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 3-bedroom with a kitchen, a sauna and a dining 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. Oh, and it's rugged and stable enough to take out on the ocean. Kits will start at around $50k (USD). The design has been tested in simulation and prototype; full-scale production will begin next year.

Friday, January 23, 2015

Keeping costs down

The ways I have found to save money on this project are too numerous to list. Here are some of the highlights.

Not using marine grade plywood and using exterior-grade AC plywood instead will save $13,000.

Not using expensive veneers or solid hardwoods in the cabin paneling, and using painted plywood and plastic laminates for countertops and tabletops will save around $2000.

Linoleum tile for the cabin sole will save a few thousand.

Not using portlights but using deadlights covered over with lexan will save at least $3000.

Using concrete for ballast saves a lot. Lead is around $15 per pound for wheel weights (a convenient form); concrete is $0.25 a pound. A 3" slab of concrete will weigh around 17,000 lbs, or $4250. The lead equivalent would have cost $255,000.

Rigging

There will be about 60 sheaves in a number of blocks for routing all the lines, over a dozen fairleads (rounded holes for feeding lines through without resistance or chafe. If purchased from a marine parts supplier, each sheave works out to about $30, or around $120. So I plan to make my own. A 3.5" diameter Acetal (Delrin) rod is about $50 a foot; grooved on a lathe, chopped into 1" disks and drilled through the center, each foot length makes 10 sheaves, at $5 a sheave. To make blocks, 1"x1/4" aluminum bar is drilled and bent into various shapes, then bolted together using 1/4" stainless steel bolts and washers. The cost savings are around 60%.

Most sailboats use fairly thick double-braided Dacron line, which is quite expensive. QUIDNON will use 1/4" 3-strand nylon for the sheets, $60 total. For everything else, 3/8" polypropylene "trucker's rope" will suffice, about $150 total.

Wiring

A great deal of expense goes into "marine-grade" wiring and electrical fixtures. Marine-grade means tinned wire rather than stranded copper. Experience shows it to be unnecessary. The cheapest way to wire a boat is to use heavy-duty extension chords. An AC circuit beaker panel is around $150 from home depot; a similar-featured marine-grade one is around $350. The situation is similar for DC circuitry; marine grade parts more than twice the cost of RV parts.

Plumbing

The most cost-effective solution is to use PEX plumbing, available from Home Depot. Runs of pipe will be kept short by locating both the heads and the galley close together and directly aft of the water tanks. Instead of deck fills for the water tanks there will be hose connectors hidden behind plates set into the topsides. These will make it possible to use tarps stretched over dinghy forks for rainwater collection while at anchor. The two sides of the pilot house roof will drain into their respective tanks via additional runs of hose.

Sanitation

Having used both a regular marine toilet and a composting one, I have decided that I hate both, but that I hate the regular marine toilet even more. This is normal; toilets aboard small boats always elicit strong emotions and lots of discussion. The least offensive solution I can think of is as follows:

There are two seats. The one for “number one” is plumbed directly into the shower sump and drained overboard immediately. This is not illegal; storing and dumping urine is illegal in some harbors; urinating directly into the water is not. The seat for “number two” will use a two-bucket system: while one is being used for collection, the other is composting away, and when the time comes to dump its contents (overboard or in the marina dumpster, as local conditions dictate) it is light and looks and smells like soil.

The cost of this system is the cost of the plywood shelf on which the seats are installed ($20 finished) plus two 5-gallon buckets ($6), two toilet seats ($12), a computer fan ventilating the buckets ($12). The rest is odds and ends: a length of sanitation hose and some 12V wiring to hook up the fan, a large funnel and some sanitation hose to hook up the drain for the #1 toilet seat.

The "marine" alternative is a marine toilet ($140 for the cheapest one), holding tank, macerator pump, deck fitting for pump-out, through-hulls for raw water intake for flushing and discharge (while at sea), lots of hose, electronic holding tank overflow sensor (the most important part of the whole system, believe me!) lots of sanitation hose... ugh!

Instrumentation

The entire instrumentation budget is around $3000. It will include a GPS chartplotter with a touchscreen, radar, depth sounder/fishfinder, VHF radio and autopilot with sail-to-compass and sail-to-wind capabilities. An AIS receiver integrated with the chartplotter (which displays ships' names right on the chart, together with their radar blip) would cost an additional $300 or so.

With all these various cost savings, there is a good chance that the total sail-away price of this boat will come in under $50,000, my labor not included.

19 comments:

  1. Lots of DIY stuff there! Are there any systems mentioned above where you *will* use "official" marine grade? I think you mentioned some plywood must be marine grade, for example. Any lines for rigging that would be Dacron, instead of polypropylene? I just looked up the differences; polypropylene degrades in UV (how much, I don't know). These folks mention a year,

    (http://www.boatus.com/boattech/articles/rope.asp)

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    1. A "marine" source of information will invariably tell you to only use "marine-grade," implying that it is invariably higher-quality rather than simply higher-cost. But better is the enemy of good enough.

      All plastic UV-degrades. In my experience, black polypropylene line lasts for many years. It is much lighter than Dacron, important for a junk rig, which has lots of line up top, and less stretchy than nylon, important for halyards, topping lifts, downhauls and reefling lines. Polypropylene is mandatory for some applications, such as towing lines, which have to float. Because the fishing industry uses polypropylene line almost exclusively, there are huge economies of scale built into buying big spools of it, whereas Dacron braided line is a boutique market and therefore much more expensive.

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    2. Most black plastics are far more UV resistant than non-black plastics. The carbon-black filler adds some strength, also. You can experiment by comparing the longevity of a piece of black trash bag alongside a piece of clear "drop-cloth" of similar thickness.

      Are your polyacetal (Delrin) blocks going to be black?

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    3. Yes, I go with black plastic whenever possible, for this very reason. There is a reason why car tires are black: if they weren't, they would dry-rot a lot faster.

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  2. Open source boat design..... how cool. It's always fun to shop the local hardware store for solutions than to pull out the marine catalog. Wouldn't it be neat to see this set up for mass production? Even more savings per boat and a chance for a cargo version. Coupled with a three year apprenticeship program: year one boatbuilding work and skills in the yard and seamanship classes. Year two spent out in the fleet with hands on experience. Year three a combo of both and polishing to graduate as first mate. Constant stream of trading vessels coming online and skilled personnel to mann them. That reverie and maybe $1.20 buys me a stiff cup of joe. Sure sounds good though!

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    1. I don't think any sane person would want to invest in QUIDNON until one of them gets built, sailed around and lived on. But if it can be demonstrated to be a strong, safe ocean sailor, then, yes, it would make an awesome cargo boat, for a lot less money. The entire cabin can be emptied out except for the two aft cabins that will remain as crew quarters, and used as a cargo hold. The combination of the large central hatch and the hoist on the boom gallows directly overhead makes it easy to load and unload using cargo nets. And the cargo capacity is quite huge: QUIDNON submerges 1 inch for every 2500 lbs of cargo. With a design draft of 2.5 ft and a maximum of 4, the cargo capacity is thus 45000 lbs, or 22 short tons. That's quite a lot. Since QUIDNON can be operated by a crew of just two, that's 10 tons per crew member, which is probably enough to make a decent living on a large number of runs.

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  3. "...My labor not included." Your labor is worth more than anything money could purchase. Having your hands fully in this project from start to finish, you will have first-hand knowledge of every last inch of your home. Which is not just useful information, but in your case critical information. But, I am sure you already know this.

    Will you be "contracting-out" the milling and machining to a machine shop, or will you have access to the machinery yourself?

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    1. I will probably contract the milling of the aluminum plugs that will fit inside the masts, since accuracy is critical there. I will probably weld the tabernacles myself, since that's just stick welding, which I know how to do myself. I'll also try to get access to a lathe and a drill press to make all the sheaves I'll need. I haven't worked out the steering linkage yet, but I am pretty sure it will involve standard parts from an industrial catalog. Everything else can be fabricated using a skill saw, a jig saw, a drill, a sander and a grinder.

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    2. You can probably get access to a lathe and drill press at a hackerspace/makerspace. There is usually one in every big city these days. As for using heavy duty extension cords, 'heavy duty' in this case means it's 14 gauge wire, which is only good to 15 amps; if you need larger you should look into SO cord. It's very similar, comes in any size wire, and SO cord connectors are (generally) weather or waterproof.

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    3. If you spend enough time living at a marina, like I do, you can trash-pick 50-amp marine shore cable. It is about the diameter of garden hose. People throw it out once one of the end connectors gets charred. The replacement connectors aren't particularly expensive while the cable itself is many hundreds of dollars.

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  4. When I decided to build my 30' sternwheeler riverboat I came to the conclusion that aluminum would be a big part of the construction, along with glue & screw ply.

    Having never welded before I was intimidated by welding alum so I bought a spool gun mig welder kit online to learn with. It is a spool gun with jumper cables that you hook to batteries and a hose for the argon gas and thats it. It all fits neatly in a briefcase. You adjust to metal thickness by adding batteries in series to up the voltage. I did 90% of the welding with 24 volts.

    I found it worked so well that I started fabrication after just a couple days practice, almost like a glue gun.

    I would highly recommend purchasing something like this as I have made countless fittings that are extremely overkill heavy-duty for a fraction of the cost of marine hardware. You could easily bring this along with you for emergency repairs also. Aluminum can be cut, drilled and shaped using quality wood working tools which also cuts cost.


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    1. I've tried welding aluminum and didn't like it much. For the limited amount of custom hardware I'll need for this project, drilling, bending and screwing together aluminum bar will suffice.

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  5. I love the concept and there are many good ideas here; I'm eagerly following your blog. But I was immediately stopped by your first item -- substituting exterior A/C plywood for marine grade. In my experience, it's not worth taking the chance for the $1300 savings you expect; the A/C will have a high failure rate because of the voids in the laminations and other imperfections. No matter the covering, these voids will absorb and retain moisture and the plywood will rot from the inside out. I say this from hard experience. While my own boat project failed for other reasons, the bad plywood didn't help any.

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    1. There are a few boats out there that have been built with exterior AC instead of marine plywood, and they have had no issues at all. People who have experience with it tell me that it's exactly the same stuff. The key to longevity in a plywood hull is making sure the fiberglass outside is thick enough so that osmosis keeps the wood dry because it dries from the inside faster than water molecules sneak in from the outside. And the savings are $13000, not $1300, thanks for catching the typo.

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    2. I wonder if switching to AC exterior plywood alters the economics of your plan to build a disposable concrete form. Granted, the form can be made out of the cheapest plywood available, but would the savings of not using marine plywood on the bottom of the hull contradict the advantages of pouring a disposable form in the first place? Could your hull now be made completely of AC exterior plywood and the concrete sole be poured into it right side up, and still have the formed features you're looking for?

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  6. I thought of something that might help in major crossings, but not cost too much. What about installing a permanent water temperature sensor on the bow of the boat, just below the water line. In this way, using data logging on a laptop, you can locate and remain within the gulf stream (or other similar current) for a major passage. Granted, charts can give you a pretty good idea of where to expect it, but it's typically defined by the temperature difference, so hunting around with an eye on the water temperature can tell you when you've left the current, so that you can get back into it to take the greatest advantage of the extra knot. Of course, you might want to avoid the gulf stream as well, and the temperature sensor could help you do that as well.

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    1. Most through-hull transducers for depth sounders incorporate a water temperature sensor and spew out NMEA2000 sentences with temperature readings. Most GPS chartplotters display this information. But I don't like through-hull transducers, because they require a hole in the bottom of the boat, and a hole in the bottom of the boat is, I believe, a bad idea. My preference is for in-hull transducers, mounted on a Lexan window. As far as temperature readings, it's easier to just look at the water and read the waves. The Gulfstream looks and smells different. The edges of the stream are the most obvious, because where the warm, nutrient-depleted water mixes with the colder, nutrient-rich water there is an abundance of life.

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  7. On the toilet problem. I looked at a tri-maran that had a hole in the cockpit seat, basically a "poop" deck that went straight overboard. Was quite comfortable to sit on, and the poo went straight over, never stayed on board to smell up the boat. Doesn't work in harbors, but everywhere else. Perhaps a comfortable seat on the bow or stern?

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    1. Well, that's the original etymology of the term "heads": a plan in the bows with holes in it. When underway, it was a toilet and a bidet all in one. But it's safer and more comfortable to use a bucket with a toilet seat over it.

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