Both the Tiara Yachts 3100 Open 2012 and the Tiara Yachts 3900 Open 2012 are deep-V designs, both built in fibreglass, 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?

Size is the most obvious dividing line here. The Tiara Yachts 3900 Open 2012 measures 41,9 feet overall (2012), giving it roughly 8,9 additional feet of deck space compared to the Tiara Yachts 3100 Open 2012 at 33,0 feet (2012). Weight tells a clearer story for trailering families: the Tiara Yachts 3900 Open 2012 tips the scales at 24 500 lbs - 11 275 lbs less than the Tiara Yachts 3100 Open 2012 at 13 225 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 600 hp, the Tiara Yachts 3900 Open 2012 has a 225-hp advantage over the Tiara Yachts 3100 Open 2012's 375-hp ceiling - enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Fuel capacity breaks the other way: the Tiara Yachts 3900 Open 2012 carries 535 gallons versus 210 gallons in the Tiara Yachts 3100 Open 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 Tiara Yachts 3900 Open 2012 is rated for 12 passengers, while the Tiara Yachts 3100 Open 2012 caps at 10. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Tiara Yachts 3900 Open 2012 could be the deciding factor.