Both the Klamath 12 ft. Deluxe 2005 and the Klamath 18 Open 2011 are modified-V designs, 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?
Size is the most obvious dividing line here. The Klamath 18 Open 2011 measures 18,3 feet overall (2011), giving it roughly 6,3 additional feet of deck space compared to the Klamath 12 ft. Deluxe 2005 at 12,0 feet (2005). Weight tells a clearer story for trailering families: the Klamath 18 Open 2011 tips the scales at 500 lbs - 350 lbs less than the Klamath 12 ft. Deluxe 2005 at 150 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 75 hp, the Klamath 18 Open 2011 has a 60-hp advantage over the Klamath 12 ft. Deluxe 2005's 15-hp ceiling - enough to notice on acceleration and at cruising speed, particularly with a full passenger load.
For family outings this is probably the sharpest distinction between the two. The Klamath 18 Open 2011 is rated for 8 passengers, while the Klamath 12 ft. Deluxe 2005 caps at 3. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Klamath 18 Open 2011 could be the deciding factor.
Bottom line: Choose the Klamath 18 Open 2011 if your priority is putting more people on the water - it handles 8 passengers and at 18,3 ft it has the deck room to back that rating up comfortably. The Klamath 12 ft. Deluxe 2005 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 3 that costs less to run day-to-day.