When two boats share the same hull type — in this case both the Weldcraft Marine 173 2011 and the Weldcraft Marine 21 Legacy 2011 are deep vee designs with aluminum 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 Weldcraft Marine 21 Legacy 2011 measures 21,0 feet overall (2011), giving it roughly 3,8 additional feet of deck space compared to the Weldcraft Marine 173 2011 at 17,3 feet (2011). Weight tells a clearer story for trailering families: the Weldcraft Marine 173 2011 tips the scales at 1 305 lbs — 1 274 lbs more than the Weldcraft Marine 21 Legacy 2011 at 31 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 Weldcraft Marine 173 2011 carries a rated maximum of 115 hp. Engine data for the Weldcraft Marine 21 Legacy 2011 wasn't available in our records — check the manufacturer's spec sheet before sizing a motor.Fuel capacity breaks the other way: the Weldcraft Marine 21 Legacy 2011 carries 62 gallons versus 42 gallons in the Weldcraft Marine 173 2011. 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 Weldcraft Marine 21 Legacy 2011 is rated for 6 passengers, while the Weldcraft Marine 173 2011 caps at 5. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Weldcraft Marine 21 Legacy 2011 could be the deciding factor.