The Crestliner Backwater 1860 SC 2011 is a modified-V design and the Crestliner CR 1648T 2010 is a flat-bottom 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 - Crestliner Backwater 1860 SC 2011 at 18,4 ft versus Crestliner CR 1648T 2010 at 15,8 ft. Weight tells a clearer story for trailering families: the Crestliner Backwater 1860 SC 2011 tips the scales at 880 lbs - 460 lbs more than the Crestliner CR 1648T 2010 at 420 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 115 hp, the Crestliner Backwater 1860 SC 2011 has a 80-hp advantage over the Crestliner CR 1648T 2010's 35-hp ceiling - enough to notice on acceleration and at cruising speed, particularly with a full passenger load.
Both boats are rated for 4 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: The Crestliner Backwater 1860 SC 2011 at 18,4 ft is the right call if deck space, comfort, and entertaining are top of your list. The Crestliner CR 1648T 2010 at 15,8 ft wins on trailering ease, likely lower purchase price, and simpler docking - a solid choice for a buyer who wants more boat for less money.