Sailing World named it 2007 One-Design of the Year. The design has since found a dual role. It was created for sailing schools, rental fleets, clubs, and young sailors operating with reduced supervision, but it also suits regatta sailors who have outgrown dinghy acrobatics. The boat is solid, simple, transportable, unsinkable, and hardly capsizable.
Design and Construction
The Open 5.70’s molded hull is built from glass-fiber-reinforced polyester, with an internal foam core. The deck is a sandwich construction with a 15mm PVC foam core. A large, fixed longitudinal structure connects the deck and hull, giving the 450 kg hull its rigidity.
Ballast totals 180 kg, split between a 30 kg glass-injected fin and a 150 kg lead bulb. The T-keel lifts: fully deployed, it draws 5 feet 9 inches, but it can be blocked at 1.40 m for shallower water, providing a 4 foot 6 inch shallow-water mode. Twin retractable rudders complete the underwater arrangement.
The hull combines a 5.70-meter waterline with a 2.55-meter beam, the maximum permitted for road transport. Its waterline remains narrow to reduce wetted surface, while the design uses the longest possible floating waterline of 5.70 meters. This is a deliberate trade-off that favors speed over interior volume.
Rig and Handling
The Open 5.70 carries a fractional sloop rig with a pivoting wingmast, supported by a forestay and two aft shrouds. It uses the same rotating mast and boom as the Hobie Tiger catamaran. A bolt jack beneath the mast sets rig tension, while a diamond arrangement pressing on two small spreaders—which rotate with the mast—helps stabilize it.
The mainsail measures 18 square meters and the genoa 8 square meters. A 32-square-meter asymmetric spinnaker flies from a telescopic boomsprit. The kite hoists through the gap between the shroud and mast, and one person can handle both the hoist and takedown alone.
A stern-mounted mainsheet and traveler, typical of modern catamarans, uses the boat’s extreme beam to provide a long traveler span. Test sailors found that the combination of leech tension and traveler throw is the key to making the 5.70 go uphill. With two sailors aboard, they easily reached boatspeeds in the mid-teens in a 12- to 14-knot breeze.
Rigging, tensioning, and launching take about 30 minutes. The boat can be launched from a ramp or by hoist.
Cockpit and Crew
There’s no enclosed cabin. Instead, the Open 5.70 has a large, open cockpit with ample room for sailhandling and enough space for crews to adjust weight placement. Testers describe the cockpit as wide open.
The beamy layout supports a class maximum crew weight of 573 pounds, allowing ample load capacity. European fleets usually race with three sailors, while U.S. testers sailed with two. The open cockpit and lifting keel make the boat suitable both as a trainer for schools and clubs and as a regatta boat.
Buoyancy and Stability Claims
The builder claimed that the foam-core construction and sealed volumes made the boat unsinkable, according to U.S. importer Jerome Sammarcelli. The manufacturer also describes the design as unsinkable and hardly capsizable.
Transport and Ownership
Transportability and simplicity are central to Open 5.70 ownership. The 2.55-meter beam is the maximum road-transport width, so the boat can be trailered easily. Its roughly 30-minute setup also keeps operation straightforward for clubs and private owners.
The rotating wingmast, boom, and catamaran-style traveler use proven hardware shared with the Hobie Tiger, simplifying spares.
The Verdict
The Open 5.70 is a purpose-built sportboat that trades creature comforts for outright fun and accessibility. It suits sailors who want catamaran-style speed in a monohull they can trailer and ramp-launch, as well as junior programs looking for a solid, simple boat designed for young sailors operating with reduced supervision.
The lifting keel and twin retractable rudders extend its use from shallow estuaries to open regattas. Its foam-core hull and sealed volumes also support the schools-and-clubs role, although the unsinkability and capsize-resistance descriptions remain manufacturer claims.
Pros
- Lifting T-keel with a shallow-water mode, plus ramp or hoist launching
- Foam-core hull, sealed volumes, and a fixed longitudinal structure
- Catamaran-derived rotating wingmast and traveler, with recorded boatspeeds in the mid-teens
- Road-transport-width beam and approximately 30-minute setup suit clubs and trailer sailors
Cons
- Open cockpit only, with no cabin accommodation
- Narrow waterline limits interior volume relative to the boat’s beam
