The Lagoon 46 2019 vs Lagoon 51 2021 comparison sits squarely in the category of decisions where specs alone won't tell the whole story — intended use, storage, and long-term ownership costs all factor in.
Size is the most obvious dividing line here. The Lagoon 51 2021 measures 50,4 feet overall (2021), giving it roughly 5,3 additional feet of deck space compared to the Lagoon 46 2019 at 45,1 feet (2019). Weight tells a clearer story for trailering families: the Lagoon 51 2021 tips the scales at 43 910 lbs — 9 187 lbs less than the Lagoon 46 2019 at 34 723 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 80 hp, the Lagoon 51 2021 has a 23-hp advantage over the Lagoon 46 2019's 57-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Both carry nearly identical fuel loads — 137 gal and 137 gal — so range won't be a tiebreaker here.
For family outings this is probably the sharpest distinction between the two. The Lagoon 51 2021 is rated for 15 passengers, while the Lagoon 46 2019 caps at 13. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Lagoon 51 2021 could be the deciding factor.
Displacement is where these two sailboats genuinely part ways. The Lagoon 51 2021 displaces 43 910 lbs — a 9 187-lb difference over the Lagoon 46 2019 at 34 723 lbs. That gap separates two entirely different categories of sailing: the heavier boat is built for offshore passage-making and load-carrying, while the lighter hull rewards performance sailing and easier handling in lighter air.
Both boats draw a similar depth — 4,5 ft and 4,6 ft respectively. Marina access and anchorage options should be broadly equivalent between the two.
The Lagoon 46 2019 is rigged as a Sloop while the Lagoon 51 2021 carries fractional_rig_sloop rigging — a meaningful difference in sail handling complexity, upwind performance, and the size of crew you'll need to work the boat comfortably. For auxiliary power the Lagoon 51 2021 carries a 80-hp engine against 57 hp on the Lagoon 46 2019. Motoring range and ability to punch through a foul current or enter a tight marina under power will favour the more powerful installation.
For extended cruising, water capacity matters: the Lagoon 51 2021 carries 219 gallons versus 79 gallons on the Lagoon 46 2019 — a significant advantage on longer passages where watermaker or provisioning stops aren't guaranteed.
Bottom line: The Lagoon 51 2021 is the offshore and bluewater choice — at 43 910 lbs displacement and 50 ft it has the load capacity, range, and seakeeping for extended passages. The Lagoon 46 2019 at 34 723 lbs is the more nimble, accessible option — easier to single-hand and better suited to coastal and inland sailing.