The DUO 425 was the first parallel rig cat designed for amateur construction. The prototype was shown at the boat show in Düsseldorf in 1984. We have the most experience with this sort of rigs. Many very fast, record-breaking catamarans have used and still use this configuration.
I lost count of how many DUO 425 are sailing worldwide, but it has to be more than 1000.
This is the easiest cat imaginable to build. Transport on the roof of a car is no problem. Setup time is about 20 minutes.
The DUO 425 can be built in 120 hours With this construction sequence, you can do it in that time. Many clients with no experience have proven it, from doctors to mechanics to bureau workers.
The hulls are wood/epoxy constructions. We use a sort of "matched hole technique" used in Aluminum aircraft construction. You start with some precisely drilled holes; instead of Clegos, we use screws. You can build the asymmetrical hulls flat on a table or the floor.
Material needed
Each hull uses only 16 main parts.
Here the list of materials
4 panels 4mm plywood
1 panel 8mm plywood.
16m wood strips 20x20mm
5kg Epoxy as a base.
Plus, of course, two 2 windsurf rigs.
That is all. Check what you normally need for a boat 4.25 m long. Use the list to find the boat's costs.
The boat can handle strong winds. I sailed the boat till wind force 9 without any problem. And believe me, the boat is faaaast ! The picture on the right shows the "sharked DUO". It was a second-hand boat, by the way. He reached at a channel near Lelystad 64 kmh (34 knots). Of course, the boat is easy to beach. No problem with my well known vertical rudder automatic.
I lost count of how many DUO 425 are sailing worldwide, but it has to be more than 1000.
This is the easiest cat imaginable to build. Transport on the roof of a car is no problem. Setup time is about 20 minutes.
The DUO 425 can be built in 120 hours With this construction sequence, you can do it in that time. Many clients with no experience have proven it, from doctors to mechanics to bureau workers.
The hulls are wood/epoxy constructions. We use a sort of "matched hole technique" used in Aluminum aircraft construction. You start with some precisely drilled holes; instead of Clegos, we use screws. You can build the asymmetrical hulls flat on a table or the floor.
Material needed
Each hull uses only 16 main parts.
Here the list of materials
4 panels 4mm plywood
1 panel 8mm plywood.
16m wood strips 20x20mm
5kg Epoxy as a base.
Plus, of course, two 2 windsurf rigs.
That is all. Check what you normally need for a boat 4.25 m long. Use the list to find the boat's costs.
The boat can handle strong winds. I sailed the boat till wind force 9 without any problem. And believe me, the boat is faaaast ! The picture on the right shows the "sharked DUO". It was a second-hand boat, by the way. He reached at a channel near Lelystad 64 kmh (34 knots). Of course, the boat is easy to beach. No problem with my well known vertical rudder automatic.
DUO
Record boat DUO 425 Lelystad
425
Specification
Length : 4.25 m
Beam : 2.10 m
Weight hull: 17.00 kg
Weight all in: 44.00 kg
Sail area: up to 16m2
Length : 4.25 m
Beam : 2.10 m
Weight hull: 17.00 kg
Weight all in: 44.00 kg
Sail area: up to 16m2
Observe the low weight and compare with other catamarans with the same dimensions. Car transport is with this low weigth legally possible
Here the DUO 480C hull as example for the matched hole technique and The easy set up.
Parts ready to be mounted for a hull and a rudder
editCopyright © 2026 by B. Kohler, K-designs All rights reserved
Plan with the right to build one unit
US $ 70,-
US $ 70,-
SMALL BOAT.
BIG SPEED.
BIG SPEED.
The fastest cat for your money. An ultra-light, easily built 4.25 m catamaran with twin windsurf rigs and exhilarating performance.
Compact, lightweight and ready for the next sailing day.
A sailing day
|
4.25 m Length |
2.10 m Beam |
44 kg All-up weight* |
120 h Approx. build time |
34 kn Reported top speed** |
How work
biplane (parallel)rigs
biplane (parallel)rigs
That asymmetric hulls are easy to build is logical. 40% less time is needed. Push the button to see how easy it is.
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