NACRA 5.8 Based Trimaran

I would like to have a go at designing and building a 25' ish trimaran based on a NACRA 5.8. The idea would be to utilised as much as possible from the NACRA "donor boat" (hulls, rig, sails running rigging) to reduce the cost of building the trimaran as much as possible. Highly affordable is the number one objective!

This type of thing has been done before using the Tornado Cat as a donor boat. The boat was designed by a guy named Kelsall and was called a Typhoon.

Typhoon study plans and photos...

NACRA 5.8

The L7 a similar kind of boat...

The Typhoon was a production boat and unfortunately there are no plans available.

I have downloaded Freeship and I am getting used to using it but other than that I have no design skills at all. I have in the past rebuilt boats and converted a swing keel yacht into a fixed keel yacht so have some idea... but thats about the extent of it.

My thoughts are to try and create a fairly fine central hull that flares above the waterline, (the NACRA 5.8 rig will be on the light side if the weight is not kept down) with a cuddly cabin (2 berths/seats is about all) and a reasonable cockpit. I thought the easiest thing to do would be to retain the NACRA's rig position relative to a centre board/ dagger board in the main hull and the floats (NACRA hulls) and balance the main hull evenly (fore and aft) against the floats. Construction would probably be tortured ply or strip plank cedar..

If anyone feels inclined to get involved I can use all the help/advice I can get !

What do you think... am I mad or what?

Has it already been done? (ie Should I just buy the plans!)

Tri from Cat Conversion

Hi Zoro,

If you're set on 24' then this design is out. If you could see yourslef building a slightly smaller boat to the design criteria you mentioned, then I am submitting my Zona65 for your consideration.

This is a stitch and glue construction trimaran that utilizes the resources of a big beach cat for many of its component elements. The suggested list for donor cats is: Nacra 6.0 or 5.8, Hobie 20, Prindle 19. All of these boats have suitable hull forms and properly sized rigs for the Z65 conversion.

The cockpit is roomy enough for comfortable sailing and the cabin will sleep two with ease, though I have not specced the boat as a full-tilt cruising craft. I did this to keep build times lower as well as costs.

Even with the purchase of a used cat in very good condition from the above list, this boat can be built for less than US$12,000.

The added bonus for your effort is that the Z65 will fold, easily, for trailering.

Let me know if the design suits your interest.

Chris Ostlind
Lunada Design
Chris at Wedgesail dot com

Do you know Tremolino, 23 ft tri based on hoby donor parts? You could get a lot of useful ideas for your project looking at her. Keep in mind is that your Nacra parts will be more stressed as a part of the tri then what was originally calculated.

http://groups.yahoo.com/group/tremolino/

Hi Milan,

Yes I know the Tremolino 23 but she is just a bit small for the bay here. My better half will need some protection should it cut up rough so I really need a reasonable cuddy cabin of some sort.

Chris,

The Z65 looks close to the money, I am not completely in love with the stitch and glue idea, but I suppose its the cheapest way to go... {I think}. Do you have study plans I could use to price the project and get a clearer idea of space etc? Have any been built?

Thanks
Z

PS. Typhoon link now works!

Super Tri

It would be great to someday see a small tri built using the maximum performance concepts of an Orma 60 such as being designed to fly the main hull, beam at least as wide as the boat is long, foil assist boards in the amas and trapezes for those days when you're after a big "beach" cat.

Chris, your design looks great. I like the idea of the boards in the amas, especially if the originals can be used. This could greatly reduce construction time and cost, and gets the board case out of the main hull.

Heck, I'd build one of these! I like the L7 too, but yours would be a lot cheaper.

What concerns me about boats like these is, are the beach cat parts strong enough for the greater righting moment, and bigger boat?

May I add that the Farrier Tramp was one of the nicest family daysailors ever? The new F22 with big cockpit is probably close, but still too expensive.

Z65 questions/comments

Hi guys,

A big thanks, collectively, for the time you took to look at the new, Z65 design.

Zoro: If you write to me off-list, I'll answer all your queries straight-up so the possible business aspect is kept off the forum. I just think it's good form to not do that here.

Doug: I, too, would like to see a really potent 20-22 footer along the lines you describe. I'd love to do one personally, but right now I've got enough burning sticks in the fire to last several months.

Matt: All the structural segments of the design have been (or will be soon) engineered to handle the added righting moment as you wondered. The Z65 is twice as wide as a normal beach cat, so there are some considerations in that regard. I took a long look at the history of the Tremolino and found the boat to be well within normal maintenance and failure for the parts that were of beach cat origin. That proving ground was very valuable in that regard.

I'm still looking at the vaka hull centerboard option for the Z and not using the daggerboards in the cat hull amas. That option is the last issue on the table with the engineer at this point and then things can go forward.

OK, here's the deal on the plans for the Z65: Because I am so wrapped right now with two other projects that need to get done in a timely fashion, I will provide free plans and email support to the first builder of the Z65. If you are in the US, I will also help to arrange for better pricing on the marine plywood as well as the epoxy. I'd really like to see this boat get built and out on the water because I think it's a solid solution to the dilemma of the high entry price in the folding sport trimaran field.

What do I want out of the transaction? The recipient of the plans will shoot digital photos of the build process and write a brief explanation as they proceed through the construction of their new boat. They will also agree to let me post the building report on the new, Lunada Design, website so others can see the boat coming together. Simple. You'd probably do something close to this anyway, so there's hardly any hassle involved.

Write me at: Chris at Wedgesail dot com and tell me why you should get the free plans and construction support.

Chris Ostlind
Lunada Design

Chris,

I have emailed you...

Cheers
Z