The purpose of this project is to design and mass-produce kits for a floating tiny house that can sail. It combines high-tech modeling and fabrication and low-tech assembly that can be carried out DIY-style on a riverbank or a beach. This boat is a four-bedroom with a kitchen, a bathroom/sauna, a dining room and a living room. The deck is big enough to throw dance parties. It can be used as a river boat, a canal boat or even a beach house. It's rugged and stable enough to take out on the ocean.

Sunday, June 16, 2019

Dismasting Made Easy

You are sailing along on a passage, on autopilot, the radar set up to wake up and do a sweep every 10 minutes or so and sound an alarm if it detects a collision course, with the entire crew (which could be just me and the ship’s cat) down below doing whatever people and cats do when they aren’t sailing. Then a squall kicks up, or a waterspout (a sort of water-borne tornado), or you royally screwed up and plotted a course that takes you under a bridge that’s too low. Suddenly, you find yourself minus the masts. This can be very dramatic, or not, depending on how the boat is designed. And since Quidnon is primarily a houseboat (that sails), drama is specifically what we don’t want.

There are a few different solutions for installing masts. First, there are deck-stepped masts. They are installed using a crane which lifts the mast up by a point somewhere above its center of mass so that it hangs down more or less straight. The heel of the mast is placed where intended, and then the standing rigging is hooked up, which consists of wire rope and turnbuckles with which to tension it. Standing rigging consists of a forestay, a backstay and some number of shrouds that go off to the sides of the deck and may go around spreaders. (By the way, spreaders are a terrible idea, unless you like your deck to be covered in guano, because they provide nice perches for sea birds.) Where there isn’t room for a backstay (such as with a mizzen mast on a ketch or a yawl) there are often running stays which are clipped on and tensioned as needed. There may also be baby stays (miniature forestays) and triatics that tie the tops of masts together.

Second, there are the keel-stepped masts. These go through a reinforced hole in the deck (which will at some point leak water into the cabin) and the heel of the mast is stepped in a bracket that’s bolted to the top of the keel. The nice thing about keel-stepped masts is that they don’t flop down instanter whenever some bit of standing rigging fails. On a deck-stepped mast, if the forestay fails, then the mast flops down on the cockpit, braining whoever happens to be in it; if the backstay fails, then it flops forward. The standard material for standing rigging is stainless steel wire rope, used because it’s less stretchy than regular galvanized wire rope, and stainless steel fittings to attach it (turnbuckles, shackles, etc.) The nasty thing about stainless (other than its exorbitant cost) is that unlike regular mild steel it tends to develop invisible microfractures over time, then fail catastrophically.

When standing rigging on a keel-stepped mast fails, it may soldier on for quite a while, enlarging its hole in the deck as it swings about. When it finally fails, it is likely to snap off at the deck, since that’s the point of greatest stress. Either way, what you end up is a rather large stick flailing about uncontrollably, tugging at a mad tangle of rope and cable that gets caught up on everything it possibly can, trying to rip it off. At that point, people generally rush about the deck with bolt cutters, tying to snap every bit of line and cable that connects the mast to the boat, in order to set the mast on a journey of is own, down to the murky depths.

There are also unstayed masts which have no standing rigging at all. These are always keel-stepped, since if they were deck-stepped they would simply fall over. They have to be quite a bit stronger than stayed masts, since they rather than the standing rigging have to withstand the press of the sails. To keep their weight reasonable, they are usually tapered. Mast-stepping techniques are a bit like the techniques for holding up your pants: deck-stepped masts with standing rigging are like wearing suspenders, keel-stepped masts without standing rigging are like wearing a belt, and keel-stepped masts with standing rigging are like wearing both. Which of these makes for the most exciting strip-tease (dismasting, that is) is, I suppose, a matter of taste.

Keel-stepped masts have some disadvantages. I already mentioned the almost inevitable leaks through the hole in the deck. There is also the problem of sagging, especially if there is standing rigging: the mast pushes down on the center of the boat while the forestay and the backstay pull up on the bow and the transom. Over time, this causes the hull to acquire a slight banana shape. In turn, this causes bilge water to pool around the mast heel. The bracket the mast heel rests in is usually made of mild steel while the mast itself is usually aluminum, and the two undergo a galvanic reaction: the bracket rusts while the mast heel rots away. If the forestay or the backstay and the mast heel both fail, then you have the bottom end of the mast ripping through the cabin.

Finally, keel-stepped masts chill the cabin. Aluminum is an excellent conductor of heat, and having an aluminum stick part of which is inside the cabin and part of it outside sucks heat out of the cabin most efficiently. Wrapping it in layers of radiant barrier and fabric helps somewhat, but it’s much more pleasant not to have it there in the first place.

Mounting the masts on Quidnon presents a rather interesting design problem. Since there is no keel, keel-stepped is not an option. Since there is a requirement that the masts be easy to raise and lower without recourse to a crane, deck-stepped is not an option either. And since the sails are Junk rigs, which rise above the top of the mast when fully raised, having forestays and backstays is not an option either. Lastly, Quidnon is a houseboat, and whereas with a sailboat built for sport or ostentation it is acceptable to respond to a dismasting at sea by declaring it a total loss, abandoning ship and setting off in a life raft expecting to be rescued (or not, as the case may be) with Quidnon the loss of two large vertical sticks should not compromise its ability to serve as a floating domicile, albeit one now temporarily deprived of its ability to sail. It is thus a requirement that a dismasting does not compromise the integrity of the hull.

Since Quidnons will spend most of the time sitting at anchor or at the dock and only once in a while undertake a journey under sail, perhaps as a seasonal migration to shift berth between summer and winter quarters, perhaps to relocate to a different permanent location as conditions warrant, most of the time the masts can be kept lowered and the sails bundled up into their sail covers and stowed on deck. Thus, it is yet another requirement that the masts be unobtrusive when lowered.

This mast tabernacle design has gone through a number of changes but is now in a state that fulfills all of these requirements. Here are the plan and elevation views with the masts lowered and resting on the deck arches. Note that with the masts lowered Quidnon is not any longer overall than with the masts raised. This is important, because marinas charge slip fees by overall length, which includes any overhanging objects. Quidnon fits into exactly 36 feet, makes full use of the width of a marina slip with its 16-foot beam, and provides very close to 36 by 16 feet, or 576 square feet of interior living space with ample headroom.

There are three deck arches, and they serve a large number of purposes:

• They provide support for the masts when they are lowered

• They allow the masts to slide back and forth, back before being raised, forth after being lowered, on rollers positioned close to the centerline

• The second and third deck arches have T-track with sheet blocks running along their tops

• They provide cabin ventilation through openings in their front and back, blowing air into the cabin and sucking it out again

• They serve as a frame for either a canvas cover or shrink-wrap for winterizing the boat

• The second deck arch has a block and tackle for loading and unloading the boat through the deck hatch

• The third deck arch has a block and tackle for installing and removing the outboard engine that lives in the engine well

• The first deck arch provides a mounting place for the radar’s radome

• The deck arches provide places to hang hammocks or swings, to mount solar panels, etc.

In short, deck arches are fantastically versatile and useful, which is why Quidnon has not one, not two, but three of them.

Here is the elevation view of Quidnon viewed from the transom, with the masts lowered and sitting side by side on the deck arches.

Note the various dimensions. The hull is basically an 8-foot by 16-foot by 36-foot box. It is 1 plywood sheet tall, 2 plywood sheets wide and 4.5 plywood sheets long, arranged in a pattern that generates minimum scrap. There is 5½ feet of vertical clearance below the deck arches, and the taller people will have to stoop to walk under them. On the other hand, they are low enough for most adults to be able to work with them, and with the masts that rest on them, without having to resort to footstools or stepladders. It’s a compromise. The bridge clearance with masts lowered is 14 feet, and most fixed bridges on navigable waterways provide at least that much.

Now let’s go through the details of the mast stepping arrangement. Here is a drawing of a mast (in this case, the mainmast, but the differences are subtle). There are three main elements:

• The mast itself, which includes a masthead fitting at the top and a heel plug at the bottom. The mast is made up of either a single 36-foot length of 6-inch Schedule 40 aluminum pipe or (since 6-inch Schedule 40 pipe is most easily obtained in 20-foot sections) two pieces joined together using a short length of inner tube and some epoxy. (Welding the two pieces together is also possible, but making structurally sound welds in aluminum is quite an art while the epoxied joint is dead simple and relatively idiot-proof.)

• The tabernacle, which is made of galvanized mild steel and can be fabricated using an oxyacetylene cutting torch, a stick welder and a grinder (although a plasma cutter and a TIG welder would work even better) and includes a mast hinge at the top and a pressure plate at the bottom.

• The mast trunk, which is a cylindrical piece of lumber that runs from the bottom of the hull through a hole in the deck and protrudes 3 feet above it. The mast tabernacle fits over it.

The set-up is basically of a deck-stepped mast, because the pressure plate rests on the deck. But the mast doesn’t topple without standing rigging because the tabernacle sits over the mast trunk, which is constrained to being vertical. It goes through a hole in the deck, where it is secured using a pin and caulked into place, so that there are no deck leaks. The heel of the mast trunk sits in a cup that is fastened to the bottom. There is an air gap between the bottom of the mast trunk and the hull bottom of the cup, so that the mast trunk does not exert any vertical force on the hull bottom as the hull flexes. It does exert horizontal forces, which the bottom can readily withstand.

Taking each of these elements in turn. The masthead fitting is a simple affair; like all the other elements except the mast and the mast trunk, it is made of galvanized mild steel. It consists of a short piece of pipe that fits over the masthead welded to an oval plate with two gussets that face fore and aft. The gussets have holes which take the pin of a D-shackle. This shackle is then used to attach, using teardrop-shaped thimbles, all of the needed lines: the halyard, two topping lifts and four running stays (of which more later).

Masthead fittings generally include some number of brackets for mounting a VHF antenna, an illuminated wind direction indicator and a wind instrument that measures wind speed and direction. It is also a good place to mount a 3/4/5G router; at some 50 feet above water it will “see” towers quite far over the horizon, making it possible to have internet and VOIP access even when sailing outside of sight of land.

All of these masthead instruments generate quite a mess of wiring which has to be sent down the mast and into the hull. To keep it banging around inside the mast, keeping people awake at night, a good trick is to squeeze the wiring into a tight bundle using large zip ties every foot or so and leaving the tail of the zip tie in place to push the wiring to one side of the mast. The masthead fitting plate has a hole in it for sending the wiring bundle through. It is then closed off with a plastic plug and the cracks caulked.

At the mast heel there is an indexing bolt that is used to align the mast with a recess milled into the mast hinge. It also serves the function of keeping the mast captive within the mast hinge.

Next down is the mast tabernacle. The mast slides through the 1-foot pipe that is part the top tabernacle hinge and is held captive by it because neither the masthead fitting nor the mast heel fitting can slide past it. The inside of the top tabernacle hinge pipe is coated with graphite-loaded epoxy to create a low-friction surface. When raising the mast, it is slid aft until the mast heel is aligned with the bottom of the hinge plate and rotated until the head of the indexing bolt fits into the matching recess in the hinge plate. Another bolt is then screwed in to hold the mast to the hinge, preventing it from slipping as it is raised.

Part of the top tabernacle hinge is a fitting that accepts a 5-foot gin pole which is used to raise and lower the mast using a hand winch. It is a solid 2½-inch steel rod that has to accept well over 1000 lbs. of load without flexing.

The top tabernacle hinge is connected to the bottom hinge using a slightly tapered hinge pin. A second tapered hinge pin is inserted on the opposite side of the hinge to secure it in place as soon as it is raised. The hinge pins can then be pounded until the joint and tight and secured using a nut and a stop nut. This immobilizes the hinge, preventing friction and wear.

All of the wiring going through the mast has to be fitted with connectors at the mast tabernacle. The connectors should be waterproof, because there will inevitably be condensation inside the mast.

At the bottom of the tabernacle is the thrust plate, which rests on deck, where it is, again, coated with epoxy loaded with graphite powder, creating a low-friction bearing surface. The tabernacle fits snugly over the mast trunk, which rises 3 feet above the deck.

Where the mast trunk penetrates the deck it is pinned into place and caulked, to prevent deck leaks. Thus, the mast trunk hangs from the deck rather than resting on its heel. Instead, its heel floats in its heel fitting, which is fastened to the bottom of the boat via a wooden block cut to the appropriate angle. The mast trunk heel fitting is not subjected to any vertical loads, only horizontal ones, which the bottom of the boat can readily handle. The mast trunk incorporates a slot that accepts the mast wiring bundle, which snakes all the way down into the bilge, through the mast trunk heel fitting, and back toward the cockpit. Within the cabin the wiring is hidden by installing a decorative cover over the slot.

A key feature of the mast trunk is the notch. It is located an inch or so above the deck and is the designated failure point in a dismasting event. The depth of the notch is calibrated so that the mast trunk is only slightly weaker than the mast tabernacle or the mast. Once the mast trunk snaps off, the mast and the tabernacle are free to topple overboard as a unit. Some amount of additional damage is inevitable. The wiring bundle will be pulled apart and the masthead instruments are likely to be destroyed. To free the mast, several lines need to be released: 4 running stays, the sheet, the halyard and the reefing line. But this isn’t a lot of work: 4 on snap shackle pins released and three rope clutches opened. Dismasting made easy!

But what is most important is that the rest of the boat remains undamaged. After a dismasting event, a Quidnon owner can say “Masts? What masts?” shrug and motor on nonchalantly. When the time comes to replace the masts, any welding/machine shop can fabricate a new mast tabernacle and mast fittings, any wood shop can make a new mast trunk, any canvas shop can stitch together the sail out of Sunbrella fabric (a tough material used for awnings), the pipe for the masts is quite standard and easily obtained, and masthead instruments and rigging components can be mail-ordered from the usual outfits. The rest is just puttering about, to be done at one’s leisure. And if the masts and the sails can be salvaged, then all that needs replacing is a piece of wood (the mast trunk) and some masthead instruments.

The only difficult task in replacing the masts is heaving them onto the deck arches. Each mast weighs around 200 lbs, so it is best to have at least three strong-backed people on hand to assist with this operation. The easiest way to do this is to place the masts on the dock next to the boat and roll them aboard using two loops of rope or strapping, one placed fore, one aft. One end of each loop is secured, and the other one pulled, rolling the mast onto the deck arches and into place. With this technique and four people, two people are pulling, exerting 50 lbs. of force each, and two more are making sure that everything stays nice and even. Once all the pieces are in place, the masts can be raised.

Prior to being raised, seven lines have to be attached to the masthead:

• Four running stays, two forward, two aft

• Two topping lifts, one forward, one aft

• One halyard, aft

These can be draped over the deck arches to keep them from snagging on things or getting dropped in the water as the mast comes up. The running stays can be shackled to their respective pad eyes on deck ahead of time; the rest of the lines can be tied off at the nearest available deck cleat.

For the foremast, the gin pole interferes with the forward deck arch, and so the deck arch, which is hinged at the front, is tilted forward and out of the way for the duration. This involves loosening two turnbuckles and removing two clevis pins.

The masts tend to wobble between port and starboard as they come up, or lean to port or starboard, or both, especially if there is a bit of a sea running, or if the boat lists a bit from the way it is loaded, or if there are wakes from passing boats. This is nothing to worry about: the mast tabernacle can spin around on the mast trunk. Once the mast is all the way up it can be rotated to the correct fore-and-aft position out by putting some extra tension on the hand winch line.

The masts have 1º forward rake (meaning that they lean forward 1º) and once they come up all the way they flop decisively into place. At that point, the second, forward hinge pin is inserted and the hinge pins pounded in and secured in place using nuts and stop nuts. The hand winch line can then be removed. The next step is to install the running stays.

Quidnon’s method of keeping the pants up is the “belt and suspenders” method. The mast trunk is the belt, and keeps the mast up even by itself, but it is not sufficient to withstand the pull of the sails or the rocking of the masts in heavy weather. For this, running stays (suspenders) are needed as well.

For the running stays, galvanized steel wire rope is an economical choice, but it tends to be rather cumbersome to store between sails because it has to be coiled. A more expensive but excellent choice is Spectra or Dyneema, which are synthetic fibers that are just as strong but so flexible that they can be stuffed into a bag. There are four running stays per mast, all going to the sides of the deck, two forward (to oppose the weight of the sails) and two back (to oppose the pull of the sails). The running stays need to be clipped into place and tensioned before the sails can be put up.

The procedure for raising the masts is now pretty simple:

1. Attach lines to masthead fitting, drape them over the deck arches; clip running stays into place

2. Roll the mast into position

3. Rotate the mast until the indexing bolt fits into its matching recess

4. Thread a bolt through the tabernacle hinge and into the mast (wait to tighten it until the mast is up)

5. Connect mast wiring cables at tabernacle hinge; test the circuits for opens and shorts

6. Attach gin pole (insert into top tabernacle hinge, insert retainer clevis pin and ring-ding)

7. Attach line from hand winch to D-shackle at the end of the gin pole

8. Heave the mast upright using the hand winch

9. Insert second (forward) hinge pin

10. Pound in and secure hinge pins

11. Tighten the bolt in the tabernacle hinge that holds the mast in place

12. Tension the running stays

The procedure for taking the mast down is almost the exact reverse of the one for raising it:

1. Pull the lines in the running stay purchases out of their jam cleats and flake their lines on deck so that they run out as the mast comes down

2. Loosen the hinge pins (loosen the lock nuts and the nuts and given the pins a tap so that they turn freely)

3. Attach the line from the hand winch to the D-shackle at the end of the gin pole and take out most of the slack

4. Take out the second (forward) hinge pin

5. Get the mast started by pulling back on it using any of the lines that run from the masthead

6. Ease it down using the hand winch; horse it onto its rollers if it comes down at an angle.

7. Detach the line from the hand winch to the D-shackle at the end of the gin pole

8. Detach gin pole (take out ring-ding, slide out clevis pin, remove gin pole from tabernacle hinge)

9. Disconnect masthead wiring at the tabernacle hinge

10. Remove the bolt that holds the mast in position

11. Slide the mast forward

12. Detach lines from masthead

I wish it were possible to simplify this procedure from this 12-step program, but I don’t see how. As it is, the design achieves the following important objectives:

• The masts are secure and unobtrusive when stored on the deck arches and don’t add to the overall length of the boat (thus avoiding any added expense)

• The masts can be raised and lowered by just one person in a couple of hours (probably less with practice)

• In the unlikely event of a dismasting, there is unlikely to be severe damage to the hull and the injured mast can be dropped overboard by undoing four snap shackles and releasing three rope clutches.

• A salvaged mast (which may survive undamaged) can be reinstalled after replacing a single sacrificial wooden component, spares of which can be kept on board, plus the ruined masthead instruments

The entire sailing rig design is at this point far enough along to be set aside for now; the next step is to produce detailed fabrication drawings. Some other previously missing parts of the design, such as the engine bracket (which slides up and down) are pretty much done too, and are at the same stage, but are not exciting enough to deserve an entire blog post.

Therefore, we will now move on to mapping out the build process, starting with the deck, then moving on to the frame and the bulkheads, the bottom, the topsides and, finally, the surface of the deck and the superstructure (which can be completed with the boat in the water).