When two boats share the same hull type — in this case both the South Bay 516C 2010 and the South Bay 620C 2008 are pontoon 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 South Bay 516C 2010 measures 16,3 feet overall (2010), giving it roughly 14,3 additional feet of deck space compared to the South Bay 620C 2008 at 2,0 feet (2008). At 124 lbs and 195 lbs respectively, both sit in a similar weight class — either should pair comfortably with most mid-size SUVs and half-ton trucks, though always confirm your specific tow rating with the motor added.

The power gap is worth calling out. Rated to 90 hp, the South Bay 620C 2008 has a 30-hp advantage over the South Bay 516C 2010's 60-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load.

For family outings this is probably the sharpest distinction between the two. The South Bay 620C 2008 is rated for 11 passengers, while the South Bay 516C 2010 caps at 7. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the South Bay 620C 2008 could be the deciding factor.

At this size, power-to-weight ratio matters more than outright horsepower. The South Bay 516C 2010 comes in at 2 lbs per hp versus 2 lbs per hp for the South Bay 620C 2008. The lower the ratio the more explosive the acceleration — meaningful on a short RIB where bursts of speed, quick planing, and agility in surf or tight waterways define the experience.

Both are 2-tube and 2-tube pontoon designs respectively. Tube diameter and gauge affect stability and load capacity — more so than most buyers realize when comparing on paper.