FairKeel → Buyer's guides → Lagoon 420
2006–2009 · designed by Marc Van Peteghem and Vincent Lauriot-Prévost (VPLP) · built by Lagoon
Comfort-oriented cruising catamaran notable for its early diesel-electric propulsion option. A purchase assessment starts by identifying the machinery: Lagoon's period inventory documents hybrid and conventional diesel versions, which need different inspection expertise and maintenance plans.
Check this first — Hybrid boats use electric motors on shafts with a diesel generator; the conventional installation uses diesel saildrives. A converted boat needs conversion records as well as original build details. The period sheet gives different light displacements for the two packages, so no single displacement is shown. This guide covers the early 420 generation through the 2009 transition to the distinct 421; check boundary-year identity by HIN. It does not cover either generation of Lagoon 42.
This is a general read on the Lagoon 420 class — informed background, not a verdict on any individual boat. Condition, refit history, and how a particular hull was sailed and stored matter far more than class reputation. Use it to know what to look for; for a read on a specific listing, run a free FairKeel report on that boat.
Looking at a specific Lagoon 420? Run it free → We grade that listing's own claims against what's known about the class, and flag the gaps a survey would catch. Free, no account.
Trace the current installation from original build documents through every conversion. Ask who can service it locally and what evidence demonstrates full operation.
On a hybrid, commission a specialist assessment of batteries, controllers, generator and charging. Demonstrate both propulsion channels and fault handling; a running generator alone is insufficient.
On a conventional diesel boat, obtain separate records and engineering checks for each engine and drive. Confirm fitted equipment before applying any service interval.
The inventory distinguishes balsa sandwich from solid underwater laminate. Ask the surveyor to locate moisture, impacts and prior work, particularly where equipment has been added.
Inspect the coachroof mast support and control attachments. Demonstrate reefing and emergency steering and confirm access remains clear after refits.
This guide is the class. A report is that hull. Paste the listing you're looking at and FairKeel grades every claim in it against what's known about the Lagoon 420 — where the evidence is thin, the red flags worth a second look, the costs likely to land in your first season, and whether the boat suits the plans you describe in a few short questions.
It won't read the photos or put a number on the boat — that's the $249 Deep-Dive, and for the real answer, a surveyor. It will tell you when a Deep-Dive isn't worth buying. Free, no account, usually a minute or two.
Run a free report on your listing →See something that doesn't look right? We'd love to know — email us about the Lagoon 420 →