Interlake
Description
The Interlake is an 18-foot, fixed-keel one-design racer/daysailer designed in 1933 by Francis Sweisguth and continuously built in Sandusky, Ohio since then, with over 1,500 hulls produced and still in production today by Customflex. With a 52% ballast ratio, 175 sq ft fractional sloop rig, and a big, dry cockpit that seats six, it is one of the stiffest, fastest, and most family-friendly small keelboats ever made—routinely planes upwind in 12–15 knots, carries full sail in 25+ knots without anyone on the rail, and regularly draws 70–90 boats to its annual National Championship on Lake Erie. Strict one-design rules keep 1940s wooden boats fully competitive with brand-new fiberglass ones, making it a true “race one weekend, picnic the next” classic that remains one of the strongest and most beloved regional classes in North America in 2025.
Construction Details
| Designer | Francis Swiesguth |
|---|---|
| Builder | Customflex (USA) |
| Length | 18.000 ft |
| LOA | 18.000 ft |
| Beam | 6.250 ft |
| Displacement | 650 lb |
| Max Draft | 4.580 ft |
| Min Draft | 0.670 ft |
The standard boat dimensions
| i | - |
|---|---|
| j | - |
| p | - |
| e | - |
| p2 | - |
| e2 | - |
| i2 | - |
| j2 | - |
| I | J | P | E | P2 | E2 | I2 | J2 |
|---|---|---|---|---|---|---|---|
| - | - | - | - | - | - | - | - |
Documents
Blueprints
Sails
Interlake - MAINSAIL
| Luff | 21 ft - (6401 mm) |
|---|---|
| Foot | 12.25 ft - (3734 mm) |
| Leech | * 22.95 ft - (6995 mm) |
| Tack Angle | * 84.37 ° |
| Diagonal | 23.25 ft - (7087 mm) |
| Head (inches) | 6 in - (152 mm) |
| Area | * 132.62 ft² |
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Interlake - JIBSAIL
| Luff | 16 ft - (4877 mm) |
|---|---|
| Foot | 7 ft - (2134 mm) |
| Leech | 14.33 ft - (4368 mm) |
| Length Perpendicular | * 6.27 ft - (1911 mm) |
| Area | * 50.15 ft² |
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Interlake - SPINNAKER
| Stays | 18.5 ft - (5639 mm) |
|---|---|
| MidGirth | 12.5 ft - (3810 mm) |
| Foot | 13.83 ft - (4215 mm) |
| Area | * 217 ft² |
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Disclaimer. Boats are not all the same -- even when produced in the same factory of the same model. Sailrite does its best to publish accurate dimensions, but we often find it worthwhile to have our customers measure their boats carefully before we produce kits for them. You should take the same precautions, especially when the data is not from Sailrite. The information on this site is not guaranteed to be accurate. Sailrite offers this content as a service to our community, but takes no responsibility for the reliability of the data provided.