ride.
Bottom line: Choose the Achilles SU-18 2011 if your priority is putting more people on the water — it handles 11 passengers and at 18,0 ft it has the deck room to back that rating up comfortably. The Achilles RS-116 2013 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 6 that costs less to run day-to-day.