Multihull designer Bernd Kohler contacted me last week and let me know about his newest design – “Little Tri.” Bernd initially designed and built this boat as a daysailer for he and his wife. (He explains in the story below). But then many people started asking him if he could make plans available so they could build this boat too.
It appears to be a fast, light boat. And may be of particular interest to anyone who’d like to build a small tri on a budget.
As you’ll see here, there’s nothing “fancy shmancy” about this boat. It utilizes a used “Sunfish” sail, for example. And yet, the sailing comfort and performance of this boat seems quite remarkable.
by Bernd Kohler
Being boat-less for some years, the time was ripe for a new boat. Besides other considerations, I would
prove to myself that I can built a multihull in 100 hours for €1000,00 as I have done 1979.
Then there where different monohulls, from small dinghy’s to cruisers. My last new experience was sailing a kite buggy (not built by myself) some weeks ago.
In 1979 I started with catamarans. And now a trimaran or better, a double outrigger boat.
This for various reasons. One of them, after a stroke my wife is paralyzed on one side. She would like to sail again too. So it had to be a boat where one can sit in. The logical choice was a trimaran.
The result is more along the lines of the double outrigger boats which are common in some parts of the
Pacific. So hiking out would be necessary. No problem. The trampoline/seats are a perfect place to do so.
To connect the akas to the hull and amas, robes are used as on Pacific outriggers. Only to connect the akas to the hull I now use stainless steel clasps. (Is a lot faster than attaching the akas with ropes.)
The hull is a high aspect ratio sharpy hull. With its slap sides easy and fast to build. Construction is with
Plywood / glass / epoxy composite, as all my designs.
For good windward performance, I chose for a dagger / leeboard. The daggerboard rudder is in a cassette.
I managed to build the hull in 73 hours. But then it started. The irrigation tubes I could get where only 3 m
long. But the amas have to be 4 m long. There was extra work gluing and glassing them together.
The delivery of the Aluminum tubes was 3 mounts too late. They where also wrong size; instead of a wall thickness of 2,5 mm, they were 5 mm. So by the end, it took 110 hours to build the boat and the total end cost was €1139 – Euro. With good tubes initially, the cost would have been €1019 Euro.
Did I meet my goal? I would say, “Yes.”
Here is a short “walk around” video of the boat…
Because of the late delivery time there was sailing time lost and it would have been done under better circumstances. I am very satisfied, however, with the performance and handling of the boat.
The first two sails where in light wind. Here is video taken during one of them…
The last sail was under better conditions. Strong offshore wind with a flat sea. The maximum speed I could observe was around 13 knots. More important for me though was that this boat has a very good handling quality.
Coming about is a tootle. The boat sails surprisingly dry too … so no test yet for the self-training cockpit.
Here the main particulars of the boat:
Length: 4.70 m
Length ama: 4.00 m
Beam: 3.80 m
Weight: 75 kg
Positive floatation: 275 kg*
Sail area till: 13 m2
* Hull only, under foredeck and cockpit floor, without aft compartment
At last, a cockpit that is self-draining and 2 m long. It measures a maximum 0,57m and minimum 0,5 m in size. With a tent cover, one would have a snug yet nice place to sleep.
The boat would make a nice little trekking boat for one person. For dry storage, the mast compartment and aft compartment can be used.
This boat was meant as a personal project. But many people where asking me to make plans available. In the end I did.
— Bernd Kohler
Update 11/12/14 – Short video about the building process for Little Tri…