The Marathon Otisco 12 2007 vs Marathon Seneca 13 2007 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 - Marathon Otisco 12 2007 at 12,0 ft versus Marathon Seneca 13 2007 at 13,0 ft. At 110 lbs and 150 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 Otisco 12 2007 and 15 hp for the Marathon Seneca 13 2007. 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 Seneca 13 2007 is rated for 4 passengers, while the Marathon Otisco 12 2007 caps at 3. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Marathon Seneca 13 2007 could be the deciding factor.
At this size, power-to-weight ratio matters more than outright horsepower. The Marathon Seneca 13 2007 comes in at 10 lbs per hp versus 16 lbs per hp for the Marathon Otisco 12 2007. 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 Seneca 13 2007 if your priority is putting more people on the water - it handles 4 passengers and at 13,0 ft it has the deck room to back that rating up comfortably. The Marathon Otisco 12 2007 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 3 that costs less to run day-to-day.