The Steiger Craft 21 DV Block Island 2010 is a deep-V design and the Steiger Craft Super Fly 21 2010 is a modified-V design, so you're likely deciding between two noticeably different on-water experiences. Hull type shapes everything from ride quality and fuel burn to dock handling and resale trajectory.
On paper these two are close siblings in the size department - Steiger Craft 21 DV Block Island 2010 at 21,0 ft versus Steiger Craft Super Fly 21 2010 at 20,0 ft. Weight tells a clearer story for trailering families: the Steiger Craft 21 DV Block Island 2010 tips the scales at 4 500 lbs - 1 600 lbs more than the Steiger Craft Super Fly 21 2010 at 2 900 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 225 hp, the Steiger Craft 21 DV Block Island 2010 has a 25-hp advantage over the Steiger Craft Super Fly 21 2010's 200-hp ceiling - enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Fuel capacity breaks the other way: the Steiger Craft 21 DV Block Island 2010 carries 124 gallons versus 60 gallons in the Steiger Craft Super Fly 21 2010. On a lake day that's negligible, but for coastal cruising or long reservoir runs the extra range matters.
Both boats are rated for 6 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: Performance buyers should lean toward the Steiger Craft 21 DV Block Island 2010 and its 225-hp ceiling. If fuel economy and quieter running matter more than top-end speed, the Steiger Craft Super Fly 21 2010 with its 200-hp rating is the more economical daily driver.