When two boats share the same hull type — in this case both the Larson FX 1850 DC O/B 2012 and the Larson LX 2150 I/O 2012 are modified vee designs with composite 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 — Larson FX 1850 DC O/B 2012 at 18,5 ft versus Larson LX 2150 I/O 2012 at 21,4 ft. Weight tells a clearer story for trailering families: the Larson FX 1850 DC O/B 2012 tips the scales at 182 lbs — 151 lbs more than the Larson LX 2150 I/O 2012 at 31 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 175 hp, the Larson FX 1850 DC O/B 2012 has a 153-hp advantage over the Larson LX 2150 I/O 2012's 22-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Both carry nearly identical fuel loads — 35 gal and 36 gal — so range won't be a tiebreaker here.
For family outings this is probably the sharpest distinction between the two. The Larson FX 1850 DC O/B 2012 is rated for 7 passengers, while the Larson LX 2150 I/O 2012 caps at 1. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Larson FX 1850 DC O/B 2012 could be the deciding factor.
Bottom line: Choose the Larson FX 1850 DC O/B 2012 if your priority is putting more people on the water — it handles 7 passengers and at 18,5 ft it has the deck room to back that rating up comfortably. The Larson LX 2150 I/O 2012 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 1 that costs less to run day-to-day.