Quidnon 2.0

This boat design project started out by setting out some very ambitious requirements:

• A houseboat that makes a comfortable tiny house big enough for a family
• A competent, seaworthy sailboat, with masts that can be put up and taken down by a single-hander with the boat in the water
• A motor boat with an outboard motor for an engine that can be installed and removed easily, positioned in an engine well to prevent cavitation, collision damage and other problems with transom-mounted outboards
• Never needs a haulout: copper-surfaced bottom resists marine growth; settles upright and can be dried out and scrubbed at low tide
• Can be beached and relaunched by rolling over logs using anchor winch
• Can be assembled quickly from a kit on a beach or a riverbank by moderately skilled people
• Uses materials that are readily available almost everywhere: plywood, softwood lumber, bolts and screws, fiberglass and epoxy, galvanized mild steel, polypropylene three-strand rope
• Designed for all climates and seasons, from frigid to torrid
• Can be constructed and maintained at minimal expense

Over the past four years since I launched this project several people have made significant contributions to it: modeling, prototyping, contributing ideas and criticisms, helping spread word of it. Taking our sweet time with it has been very helpful in preventing us from building the wrong boat.

But what would be the right boat? How will we know when we have the right design? Well, one very basic indicator would be an empty list of unsolved problems—problems not in the sense of having every last detail worked out on paper (that’s largely a matter of grinding out mechanical drawings) but in the sense of not being sure what to do. And until very recently the list of unsolved problems contained the following big ones:

• No good, useful interior layout for the U-berth (the front section, normally called the V-berth, but Quidnon’s bow is semicircular, making a U). We went round and round on it, but the space was just too awkward.

• No reasonable procedure for installing and removing the keelboards or the rudder with the boat in the water.

• Complex joinery that required pieces of lumber to be milled to a variety of bevels, then steam-bent, adding expense and making the kit difficult to pack flat.

• The angled twin rudders, and the rudder linkage that went with them, gradually grew in complexity to include Ackermann geometry, a system of levers for amplifying the tiller angle and various other details, making it quite baroque.

• There was no straightforward way to construct the chine runners so that they would be neither too fragile nor too heavy and expensive.

• Rolling the hull over logs is made difficult because the bottom is curved throughout, causing the logs to squirm out from under it.

There were a couple of other, relatively minor problems as well. I will mention them later on.

And then something happened that broke this entire logjam: I consulted with a marine architect who raised certain criticisms of the design. They made perfect sense, and forced a rethink that made all of these problems go away.

• The hull doesn’t heel enough to make chine runners effective. They only work well at a considerable angle of heel, and with a hull as wide as Quidnon’s the heeling angle is insufficient to make them scoop up enough water to stop the sideways slide. Solution: get rid of them altogether.

• The hull doesn’t heel enough to make it necessary, or at all useful, to angle out the keelboards or the rudder blades. Solution: make them all vertical. It then begins to make sense to make the keelboard trunks into full double longitudinal bulkheads with a slot between them, leaving them open both at the bottom and at the deck. Keelboards can then be loaded into the trunks from the deck. An added bonus is that this creates a double baffle between the salon and each of the pilot berths, providing sound insulation. Another added bonus is that there are now two large deck drains, to quickly get rid of any seas that climb aboard.

• There is no reason to introduce the cost and complexity of twin rudders. Solution: have just one rudder, mount the rudder post on gudgeons and pintles along the aft wall of the engine well with the rudder blade nestled in a recess under the transom (which is already included in the design, to let through the stream from the prop). Instead of the baroque linkage, we can then have a simple tiller connected to the top of it. When at anchor or at the dock, the rudder can be pulled out to reduce noise and wear.

• There is no reason to curve the sides or to angle them out. It doesn’t improve sailing or motoring performance at all, but it complicates the joinery. It is better to simplify the construction, minimize the cost and maximize useful interior space by making them flat and vertical. This gets rid of most of the complex joinery and the need to steam-bend pieces.

• If the sides are flat, there is no reason to curve the bottom throughout. It has to have a curve at the bow, to help it move smoothly over the water, and it has to curve up gently toward the transom, to avoid dragging water behind it and to keep its center of buoyancy where the ballast is. Giving it a generous flat section in the middle makes it possible to roll it over logs while further simplifying the joinery.

• The fancy bow, where the sides sweep together to meet the bottom at a flat point, will not help performance. On the other hand, it is what makes the space in the bow so difficult to make any reasonable use of. The solution is to make a simple barge hull: at the bow, the bottom curves up to the deck with constant curvature while the sides are perfectly flat. This makes it possible to use the space as a comfortable livingroom of 114 sq. ft. (10 m^2).

What will the result look like? Well, my new motto is “Start your morning with a 3D model and get it over with.” Here is the 3D model, constructed out of highest-quality cardboard and scotch tape.



Yes, Quidnon looks like a barge. That’s because it is a barge. Efforts to make it look like something else—by slanting and curving the sides and giving it a fancy bow added complexity and expense while taking away useful internal space. Also, these little nods in the general direction of yacht design did nothing to appease people who like fancy yachts with curvy lines—there is no pleasing some people!

These major simplifications make it possible to produce the detailed plans over the course of the next few months. This is important, because the money with which to build the first Quidnon should be in hand over the course of the next year, allowing us to move on to the next phase: building and testing it.