Production reached roughly 675 boats, making the M-20 one of the most successful scow classes of its era. The class remains active on lakes including Geneva in Wisconsin and Okoboji in Iowa.
Design and Construction
The M-20 has a flat-bottomed scow hull and twin centerboards, or bilgeboards, which provide lateral resistance without the intrusion of a centerboard trunk. The hull is 20 feet overall, with a 14-foot waterline and a narrow 5.67-foot beam. At 595 pounds displacement, it’s featherlight by keelboat standards.
That low weight, combined with the scow’s planar underside, allows the design to emphasize speed and planing ability on flat inland lakes. With the boards raised, minimum draft is just 0.67 feet, so the boat can be dried out or trailered. Lowering the boards increases draft to 3.5 feet for upwind grip.
Rig and Handling
The M-20 carries a fractional sloop rig with a 113.85-square-foot mainsail and a 62.27-square-foot jib. Together with the boat’s low displacement, that working sail area gives it a lively power-to-weight character.
A 293-square-foot spinnaker transforms the downwind leg. The source describes the sail plan as powerful and capable of thrilling downwind runs. The mainsail’s modest 4.5-inch head and 87.99-degree tack angle reflect a fractional, masthead-light configuration suited to a planing scow rather than a displacement cruiser.
On the broad, windswept Midwest lakes for which the class was designed, the rig rewards athletic crew work and precise weight placement.
Racing and Class Life
Strong one-design racing under the Inland Lake Yachting Association and the North American Scow Sailing Association has kept the M-20 relevant decades after its introduction. Its continued presence on Geneva, Okoboji, and other lakes shows that the roughly 675 hulls built established a self-sustaining competitive fleet rather than a short-lived production run.
For a 20-foot scow, that institutional support makes the difference between a collector’s curiosity and a boat that can still be campaigned on summer weekends.
Ownership Context
The M-20 was designed as a racing scow, not a cruiser, so ownership centers on trailering, rigging, and fleet participation rather than systems and refits. Surviving boats come from two builder lineages—Melges Boat Works and, later, Windward Boatworks—which is useful to know when tracing a particular hull’s provenance.
The Verdict
The M-20 Scow is a purpose-built inland racer that trades creature comforts for planing speed and a deep one-design structure. Its twin bilgeboards and flat scow bottom neatly reconcile the conflicting demands of shallow launch ramps and upwind performance. The class’s continuing health also makes it a rare vintage racer that can still be sailed competitively.
Pros
- Flat-bottomed scow hull with twin centerboards, providing lateral resistance without an intrusive centerboard trunk
- Light 595-pound displacement that enables planing and lively sailing on flat inland lakes
- Active one-design racing under ILYA and NASSA, with fleets still sailing on Geneva, Okoboji, and other lakes
- Fractional sloop rig with powerful, spinnaker-driven downwind performance
Cons
- Purpose-built racer with no cruising accommodation or offshore intent
- Narrow 5.67-foot beam limits the stability margin compared with wider sportboats
