When two boats share the same hull type — in this case both the Mariah R19.9 2009 and the Mariah R21 2011 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 R19.9 2009 at 19,0 ft versus Mariah R21 2011 at 21,4 ft. Weight tells a clearer story for trailering families: the Mariah R19.9 2009 tips the scales at 365 lbs — 331 lbs more than the Mariah R21 2011 at 34 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 300 hp, the Mariah R21 2011 has a 75-hp advantage over the Mariah R19.9 2009's 225-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Both carry nearly identical fuel loads — 38 gal and 36 gal — so range won't be a tiebreaker here.
Both boats are rated for 1 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.
Bottom line: The Mariah R21 2011 at 21,4 ft is the right call if deck space, comfort, and entertaining are top of your list. The Mariah R19.9 2009 at 19,0 ft wins on trailering ease, likely lower purchase price, and simpler docking — a solid choice for a buyer who wants more boat for less money.