Small trimaran with Tornado/Nacra 5.8 center hull

Made a sketch with a few versions of the trailer application.
The first one is with the wheels removed from the beach trolley and the two others with the wheels left. The smaller 255mm wheels are paired side by side with some distance between them. The rear swivel is also with double 255´s. One bowguide at each end of the platform will keep the center hull upright.
Quite a few loose ends, will have to do mock up´s.
In the image I am using the trailer vinsch to pretension dyneema splices.

 

After more than a year of house rebuilding, it is finally time to finish the tri after moving back home to Kristinehamn by lake Vänern, western Europe´s largest lake. Living just above my new sailing club, "Kristinehamns Kappseglare" with a reserved tribuilding area just 20m from my house, I will start again in June after an ice cold spring.

 

Hi, Lars
I have just improved my Strike 20 by using Nacra 6.0 hulls instead old Nacra 5.80 .
She Looks nose down at mooring, but looks perfect when sailing
Last week I achieved 15.5 kt mean velocity over 10 s (Velocitek speedpuck doppler measurement) with only Main and jib.
Good sailing !

 

Good choice Patrick!
I guess she needed some more volume in the amas. Nose down looks nice even at the mooring. I still have to wait to see if I have added enough. But mine are easily adjusted if not enough angled. Are the 6.0´s heavier than the 5.8´s?

 

Hi Lars
I think the weight of 6.0 hulls is close to 5.80, and perhaps lighter : they are longer, but slimmer and a little less freeboard. Wen carrying by hands
they looks lighter.

 

Finally the build is up and running after not being able to spend much time with it last summer. I am now adding the floor in the cockpit and sewing the trampolines. The polypropylene honeycomb material for the floor that I bought earlier was to weak, was not UV protected and was close to impossible to glue. The new glass fiber reinforced board I now found will be better in every aspect, normally being used for scaffolding lightweight platforms.

 

I am out of ideas on how to fit the Marstrom Tornado rudders to the lowish ama transoms. The transoms are also to forward slanted. I have got the fittings. This is just a mockup, rudders will be attached a few centimeters lower.

Anyone with the obvious solution?

 

Do you guys have any idea what materials Nacras, Tornadoes, etc. are made of? I once came across an epoxy Tornado...
How much does one float weigh exactly?

 

Which float do you refer to? My 5.5 is about 50kg.
GRP, carbon, epoxy, foam, honeycomb depending on model.

 

I thought about using some hulls, but they were all polyester and 50kg each.

A-cats are well constructed but a bit pricey and small.

Where the logic is full carbon Nacra 20 also weight 155kg. I understand there are some class requirements regarding weight and that's the reason .

 

If it were me, I’d make a false transom bracket that attaches to the float using the original holes that then changes the angle and sits taller providing enough surface area for the Tornado rudder assembly to be bolted up using its original mounting points.

Could be made from wood, aluminum, glass or a combo.

For added strength, I would make my brackets run vertically to pick up the top and bottom holes in the transom, then the new transom plate would attach to those.

There’s an opportunity to make the rudder angles adjustable if there isn’t already a way to do so by making the brackets two piece and scissoring with slotted adjustment holes and bolts that lock it into position to adjust the angle of attack.

This could be done using two pieces of aluminum right angle stock.

 

Nothing wrong with polyester/GRP, 50kg could be good enough depending of length. My hulls are 160kg together, total weight of boat ca 260kg.
Noticed you are in Poland. I have one 5.8 hull lying around.
If you know some polish OK-sailors going up to Open Nordic in my hometown in August, that could be an option for bringing it home.
There is also a Dragonfly ama in Denmark, could be used as center hull with a lot of work.

 

Thanks Solgato, we seem to think in the same direction using a bracket.
I actually have a large piece of 20mm HDPE that can be cut in two 10.5 cm wide strips. Will check it out and see if it is long enough tomorrow. No problem to fit them at the lower end against the transom through the original holes. Weight should be acceptable with below 1kg each with spacers.
Maybe just add spacers of the same material and use the upper holes? Angle is harder to find out but I guess I will have to add 3-5cm of spacers.
I have the fittings somewhere around, must search.
Have measured a Marstrom T and the lower fitting should be 42mm up from the keel line and 30mm out from the transom.

 

Have cut the pieces from 14 and 20mm HDPE. Still some milling and drilling is needed to make the parts look decent. Need a set of new 1/4" bolts, nuts and washers, will mailorder tonight. Not easy to find in metric Sweden.

 

I was going to post this photo for inspiration.

Looks like you’re already making good progress.

When I converted my Cat to electric, I wanted the motors to bolt on using the existing threaded inserts molded into the plastic hulls so it could be converted back and because I knew the hulls were designed to handle the loads in this area.

I made mine out of Ipe as prototypes, but almost 10 years later now and they have held up well without the need to replace them although I always intended to make lighter versions with some buoyancy built into the anti-cavitation portions.

Later down the line when you’re looking to squeeze every bit of speed out of your boat, you can take a page from Hot Rodders and drill a bunch of “lightening” holes in your plastic adaptor brackets