When two boats share the same hull type — in this case both the Triton Boats 18RX3 2009 and the Triton Boats 21HP DC 2010 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 — Triton Boats 18RX3 2009 at 18,0 ft versus Triton Boats 21HP DC 2010 at 21,0 ft. At 169 lbs and 184 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 power gap is worth calling out. Rated to 200 hp, the Triton Boats 21HP DC 2010 has a 25-hp advantage over the Triton Boats 18RX3 2009's 175-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Fuel capacity breaks the other way: the Triton Boats 21HP DC 2010 carries 54 gallons versus 37 gallons in the Triton Boats 18RX3 2009. On a lake day that's negligible, but for coastal cruising or long reservoir runs the extra range matters.
For family outings this is probably the sharpest distinction between the two. The Triton Boats 21HP DC 2010 is rated for 675 passengers, while the Triton Boats 18RX3 2009 caps at 600. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Triton Boats 21HP DC 2010 could be the deciding factor.
Bottom line: Choose the Triton Boats 21HP DC 2010 if your priority is putting more people on the water — it handles 675 passengers and at 21,0 ft it has the deck room to back that rating up comfortably. The Triton Boats 18RX3 2009 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 600 that costs less to run day-to-day.