The Sun Tracker Party Barge 18 2004 vs Sun Tracker Party Deck 21 I/O 2005 comparison sits squarely in the category of decisions where specs alone won't tell the whole story: intended use, storage, and long-term ownership costs all factor in.
On paper these two are close siblings in the size department - Sun Tracker Party Barge 18 2004 at 18,0 ft versus Sun Tracker Party Deck 21 I/O 2005 at 20,0 ft. Weight tells a clearer story for trailering families: the Sun Tracker Party Deck 21 I/O 2005 tips the scales at 2 250 lbs - 870 lbs less than the Sun Tracker Party Barge 18 2004 at 1 380 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 Sun Tracker Party Deck 21 I/O 2005 tops out at 220 hp. Engine specs for the Sun Tracker Party Barge 18 2004 aren't listed - confirm with a dealer before selecting an outboard.Fuel capacity breaks the other way: the Sun Tracker Party Deck 21 I/O 2005 carries 41 gallons versus 26 gallons in the Sun Tracker Party Barge 18 2004. 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 Sun Tracker Party Deck 21 I/O 2005 is rated for 10 passengers, while the Sun Tracker Party Barge 18 2004 caps at 7. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Sun Tracker Party Deck 21 I/O 2005 could be the deciding factor.
Bottom line: Choose the Sun Tracker Party Deck 21 I/O 2005 if your priority is putting more people on the water - it handles 10 passengers and at 20,0 ft it has the deck room to back that rating up comfortably. The Sun Tracker Party Barge 18 2004 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 7 that costs less to run day-to-day.