Both the Supra Launch 20SSV 2008 and the Supra Launch 21V 2009 are modified-V designs, both built in fibreglass, so 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 - Supra Launch 20SSV 2008 at 20,0 ft versus Supra Launch 21V 2009 at 21,0 ft. Weight tells a clearer story for trailering families: the Supra Launch 21V 2009 tips the scales at 3 800 lbs - 600 lbs less than the Supra Launch 20SSV 2008 at 3 200 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.
Both boats share a closely matched power ceiling - 340 hp for the Supra Launch 20SSV 2008 and 325 hp for the Supra Launch 21V 2009. Real-world performance will come down more to which motor is actually bolted on, its load at the time, and whether it's a 4-stroke or 2-stroke setup. Fuel capacity breaks the other way: the Supra Launch 21V 2009 carries 52 gallons versus 40 gallons in the Supra Launch 20SSV 2008. 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 Supra Launch 21V 2009 is rated for 14 passengers, while the Supra Launch 20SSV 2008 caps at 10. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Supra Launch 21V 2009 could be the deciding factor.
Bottom line: Choose the Supra Launch 21V 2009 if your priority is putting more people on the water - it handles 14 passengers and at 21,0 ft it has the deck room to back that rating up comfortably. The Supra Launch 20SSV 2008 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 10 that costs less to run day-to-day.