When two boats share the same hull type — in this case both the Navigator Yachts Navigator 4200 2010 and the Navigator Yachts Navigator 5100 2010 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 Navigator Yachts Navigator 5100 2010 measures 51,7 feet overall (2010), giving it roughly 9,0 additional feet of deck space compared to the Navigator Yachts Navigator 4200 2010 at 42,7 feet (2010). At 37 lbs and 5 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 500 hp, the Navigator Yachts Navigator 5100 2010 has a 498-hp advantage over the Navigator Yachts Navigator 4200 2010's 2-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Both carry nearly identical fuel loads — 4 gal and 6 gal — so range won't be a tiebreaker here.

For family outings this is probably the sharpest distinction between the two. The Navigator Yachts Navigator 5100 2010 is rated for 15 passengers, while the Navigator Yachts Navigator 4200 2010 caps at 13. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Navigator Yachts Navigator 5100 2010 could be the deciding factor.