When two boats share the same hull type — in this case both the Achilles FRB-104 2008 and the Achilles LSI-310 2010 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 LSI-310 2010 measures 10,2 feet overall (2010), giving it roughly 9,2 additional feet of deck space compared to the Achilles FRB-104 2008 at 1,0 feet (2008). At 108 lbs and 79 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.

Both boats share a closely matched power ceiling — 15 hp for the Achilles FRB-104 2008 and 10 hp for the Achilles LSI-310 2010. 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.

Both boats are rated for 4 passengers — a good fit for a family of four or five plus guests. Comfort at capacity is another matter; the longer hull typically means more seat options and better weight distribution.

At this size, power-to-weight ratio matters more than outright horsepower. The Achilles FRB-104 2008 comes in at 7 lbs per hp versus 8 lbs per hp for the Achilles LSI-310 2010. 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.