When two boats share the same hull type — in this case both the Riviera Yachts 51 Enclosed Flybridge SII 2011 and the Riviera Yachts 73 Motor Yacht with Volvo Penta IPS 2011 are deep vee 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 Riviera Yachts 73 Motor Yacht with Volvo Penta IPS 2011 measures 73,5 feet overall (2011), giving it roughly 18,8 additional feet of deck space compared to the Riviera Yachts 51 Enclosed Flybridge SII 2011 at 54,7 feet (2011). Weight tells a clearer story for trailering families: the Riviera Yachts 73 Motor Yacht with Volvo Penta IPS 2011 tips the scales at 11 022 lbs — 6 216 lbs less than the Riviera Yachts 51 Enclosed Flybridge SII 2011 at 4 806 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.

Both boats share a closely matched power ceiling — 825 hp for the Riviera Yachts 51 Enclosed Flybridge SII 2011 and 835 hp for the Riviera Yachts 73 Motor Yacht with Volvo Penta IPS 2011. 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. Fuel capacity breaks the other way: the Riviera Yachts 73 Motor Yacht with Volvo Penta IPS 2011 carries 2 117 gallons versus 977 gallons in the Riviera Yachts 51 Enclosed Flybridge SII 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 Riviera Yachts 73 Motor Yacht with Volvo Penta IPS 2011 is rated for 22 passengers, while the Riviera Yachts 51 Enclosed Flybridge SII 2011 caps at 16. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Riviera Yachts 73 Motor Yacht with Volvo Penta IPS 2011 could be the deciding factor.