Tuesday, December 6, 2016

The Final Sheeting Arrangement

One of the problems with Junk rigs is that they tend to twist: the upper panels end up sheeted in less tight than the lower ones. Since the direction of the wind is generally the same at every height (while its strength varies) what this means is that only part of the sail is able to perform at optimum efficiency; either the lower panels are pinching or the upper panels are luffing, or both.

One classical way to deal with this problem is by using a euphroe. It is a piece of wood with holes in it to send sheetlets through, and it allows one to distribute the sheet tension across the battens in such a way that the upper battens are sheeted in with more force than the lower battens, counteracting the twist. Sailboat designer Tom Colvin, who circumnavigated with a Junk rig, favored the euphroe. Other people are less in favor of it, because it tends to flail about and hit things when tacking or jybing. I don’t particularly like the euphroe and would prefer something simpler to set up.

Previously, I proposed a design for an automatic traveler system that would move sheet blocks back and forth to counteract the twist. I don’t know whether it would work, because I haven’t tested it, mainly because I don’t like it. It’s too complicated. But I didn’t know what else to do… until yesterday.

Yesterday I looked at some traditional Chinese Junk set-ups, which use twin sheets. There are two separate sheeting set-ups for port and starboard tacks. Having two sets of sheets solves a couple of problems. One is that there doesn’t have to be a gap between the leach of one sail and the luff of the next for the sheets to move through, and a sail can overhang the transom without requiring a boomkin for sheeting, because each sheet hangs to the side of the sail. The other is that with the Junk rig the force on the sail acts differently depending on the tack: on one tack, it pushes the battens against the mast; on the other, it pulls them away from the mast. Because of this, the optimal sheeting angles are different for each tack, but with a single sheet there is just one attachment point on deck.

Now, that alone isn’t too interesting, but it becomes very interesting when combined with QUIDNON’s super-wide deck arches. You see, the twist happens because the forces on the different sail panels are different but the sheetlets all go to blocks that are all the same spot, at the same angle to the sail. But the deck arches allow the sheet blocks to be spaced apart so as to counteract the twist.

And so that’s the solution I finally arrived at. The sails are set up with blocks that hang from the boom and from each of the four battens. Since the higher battens need more sheeting force, because of higher wind speeds up top, the attachment points of the blocks move progressively further aft the higher up on the sail they are, with the topmost one almost all the way to the leach of the sail. The deck arches are set up with a padeye right in the center, and then two sets of blocks on two separate tracks to port and to starboard, for each of the sheets. The sheetlets start up at the padeye, go up to the block on the boom, then down to the innermost block on the track, then up to the lowest batten, then down to the next block on the track and so on.

The track allows the blocks to move, allowing the setup to be fine-tuned depending on conditions. For example, on the relatively flat and windless Chesapeake, where the most you might get is a few feet of chop, the lower part of the sail gets not much less wind than the upper part, and tends to twist less. On the other hand, out on the Pacific the swell can run at 20 feet or so, blanketing the lower part of the sail a considerable portion of the time, twisting the sail much more. To make an adjustment, one reaches up to the deck arch, unscrews the knob that holds the block in place, and slides the block over a bit. A bit of trial and error will give you a sail that can be sheeted in perfectly flat in the prevailing conditions.

I like this solution because of its simplicity. The trade-off is that the running rigging has gained two more lines, because now there are four sheets to manage instead of two. But then that’s not a big increase in percentage terms. Before splitting up the sheets into port and starboard there was the one sheet, two halyards (peak and throat), two topping lifts (fore and aft) and one downhaul. That’s 7 lines per sail. And now there are 8.

The twin sheets have a few additional advantages. They make it possible to backwind the sails, to slow down or even to sail backwards. This is sometimes useful; for example, for sailing into a slip at a marina. (Yes, Junk rigs make it possible to do things under sail that sloop and ketch sailors can only dream of.) It also makes it possible to heave-to in the traditional manner, by sheeting in the main, backwinding the foresail and lashing the tiller to leeward, rather than in the Junk manner—by simply letting go the sheets and playing with the rudder until the sails trail off to leeward at some comfortable angle. When becalmed in a swell they make it possible to tighten both port and starboard sheets so that the sails do not swing back and forth on the swell, snubbing at the sheets. Lastly, if a sheet parts (as they all do eventually) then it is still possible to sail—perfectly well on one tack, less well on the other.

There is just one question left to answer: Does this actually work? (I know, details, details...) Well, I rigged it up on the 1:12 model, and, lo and behold, it does! Here's the money shot: the mainsail sheeted in sets perfectly flat. This is about as good as it gets. This boat is going to sail to windward and short-tack like a dream!

Friday, December 2, 2016

It sails!

I finally found time to finish building the 1:12 model and outfitting it with sails and radio controls. Yesterday I sailed it around the marina, and I liked the results. It is fast and nimble on all points of sail, doesn’t leave a wake, and is very stiff. The shape of the bow provides for clean entry and little resistance. I didn’t notice any strange tendencies at all. Here is a video of QUIDNON sailing upwind in what for a 3-foot boat amounts to too much wind and quite a bit of chop, overcanvassed, with minimal heeling and good balance, and short-tacking successfully.

video

I might do a few more towing and stability tests, to verify hull speed and initial stability angle, but we already have these numbers from the hydrostatic and hydrodynamic analysis. I don’t expect any surprises, and so there probably won’t be anything to report. I am quite happy with how boring this design has been—doing everything it’s supposed to—and I am glad that the phase of playing with models is over. I am a serious person, and I find model sailboats to be silly. They are part of due diligence, but I won’t be taking them up as a hobby.

That said, the model-building process has been incredibly useful in three separate ways.

First, I had a chance to verify our technique for joining the plywood pieces using box joins and locking tabs and slots. I did find a few problems, three of them significant. We are changing the design in light of what I discovered, and will do another test at the 1:12 scale just to make sure we got it right this time before committing to a full-scale build.

One problem had to do with the curves at the bow: the plywood panels that make up the sides and the bottom as they come together to a point at the bow cannot be cold-molded and will need to be steam-bent, which is what I did.

Another problem came up while fitting the sheer strips—the long strips with the deadlights that run all around the boat just under the deck. It is not enough to secure them in place by locking them to tabs, because that produces a scalloped profile with many small gaps. Instead, they have to be pulled into place, by applying force to them at the transom. We will design jigs for steam-bending and for sheer strip-pulling.

Also, it turned out that while box joins with a rectangular toothed profile work fine for straight segments, for curved segments the teeth have to be trapezoidal rather than rectangular, with the angle of the sides of the trapezoids proportional to the angle of curvature. This turned out to be a problem when fitting the bottom to the sides.

We also had the problem of too much joinery—too many tabs and slots. Since they are free (the slots cost something in terms of the extra machine time it takes to mill them) we used a lot of them. It turns out that too much joinery is as bad as not enough, and will now work to find a happy medium, using the minimum of joinery that still allows the entire structure to be self-aligning and self-supporting.

Another major problem I was able to solve is how to eliminate virtually all finishing work on the interior of the hull. This should make construction go much faster by eliminating interior painting. The plywood panels will be treated with penetrating epoxy prior to milling parts out of them. Interior-facing surfaces will also be sanded, primed, sanded again, and painted with very durable two-part polyurethane paint, providing a surface almost as hard as a laminate. Exterior-facing surfaces will only be sealed with epoxy, to make them waterproof, since they will receive a coat of fiberglass prior to fairing and painting. The edges of the milled panels will be left unfinished, since they will be saturated with epoxy and filleted as part of the assembly process. Where the joint is exposed, it will then be dressed up with hardwood trim, while everywhere else, such as inside lockers, it will be left as is.

Lastly, I completely reworked the sail plan. The initial sail plan was based on Hassler & McLeod's Practical Junk Rig. They modified the original Chinese design, in which the entire sail is made up of fan-shaped panels, and replaced all but the top panels with rectangular ones, claiming that they stack more tidily and don't make much difference otherwise. After thinking about this quite a bit, I have come believe that they are wrong. In the original Chinese design, each fan-shaped panel forms a conic section, and is essentially a Lateen sail, which makes an excellent, efficient airfoil when cut as a perfectly flat piece of fabric. Lateen sails can sail very close to the wind. Keep in mind that the ability to sail to windward took a long time to make it all the way to Europe. The Chinese had this ability for centuries, using their traditional Junk sails. In other parts of the east, dhows used Lateen sails to the same effect. Only when Arab raiders started catching and looting European ships using Lateen-rigged corsairs did the Europeans look up and take note. But this wasn’t enough to make them abandon their backward square-rigged ships, which are terribly unwieldy and can barely move to windward at all.

But what Hassler and McLeod appear to have done in making the panels of the Junk sail rectangular is change their shape from a Lateen sail to square sail, and square sails are quite terrible upwind, tacking through no better than 60º. In theory, an airfoil can still be formed using the flex of the battens, but there are two problems with this: first, the battens flex more in stronger winds, which is the opposite of what’s needed, because the stronger the wind the flatter the sail needs to be; second, the battens flex asymmetrically depending on the tack, because on one tack the mast gets in the way.

To compensate, some people have recently decided to add camber, or “belly,” to rectangular sail panels. That was my original plan, which I thought was state of the art with regard to Junk sails. I was wrong; state of the art with regard to Junk sails is centuries-old. After I realized this, I designed a fan sail, which, as I have demonstrated yesterday, works remarkably well to windward. Here's my recipe. There are 5 panels, all fan-shaped, and 6 spars. Starting at the bottom, there is a boom, 4 battens and a gaff. All the panels are exactly the same in height at the luff and taller at the leach. The boom is horizontal, while each spar going up is angled 8º more than the previous spar, adding up to a 40º angle for the gaff.

At this point, we are able to declare QUIDNON’s design to be proven, in both digital and analog forms. It handles well under sail and motor, it is stable, stiff and steady, and, based on feedback from all the passers-by at the marina, it is pleasant to look at. We will now work on pushing the design to completion, since all that remains to work out is a very large number of relatively minor details.

Monday, November 7, 2016

It floats!

The 1:12 scale model is now complete except for the sails and the radio control componentry, which are in the works. The maiden voyage went uneventfully: QUIDNON sat quietly on its lines. The first and most important requirement for a boat, and especially a houseboat, is that it has to float really well. And it seems that this hurdle has been passed. More to come soon; in the meantime, feast your eyes.

Thursday, October 13, 2016

A Safe Space for Survivors

In spite of nature’s best efforts to derail my plans, in the form of Hurricane Matthew, they are proceeding apace, including the plan to design QUIDNON—the houseboat that sails. The hurricane provided a teachable moment on surviving hurricanes aboard boats, confirming many of my intuitions about what makes QUIDNON a safe design for any situation, hurricanes included.

We were in a mandatory evacuation zone, and although we could have sheltered in place, I decided to avoid subjecting my family to such an ordeal. And so we jumped in a rental car, drove away from the coast and sat out the hurricane in a motel room. When we got back, picking our way between piles of debris that were littering the roads, we found that the boat had suffered zero damage, but that the entire marina came within a foot or so of being annihilated: another foot of storm surge, and only some concrete pilings would have been left, with the rest of the marina, boats included, washed up on shore, with the boats crushed underneath the floating docks. In fact, this is what happened to many of the other marinas in the area. Since the height of the pilings was set a long time ago, when ocean levels weren’t rising as quickly and catastrophic storms were less frequent, this is going to be happening more and more frequently. Everyone here considers the fact that the marina survived something of a miracle.


Boats at anchor did not fare too well either; most of them have ended up on shore when their anchors dragged or failed. Of these, the sailboats did the worst: the combination of a lead keel mounted to an eggshell-like fiberglass hull is a bad one when it comes to tackling land. Once the keel hits and the boat flops over, total damage becomes almost inevitable. The boats that did the best were mored to stationary anchors with chain: large concrete blocks embedded in the bottom. Well-designed boats don’t care too much about wind and water; it’s solid objects that kill them.

These observations validate some of the design decisions that went into designing QUIDNON:

1. The ability to get out of the marina in a hurry is very important. Most people who live aboard boats don’t put too much effort into making sure that the engine is in good running order. For an inboard diesel this is quite a lot of effort and expense. And so when the time comes to move the boat out of the marina and put it on a mooring, the engine may not even start, or start and then stall because the fuel is old and the fuel filter becomes clogged with sediment. But since QUIDNON is going to be powered by an outboard motor mounted in an inboard well, this will be less of a problem. First, the motor can be used to power a dinghy when QUIDNON is at rest; secondly, outboard motors are much easier to lay up, and usually fire up afterword with just a bit of effort. Gasoline does not grow bacteria like diesel fuel, and can be stabilized and stored over long periods of time.

2. No matter how hard you try, your boat may end up on dry land. Therefore, it is very important that QUIDNON goes aground well. Having a wide, flat bottom covered in roofing copper over tarred felt will make QUIDNON relatively shore-friendly: roofing copper is tough material, and will work-harden rather than rip. Once the extreme weather passes, it should be possible to drag QUIDNON back into the water over round sticks using the anchor winch.

3. A hurricane is not a convenient time to go sailing. Sailboats have masts, which generate windage during a hurricane, and are not useful unless you plan to go sailing. After a hurricane some number of masts can be seen poking out of the water at low tide: not only were these masts of no use during the sinking, but they now pose a hazard to navigation. QUIDNON’s masts can be taken down and lashed to the deck by a single person in an hour or so, reducing windage and weight up top.

4. Once the hurricane is over, weeks may pass before the local economy gets back to normal. Food, electricity and gasoline are likely to remain scarce for some time. In order to make it, is important to have lots of storage space stocked with food and water. QUIDNON’s ample lockers and massive water tanks (which double as ballast) can provide for months of autonomous survival.

5. The safest place for a boat during a hurricane is on shore. This is true even for keelboats, which are stored on jacks and can get pushed over in a hurricane. QUIDNON needs no special arrangements of this sort, and can simply sit on a patch of dirt, next to your house, stocked and ready to serve as hurricane shelter or, if the waters reach high enough, a floating escape capsule. Moored between two pilings in a flood zone, it will simply float up in case of a flood, then settle again.

6. Even if the motor runs, it may turn out to be impossible to move the boat out of harm’s way because its bottom and prop are fouled with marine growth. People who live aboard boats don’t usually find it necessary to haul them out and repaint the bottom with anti-fouling paint every where. And so they find that their boat won’t move when it has to, even with the engine at full throttle. QUIDNON’s bottom is surfaced with roofing copper designed to provide anti-fouling for the expected lifetime of the boat (around 30 years), will never need to be hauled out and repainted, and will always be ready to move.

7. There are cases where there is simply nowhere for a boat to shelter near land, and the safest survival strategy is to head for open water and away from any dirt or rocks. Remember, sticks and stones will kill a boat, but wind and water are its natural element. Here, it is very important that the boat have certain characteristics that allow it to survive any conditions, no matter how wild. Stability and the ability to self-right is very important, and QUIDNON's impressive 130º of primary stability will help it stay right-side-up no matter.

9. Although staying well away from dirt and rocks buys a large amount of safety, there is still the small chance of encountering floating debris that can hole a hull. Here, QUIDNON's self-rescuing characteristics are very helpful: blowing out the water tanks with compressed air, making them buoyant and blocking off the aft cabins to allow additional flotation, allows it to remain afloat with the cabin knee-deep in water until the hole is plugged and the water pumped out.

10. When disaster strikes and you happen to be possessed of a secure, well-stocked, self-sufficient survival capsule such as QUIDNON, you may find that you have more company than you expected. Most 36-foot sailboats usually can’t accommodate more than four or five people with any degree of comfort. In contrast, QUIDNON’s interior space is rather carefully carved up to provide the maximum of accommodation with a maximum of flexibility. There are two aft cabins that can sleep two adults each, four settees (two in the main salon, two in the bow cabin), two pilot berths in the main salon that provide beds for two adults each, or a larger number of children, and two generous shelves in the bow cabin that can provide cribs for babies. There is a full galley to cook for all of them, and a heads with a full-size shower stall and a mini-bathtub for the kids to wash them all.

* * *

This last point is the one that I would like to discuss here at some length, because we are nearing the end of the design process to maximize the interior space. The interior structure—the bulkheads, the sides and the top of the water tanks and the board trunks, the settees, the cabin soles and the various partitions—are all made of plywood pieces that are joined together in a variety of ways: jigsaw joints, box joints, and mortise and tenon joints. Each element serves two purposes: it maximizes the use of space, and it also maximizes structural rigidity: everything is structural.

It's a split-level
Next project on the list is to analyze the structure using software, to identify stress concentrations and weak points, to select appropriate thicknesses of plywood for all the elements, and to add gussets and other reinforcements where necessary.

Top view of interior structure

At the center of the boat is the companionway. It is trapezoidal in shape, and has openings in six directions: up the companionway ladder to the cockpit, two openings leading to the aft cabins (equipped with sliding doors for full privacy), an opening to port going to the heads (also set up with a door), an opening to starboard to the galley (always open) and, finally, an opening to the main salon, equipped with a curtain. There is a similar opening, with a curtain, between the main salon and the bow cabin.

Lots of room between the deck and the cabin soles

Because of the curve of the bottom the cabin soles are at five different levels. The lowest are in the galley and the heads, where people (including very tall people) are most likely to be standing for extended periods of time, with a full 6’10” (2 m) of headroom. The cabin sole in the companionway is a bit higher, because there is 3 tons of solid ballast under it.

Bottom view of the interior structure

The aft cabins are not designed for standing room, and are just 4’7” (140 cm) in height, but provide plenty of locker space below the cabin soles. They can be used as storage, as sleeping accommodations, and, with the bed rolled up and stowed and a drop-leaf table and a fold-out seat, serve as a workshop, a study or even a miniature classroom.

The main salon has 6’3” (190 cm) of headroom, which is enough for some 90% of the people to avoid having to stoop. The settees and the pilot berths, at 10’ (3 m) long, provide room for up to eight people to stretch out with their heads pointed in opposite directions (with some overlap between their legs).

Cabin measurements. Beam is around 15 feet except at the bow

The bow cabin, with 5’9” (175 cm) of headroom and the settees 6’9” (205 cm) long, is still adequate for all but the tallest people.

Because every element is both functional and structural, we have made every effort to keep the layout as generic and multipurpose as possible while maximizing both living space and locker space. Completely missing are shelves, cabinets, hanging lockers, slide-out drawers and other typical cabinetry. There will be some built-in cabinetry in the galley and the heads, to be sure, but the overall approach is to provide a minimum of structure, which will be unalterable, and allow people to customize the rest as they see fit.

Tuesday, July 19, 2016

On Women, Boats and Plumbing

Plumbing systems on boats run from the very simple (a blue jerrican of water brought in from shore) to simple (a fresh water tank, a foot pump and a spigot over a tiny sink that drains overboard) to ones that are equivalent to the ones found in houses on land. Houseboats, in particular, generally have running hot and cold water supplied to a faucet in the galley, the one in the heads, and the shower head in the shower stall. QUIDNON will follow this general pattern, providing all the amenities people are used to having in their home on land.

Although the details of boat plumbing systems vary, all but the simplest ones share two significant commonalities: all of them break from time to time, and when they do repairing them involves the use of significant amounts of foul language while groping around in a cramped locker full of hoses cutting up one’s forearms on the sharp ends of hose clamps. Boat plumbing systems are virtually never designed with ease of maintenance in mind; mostly they are an afterthought, not so much engineered as crammed together in any space that’s available. A very common problem is that working on them requires the use of tools—screwdrivers, channel locks, sockets with ratchets—but there is no room to wield these tools in the normal manner, and just about every operation requires one to become a contortionist. Another common problem is lack of space for both the arm (with which to work on things) and the head (with which to look at what you are doing), meaning that much of the work has to do be done “by Braille.”

Boat plumbing is also a topic that brings out gender differences in stark relief. There is no shortage of men living quite happily aboard boats with minimal plumbing systems. They drink from a water battle, and sanitary arrangements consist of a “relief bottle” (what is done with its contents is rarely discussed). They shower ashore, at the marina or the gym, they eat out a lot, and all they really care about is having a place to sit, a bed to sleep in and a cooler for the beer. They may entertain female visitors on board, but if the accommodations are sufficiently spartan virtually none of the women volunteer to move aboard and see it as a sort of survivalist camping trip—interesting, perhaps, but unappealing for the long term. Sometimes this is by design. There is an abiding superstition among sailors that having women (and priests) on board brings bad luck. But there are also plenty of men, and women, who would like to live aboard as families, children included—provided the accommodations include a good plumbing system that provides hot and cold running water in the galley and the heads.

Very importantly, the plumbing system has to actually work. Since the system is on a boat, one naturally expects it to break on a semi-regular basis (a boat being a hole in the water you throw money into and all that) and when it does break, this tends to seriously disrupt domestic tranquility. This is because fixing the plumbing is, more often than not, considered “men’s work.” It is dangerous to generalize, and there are some exceptionally handy women, but there is also a preponderance of anecdotal evidence that the vast majority of women who live aboard boats limit their participation in dealing with plumbing issues to making announcements and asking questions.

The announcements can be quite emphatic, ranging from “There is no water!” or “There is salt water coming out of the tap!” to “I am going to the gym, because I want to take a normal shower!” and “I can’t stand this any more!” The questions can be quite challenging as well: “Why is the plumbing breaking down all the time?”, “Why can’t it be made to work reliably?” and “Why can’t we live like normal people?” As you may rightly surmise, plumbing emergencies occupy a spot at the top of the list of things that negatively affect domestic tranquility among liveaboard couples.

When an onboard plumbing emergency arises, the male part of the seasteading team takes out the tools, plunges his hands into a cramped locker filled with a tangle of hoses, promptly cuts himself on a hose clamp and starts using foul language. He would much rather work on something—anything—else, but he knows that if he can’t fix the plumbing problem quickly and definitively, his stock will plummet in value. Now, fixing the problem is generally quite possible—plumbing isn’t exactly brain surgery—but there are several adverse factors:

1. Most men aren’t plumbers and don’t quite know what they are doing.
2. Boat plumbing systems are weird and challenging even to natural born plumbers.
3. If you are on a boat, calling a plumber is an even more expensive option than it is on dry land.
4. If you need to replace something, you quickly find that “marine” replacement parts are at least twice as expensive as regular replacement parts simply because the word “marine” appears somewhere on the package.

But with QUIDNON things are going to be different, and in a good way, because the design of its plumbing system explicitly addresses these questions and concerns. All of the controls are laid out in a way that makes sense and makes them easily accessible. Schematic diagrams, diagnostic procedures and work-arounds for most common and even some uncommon problems make it easier to make repairs when something goes wrong.

The first two problems to address are the ones of cost and of the need for expert knowledge of plumbing. The solution is the same for both: use ¾-inch garden hose throughout: green hose for raw water, white hose for potable water, red (industrial) hose for hot water. Most men (in the US and Canada) can handle tasks associated with lawn care; lawn care involves the use of garden hoses; ergo, most men know how to screw together and fix garden hoses. You cut a specific length of hose that you look up on a chart, you slide on the ends of the appropriate gender onto each end, and you tighten them with channel locks. You make sure that the female end has a rubber gasket in it. Then you snake it into place and screw in the ends, by hand.

The garden hose-based solution is by far the cheapest, and the spare parts are very easy to come by: the gardening section of any hardware store is likely to stock all of them, while the plumbing section will provide the faucets and the shower head (no need for specialty “marine” parts). What’s more, people are always throwing away hose as soon as they get a single puncture in them, and so you can pick up all the spare hose you could ever need simply by making a habit of strolling past the marina dumpster. There are a few unusual items: a pressure reducer (the boat works at 15 PSI, not at “house pressure,” which can be anything), two demand pumps that run on 12V, an electric water heater and some additional odds and ends. These need not be “marine” either: any RV (recreational vehicle) supply place is likely to have all of them in stock.

Next is the problem of layout. On QUIDNON, the various valves are not located deep inside some locker but laid out sensibly between the three bottom steps of the companionway ladder, right above the slide-out shoe drawer. On every other boat I’ve looked at the companionway ladder is just a ladder, but QUIDNON is different: every item does several jobs. And so QUIDNON’s companionway ladder is at once a ladder, a shoebox, a plumbing control panel, an electrical control panel for both AC and DC circuits, a locker for boat documents, a locker for flares, handheld VHF radios and other emergency signaling equipment, and a firearms locker big enough to hold a shotgun, a rifle, a Glock and their assorted ammo. (If you don’t like guns, you can use it as a wine rack.) Here’s what the plumbing control panel looks like. Those little green valves are $2.49 each at Target, but I am hopeful that a quantity discount can be obtained.


Next is the problem of having plenty of freshwater on board, for those members of the crew who would never consider just shaving their heads and use shampoo and conditioner, and may even lather, rinse and repeat. The simplest solution is to live at the dock and to hook up a hose to the shore water system at the marina. In the north there is usually a summer water system and a separate winter water system with hoses run underwater and wrapped in electrical heating tape and insulation between the water and the boat. Further south there are no winter water systems and when there is a cold spell the water is simply shut off “until further notice.” Winter water systems sometimes freeze and get shut off “until further notice” anyway, and then everybody has to wash and shower at the marina bathroom, which gets crowded, causing tempers to fray. The solution, of course, is to have plentiful on-board water, which can be periodically replenished by pulling up to a fuel dock to fill the tanks. QUIDNON’s water tanks double as ballast—5 tons of it, or 1300 gallons—so there will be plenty of water on board. But it eventually runs out anyway, in which case you need to do the following:

• Dock some place where there is a water hose available (such as a fuel dock)
• Attach the water hose to the water intake
• Turn off raw water pump
• Open the raw water drain valves (to make room for fresh water)
• Program the DigiFlow 8000T water meter ($36.98 well spent) to count down from 1300 gallons
• Open the shore water intake valve
• Wait until the water meter starts beeping
• Close shore water intake valve
• Close raw water drain valves
• Program the DigiFlow 8000T to count down from 1000 gallons, so that it beeps when it’s time to start thinking about filling the tanks again
• Turn raw water pump back on

This is all simple so far, but now it gets a bit more complicated. Since the water tanks double as ballast, they have to always be kept full. This is accomplished by storing the fresh water inside a bladder that’s floating in salt water pumped in from overboard. When you turn on a tap, the raw water pump starts squirting salt water into the tank, squeezing fresh water out of the bladder and out of the tap. But what happens if QUIDNON is drying out on a sand bank or a beach at low tide (a fun thing to do with a ruggedly built flat-bottom boat) and salt water isn’t available? Now it gets complicated! You need to do several things, ideally before the raw water pump starts sucking air, and they may sound technical and complicated, but they really aren’t.

• Turn off raw water pump
• Close bypass valve
• Open both vent valves
• Turn on fresh water pump

Turning off raw water pump is an obvious thing to do; water pumps don’t pump air, and when you are drying out there is no raw water available. The bypass valve allows fresh water to flow around the fresh water pump when the pressure is supplied by the raw water pump, but since we will be using the fresh water pump, we need to close it. The vent valves need to be open to let air into the tanks as water is pumped out of them to avoid vapor lock. Turning on the fresh water pump is also an obvious thing to do.

Now, suppose you like living on the beach so much that you decide to stay, haul QUIDNON some distance away from the surf into the shadow of some coconut palms, and use it as a beach house. To do this, you walk the anchor to the shore, bury it, and then use the anchor winch to roll QUIDNON onto the shore over some logs. But while you are doing this you don’t want to be hauling five tons of water; you want the boat to be as light as possible. (You’ll deal with stocking up on freshwater later.) How do you do that? Here’s the step-by-step procedure, which starts where the previous procedure left off:

• Shut off fresh water pump
• Open all 4 drain valves
• Wait for water to dribble out

Bored of living on the beach and want to be sailing again? Once QUIDNON is afloat again, it’s time to fill the tanks with salt water:

• Make sure all drain valves are closed and both vent valves are open
• Open bypass valve
• Turn on salt water pump
• After pump stops running, close both vent valves

Bladders don’t last forever and although many years may pass uneventfully, eventually you will hear the words “There is salt water coming out of the tap!” What do you do? First, you isolate the problem. Run the tap, close the port fresh water tank valve and have a taste. Problem fixed? Then it’s the port tank bladder that’s leaking. There is nothing more that you have to do immediately. Is water still salty? Then it’s the starboard tank bladder that’s leaking. Open the port freshwater tank valve, close the starboard freshwater tank valve, and confirm that the water is no longer salty. Inform your partner that the problem is fixed (for now).

Now, to really deal with the problem you have to replace the leaky bladder. First, you have to drain the tank. For the bad tank:

• Open vent valve
• Close raw water tank valve (fresh water tank valve is already closed)
• Open both fresh and salt water drain valves
• Wait

Once the tank is drained, find the access plate. It’s a round piece of plywood bolted onto the back wall of the tank, held in place by six ¼-inch bolts arranged in a circle with a rubber gasket sandwiched in between. The port access plate is in the shower stall in the heads; the starboard one is under a cabinet in the galley. Empty the cabinet and put something underneath the plate to catch any water. There is a hose attached to a threaded nipple that sticks out of the access plate. Unscrew the hose, undo the 6 bolts, remove the plate and pull out the bladder that’s attached to it. Undo the hose clamp securing the bladder to the nipple inside the plate and remove the bladder. Coat the nipple with caulk and slide on the new bladder. Install and tighten the hose clamp, but not all the way. Wait for the caulk to harden, then tighten the clamp the rest of the way. Gently stuff the bladder inside the tank, reinstall the access plate (a bit of vaseline on the gasket should help keep it watertight) and reattach the hose. Open raw water tank valve. Once the tank is full, close vent valve and open fresh water tank valve. This is probably the most complicated and delicate plumbing repair that QUIDNON could call for.

But what happens if the pumps stop working? You are off sailing, or living at anchor, and suddenly one of the batteries develops an internal short circuit, discharging the rest of the batteries. (You probably shouldn’t have kept the battery bank selector set to “both,” but it’s too late now.) “There is no water!”—nor is there anything else that requires electricity! You need to isolate the faulty battery, disconnect it from the bank, then start the motor using the emergency pull chord and run it until the remaining good batteries are charged. But that’s thirsty work, and how will you keep yourself from becoming dehydrated in the meantime? Easy: open the tank vents and use the foot pump in the galley. Filtered fresh water will come gushing out of the spigot. You still need to fix the electrical system before you drink up all of your ballast, but it’s not too huge of a hurry—unless somebody really needs to take a shower right there and then. Be sure to close the tank vents once the raw water pump starts running again and the tanks are full once again.

Finally, there is the worst-case scenario: you are sailing along and hit something hard and pointy—a floating shipping container or a coral head—and put a hole in QUIDNON’s bow. This is hard to do, because the bow is clad in tough copper sheets, a thick layer of fiberglass and an inch of plywood, but there is simply no arguing with sharp rocks. Water starts gushing in faster than the bilge pump can pump it out. Under these circumstances, most sailboats quickly disappear under the waves, leaving the crew treading water. But what about QUIDNON?

Well, here’s the procedure. Unless the problem is relatively trivial—something that can be fixed with an oil-soaked rag, a hammer and a screwdriver—do not immediately deal with the leak because there are more important things to do. First, stop the boat. Raise the motor to the top of its well. Anchor if the depth allows, otherwise just drift. Close the watertight doors to the aft cabins (first making sure there’s nobody inside them); they will be used as emergency flotation. There are also large slabs of foam lining the walls of the engine well; as is usual, they have two jobs: 1. insulate against engine noise, so that the aft cabins are nice and quiet; and 2. provide emergency flotation when the boat is swamped.


Now you need to “blow the tanks,” just as you would on a submarine. Find the emergency SCUBA tank (it’s in one of the aft cabinets in the galley, strapped to the bulkhead) and open the valve on it. Make sure the regulator is set to somewhere between 15 and 25 PSI. Now do the following:

• Close all tank valves
• Open all drain valves
• Make sure vent valves are closed
• Open air valves
• Wait
• When you hear loud bubbling sounds coming from the engine well, close all drain valves and air valves. Close valve on SCUBA tank. Water tanks now provide 5 tons of additional flotation.

QUIDNON will now remain afloat while you effect repairs. When swamped, QUIDNON will sit low in the water, but it will not sink. The stuff that you don’t want to get wet should be stored in the aft cabins or on top of the water tanks.


The next step is to break out the emergency hull repair kit. It contains some canvas, a few pieces of plywood and MarineTex epoxy. Mix the epoxy, and use it to coat a piece of plywood large enough to cover the hole in the hull. Note that the plywood has kerfs (little slots) cut into one side, to make it bendy. When you put the plywood over the hole, the kerfs should face out, not in. Also coat a piece of canvas cut big enough to cover the entire area of the repair. Now go up on deck, dive overboard and apply first the plywood, then the canvas over it. Once the leak is stopped, start the motor (it may need to be partway up on its slide to keep the air intake above water) so that there is electricity for the bilge pump and wait for the water inside the cabin to be pumped out. Now fill the water tanks with seawater (to get your ballast back). Sail to some place where you can pick up some fresh water, then think about hauling out for more permanent repairs. The emergency repair needs to be ground off, the ragged hole cut out and replaced with fresh fiberglass and plywood, and the copper sheathing either hammered flat and reattached or replaced.


One last QUIDNON plumbing-related thing worth mentioning: there are three signal lights to tell you which of the three pumps is running, and three alarms, all wired up to a single bell, each with a silencer switch:

• Signal lights for raw water pump, fresh water pump and bilge pump
• Bilge high water alarm (means you have water coming in faster than the bilge pump can deal with it, or the bilge pump isn’t working)
• Starboard tank low water alarm
• Port tank low water alarm

The low water alarms are important because the tanks provide ballast, which is necessary for stability when sailing. Thus, when they aren’t full, this is something that the crew needs to know about. Of course, when the boat is drying out and the raw water pump isn’t running, the low water alarms are a bit of an annoyance, but they are there to remind you that you need to fill the tanks before you go sailing again. The silencer switches are important because in practice every alarm has a silencer, but if it isn’t a switch then it’s a mad person wielding a hammer or wire cutters, and that isn’t good for safety. Other signal lights are useful too. The bilge pump light tells you that water is getting into the boat from somewhere. If the raw water pump is running for no reason you could have a leak, a tap left open, a clogged strainer or you could be drying out at low tide. If the freshwater pump is running, you could have a leak, or out of freshwater, or maybe you left the bypass valve open by mistake, causing it to pump water in a circle.

To summarize, QUIDNON’s plumbing system will provide lots of tankage (you are unlikely to find another 36-foot boat with 1300-gallon tanks), all the usual amenities, plus a powerful safety feature that makes QUIDNON self-rescuing when holed and swamped. It achieves all of this functionality at minimal cost, thanks to the use of garden hose and fittings and RV instead of marine components. It is laid out in a way that makes it easy to work on. It is documented with schematics and troubleshooting procedures. And it will, I sincerely hope, prove to be conducive to preserving domestic tranquility.

Saturday, July 9, 2016

Progress Report

Much of the design work has been completed over the past few months. The 3D model, drafted in Rhino 3D, is largely complete. Construction techniques, including materials selection, joinery techniques and order of assembly have been largely worked out.


The cockpit design, the deck arches, the tiller linkage, tanks and lockers and many other details have been worked out in detail. We have designed a very strong structure for stepping the mast tabernacles, constructed out of 4x4 hardwood timbers glued and bolted together.


This structure, fastened and glued to the deck, bottom and sides of the hull, will also provide plenty of resistance to torsional loads, side loads when docked and strengthen the foredeck.


We are still working out such minor details as tiller design, hatches, interior cabinetry, wiring and plumbing, and running rigging.


The model has been hydrostatically tested using Orca3D software. (We are very grateful that Orca3D has agreed to sponsor our project, and has donated two seats of their excellent software for our use.) Hydrodynamic tests will have to wait until we build a 1:12 scale model, and conduct towing tests and other types of in-the-water testing.


The good news is: there are no surprises at all. The hydrostatic tests have confirmed the initial calculations: QUIDNON, ballasted as initially designed, is going to be seaworthy and reasonably fast.


Moreover, it will be able to carry considerable freight. Here is a table of draft (with centerboards and rudder blades retracted) vs. load.

Load Draft
0 12.9 inches
10 tons 25.3 inches
20 tons 34.6 inches


Shown above is the aft amidships section: two 20 lb. propane cylinders in an ABYC-compliant propane locker with an overboard drain, a 100-gallon gasoline tank below it, and a 40 hp outboard engine forward of it in an inboard outboard well.


According to results from Orca3D analysis, fuel consumption and speed will be as expected. As the above chart shows, even when loaded with 20 tons of freight, QUIDNON will do a comfortable 7 knots with a 40hp outboard at half-throttle, burning 2 gallons per hour, for a 350 nm cruising range. Without freight, its cruising range increases to over 600 nm.

It is interesting to note that when QUIDNON isn't loaded, as speed increases from 7 kt, power requirement shoots up. This is because the hull form is a compromise, and at 0 load the transom bogs down faster than when loaded. But this effect will be pronounced mostly when motoring; when sailing the center of force will be further forward, keeping the bow down and presenting a smaller profile to the water.

And so it is safe to conclude that QUIDNON will work very well as a live-aboard boat. You pay for a 36-foot slip and you get around 540 square feet of interior living space, plus just as much space on deck, which is plenty of space for living aboard and for throwing dockside parties. It is fast and economical enough to make a good canal boat, and with a 20-ton cargo capacity it can be used to bring back a year’s worth of harvest from wherever you hunt, gather or grow it back to your winter quarters.

But is it seaworthy?


But, you probably still want to know, Is it seaworthy? To an engineer, this is a fairly annoying question, because there is no technical definition of seaworthiness. And so I will apply my own definition. Seaworthiness is the ability to survive arbitrary conditions at sea. By “arbitrary conditions” I mean something that includes arbitrarily high, almost vertical walls of very angry water, with spindrift blowing from the wave tops at well over 100 miles an hour.

By this standard, few boats are actually seaworthy. We can immediately rule out all catamarans and trimarans: they are more stable floating upside-down than right-side-up, and once a rogue wave flips them over, it’s game over every time.

We can also rule out most yachts, large and small, with tall masts: once the masts hit the water, more often than not they snap off, and, again, it’s game over, every time. So masts have to kept quite stubby. In QUIDNON’s case, the masts measure exactly 36 feet from the mast tabernacle hinges, because they can’t overhang the bow or the transom when the masts are dropped and secured to the deck arches (for canal work, to pass under bridges). And the reason they can’t overhang is because that would increase QUIDNON’s overall length (LOA), incurring increased slip fees at marinas, and we can’t have that.

Secondly, we can rule out all large commercial ships: tankers, cruise ships, dry bulk carriers, container ships, etc. All of them are designed for a maximum wave height, and a big enough wave will capsize them, break them in half, or both. Over a hundred ships are lost every year in just this manner. But “fixing” this problem would be too expensive, and rogue waves are rare enough to keep marine insurers in business.

But we who sail around in small boats do like them to be able to survive almost arbitrary sea conditions. And if you try to design something that is completely seaworthy, by this definition, you end up with a coconut every time. But who wants to sail around in a coconut? (Actually, QUIDNON’s hull shape comes pretty close.)


Hydrostatic analysis shows that QUIDNON is self-righting up to 130º. It is very tender when level, and just walking across the deck is enough to make it list a few degrees. But beyond 10º it puts up a very serious fight. In fact, while sailing, it is probably not possible to make it list more than about 25º, in any sort of useful wind. It continues to put up a very serious fight until about 70º. Thus, any sort of sudden squall will lay it over for a bit, but with no serious consequences (unless you fall overboard, but that's verboten).

At around 90º, it gets ready for Round Two, because at that point the masts are in the water, and they are buoyant because they are filled with foam, weighing in at negative 8.5 lb. per foot of length, with a huge lever arm. Only beyond 130º does QUIDNON develop a propensity to turn turtle and settle.


When inverted, it is only about half as stable as when it is floating right-side-up, and if it lists by more than 50º it will right itself. Thus, if a big enough wave flips it over, leaving it floating at some arbitrary angle, there is only a 27% chance that it will be left floating upside-down. And if a wave big enough to capsize it comes along, there is about a 50% chance that the following wave will be at least half as big, enough to lean it over by at least 65º, and since 65>50, QUIDNON will then right itself. And so the chance of QUIDNON remaining bottoms-up after a rogue wave event is no more than 15%.


This, I would think, is quite seaworthy—for a houseboat. However, we must keep in mind that it is a houseboat, and even though we can take it out on the Big Wobbly with quite a lot of confidence, we should still remember that we are just moving house, not embarking on an extreme survivalist adventure at sea. And so, we should take certain precautions. These are divided into strategy and tactics.

The strategy is to avoid storms by carefully picking weather windows. For longer passages, on which storms are impossible to avoid completely, the strategy is to carefully pick weather windows for getting away from land, and for making landfall. The idea is to be nowhere near anything at all when bad weather hits. Rocks and shoals kill boats; wind and water—not so much. This is the sort of advice you can get from any number of books.

Another part of the strategy is preparing QUIDNON for bad weather, and it is QUIDNON-specific. QUIDNON can sail just fine with unstayed masts, but when making ready for the open ocean a bit of standing rigging makes a lot of sense. A triatic line is connected between the mast-tops, and two running stays are connected to each of the mast-tops and tensioned, the two from the foremast running forward, and the two from the mainmast running back. This set-up is traditional; Tom Colvin had lots of luck with this arrangement. Also, obviously, anything that could possibly shift in a capsize should be secured, both above and below deck.

The tactic is simply to ride out the weather, in the usual sequence: heave to, lie ahull, lie to a drogue, scud off under bare poles. Make a pot of stew, batten down the hatches and hunker down. Again, you can get this sort of advice from any number of books. Unless you are particularly unlucky, seriously bad weather generally passes in 2-3 days, and so with QUIDNON drifting at about 1 knot you’ll need about a 100 nautical mile offing from the nearest hard object to drift safely.

Since this is much more seaworthiness than one has any right to expect from a houseboat, and since it comes at very little additional expense (filling the masts with foam and rigging some running stays is pretty cheap) we will consider this aspect of the design handled.

Thursday, April 7, 2016

Mast Tabernacle Rethought

Sometimes delays are helpful because they allow more time for examination, and for rethinking parts of the design. And so it was with the tabernacle design. My initial plan was to use a joint that transferred all of the tension and compression loads into sheer loads on two large bolts, which I called “Jesus bots,” after the “Jesus nuts” that hold helicopter rotors in place. But then Alan, who is designing a boat similar to QUIDNON—a houseboat that sails, but for inland waterways—pointed out that my design would require extremely high precision in the way the components are fitted, or they would start to move and flex under load, and fail. Alan has lots of experience in aerospace engineering, and a keen appreciation for structural elements. What he proposed was two flanges bolted together, connected by a hinge on one side. This approach is very standard: look at your average streetlight, and that's how it's mounted. It is so standard that it doesn't require any interesting structural analysis: one can simply look it up and plug in the numbers. Since the bolts that hold the two flanges together are subjected only to tension loads, they don't need to be fitted precisely, and the math for sizing them is simple.


Alan's idea solved one problem but created another: how to fit the mast in place prior to raising it. He is used to working in a hangar, on land, when doing such things, but raising a mast on a boat in the water is a different matter. Precisely maneuvering a heavy mast on a swaying deck in order to insert the hinge pin is no easy matter. After much back-and-forth, we arrived at a solution. The hinge pin is welded onto the bottom flange—the one that's part of the tabernacle. The top flange has two slotted tabs that fit onto the hinge pin and two latches that capture it. And so all you have to do to raise the mast is get it into position and flop it onto the tabernacle. Click! After that, the procedure is simple: insert gin pole, attach hoist, and click-click-click until the mast flops forward. Then assemble and torque the flange bolts.


Another bit of very useful information Alan provided had to do with the design of the mast itself. I was thinking of using flagpoles, which are tapered, and of using them as unstayed masts. Alan tried to calculate the righting moment that would be generated by his hull in the event of a knockdown, and realized that such a wide hull would snap any unstayed mast. We also realized that there are a few other, minor problems with the unstayed design. The first is that there is nothing to prevent the mast from swinging side to side as it is being raised. The second is that the taper of a flagpole results in a sloppy fit up top, because the parrels on the junk sail have to be loose enough to be able to lower the sail all the way down. A straight, non-tapered mast would work better. Lastly, flagpoles are not the cheapest solution, which is to use 20-foot sections of 6-inch Schedule 40 aluminum pipe joined into the correct length for the mast using plugs made of smaller-diameter sections of pipe. The same pipe can be used for both the mast and the tabernacle.

And so the revised design has a mast tabernacle that uses flanges and a hinge, a mast made of straight 6" aluminum pipe, and two shrouds to at serve three functions: 1. prevent the mast from breaking in the event of a knockdown, 2. keep the mast from swinging side to side as it is being raised, and 3. take up some of the sideways load while sailing (which can be considerable, especially when sailing to windward, when the forward force is generated by two much stronger opposing forces of the sails and the centerboards acting at a small angle to each other). The design will remain unstayed as far as fore-and-aft forces are concerned, and the risk of dismasting from pitchpoling cannot be dismissed. Here, the addition of a couple of running stays, to be deployed fore-and-aft in particularly bad conditions, seems like a good idea.

There aren't too many options for shrouds on a junk rig. Since the sail slides up and down the entire length of the mast, there can be no spreaders. Nor are spreaders needed for a hull this wide. And so the two shrouds will run directly left and right between the mastheads and the ends of the deck beams that support the tabernacle at the deck, which are part of a trapezoidal frame made of hardwood timbers on which the tabernacle is stepped.

Problem solved... at least until somebody comes up with an even better idea, or finds a problem with this one.