The Nitro 640 LX 2006 vs Nitro Bay 1900 Tunnel 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 — Nitro 640 LX 2006 at 16,0 ft versus Nitro Bay 1900 Tunnel 2005 at 19,0 ft. Weight tells a clearer story for trailering families: the Nitro 640 LX 2006 tips the scales at 1 092 lbs — 960 lbs more than the Nitro Bay 1900 Tunnel 2005 at 132 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 150 hp, the Nitro Bay 1900 Tunnel 2005 has a 60-hp advantage over the Nitro 640 LX 2006's 90-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Fuel capacity breaks the other way: the Nitro Bay 1900 Tunnel 2005 carries 47 gallons versus 24 gallons in the Nitro 640 LX 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 Nitro Bay 1900 Tunnel 2005 is rated for 6 passengers, while the Nitro 640 LX 2006 caps at 4. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Nitro Bay 1900 Tunnel 2005 could be the deciding factor.
Bottom line: Choose the Nitro Bay 1900 Tunnel 2005 if your priority is putting more people on the water — it handles 6 passengers and at 19,0 ft it has the deck room to back that rating up comfortably. The Nitro 640 LX 2006 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 4 that costs less to run day-to-day.