When two boats share the same hull type — in this case both the Sea Ray 390 Sundancer 2011 and the Sea Ray 580 Sedan Bridge 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 580 Sedan Bridge 2012 measures 58,6 feet overall (2012), giving it roughly 19,6 additional feet of deck space compared to the Sea Ray 390 Sundancer 2011 at 39,0 feet (2011). Weight tells a clearer story for trailering families: the Sea Ray 580 Sedan Bridge 2012 tips the scales at 515 lbs — 269 lbs less than the Sea Ray 390 Sundancer 2011 at 246 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 861 hp, the Sea Ray 580 Sedan Bridge 2012 has a 436-hp advantage over the Sea Ray 390 Sundancer 2011's 425-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 390 Sundancer 2011 carries 25 gallons versus 7 gallons in the Sea Ray 580 Sedan Bridge 2012. On a lake day that's negligible, but for coastal cruising or long reservoir runs the extra range matters.

For family outings this is probably the sharpest distinction between the two. The Sea Ray 580 Sedan Bridge 2012 is rated for 17 passengers, while the Sea Ray 390 Sundancer 2011 caps at 11. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Sea Ray 580 Sedan Bridge 2012 could be the deciding factor.