The Beneteau Oceanis 390 1987 vs Beneteau Oceanis 51.1 2020 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 Beneteau Oceanis 51.1 2020 measures 52,4 feet overall (2020), giving it roughly 14,2 additional feet of deck space compared to the Beneteau Oceanis 390 1987 at 38,2 feet (1987). Weight tells a clearer story for trailering families: the Beneteau Oceanis 51.1 2020 tips the scales at 30 702 lbs — 16 372 lbs less than the Beneteau Oceanis 390 1987 at 14 330 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 110 hp, the Beneteau Oceanis 51.1 2020 has a 60-hp advantage over the Beneteau Oceanis 390 1987's 50-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Fuel capacity breaks the other way: the Beneteau Oceanis 51.1 2020 carries 53 gallons versus 46 gallons in the Beneteau Oceanis 390 1987. 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 Beneteau Oceanis 51.1 2020 is rated for 15 passengers, while the Beneteau Oceanis 390 1987 caps at 11. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Beneteau Oceanis 51.1 2020 could be the deciding factor.

Displacement is where these two sailboats genuinely part ways. The Beneteau Oceanis 51.1 2020 displaces 30 702 lbs — a 16 372-lb difference over the Beneteau Oceanis 390 1987 at 14 330 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.

Draft is a practical consideration that many buyers underestimate until they're already at the marina. The Beneteau Oceanis 51.1 2020 draws 9,5 ft, compared to 5,5 ft for the Beneteau Oceanis 390 1987. That 4,0-foot difference affects which anchorages you can access, which haul-out facilities will take you, and how carefully you need to read the tide tables in shallower cruising grounds.

The Beneteau Oceanis 390 1987 uses Sloop rigging. Helm style differs too: the Beneteau Oceanis 390 1987 uses a 1 wheel versus a 2 wheels on the Beneteau Oceanis 51.1 2020. Wheel helms give better leverage and visibility on larger boats; tillers offer direct feedback and simplicity on smaller ones. For auxiliary power the Beneteau Oceanis 51.1 2020 carries a 110-hp engine against 50 hp on the Beneteau Oceanis 390 1987. Motoring range and ability to punch through a foul current or enter a tight marina under power will favour the more powerful installation.

Hull speed is rated at 9,3 knots for the Beneteau Oceanis 51.1 2020 and 7,7 knots for the Beneteau Oceanis 390 1987. For extended cruising, water capacity matters: the Beneteau Oceanis 390 1987 carries 169 gallons versus 116 gallons on the Beneteau Oceanis 51.1 2020 — a significant advantage on longer passages where watermaker or provisioning stops aren't guaranteed.