The Duckworth 723 2011 is a modified-V design and the Duckworth Navigator Sport 20 2012 is a deep-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 - Duckworth 723 2011 at 23,0 ft versus Duckworth Navigator Sport 20 2012 at 20,3 ft. At 1 700 lbs and 1 600 lbs respectively, both sit in a similar weight class - either should pair comfortably with most mid-size SUVs and half-ton trucks, though always confirm your specific tow rating with the motor added.
The Duckworth Navigator Sport 20 2012 tops out at 150 hp. Engine specs for the Duckworth 723 2011 aren't listed - confirm with a dealer before selecting an outboard.Both carry nearly identical fuel loads - 42 gal and 42 gal - so range won't be a tiebreaker here.
For family outings this is probably the sharpest distinction between the two. The Duckworth 723 2011 is rated for 7 passengers, while the Duckworth Navigator Sport 20 2012 caps at 6. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Duckworth 723 2011 could be the deciding factor.
Bottom line: Choose the Duckworth 723 2011 if your priority is putting more people on the water - it handles 7 passengers and at 23,0 ft it has the deck room to back that rating up comfortably. The Duckworth Navigator Sport 20 2012 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 6 that costs less to run day-to-day.