Both the Marathon DN 1236 Jon 2012 and the Marathon Jon - DN 1036 2009 are flat-bottom designs, both built in aluminium, 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 - Marathon DN 1236 Jon 2012 at 12,0 ft versus Marathon Jon - DN 1036 2009 at 10,0 ft. At 110 lbs and 96 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.
Both boats share a closely matched power ceiling - 7 hp for the Marathon DN 1236 Jon 2012 and 3 hp for the Marathon Jon - DN 1036 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.
For family outings this is probably the sharpest distinction between the two. The Marathon DN 1236 Jon 2012 is rated for 3 passengers, while the Marathon Jon - DN 1036 2009 caps at 2. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Marathon DN 1236 Jon 2012 could be the deciding factor.
At this size, power-to-weight ratio matters more than outright horsepower. The Marathon DN 1236 Jon 2012 comes in at 16 lbs per hp versus 32 lbs per hp for the Marathon Jon - DN 1036 2009. The lower the ratio the more explosive the acceleration - meaningful on a short RIB where bursts of speed, quick planing, and agility in surf or tight waterways define the experience.
Bottom line: Choose the Marathon DN 1236 Jon 2012 if your priority is putting more people on the water - it handles 3 passengers and at 12,0 ft it has the deck room to back that rating up comfortably. The Marathon Jon - DN 1036 2009 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 2 that costs less to run day-to-day.