"Twill Do"—Sailboat Becomes Displacement Cruiser

Converting a Neptune 16 to a power-cruiser

Article by Bill Conway

For the past 45 years I’ve owned sailboats ranging from an 8-foot El Toro pram dinghy to a Catalina 25, and chartered larger craft. At the grand old age of 73 I’ve found it more work than I want to rig and sail and then de-rig a trailer sailboat—but I am still perfectly content to cruise at 4-6 knots. I decided that what I needed was a small displacement cruiser that I could launch and retrieve in five minutes. I’m also a do-it-yourselfer and didn’t want to spend a lot of money, and besides that winter snow was due in southeast Idaho. I needed a project.

For a number of years my son had owned my old 1976 Neptune 16 but rarely found time to use it. I had minimally modified it some years earlier and had even cruised the San Juans in it for a week with my wife. I had a soft spot for the old boat. When he offered it for $800 I bought it with the thought that it would become my small-displacement cruiser. Yeah, I know it was a dirty trick to pull on a sturdy little sailboat.

After sitting out in my shop and staring at the boat I began to visualize what it could become. I had a few design criteria in mind—mostly relating to personal comfort. It had to have good sitting headroom for me in the cabin (I’m 6' 2"), a V-berth to comfortably sleep two, an enclosure for privacy and rainy days, and comfortable seating. Whatever I did to it, the cost had to be low. My operating principal for the modifications was “simple is better.”

I decided to keep the 200 pound swing keel, folded up of course, to lend stability down low. For balance fore and aft I placed the two seating positions at the widest part of the beam just about where we always sat when we were sailing. My hope is that the weight of the two of us this far forward will offset the weight of the engine and gas tank in the stern. By distributing our cruising package evenly in the cockpit locker and cabin, I hope to run the boat on its lines.

I also wanted us to be out of the wind and sun but was keenly aware that adding much structure to the top of the boat would make it top-heavy. The solution was to have a minimal enclosure with open sides and back: the top made of ¼ inch plywood, the structure below made of pine. The cabin, partially tucked under the front of the flat-topped enclosure, is made of ½-inch plywood. A few deck screws were used to install the sides of the cabin. The curved cabin front was bolted down with stainless steel bolts and fender washers to pull it into shape. I nailed all the rest of it together with my pneumatic nail gun. A good coating of epoxy resin topped with several coats of quality water-based paint finished the project. I feel this type of construction was appropriate for a boat used primarily in freshwater and stored inside when not in use.

For privacy at night when cruising, and for protection from the weather, I added snaps to the wooden structure and cut up a poly tarp to enclose the three open sides. The tarp reflects heat, is waterproof, and is functional yet very inexpensive. The downside? It’s ugly!

Some of you may wonder at the long steering/throttle handle (8') that you see in the pictures. I priced out various steering systems and even designed some of my own, but decided all were primarily too expensive and/or complex. My steering tiller is made of hollow plastic pipe with a home-made articulated joint that makes it very easy to sit facing forward and yet push (steer) the motor to either side. It is clamped to the control arm of the motor so a twist of the tiller gives throttle response. The articulated joint has a little slack but works fine. It consists of two modified eyebolts bolted into round wooden inserts in the pipe. About 18 inches from the motor I have a through-bolt with wing nut that makes it easy to quickly remove the long tiller extension and stand at the rear of the boat with the short tiller in hand. I plan to shift the boat into forward, walk to the seat, twist the throttle/tiller and off we go. For close maneuvering I’ll stand in front of the motor with the short tiller/throttle in hand and the forward/ reverse control within easy reach.

The seating arrangement is a bit unique. To get the crew near the CG of the boat I cut the back of the cabin off with a reciprocating saw when I removed the cabin top. When the crew sits facing forward their feet rest on the bunks inside the cabin. The chairs, which can swivel 360 degrees and are easily removed, are the tops of two secretary’s swivel chairs that I bought for $5 each at a used goods store.

The modification of the keel was relatively simple. I removed the cockpit winch, trimmed the cable, cut a square hole in the cockpit floor, epoxied the cable in solidly, then ran it upward through a metal plate and bolted it to the plate. The plate seals the hole and distributes the weight of the keel over a larger area of the cockpit floor. The keel is thus permanently retracted.

The Neptune 16 was advertised as unsinkable when new. I changed the weight of the boat very little because I used light materials and because what I removed was very heavy. To increase the flotation I added 12 empty one-gallon plastic bottles in the area under the cockpit.

Now I know some are wondering what I plan to do about the call of nature. In the original factory configuration when I sat on the portable toilet in the little cabin, my head, shoulders and arms extended above the roof. You can imagine the problem I had when I stood up! In the modified boat the pot sits on the cabin floor with excellent privacy, sitting or standing. I have Velcro strips that hold up a large towel as a curtain when privacy is needed in the cabin during the day. At night the pot goes in the cockpit

The bar extending about the flat enclosure roof-mounts the VHF antenna and an all-around LED light for anchoring and night operation. The antenna has a magnetic mount so I can remove it for road travel with just a firm pull to slide it off the metal plate. The light, with internal batteries, has a clamp so it can be easily removed. All the interior lights are also LED units with their own internal batteries. I installed a deep-cycle battery in the port locker to power the VHF, depth sounder, and power outlet for my spotlight and cell phone. On the flat top I installed a 15 watt solar panel purchased from Harbor Freight.

The project, excluding the outboard which I bought for my homebuilt Nancy’s China, was relatively inexpensive: $800 boat, $45 for Plexiglas, $100 VHF, $79 solar panel, $18 stainless steel bolts, nuts, washers, $22 paint, $8 for flex-tiller parts, $20 poly tarp for enclosure, $45 snaps, $38 all around light. The antenna is from my mobile 2-meter ham station. All the wood was sitting around in my shop; I’d estimate its value at $75. I had a few cleats and miscellaneous things sitting around in my shop, but this listing should account for the lion’s share of cost: about $1300.

How does it work? Don’t know. We still have two feet of snow here and local water is only good for ice fishing. I plan to use the boat this summer for cruising and fishing and possibly a trip to the San Juans. In the next article I’ll show my cruising package and give a performance report. Oh yeah, the boat is appropriately named Twill Do. •SCA•

First appeared in issue #75