Evergreen - a Fast Expedition Catamaran

22 June 2011    Editor    0 Comments

This year’s WoodenBoat Design Challenge III, “A Fast, Expedition Sailboat”, is a theme near and dear to my Proafile heart. Last winter, I was working up a design that fit the parameters pretty well, so when Canadian designer Laurie McGowan suggested we enter the contest, we chose EVERGREEN, a 6m (19’-8”) camp-cruiser cat. We had to really push to make the May 29 deadline but in the end we got the packet in the mail and had a great time doing it.

The winning entry came from John Marples and his neat 27’ folding trimaran (Congratulations, John!) and while it would have been nice to win, the contest drew 49 entries, a number that both amazed and gratified me that so many others are thinking “small, expedition, sail”.

Evergreen 6.0

EVERGREEN is a 6 meter plywood and epoxy sailing catamaran designed for minimalist and adventurous beach cruising. My list of desires include simplicity of construction and operation, easy trailerability, ample load carrying ability, good looks, seaworthiness and strength, and excellent speed under sail.

The Biplane Rig

The defining feature of EVERGREEN is her rig: twin free-standing masts, one stepped in each hull. The two 140 sq. ft., fully battened, square-top mains provide the power, yet the center of effort is lower than an equivalent catamaran sloop. The free standing masts allow the tops of the sails to de-power in gusts, which should make for a more easy-going and safe sailing experience, compared to a typical hull flying beach cat. EVERGREEN carries no headsails, which makes tacking a simple “push the tiller over” affair.

Each 24’ mast is easily stepped by one person. The lack of standing rigging speeds up the rigging process, and complex folding arrangements are avoided with the simple sliding beam setup. Because the masts are mounted in the hulls and not on the beam, compression loads on the beam are removed along with the dolphin striker, again speeding up rigging for a variable beam cat.

EVERGREEN is a trailer-sailor. Her 8’-5” collapsed beam fits onto most beach cat trailers, and she is rigged for sail whilst sitting on the trailer. After launching, the boat expands to the full 11’-4” sailing beam. The aluminum tube beams telescope inside fiberglass tubes that are firmly bonded to the hulls, and are held in place by four bolts.

Hull Design

I chose multi-chine plywood/epoxy/‘glass construction for the hulls and hollow birdsmouth section spars. Shallow keels with lifting NACA-section rudders are a simple and sturdy solution for catamarans intended to be beached through surf and sailed through unfamiliar shallows.

The 5-panel hull is a good compromise between efficient plywood construction and efficient hydrodynamics. Nearly plumb bows and sterns maximize waterline length and payload. Styling is somewhat cutter-like. Unlike the current wave of racing multihulls, EVERGREEN is definitely NOT a “wave-piercing” design. The tall, buoyant bows and moderate flare will provide a dry and comfortable ride.


EVERGREEN’s hulls provide space for a dry berth and sealed storage compartments fore and aft in each hull, a portable head, and a small galley. There are also sealed foam flotation compartments fore and aft. While it is possible to sleep in the hulls, the 8’x5’ (2.4 x 1.5m) slatted wood bridgedeck is the preferred camping spot with the addition of a deck tent, cooler and galley box.

EVERGREEN can be sailed from a variety of positions:

1. Racing: With the deck hatches sealed, sitting on top of the windward hull with feet on the bridgedeck. The elevated decks provide a comfortable seating position.

2. Cruising: Deck hatches open, seated within the hulls, facing forward.

To sum up, the combination of free-standing rig and expanding beam creates an unusually seaworthy, powerful, and easily trailered small catamaran.

 new designs / catamarans 


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22 Jun - 18:35


Well, I’m disappointed you didn’t win, but John Marples is pretty stiff competition… :-(

But congrats to you and Laurie anyway; I find myself looking at your entry over and over again- just a remarkably beautiful boat, well laid out and highly original. I see a little Cape Breton fishing boat in her, and a whole lot that is unique & elegant. Wonderful job!

23 Jun - 04:44


Nice looking boat. Congratulations!
Is there an option for propulsion, oar or engine?

23 Jun - 09:53

Ray Aldridge

What a nicely thought-out, good-looking design.  That’s a lot of power in a modest package.  I sure hope plans will be offered; I’d love to see one built.


23 Jun - 13:12


This is a fantastic looking boat, it manages to combine classic looks and modern functionality. I’m sure many would love a chance to build one of these. Are you going to sell plans?

23 Jun - 15:43


I thought the same about the possibility of using a yuloh.

24 Jun - 14:14


I hope the sadism you’ve manifested so many times doesn’t rear it’s ugly head once again.

Time after time after time my sons and I visit your site to find absolute heartbreak in the form of gorgeous concepts with no plans offered.  I’m tired of being the one to break the news to the boys.  It’s time you share in the guilt.

At the beginning of the school-year I promised my 9-year old that if he earned straight A’s on his report card, we’d build a camp-cruise-cat.  He did so.

I,therefore, have to inform you that you’ve posted just enough detail for me to build the boat.  Sure there are plenty of details missing.  Sure they are important details.  I have neither patience, nor engineering ability.  This makes it a near certainty that your failure to produce plans quickly will result in the death of a nice guy and two nice little boys.

No pressure smile


24 Jun - 20:11


hahahaha, you may not have any engineering ability, but i have to tell you, Jim, you are a gifted negotiator smile

“no pressure” haha

26 Jun - 16:59


I think Jim’s got a good point here. A very good point, indeed. I’d love to see him building the Evergreen.

29 Jun - 13:09

John C. Harris

I sure hope some of these get built!  Outstanding work. Keeping mast loads off the crossbeam saves a lot of weight and complexity.

29 Jun - 16:06

Chris Luomanen

As ususal, Michael, lovely work.  The classic elements like the mini house and cutter bows look great.

I also dig the unstayed wishbone rig.  I’ve sailed a wyliecat 30, and it was phenomenally well balanced and flexible in a range of wind speeds.

I love the solution of getting the masts off the crossbeam, but I wonder how you’re going to deal with the interference issues.  Tom Jones’ original Dandy rig was a biplane, and he had terrible trouble with it, and re-rigged it as a sloop.  I’m sure they work great for Yves Parlier—but he’s got so much apparent wind. 

I’ve also sailed big charter cats with keels, and they don’t tend to want to tack unless you ease the main through the eye of the wind.  Only then does the jib want to bring them around. 

Have you done model testing?  Other thoughts?  I’d love to see the biplane work for all the reasons you cited.


30 Jun - 05:19


Well done! Have sailed Wharrem cats [ tiki,s ] with short long keels, no problems tacking.
this will probablly bee the last boat I,will build ,very keen
cheers Vernon

30 Jun - 16:33


Mr. John C. Harris,

Now I know why “Madness” hasn’t launched yet.
I know I speak for many of the few when I ask you to kindly remove yourself from the keyboard and go get your hands dirty.


01 Jul - 16:21


Tom Jones’ Dandy had stayed masts. He said Lock Crowther had predicted that the interference from the rigging would not be an issue but Jones lamented that it was.

Tom also said that Dandy was the best tacking catamaran he had ever experienced (or words to that effect). So there were other issues going on as well as teh masts being too close together

03 Jul - 04:36


I just re-read Jones’ comments in his book “Multihull Voyaging” on the biplane rig and he said that it would tack in 60 degrees though it wasn’t fast at these angles.

wv ‘growing 24’
plans to design a 24’ version maybe?!?

03 Jul - 09:24

Chris Luomanen

If the biplane works, that would be huge.  Truly a dream rig for a cruising boat.  It’s a cat schooner rigged sharpie with the masts side by side instead of in tandem.

It might be fun to build the prototype with Dierking style leeboards to play with a range of CLRs on a range of courses, in order to design the best possible keels for it.

+1 on the 24’ version—or maybe a Dandy II sized 26"er.

06 Jul - 12:46

Scott Veirs

Great effort!  We’ve considered trying a biplane rig on our Tiki 21, but hadn’t realized how nicely it could support a deck tent.  I’m curious: what material(s) would you use for the 24’ masts?

After our first week-long cruises last month, we definitely like the galley box idea though cooking from the sailing seat is more comfortable…  We used a portable cooler, but found perishables kept very well in a bilge given the 10oC waters of the Salish Sea!

Overall, we’ve decided a strong design constraint on sailing coastal cruising cats seems to be stowage logistics…

08 Jul - 08:01

John C. Harris

>>>Mr. John C. Harris,

Now I know why “Madness” hasn’t launched yet.
I know I speak for many of the few when I ask you to kindly remove yourself from the keyboard and go get your hands dirty.>>>>

Heh.  “Madness” was rescued from my procrastination proclivities by Mark Bayne and Sea Island Boatworks.  Construction is now 100% complete and the boat is being Awlgripped (“Cheers” yellow) this week. Photos are on CLC’s Facebook page.

19 Jul - 04:13


Oh so very tidy, do pls make plans. 
I’m thinking this would be one of those designs that if you wanted longer, you could just stretch it out lengthwise without compromising?

19 Jul - 16:55

skint for life

Complete amateur here. Just a thought regarding rig interference, perhaps a wharram soft wing sail would be better in this application as the soft sails hitting each other wouldn’t cause damage for the short amount of time it would be occurring. I really like the design, I hope it gets built smile

20 Jul - 03:18

Chris Ross

Bernd Kohler has several biplane rig cat designs sailing. There are windsurfing rigs that have 13sq meters of sail area as well. The hulls are very pretty - a lovely union of classic and modern design.

27 Aug - 05:11


A really beautiful design! I wonder if the collapsed beam might be reduced to 2.50 m / 8.20 ft to comply with the maximum legally trailorable width in many countries. Another desirable feature for me would be able to use standard windsurf rigs. Best winds for you!

03 Sep - 22:11


Cool little boat. An acquaintance built a modified Pahi 31 25 years ago with a free standing biplane rig. X number of owners later the boat still has this rig. Schionnings 8 metre Radical Bay has also been successful. With free standing masts the biplane rig appears to be slowly coming of age.

21 Sep - 15:38


Do you have any timescales for making plans available?

02 Oct - 20:18


What a great design! Love the twin free-standing masts and open deck for camping. I will second the idea of getting the beam down to 8.2ft to comply with road rules in Aus. Have been toying with idea of buidling a tiki 21 but think I will shelve that idea if you go ahead and produce some plans…Any idea when you might have plans available?

13 Oct - 22:34

Gary Lepak

I did the biplane rig on this 34’ cat back in 1980:


It worked fine.  A little interference on a reach, but heading up a bit, or heading off a bit solved the problem.  I’d do it again but not with the junk sails.  I like the Evergreen rig.

Gary Lepak

16 Oct - 20:06

Héctor de Ezcurra

Hope we see this project built and sailing. Beautiful drawings!

22 Oct - 10:39

Chris Luomanen

Hey Michael—how’s this project going?  How about an update?