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In this post we feature a couple small trimarans built from Finn dinghy hulls. Sailor Jarda Suchopar shares about these boats (all the way from the Czech Republic.)

When I asked Jarda how he first got into small tris he replied with the following explanation:

It is a bit of a humorous story. Eight years ago we sailed in Poland on the very nice Mazury lakes. We were the only open dinghy — non cabin cruiser — on the lakes. Because the Finn dighy is easy to be capsized, we had clothes and sleeping needs enclosed in barrels. We met an old Polish yachtsman and he questioned us: “What do you carry in the barrels?“, he said in the Polish language. But in Czech it sounded like “what do you smuggle in the barrels?” My wife is able to tolerate a lot, but this time she said, “No more barrels for us!” So I started to think-about how to make a very lightweight, stable, easily transportable and low-cost small cabin cruiser for two … for our summer trips all over the Europe.

The results of Jarda’s thinking are on display below. His boats show both creativity and resourcefulness. Thanks for sharing them with us Jarda!


Finn Dinghy Trimarans

My name is Jaroslav. I’m from Prague (Czech Republic) and I’d like to give you some information about my hobby – building and sailing small trimarans.

My first trimaran was build from an old dinghy Finn hull. We had been using it for about 3 years and we spent lovely times with it, for instance, in the Stockholm’s Archipelago.

See some pictures of it here: http://www.jachting.info/viewtopic.php?t=8701

Unfortunately, over time, I realized there are some things I would like to improve. So I have started a new project – a new small trimaran – version 2 – from another old Finn wooden dinghy. I saved from the first project the amas, mast and sails and I used them for the new one.

The technical data of the trimaran Old_Finn ver.2 are:

See some pictures of this second Finn dinghy trimaran here: http://jardasu.rajce.idnes.cz/Old_Finn/

The hull was enlarged from 4,5 meter to 5 meters (from 15 ft. to 16.5 ft) and laminated by epoxy resin. The whole hull is reinforced by larch battens and on the hull is built a cabin (deckhouse) from waterproof plywood – the thickness of the material is 4, 6, 9 and 12 millimetres.

As I have to consider the size of the whole ship from the point of storage and specially transport I projected telescopic beams for the amas (floats) which are made from dural (duralomin). Used tubes have diameter 100 millimetres (3.9 in) – thickness of the material 2 milimeters for the settled part of the telescope and diameter 90 millimeters (3.5 in) / 3 milimeters for (slide in) part (retractable part of the beam).

The new project have those innovations and improvements:

  • Self-bailing cockpit
  • Folding (swinging) rotatable mast
  • Folding amas are newly on a telescopic boom
  • Folding keel (fin) is kept from the original dinghy Finn
  • I have get rid of daggerboards from the amas (ver.1) and narrowed the amas from 0,35 metre (13.7 in) to 0,22 metre (8.6 in)

The wooden mast and main sail (10 sq. metres – 107 sq. ft.) are used from the Finn dinghy. The newly added sails are the jib (4 sq. metres – 43 sq. ft. ) and gennaker (15 sq. meters – 161 sq. ft.).

YAMAHA 2.5 HP, 4 stroke

The weight of the ship – including the trailer is 630 kg – 1380 lb. ,
Hull length is 5 metres – 16.5 ft. (plus rudder and bowsprit) ,
Width is 2,20 metres – 7.2 ft. folded, spaced (unfolded) 3,50 metres – 11.5 ft .

The ship is stable and for two people is basically pretty comfortable. The projected usage is the lakes and undemanding coastal cruising. Me and my wife had spent last year 2 weeks in Hungary in the Balaton lake and 3 weeks in the Croatia – Adriatic Sea. All the time we spent outside the official Marine. Of course there is always the necessity to observe weather forecasts, especially on the sea.

The price of the newly purchased materials was about $1200 – $1300 dollars.

Works on the project started in the March 2015 and were completed in the August 2015 – about 60 full days of the work. I did it outdoor in my cottage’s garden under a party tent 3 x 6 metres because of the temperatures and humidity which may decrease the quality of lamination with epoxy resin.

Best Regards,
Jarda Suchopar
Czech Republic