Searunner 31 Trimaran
Description
The Searunner 31 is a classic plywood trimaran sailboat, renowned for its innovative design, seaworthiness, and affordability. Designed by American naval architect Jim Brown in the 1960s as part of the broader Searunner series (25–40 ft models), it became the most popular variant due to its balance of speed, stability, and ease of construction. Intended for cruising, racing, or liveaboard use by 1–4 crew, it excels in coastal and offshore passages, with a strong safety record in tropical conditions. Over 500 were built, mostly by amateur builders, emphasizing its DIY appeal. Jim Brown developed the Searunner 31 amid the 1960s multihull boom, drawing from earlier plywood designs to create a folding trimaran for trailering and marina storage. The central hull provides living space, while the amas (outer hulls) fold parallel via crossbeams, reducing beam from 18.67 ft to about 8 ft for transport. It features a cutter rig for versatility, a centerboard for shallow draft, and a center cockpit for safety. Unique aspects include its molded-chine hulls for reduced wetted surface and speed, plus options for kick-up rudders and tabernacle-stepped mast for easy launching. Production spanned the 1970s–1980s, with plans still available today; it's praised for performance but critiqued for limited payload and occasional hobby-horsing in waves.
The standard boat dimensions
| i | 35.50 ft |
|---|---|
| j | 14.25 ft |
| p | 32.50 ft |
| e | 12 ft |
| p2 | - |
| e2 | - |
| i2 | - |
| j2 | - |
| I | J | P | E | P2 | E2 | I2 | J2 |
|---|---|---|---|---|---|---|---|
| 35.50 ft | 14.25 ft | 32.50 ft | 12 ft | - | - | - | - |
Sails
| Sail Type | MAINSAIL |
|---|---|
| Luff | 32.5 ft - (9906 mm) |
| Foot | 12 ft - (3658 mm) |
| Leech | * 34.01 ft - (10366 mm) |
| Tack Angle | * 88 ° |
| Diagonal | * 34.25 ft - (10439 mm) |
| Head (inches) | * 5.25 in - (133 mm) |
| Area | * 201.12 ft² |
| Sail Type | JIBSAIL |
|---|---|
| Luff | 23.4 ft - (7132 mm) |
| Foot | 19.2 ft - (5852 mm) |
| Leech | 23.7 ft - (7224 mm) |
| Percentage LP | * 123.79 % |
| Length Perpendicular | * 17.64 ft - (5377 mm) |
| Deck Angle | * 1.37 ° |
| Area | * 206.42 ft² |
| Sail Type | GENOA |
|---|---|
| Luff | 35.5 ft - (10820 mm) |
| Foot | 21.5 ft - (6553 mm) |
| Leech | 34.5 ft - (10516 mm) |
| Percentage LP | * 141.4 % |
| Length Perpendicular | * 20.15 ft - (6142 mm) |
| Deck Angle | * -1.46 ° |
| Area | * 357.68 ft² |
| Sail Type | ASYMMETRICAL |
|---|---|
| Luff | 37 ft - (11278 mm) |
| Foot | 24 ft - (7315 mm) |
| Leech | 35 ft - (10668 mm) |
| Perc LP | * 165 % |
| Area | * 666 ft² |
| Sail Type | STAYSAIL |
|---|---|
| Luff | 22.3 ft - (6797 mm) |
| Foot | 9.7 ft - (2957 mm) |
| Leech | 20 ft - (6096 mm) |
| Length Perpendicular | 8.7 ft - (2652 mm) |
| Area | * 97 ft² |
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.