The Pro-Line 18 Flats 2011 vs Pro-Line 21 Walk 2006 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 — Pro-Line 18 Flats 2011 at 18,3 ft versus Pro-Line 21 Walk 2006 at 21,0 ft. Weight tells a clearer story for trailering families: the Pro-Line 18 Flats 2011 tips the scales at 1 548 lbs — 1 523 lbs more than the Pro-Line 21 Walk 2006 at 25 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 200 hp, the Pro-Line 21 Walk 2006 has a 85-hp advantage over the Pro-Line 18 Flats 2011's 115-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Fuel capacity breaks the other way: the Pro-Line 18 Flats 2011 carries 27 gallons versus 7 gallons in the Pro-Line 21 Walk 2006. 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 Pro-Line 21 Walk 2006 is rated for 6 passengers, while the Pro-Line 18 Flats 2011 caps at 5. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Pro-Line 21 Walk 2006 could be the deciding factor.
Bottom line: Choose the Pro-Line 21 Walk 2006 if your priority is putting more people on the water — it handles 6 passengers and at 21,0 ft it has the deck room to back that rating up comfortably. The Pro-Line 18 Flats 2011 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 5 that costs less to run day-to-day.