When two boats share the same hull type — in this case both the Sea Ray 390 Sedan Bridge 2010 and the Sea Ray 580 Sundancer 2012 are semi displacement designs with fiberglass construction — 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 Sea Ray 390 Sedan Bridge 2010 measures 38,3 feet overall (2010), giving it roughly 32,3 additional feet of deck space compared to the Sea Ray 580 Sundancer 2012 at 6,0 feet (2012). Weight tells a clearer story for trailering families: the Sea Ray 580 Sundancer 2012 tips the scales at 535 lbs — 513 lbs less than the Sea Ray 390 Sedan Bridge 2010 at 22 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 1 051 hp, the Sea Ray 580 Sundancer 2012 has a 681-hp advantage over the Sea Ray 390 Sedan Bridge 2010's 370-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Fuel capacity breaks the other way: the Sea Ray 580 Sundancer 2012 carries 825 gallons versus 3 gallons in the Sea Ray 390 Sedan Bridge 2010. On a lake day that's negligible, but for coastal cruising or long reservoir runs the extra range matters.

The Sea Ray 390 Sedan Bridge 2010 is rated for up to 11 people. Passenger data for the Sea Ray 580 Sundancer 2012 wasn't available.