I’ve built more than a few boats for myself in the past 38 years, and in all that time I have never been tempted to build a multihull. Why go to all the work of building two hulls, let alone three, when I’ve never found any of my single-hulled boats lacking in any significant way? I started getting answers to that question as soon as I stepped aboard a Seaclipper 16 designed by John Marples of Searunner Multihulls and one of nine designs in the Seaclipper series of trimarans. The hull is constructed of 7 sheets of 1/4″ six-ply marine plywood, five sheets of 3/8″ nine-ply, and lumber in commonly available sizes. Fiberglass-and-epoxy sheathing is optional. The instructions are geared for novice builders; full-sized templates for the bulkheads are provided in the plans. Stringers connecting the bulkheads define the shapes of the plywood panels for the hulls. The 15′ 11″ vaka (center hull) has a flat bottom that will take to landing on the beach without digging in or causing the kind of wear you’d get with a sharp V hull. The amas (outrigger hulls)  have bottom panels set at an angle, deeper outboard than inboard. This configuration adds a fin-like element for increased lateral resistance for sailing in shallow water with the daggerboard pulled up. The angled ama bottoms also present an edge to the water, keeping the amas from slapping the waves when they’re close to the water’s surface; it’s a quieter ride. The amas’ bottoms are positioned higher than the vaka’s bottom, so their edges are not subjected to wear when the boat is hauled up on a beach.

Each of the four swing-arm akas has three bolts: one securing the pivoting part of the aka to the ama, and two (one of those anchoring the shroud bridle) connecting the pivoting part of the aka to the fixed part on the vaka. Removing the inboard bolt allows the swing arm to pivot, moving the ama aft and inward.photographs and video by the author

Each of the four swing-arm akas has three bolts: one securing the pivoting part of the aka to the ama, and two (one of those anchoring the shroud bridle) connecting the pivoting part of the aka to the fixed central section on the vaka. Removing the inboard bolt allows the swing arm to pivot, moving the ama aft and inward.

The akas (crossbeams) can  be made in three ways: as one piece bolted to the three hulls, hinged to fold the amas on top of the vaka, or as swing-wings, like LIMONADA shown here. With the swing-wing, the amas pivot aft and nest against the vaka, bringing the beam down from 11′ 3″ to 7′ 7″ for trailering and to fit in a standard marina slip. The swing wings can function whether the boat is afloat or on a trailer, so they are handy when launching or landing at a crowded boat ramp. The swing wings don’t require any hardware beyond nuts and bolts, and have an advantage over the hinged akas: there’s no need to lift an ama and set it down gently on the vaka.
The Seaclipper 16 can be built as an open-cockpit cruiser, or as a daysailer with a tandem cockpit, with the helmsman sitting in the aft position, legs straddling a centerboard trunk and the crew sitting forward. The 7′-long open cockpit has side decks between the akas that offer more options for seating, moving around while under sail, and sleeping aboard while moored.

John Marples, designer of the SeaClipper 16 and builder of LIMONADA, goes for a sail on the Mystic River.

John Marples, designer of the Seaclipper 16 and builder of LIMONADA, goes for a sail on the Mystic River.

 

LIMONADA, as an open-cockpit version of the 16, has a daggerboard deployed through a slot in the cockpit sole. A softwood stick wedged in the slot keeps the board down; it has a loop of line at its top for quick removal and raising of the board. The cockpit sole is high enough above the waterline that any water coming into the cockpit drains right out. The rudder is mounted on a false transom, hinged at the top, that allows the rudder to kick up when meeting an unexpected shoal or to be retracted when coming ashore. The downhaul at the bottom of the false transom leads to the cockpit for easy operation. The rudder blade is balanced and has enough of the blade ahead of the pintles and gudgeons to lighten the load on the skipper when coming about. It also allows the arms of the rudder yoke to be short and unobtrusive. The lines from the yoke lead forward to pedals in the cockpit to  for hands-free steering. A tiller above the yoke allows steering while sitting on a side deck and is the means of raising the rudder when coming ashore.

A hinged false transom allows the rudder to be kicked up. The tiller pulls the rudder up and holds it. The line at the bottom of the false transom holds the rudder down while the boat is underway.

A hinged false transom allows the rudder to be kicked up. The tiller pulls the rudder up and holds it. The line at the bottom of the false transom holds the rudder down while the boat is underway.

The Seaclipper 16 is designed to take a Hobie 14 sailing rig. The pivoting aluminum mast, roller-furling jib, and fully battened mainsail are readily available from a wide network of Hobie dealers and may be found used in online classifieds. The Hobie 14 has a beam of 7′ 8″, so the Seaclipper 16, with a beam of 11′3″ can take better advantage of the 146-sq-ft sail rig without flying a hull to the brink of capsizing. Dyneema shrouds, secured to bridles spanning the side decks, support the mast. The plans include specifications for an unstayed wooden mast. For auxiliary power, a short crossbeam aft of the port aka serves as a mount for a small outboard.

The side decks provide seating when two are aboard, and the steering is then done with the tiller, not the foot pedals.

The side decks provide seating when two are aboard, and the steering is then done with the tiller, not the foot pedals.

I had a chance to sail LIMONADA, the Seaclipper 16 built by Marples for Mac MacDevitt, on Mystic River near Mystic Seaport. Stepping aboard, I got my first lesson in the values of a multihull. I didn’t have to lunge for the centerline as I do with my monohulls to keep them on an even keel. The trimaran has plenty of stability no matter where I put my weight and the amas (outer hulls) have enough volume of to support my 220 lbs. Without having my movement aboard the boat restricted by the nagging demands of a monohull, I could wander around the boat. The decks are all flat, so the footing is good everywhere. While I like the sweep of a curved sheer line, the Seaclipper’s flat decks simplify the construction of the boat and provide the geometry required for the swing-wing akas.

The deck surrounding the cockpit is large enough to set up a tent for sleeping at anchor. The windsceen was added by the builder to block spray when sailing a brisk breeze.

The deck surrounding the cockpit is large enough to set up a tent for sleeping at anchor. The windshield was added by the builder to block spray when sailing into a brisk breeze.

I liked being able to walk around the boat while it was under sail with Mac at the helm. I never get to see my own boats moving through the water, so stretching out on an ama to watch the vaka’s bow at work was a treat. The 7′-square deck around the cockpit offers a place to pitch a tent. Mac has a two-person tent with an oval hole in its floor to match the cockpit opening. He can sleep to one side of the cockpit, sit comfortably upright with his feet in the cockpit and have access to the gear stowed there. The amas and vaka offer plenty of room for cruising and camping gear; commercial plastic hatches offer access.

I took LIMONADA out by myself and enjoyed steering with my feet and having my hands free to manage the sheets. Nestled down in the cockpit on a padded seat with a backrest, I was very comfortable and relaxed. The sheets were right in front and could be cleated off, making sail-handling a breeze; there was no need to switch sides or do-si-do with a tiller when coming about. During my outing the weather was warm and the wind was light, perhaps 8 to 10 knots at best with a few gusts, but in a cold wind, being mostly below deck level would be a boon. Mac had made a removable windshield that wraps around the forward end of the cockpit for even greater protection from cold wind and spray.

With Marples and owner Mac MacDevitt aoard, LIMONADA flies the windward ama. The leeward ama still has plenty of freeboard.

With Marples and owner Mac MacDevitt aboard, LIMONADA flies the windward ama. The leeward ama still has plenty of freeboard.

The light wind was more than enough to get Mac’s Seaclipper going at a brisk pace and fly the weather ama. There was no spray, so I stayed dry, and even with the boat moving at a good clip I didn’t notice any water coming up through the daggerboard slot.

I was surprised by how well the Seaclipper could come about. With three hulls in the water, I thought there would be a lot of drag in the turns and that the boat would get bogged down, but the rudder blade and the centerboard have enough area to swing the bow around before the boat loses momentum. I never got caught in irons, but I backed the jib for a moment to hasten the bow’s falling off and the filling of the main.

LIMONADA owner Mac MacDevitt reports that his SeaClipper 16 is “super fun in a stiff breeze.” Here, sailing on Lake Champlain, just south of the Split Rock lighthouse he estimated his speed at about 13 knots. “It was exciting, but I felt safe and secure.”Ben Breckenridge

LIMONADA owner Mac MacDevitt reports that his Seaclipper 16 is “super fun in a stiff breeze.” Here, sailing with a reefed main on Lake Champlain, he estimated his speed at about 13 knots. “It was exciting, but I felt safe and secure.”

By the end of my time aboard a Seaclipper 16, I could see the good sense in building three hulls to get one boat. Having a pair of amas take on the job of keeping the boat upright under the press of sail made manning the helm much easier; it didn’t require the athleticism and flexibility that I’ve always associated with sailing small boats. And at anchor, a trimaran is a bit like a small island, while my boats are more like hammocks that swing with every move I make. The Seaclipper offers the potential for some exciting sailing. Mac has sailed LIMONADA up to about 13 knots. That’s a speed I’ve never seen aboard any of my boats.

Christopher Cunningham is the editor of Small Boats Monthly.

Seaclipper 16 Particulars
Length 15′ 11″
Beam 11′ 3″
Beam, amas retracted 7′ 7″
Draft, hull only 11″
Draft, board down 2′ 7″
Sail area 127 sq ft
Displacement, dry 400 lbs
Displacement, full load 800 lbs

Plans for the Seaclipper 16 are available from Searunner Multihulls for $180.

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