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 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.
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.