Design and Construction
The Lagoon 400 uses modern vacuum-infused polyester construction, with solid laminate below the waterline and balsa core above, including in the decks. Lagoon also applies vinylester resin to the hulls as an osmotic barrier.
Compared with most 40-foot catamarans, the 400 has substantial hull beam and freeboard. The platform itself is very beamy at 7.25 meters. Beneath the nacelle, a carefully shaped surface sits 50 to 70 centimeters above the sea—a detail Multihulls World described as deliberately engineered rather than incidental.
The boat carries 75 inches of freeboard to the deck, along with a high superstructure and low-aspect keels. Together, these features show a design centered on comfort and payload rather than close-winded agility.
Rig and Sailing Performance
The Lagoon 400’s rig is taller than that of a Nautitech 44. Its standard full-battened mainsail measures 603 square feet, while the optional square-headed main increases that area to 651 square feet. For the square-headed sail, Lagoon devised an inventive line system that automatically tensions the upper luff to the spar as the main rises.
A short bowsprit carries a screecher. All halyards and sail-control lines lead aft to a dedicated steering station above and to port, which can be enclosed with zippered curtains in foul weather.
Writing in Cruising World, test sailors reported speeds of 4.5 to 5.2 knots in 6 to 7 knots of wind while reaching under the bowsprit-mounted screecher. Cruising World’s testers found that the boat performs best when sailed fully powered and eased a few degrees off the wind.
The steering-station arrangement keeps the sail controls together, but access elsewhere is less convenient. Testers were concerned about the lack of a step onto the cabin top for crew who need to reach the mainsail pouch.
Engines and Harbor Handling
The Lagoon 400 came with standard 30-horsepower Yanmars or optional 40-horsepower engines. With its twin diesels set nearly 24 feet apart, the boat can back up and twirl around almost magically. Under power, the test boat’s optional 40-horsepower Yanmars loped along at 7 knots at 2,200 rpm.
That widely spaced twin-engine layout makes docking manageable, but the boat’s substantial windage in a beam wind remains a real handling caveat when maneuvering in harbor.
Accommodations
Inside, the Lagoon 400 aims to provide luxurious living in a space comparable to that of a 60-foot monohull. Whitewash-finished panels, beech joinery, large ports, and wide soles in the hulls help keep the saloon bright. Vertical ports wrap around the bridgedeck saloon, shading the interior and lifting headroom in the signature Lagoon style.
The aft double berths sit low in the hulls and have side cutouts for easier access. Multilayer foam mattresses rest on slats for ventilation, while halogen fixtures throughout provide excellent lighting. Forward, the V-berths have sliding fillers that reveal large storage lockers.
In the three-cabin layout, one hull contains an enormous bedroom, office, and bathroom, with space for an optional washing machine. Above, a single large roof sweeps aft from the front of the cabin over the cockpit, creating an exterior saloon.
The galley includes a molded-in dish drainer. On early boats, however, the builder acknowledged that adding a second fridge or freezer would cut deeply into provisions storage. Overhead cabinets were planned for later units.
Known Issues
Cruising World’s Boat of the Year judges found the latch that holds open the sliding door and window between the saloon and cockpit hard to operate. The same panel noted that children might be able to reach the saloon electrical panel, a risk the judges felt could be prevented with a lock.
The lack of a step onto the cabin top is also a practical annoyance when handling sails at the mast or reaching the mainsail pouch.
Equipment and Ownership
The Lagoon 400 carries a CE certification rating of A:8 / B:14 / C:20 / D:20, speaking to offshore capability for a catamaran of this size. Many boats either left the factory with electric winches or received them later, easing the demands of the tall rig.
The Verdict
The Lagoon 400 is a spacious cruising catamaran that trades upwind finesse for generous living space and easy maneuvering under power. Its construction and rig reflect Lagoon’s considered third-generation approach, while its accommodations remain a strong draw for liveaboards and charter buyers alike.
Pros
- Beamy, high-volume interior with living space comparable to that of a 60-foot monohull
- Widely spaced twin diesels provide exceptional close-quarters maneuverability
- Tall rig with an optional square-headed main and automatic luff tensioning
- Solid-laminate underwater hull, balsa-cored decks, and an osmotic barrier
Cons
- Substantial windage in a beam wind complicates harbor maneuvering
- No step onto the cabin top, hindering mast-access sail handling
- Boat of the Year judges noted a hard-to-operate saloon sliding-door latch and an accessible electrical panel
- Low-aspect keels and high freeboard discourage pinching up to windward
