When two boats share the same hull type — in this case both the Mariah FS18 Fish & Ski 2008 and the Mariah R18.9 2009 are modified vee designs with fiberglass 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?

On paper these two are close siblings in the size department — Mariah FS18 Fish & Ski 2008 at 18,0 ft versus Mariah R18.9 2009 at 18,0 ft. Weight tells a clearer story for trailering families: the Mariah FS18 Fish & Ski 2008 tips the scales at 255 lbs — 222 lbs more than the Mariah R18.9 2009 at 33 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 225 hp, the Mariah R18.9 2009 has a 35-hp advantage over the Mariah FS18 Fish & Ski 2008's 190-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Both carry nearly identical fuel loads — 22 gal and 22 gal — so range won't be a tiebreaker here.

Both boats are rated for 8 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 Mariah R18.9 2009 comes in at 0 lbs per hp versus 1 lbs per hp for the Mariah FS18 Fish & Ski 2008. 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 Mariah R18.9 2009 has a documented top speed of 40 mph. Speed data wasn't available for the other model.