The Toy I Always Wanted

When I was a kid, I used to dream that I could make stuff pop into existence if I could just imagine all of the details.

Now I have SolidWorks.

I draw stuff. It takes a really long time to draw anything, compared to doing it by hand, just like I imagined it would. But once you get the hang of it, you can push a lot farther than you can with hand drawings.

Once drawn, I crank out dimensioned drawings, and then call people who build things for me. And they look just like the drawing.

This is what I wanted when I was 8.

Last weekend I made a model of one of our new gates.

Then I made a drawing of that:

While I was at work this week, Jesus came by and built it for me, and now I have the first of three new gates:

Obviously, this isn't quite the same as what I drew. The back gates are much shorter than the front gates. Jesus doesn't need a seperate drawing for each gate, just the idea of what I want.

I started out with hand drawings of the gate, and for this project, I probably could have just left it like that. But it turns out that hand drawing curves, and trying out lots of different curves and ratios to see what you like, is not so easy. With a parametric CAD system, you draw it once and then fiddle with a few numbers until you like the way it looks. Much better.

Coping being cut

Our in-ground pool is actually raised out of the ground slightly (18 inches near the house). This makes the side a nice bench to sit on, keeps cut grass from blowing into the pool, and should interfere with running and jumping into the shallow end at a steep angle.

One consequence, though, is that our coping stones are a nonstandard width. We've decided to have bullnosed coping (so these are bullnosed both sides, also nonstandard), and that requires that the coping overlap the waterline tile by over two inches. This kind of thing adds up:

• Waterline overhang: 2.5 inches
• Tile thickness: 0.25 inches
• Thinset: 0.375 inches (that's a lot, to give the mason plenty of freedom to flatten the wall for the enormous glass tile mosaics that are going in)
• Bond beam: 12 inches
• Thinset: 1 inches (the outside of the bond beam is quite uneven)
• Facing stone: 1.25 inches
• Exterior overhang: 2.5 inches

All up, we've gone for coping that is 20 inches wide.

We actually had a order placed for some very nice pearl white travertine (from Olympic Stone). When it came time for them to come by and pick up the check... they didn't. We called back and found there was some sort of problem... they didn't actually have the stone. it would be a 3 month delay to get it from Turkey.

Well, that's never a good thing to tell a customer. Martha started looking around, and found another very nice stone, this one a three color granite, from American Soil. This one is more expensive, but it really is pretty, and it's available right now. We ended up buying it. (We may use OSM's pearl travertine for the face of the pool rather than the coping, since they apparently have the 1" stuff available.)

[Update 16-Nov-2009: The pearl against the walnut travertine ended up not looking as good as we'd hoped, so we ended up using the walnut travertine on the sides of the pool. You can see this in the mid-November post.]

By "it", I mean a 12 ton boulder imported from Columbia, California. You can get a sense of scale from the pickup truck at the back right. This rock is a little shorter than I am.

It came from over here:

View Larger Map

They're chopping this thing up into 20 inch wide by 36 inch long by 2 inch thick coping stones for us.

This is a cable saw. The cable has some kind of abrasive on it (I've never actually seen the thing stopped, it appears to be running all the time). The huge wheels drive the cable through the stone. Above and below, they're whacking the top off the boulder.


Below, they're cutting the ends off. In this pass, the rock stays put and the machine basically drops through it at a half inch per minute (I'm not really sure, as I never saw the saw make any noticeable progress through the rock).

Here's one of the slabs coming off the cable saw, going into their indoor facility for shaping. You can't really see all the color here, but there is white, black, and some pink to it.

Here's the rock all chopped up:

There's a lot of white in some of these. Hopefully they'll be able to cut around that to some extent.

Not so much in others.

This equipment is usually used to make countertops.

American Soil just got a brand new Italian machine for cutting and bullnosing. This isn't it, since apparently that machine can't cut a straight line just yet.

Each stone should weigh about 140 pounds. I'm sure the mason will be very happy to hear that.

I'm really happy with how this looks. We still have some risk, in that the coping could have huge blobs of white in it, or the grain could get mismatched, but the folks at American Soil seem to be on top of that.

We've also picked up all our glass tile. It gets installed after the coping, but I'll try to post some pictures of the pieces assembled in our garage so you can get a feel for it.

The Limits to Growth

Folks in an apocalyptic frame of mind will sometimes consider what would happen if everyone in the entire world were to adopt a lifestyle which consumed resources at the rate of those of us in western countries. To keep this blog post short, I'll not address the entire problem, but I would like to point out that carbon emissions need not be a problem.

I'll take as my example the French. French people live a pretty good life on about 6.1 tonnes CO2/person/year, which is the lowest of the countries in the G8. The French low consumption is possible because their electric sector doesn't emit significant CO2 or burn significant fuel and has stable prices (it's 85% nuclear and 10% hydro). So as gasoline prices have gone up (mostly taxes, but large increases in crude costs too), folks have switched to electrified mass transit. Their electric-powered TGV trains carry almost as much traffic as their domestic airlines.

Is French low consumption really a result of nuclear electric production? Yes. Consider Germany at 9.8 tonnes CO2/person/year. That would be 5.9 tonnes CO2/person/year if their electricity sector was nuclear, which is about the same as France.

[Update: for comparison, the United States would be at 11.3 tonnes CO2/person/year if we replaced all our coal and gas fired powerplants with nukes. If we replaced half our air transport with electric trains, it would help a bit more, but I think less than 1 tonne CO2/person/year.]

My point is that the French example can be applied to many countries. Now here's an interesting thought. What if the entire world were to adopt the French lifestyle, including the carbon-free electric system? How catastropic would the emissions be?

The world population is now 6.7 billion, so at 5 tonnes/person/year, that'd be 33.5 billion tonnes/year. Compare that to our current emissions of 28.4 billion tonnes/year. It's larger by 18%. Something to work on, not a catastrophe.

Obviously, it's not quite so easy. Right now, a fair bit of the carbon going into the air comes out of the ground in solid form. If the entire world were to use nuclear electricity, coal production would nearly stop (it's still needed for steelmaking), and all that carbon would be coming from petroleum and natural gas. That would take a fairly drastic increase in production capacity for both, leading to a rapid depletion of existing stocks.

The summary: anti-growth doom and gloom is unnecessary in the electricity sector, so long as folks are willing to follow the French example.

Side note: French reactors are almost all inland and cooled by river water. This is perhaps an example best not followed. The French have laws which prohibit those plants from releasing back into the river water which is too warm. So, during a heat wave two years ago, some power plants reduced generation in order to reduce their output temperature, right as electricity demand was spiking.

Seawater cooling is much more reliable, and doesn't use up fresh water either. Some day, when we have high-temperature molten salt reactors, we will be able to air cool our nuclear plants, and then this will not be an issue. Until then, we should probably build the majority of nuclear power plants near the coast.

Almost time for a new car

Our minivan has hauled our dogs, kids, and gear for almost 9 years, and it's starting to show. In another couple of years, we'll need a new car. So, if you're building cars and wondering what to build next, let me tell you what we want.

The last time I knew I was going to buy a new car, I wrote a letter to Chrysler two years ahead of time. Fat lot of good that did. This time, I'm asking for essentially the same thing. I'll post it on my blog instead.

We want a plug-in hybrid minivan. Plug-in hybrids face a couple of big problems: the batteries are too heavy and the engine runs intermittently, which prevents the catalyst from firing up and leads to nasty emissions. I think both these problems are completely solvable for a practical vehicle that we would buy in a heartbeat.

First, I'll point out that 1100 pounds of lead-acid batteries can store 16 kilowatt-hours, which is the government's definition of an electric vehicle. Those batteries can survive five years of cycles through 30% of their capacity. 4.8 kilowatt-hours is enough to push a minivan 13 miles. That's less than the average daily drive of 33 miles, but for a minivan used for multiple short trips a day, it's easily good enough.

Next, I'll point out that the emissions problems can be solved by delaying the first ignition of the engine. If the minivan can get to 50 MPH on batteries alone, then it can avoid the engine everywhere but on the freeway. For most trips our miniman makes, that means no engine at all for most trips, and that basically eliminates the emissions problem.

Finally, I'll point out that regenerative braking extends the EV range just a bit, and comes with a lot of complexity (control interaction with the friction brakes) and cost (fancy controllers). I'd certainly be willing to live without it if it cost $1000 and only got me an extra mile of range.

Here's what the minivan would look like:

• Packaging
  • It should have seating for 7: 2+2+3.
  • It should carry many 4' x 8' sheets of plywood in the back.
  • It should have two sliding side doors, etc, just like real minivans.
  • Seats do not have to stow. They can come out like my current minivan's seats do.
  • Including battery pack, it should weigh 5200 pounds. That sounds like a main battle tank, but it's pretty reasonable once you think about the 1100 pound battery pack.
  • Weight distribution should be close to 50:50 front:rear, and the center of mass should be very low, so the thing should handle reasonably well.
  • The thing should be quiet when driving in EV mode.
  • It should plug into a normal 3 prong 120V AC outlet.
• Performance
  • 0 to 60 in 10 seconds. (Requires an average of 115 wheel HP.)
  • 0 to 60 in 20 seconds on batteries. (Requires an average of 57 wheel HP.)
  • 75 MPH up a 6% grade with 1000 pound load. (Requires 77 wheel HP, plus whatever is needed to go in a straight line at 75 MPH. 115 HP ought to do.)
  • Maximum cargo load of 1400 pounds.
  • It should go 13 miles on a 30% cycle of the batteries.
  • It should go 350 miles on a full tank.
  • EV mode should work: the car should be able to cool a hot interior and get to 50 MPH without starting the gasoline motor.
  • 20 MPG from the gas engine alone. That's about 4000 joules/meter of gasoline energy, or 15 cents/mile for gasoline at $3.00/gallon.
  • It should use about 800 joules/meter of battery energy. That's about 4 cents per mile for the electricity, at the average US residential rate (10.5 cents/kWh).
  • The batteries should charge from 70% to 90% in 90 minutes from a standard plug.
  • The batteries should charge through a 30% cycle in 5 hours.
• Drivetrain
  • It should have front-wheel drive from the gas engine.
  • The gas engine should be a 2 liter 4 cylinder engine with around 130 horsepower. That sounds anemic, but add 60 electric horsepower and it's a whomping 180 HP.
  • It should have rear-wheel drive from the electric motors.
  • The motors should deliver 60 horsepower at 30 MPH (torque limited below). This will give excellent performance in deep snow over pavement.
  • The electric motors can have their torque die to nothing at 70 MPH. Any faster and the gas engine is required anyway.
  • It should have about 1100 pounds of lead-acid batteries, which deliver 17.5 megajoules with a 30% cycle. This just hits the 58 megajoule full-cycle battery that the US government is willing to subsidize as an electric vehicle -- $7500!
  • It should have a 330 watt solar panel covering most of the roof. This sounds silly but it's actually a good idea. The panel adds about 4 miles of electric range on an average day in California, at almost the same cost per mile of range as the battery, with very little weight.
• Cost
  • The thing will go 17.5 miles a day in EV mode if charged only at night and parked in the sun, and 27 miles a day if charged at work as well. If used as a daily driver, it'll cover 6,000 to 9,000 miles a year in EV mode.
  • It will save around 5 or 6 cents per mile. Obviously, that's not why people would buy it, but it does make for $300 to $500 saved each year.
  • The roof panel will cost about $1200.
  • Battery swap costs $1800 (half of the new cost). Batteries should last 5 years, or 1800 30% cycles, so that they cost 6 cents/mile. Existing lead-acid batteries already achieve this cost.
  • The added cost will take 10 to 15 years to pay back (if you ignore the subsidy).

I think the drivetrain can be a lot simpler than a Prius drivetrain. In particular:

• The electric motor/generator on the gas engine doesn't need to be big. It needs to be big enough to start the engine quickly (maybe 10 horsepower), and that's about it. I don't want to recharge the batteries from the engine any faster than 10 HP anyway. Gasoline costs 3 times as much as electricity from the plug, so the only reason to charge the batteries with the engine is if I can avoid starting the engine later in the same trip.
• Make sure the heater and air conditioner can run off the batteries. It's important that these be able to run right at the beginning of a trip without having to turn on the gas motor.
• Lead-acid batteries. Forget the fancy batteries. Even lead-acid batteries cost more than the electricity from the plug costs, other batteries are worse. Lead-acid can deliver the necessary range and power without the availability headaches of NiMH or Li-ions.

I think that roof-mounted solar panel deserves some explanation. It has a lot of interesting benefits:

• On a sedan, there wouldn't be enough roof area to make a significant solar panel. A minivan, on the other hand, has a pretty big roof, so the idea works better.
• The car can run its fans continuously when unattended. When you get to your car sitting in the parking lot in Phoenix, it doesn't hurt to sit down or touch the steering wheel. The interior won't disintegrate in the extreme heat either.
• When the ignition is turned off, it should be possible to turn on the A/C and get 70 cfm of air cooled by 40 F. That's enough to turn over the car's air every 2.5 minutes. It won't cool a car that's already gotten to baking temperature in the sun, but it will keep a car cool after you turn it off.
• Batteries don't like to be run down for long periods. With a solar charger, the car will get some juice every day, which can keep the battery topped up if you leave the car unattended for a while. This will improve the battery life, and it's just nice to come back to a car and have it fully juiced.

In our family, Martha would drive this thing, using it primarily to move the kids around. She makes multiple short trips each day, usually not on the freeway, so it would get plugged in regularly and probably only use gas for the trips to my parent's house, which is 55 miles each way. Since we'd get plugged in while at their house, the minivan would end up driving 80 miles on gas, on the freeway, where it gets 26 MPG. If we do twenty trips like that a year, we'd burn just four tanks of gas and our overall gas mileage would be 195 miles per gallon of gasoline.

"When did you last fill up?"

"Spring."

Seems like a winner to me.

World Wildlife Foundation donations suspended

At the July 8-10, 2009 G8 summit in L'Aquila, Italy, Allianz (a global insurance company) partnered with the World Wildlife Foundation to deliver and publicize a report on how the 8 richest countries in the world are doing at reducing their greenhouse gases. Sounds good.

WWF/Allianz "does not consider electricity generated by nuclear power a sustainable option", an opinion shared by many. Their trouble was that any simple ranking of countries will show that nuclear power has made France the world leader in reducing greenhouse gases. Since WWF/Allianz doesn't want to promote nuclear power, they cooked the numbers.

They didn't lie. There have been a number of outraged comments about this report, but these folks did not lie. Their footnotes say specifically that numbers for France were "adjusted as if electricity from nuclear power was generated from natural gas." The report also includes, in footnotes, the numbers correctly calculated.

One of those same footnotes says that "without the adjustment, France would rank first with Germany." Unfortunately, this comment is not supported by either facts, or by the WWF/Allianz numbers. By any numeric measure, France is way ahead of the rest of the industrialized world.

Because I feel that this report is intentionally misleading, my wife and I are suspending our donations to the WWF until they amend their report to rank countries based on facts. We're also going to have a talk with a few friends who also donate to the WWF. We don't do business with Allianz, so there's not much leverage there.

Those of you who don't actually care that much about CO2 emissions or global warming can stop here.

The report ranks the 8 richest countries in terms of their "past, present, and future climate performance". Here I've listed their overall ranking, along with WWF/Allianz' calculation of their emissions per capita and per million dollars of GDP.

1. Germany (12 tons/capita/year, 384 tons/M$ GDP)
2. United Kingdom (11 tons/capita/year, 334 tons/M$ GDP)
3. France (9 tons/capita/year, 276 tons/M$ GDP)
4. Italy (9 tons/capita/year, 328 tons/M$ GDP)
5. Japan (12 tons/capita/year, 367 tons/M$ GDP)
6. Russia (16 tons/capita/year, 1140 tons/M$ GDP)
7. United States (25 tons/capita/year, 567 tons/M$ GDP)
8. Canada (24 tons/capita/year, 668 tons/M$ GDP)

France got dinged because they have not improved emissions much since 1990 (they'd already built most of their nuclear fleet by then). I notice they also got dinged for not having strong mandatory targets imposed on utilities to promote energy efficiency. The report fails to note that in France, saving electricity doesn't significantly reduce CO2 emissions, so there is no need for such mandatory targets.

The report completely failed to note that France is building new nuclear power plants on its borders to export more CO2-free power. Not only is this action going to cause more improvement in Germany's CO2 output than Germany's own utility policies, but it is also going to be profitable, which means that France is going to be able to do it AGAIN in a few years. Germany, on the other hand, is busy bankrupting itself with huge feed-in tariffs, and is already switching from expensive, imported aranthracite coal to cheaper domestic brown coal which emits more CO2 and other pollutants.

The United States clearly needs to clean up its act. Which country should we model our environmental policies after?

Germany: 51% of German electricity comes from coal-fired powerplants. They are building or planning another 26. These will add 23 gigawatts of production. Germany will be forced close its coal mines in 34 years when it runs out of coal, at which point their coal imports will peak until they will switch to imported Russian methane. Germany also produces 4.4 gigawatts from wind turbines. There is a lot of talk about wind turbines but the power comes and will come from coal.

France: France closed its last coal mine in 2004. 4% of its electricity comes from coal. 78% of France's electricity comes from nuclear, and produces no CO2. Most of the rest (11%) comes from hydro, and produces no CO2. France exports 18% of it's electric production, and most of that (5.9 gigawatts, more than $2 billion a year) is sold to Italy, which is one reason why Italy's CO2 outputs are low.

Bottom line: WWF/Allianz fudged the numbers to support a policy goal. That's wrong, and we're stopping our contributions until they fix it.

It's a shame, by the way. I liked some of the other stuff they were doing.

Why New Nuclear

Senator Alexander Lamar has a white paper which well summarizes how I feel about our desperate energy situation, and lays out a plan for how to fix it:

Blueprint for 100 New Nuclear Reactors in 20 Years

It does have a thought which was new to me, however: Russia, China and India, as well as a host of other countries, have already built out a fair bit of coal, and are beginning a large build of nuclear. If their nuclear build fails, they will fall back on coal, and nothing the US does will change the course of global warming. If their nuclear build succeeds and surpasses us, they will cement their existing lead in the next major source of energy, and they will end up owning the base of our entire economy.

And this base is enormous. The US GDP was almost $14 trillion in 2007. Generation of electricity, at about $40/MWh, was $170 billion that year. But that electricity sold for $90/MWh, for a total of $373 billion. Electricity sales are 2.7% of our entire economy.

And consider industries that are part of that industrial base. In 2007, the United States used 4.1% of our electricity (170 million of the 4156 million MWh) to smelt 23 billion pounds of aluminum. That aluminum sold for $26 billion. The aluminum smelters probably spent around $40/MWh for that electricity, so the juice was 26% of their cost of goods sold. Since aluminum is an easily transported global commodity, their profit margins are thin and small changes in their costs can lead to large changes in who makes the aluminum.

We need to own our energy supplies. We need our own large forge to build the reactor pressure vessels (right now we depend on Japan). We need American companies to build, own, and operate these reactors. And we need it now.

What we really need is to stop the Waxman-Markey cap&trade bill, and adopt Alexander Lamar's plan instead. Write your congressman.

My Response to the New York Times

Here's a link to the New York Times article "Combative Start to Senate Climate Hearings".

And, here's my response:

I’m a Californian, I vote, and I want more nukes in my state. I’m fed up with the high cost of electricity. I’m pissed off that we switched from making plastics with our natural gas to making electricity — and shipped our plastics industry to China. That’s not environmentalism, it’s offshoring, as a direct result of public policy that my representatives voted in.

My power company is not incented to make good decisions about the power mix: when natural gas prices rise, they pass along the cost. When they look at natural gas they see a lower capital cost, and so they get the same return on less capital. Fine for them, but we get stuck with power prices that whipsaw our producers out of business. Ever noticed how inflation is quoted without the volatile food and energy component? We chose to make our energy prices volatile!

What we need right now are projects like the Hoover and Grand Coulee Dams: big, expensive government-funded projects that get lots of people working in well-paying jobs and deliver locked-in low priced power for a century or more. Nuclear plants are way better than hydro plants since they don’t kill fish (or anything else, for that matter).

I want to vote for a future in which energy prices are not volatile, and where the aluminum smelters and plastic plants come back to where we can regulate them and work in them. But I seem to be stuck between a choice between Green folks, who want to build temporary windmills which will kill our economy, and Conservatives who want to stick with imported fuels, which will kill our economy. Give me a third choice!

Fastest Freestyle Ever

The men's 400 meter freestyle relay at the Beijing olympics was amazing. The French team absolutely crushed the world record time, and the Americans squeaked past them. Right up until the last 50 meters, the French were in front.

Don't talk to me about Michael Phelps, the second-slowest guy on our team. Let's talk about Jason Lezak. Jason gets in the water at 2:38. (Watch the video here.) Look at his stroke compared to France's Bernard Alain. He looks pretty similar (to my untrained eye). And he turns in a time on that first 50m that is pretty similar: 21.50 versus Bernard's 21.27.

And then, after that last flip turn, Jason Lezak swims the next 50 meters in 24.52 seconds. Which sounds slow compared to those first 50 meters, but it's so fast compared to everyone else that he was one of only 3 guys in that race to swim in less than 47 seconds... and he beat the other two guys (both French) by 0.57 and 0.67 seconds. That's HUGE. He nearly did it in less than 46 seconds.

Watching back in August, it was immediately apparent to me that Jason changed his stroke after his flip turn. This morning I looked up the video on the internet, and it raises more questions than it answers.

First, Jason takes 34 strokes to Bernard's 42. It's not like Bernard is some short French dude -- at 6'5", the guy is actually an inch taller than Jason. Discounting the 7 meters that both guys got off their kick at the end, Jason managed to go 49.8 inches on each stroke, vs the paltry 40.3 that Bernard manages. And, since Jason is going faster, he's got more drag and so his hands should be slipping back more. Where did he come up with an extra nine inches?

For those last 34 strokes, Jason's form appears to go to hell. His timing is no longer even -- the delay after throwing his left arm forward is less than the delay after his right. Worse still, the change in timing has his left hand grabbing the air that he's blowing out, which has to be terrible for maximizing the purchase on the water the whole way back. Compare to Bernard, who efficiently vents smaller bursts of air under the left portion of his body while his left arm is airborne.

Notice something else that Jason is doing. He's ducking his head down after he takes a breath. And watch his right shoulder roll. When Jason pulls back with his right hand, he launches a portion of his torso up, over the water, and then when he pulls back with his left hand he is porpoising the right half of his body over that water.

Has Jason incorporated some of the body motion of the butterfly into his freestyle?

Another insulated pool

Back when I posted about the insulated in-ground pool that I'm building, I asked if anyone else is building such a pool. I've received a few answers:

• One reader in Melbourne is building such a pool.
• Several have been built in the United States, but only one of the ones I've heard of is residential. The rest are all commercial facilities.
• Insulated pools are standard when the pool sits on top of a parking structure. Apparently installations like these are simply impossible to heat if the pool is not insulated, and there are structural isolation benefits as well.

Up until now, though, no pictures! Thankfully, the reader from Melbourne has recently written in to share a few pictures of his insulated pool. Here's the standard picture of the dig:

The pool is 46 feet long, which is exactly the same length as mine. His is skinnier (10 feet wide) and more shallow (max 6 feet), which is appropriate for a lap pool. Below, it looks like they are installing an in-floor cleaning system. Very nice.

Below is a pic of the insulation going in. He is using Dow Highload 100, sold there as Dow HD300, in the same thickness that I used (2 inch). He says:

The insulation I'm using is Dow HD300 in 50mm boards. This product is made for insulating under coolroom floors with trucks driving on top, and is overkill given its compressive strength specs of 2% compression (1mm) after 20 years of 250 kPa or around 25 tons per sq meter. However, the pool contractor and engineers had never seen pool insulation done before and through an abundance of caution over-specified for the highest compressive strength product they could find to be sure it wasn't going to settle. With the loads from this pool of only around 2 tons per square meter, we have more than an order of magnitude margin of safety. In the end, the cost differential between this and lesser rated products was so small that in the interests of getting the pool contractor comfortable with signing off we went with the HD300.

The contractors didn't glue the boards to the soil with foam, instead they used the rather unsubtle method of nailing it through with steel rod. I had two concerns about this:

• This will mean there's some heat conduction losses through the steel rod from the soil to the concrete, though the total surface area of steel in contract with the cement shell would still be minimal so this probably isn't a big deal.
• A risk of the rod eventually rusting and applying pressure to the concrete shell, but the foam will (I hope) compress enough to accommodate any rust expansion and prevent concrete spalling off the shell were this ever an issue.

The upside is at least I don't have to worry about the compression issues for the expanded foam glue you'd used and hence avoids the risk you mention in your blog that this may place extra strain on the shell as it settled, and from the photos it seems the contractors have got a good solid base without the rocking problems you'd mentioned.

The steel rod seems like a good idea. I tried to find an equivalent product here and failed, which is why I ended up with the polyurethane foam. One other contractor I've talked with in the U.S. also used foam, but I neglected to ask him if he chose not to use steel nails for some reason.

Here in California we use Dobies to seperate the rebar from the ground/insulation. Dobies are simple 3" x 3" x 3" concrete cubes with a wire in them. Check out the much snazzier looking rebar spacers they use in Australia. The wall does not appear to have a bond beam at the top, but instead is pretty thick the whole way up.

Insulating the piping has been a major effort on my project. It's not clear in these pictures if this pool's piping is insulated.

Gunite going in:

His pool is in basically the same condition as mine right now. Note the clever combination of bench seat and stairs at the right hand side of the pool. Very nice. The pool looks deeper than it is because the lot slopes up to the left, and the left hand side of the pool is a retaining wall (raised bond beam).

It's a nice looking project, and I'm very curious to see how it turns out. Thanks a lot, Melbourne!

A professional look at The Day After

Here is a set of essays on the calculus of nuclear war, written by someone who used to plan nuclear war.  They are short, funny in places, reassuring in places, and generally scary.

http://homepage.mac.com/msb/163x/faqs/nuclear_warfare_101.html

http://homepage.mac.com/msb/163x/faqs/nuclear_warfare_102.html

http://homepage.mac.com/msb/163x/faqs/nuclear_warfare_103.html

Of course, no mention of nuclear weapons is complete without directing readers to the Nuclear Weapons Archive, by Carey Sublette.  I remember first reading the FAQ in 1996 or so, and being astounded.  It changed the way I thought about The Bomb.

http://nuclearweaponarchive.org/

It's the physics bit that got me.  I had previously though of fusion bombs as being somewhat like the Sun, only, here.  But it turns out that fusion in the Sun proceeds along quite slowly, at comparatively low temperatures and pressures.  Fusion bombs operate at much higher pressures and temperatures than stars do, and (obviously) on much shorter timescales.  It turns out to be almost completely different physics.

For some reason that really bothers me.  The notion that we use physics that can't even be observed anywhere in the natural world seems odd.  Perhaps I'm succumbing to nuclear hocus pocus, since I can't think of anywhere in the natural world that we can observe hydrocarbon-oxygen combustion at dozens of atmospheres of pressure, and yet our cars and airplanes do that all the time.

You are so beautiful, Kathleen

Reynolds number

It looks like one of the problems with the fountain is that I'm pushing slightly too much water through the flow straightener.

At very low velocities, flow through a pipe is laminar.  I wanted laminar flow in the flow straightener because laminar flow has no turbulence which can then break up the output jet.  It turns out that the flow velocity in the pipe has to be incredibly slow, and it turns out that I managed to design my fountain to be right in the transition region between turbulent and laminar flow.

Here is the Engineering Toolbox link on Reynold's numbers.

At full flow, I'm pushing about 180 gallons/minute through 16 of those flow straighteners.  Each has an internal diameter of 15.3 cm, so that the flow rate is 3.85 cm/sec.  Plug that into the handy calculator (the one using kinematic viscosity) and you get a Reynold's number of 5213.  That's turbulent flow.

At the flow tested in January (which worked properly), I was going up about 33 inches instead of 65 inches, so my jet velocity was 71% of full flow now.  Also, the cross section of the jets was .41 inches instead of 0.5 inches as it is now, so that the velocity inside the flow straightener was 48% of what it is now.  Plug 1.84 cm/s into that Reynold's number calculator and I get... 2491.  That's transient flow, but quite close to the 2300 needed for laminar flow.

If this is really the only problem with the fountain, then I ought to be able to slow down the flow enough to get the Reynold's number down to something around 2300, and see laminar flow at the output.  How slow?  To get half as much flow, the jet velocity is halved, and the arc height goes to 1/4 of what it is now, or 16.5 inches.  In fact, at that velocity, I do indeed get laminar flow:

Note that the impact here is on the first step into the hot tub, which is a little lower than the nominal water surface, and the arc is about 20 inches above the nozzle rather than 16.

The jet is well behaved until it gets to the top of the arc, where the bottom of the jet interferes with the top of the jet, and the result is that is spreads out laterally. That lateral spread then turns into an oscillation in the flow until it hits the step.

Anya demonstrates that the jet is 18 inches above the bond beam, or about 20 inches above the nozzle.

At this point the default setting for the fountain is to throttle back to 40 inches throw height, which clears the occupants of the hot tub and isn't too noisy.

If we wanted to get the tall jets to behave properly, it appears we'd need to cut the flow rate approximately in half, which means we'd have to reduce the jet diameter to 0.350 inches instead of 0.500 as it is now (so the finished hole diameter would be 0.440 inches).  That means I'd have to pull the stainless steel nozzles (recall they are epoxied into the PVC heads right now), get new nozzle made (probably $300), and epoxy them back in.  That all sounds possible, and certainly cheap enough, and probably can be done fast enough given that it's going to take 5 weeks to get the tile delivered.

However, there's a good chance I'd just destroy the PVC heads in the process, and there is also a good chance I'd get the nozzles glued back in crooked.  I don't think we're going to try.

We're getting more comfortable with how it looks.

Camera Guy at work

One of the nice things about working here is that when we need stuff, we get it.

Fountain test

Belle, non?  (1/80 sec exposure)

Non. (1/4000 sec exposure)

Here it is with Martha for a sense of scale:

First, what went right?

• The geometry is right.  In this spreadsheet, I calculated the height of the fountain (69.4 inches, was actually 65.5 inches), and how far it would throw the water, and where the jets would come down into the hot tub.  Although some of the jets land about 5 inches off where I expected, and two jets collide in midair just before they hit the water, the geometry is about as good as can be expected, and fulfills my goals, which were:
  • It should be possible to walk between the rising jets without being hit by them.
  • It should be possible to sit in the hot tub without being hit by the jets.
  • It should be possible for a child to stand in the middle of the hot tub and have the jets come down all around, without actually hitting the child.
• All the jets rise to the same altitude, within about half an inch or less, which means the balanced binary tree distribution system with the shorted end terminals worked.
• The pump-side pressure stack does not overflow.
• The pumps don't cavitate.  They are incredibly quiet.  You cannot hear them unless you walk over to the pump vault and stand on top of it.  Once the lid is installed on the pump vault, I doubt you will hear the pumps even when you are on top of it.

However, the jets are not laminar.  Gloppy blobs of water fall into the water and make a dull roar instead of the quiet sizzle that I had wanted.  There is enough splashing from the jets entering the water that you wouldn't want that a few inches from your face.  The kids love it, of course, because it's loud, fast, and wet, but it's not so great for the adults.

I'm pretty bummed.  What happened?

The individual jets were flow tested in January, and this is what they looked like then:

As you can see, the jets were smooth, and landed smoothly and quietly, back in January.  Now Martha jokes that if we move the back yard table to the farthest corner of the yard, we can still have a nice conversation.

I'm not entirely sure why there is a difference.  Here are possibilities, ranked by my guess of most to least likely.

• In January, the heads had no lateral ports in them.  In this latest trial, there are two ports in each head, connecting each to the heads on either side.  These ports keep the pressure even across all the jets, which makes them shoot to the same altitude.  But these ports may also be causing the water to tumble slightly as it passes the edges, and that turbulence may be causing the breakup that I'm seeing.
• In January, the heads were surrounded by nothing, and so small amounts of water on top of the heads ran down the sides, away from the jets.  Now, the heads sit inside recesses in the gunite.  Each head has a small pool of water in it that terminates at the jet.  The water in this pool greatly disturbs the jet during startup, but it gets cleared in two or three seconds and then I don't think there is any more water recirculating through that pool and into the jet.
• In the January trial, I had an open-topped pressure stack between the pump and the jets.  In the production version, I have a stack after the pump, but it's not quite the same.  In this one, the water from the pumps goes to a Tee.  In one direction, the water heads for the jets, and in the other direction, the water heads for the stack.  It's possible this alternate arrangement works less well.
• This test has a closed air volume right before the jet, which was intended to be an additional flow smoothing device.  The January arrangement used open-topped pressure stacks either right before each flow straightener, or right after the pump, and both worked well.  The closed air volume is known not to work as well (since the pressure changes more with a small surge in water).  Also, since the current arrangement has two capacitors with an inductor between, it's possible that there is oscillating pressure being stored between the two capacitors.
• The nozzle holes are 0.590 inches, rather than the 0.500 inch holes that I tested in January.  This makes the jet diameters about 0.500 inches, which is necessary for all 200 gallons/minute to flow.  As a result of the larger jet and the larger jet velocity, the flow through the flow straightener is perhaps twice as fast as it was in January.  It would be great if this were the problem, since I can reduce the flow later when I have that plumbing finished.
• In January, the pump had air in the lint basket bowl, and the pump could be heard continually injesting air.  Now the pumps have no air in their lint basket bowls.  I would expect this to make things better now, but I thought I'd list it because it is a difference.

I also have two unexpected observations which may be a clue to a solution if I can figure it out:

The ports in the sides of the fountain heads are connected via riser pipes to a plenum that is fed from a pipe that will ordinarily lead to a blocked valve.  This valve is used when the fountain is off to backflush the flow straighteners.  However, that plumbing is not yet finished, and so the pipe currently leads to many other pipes that are currently filled with air.  There is also a hose bib and a pressure gauge connected to those pipes (this is how we did the pressure test).  I have calculated that the static pressure at the top of those fountain heads is about 3 psi above ambient, and so I expected the plenum to be pressurized at 3 psi.

But that's not what the gauge says.  The gauge shows zero pressure (I don't have any gauges that show negative pressures).  If I open the hose bib while the fountain is running, then cover the opening with my finger, I feel a little pull.  It's very feeble, but it's there.  WTF?

The flow in the head is moving at 1.6 inches/second, and I calculate a dynamic pressure of 0.85 Pascals, or 0.00012 psi.  That isn't diddly compared to 3 psi pushing out.

[Update: Mystery retired: it turns out that the pipe connected to the top manifold is capped off right now, and those other pipes are just not connected to the fountain.  I can't explain why I was thinking that there was a small pull of air, but it certainly wasn't measureable.]

The second unexpected thing happened the first time I started up two of the three fountain pumps.  All three pumps are in parallel.  I had difficulty taking the lid off the third pump's lint basket bowl, so I had left that bowl filled with air, and just started the other two (which were properly filled with water).  I expected the first two pumps to push water backwards through the third pump, flushing the air into the intakes of the first two, where it would be blown into the fountain or otherwise ejected from the system.

Nope.  There was no noticeable flow through that third pump.  Later, I pulled that lid off and removed the air.  When I ran just two pumps again, the third pump did have flow going backwards, and in fact the impeller was turning backwards at perhaps half the RPM of the two powered pumps.

It's not clear to me how the air can block a >3 psi pressure drop.  The total drop from the top of the pump to the bottom of any associated piping is perhaps two feet, which would account for a 1 psi drop block, but not 3.

I suspect that the solution to these mysteries, especially the first, will tell me something about the fountain behavior.

Relative safety of stairs and swimming pools

[Post updated: A friend called BS on my previous estimate of the number of houses falling into the CPSC's "Stairs, Ramps, Landings, Floors" category, so I've fixed that. The change affects the magnitude but not the polarity of the bottom line.]

As we're finishing up our swimming pool, my wife and mother-in-law and I were naturally led in a recent dinner conversation to consider whether the pool is dangerous. This is, of course, an ill-posed question.

So I changed the discussion to which of the stairs or pool was more dangerous. The stairs typify a common threat which which everyone is familiar. The pool typifies a threat for which there is plenty of hype.

I was able to remember the gist but not the exact numbers in my previous blog post on this subject. Now see, there's the value of my blog (I knew it was going to pay off someday!) -- I have a nicely written set of notes available online to which to refer. Sadly, I had not completely anticipated my mother-in-law's argument, so here's an update:

There are 8.6 million swimming pools in the United States, and 116 million homes. If we make an approximation that all those swimming pools are residential, 5322 deaths/year for 8.6 million residential pools is 62 deaths/year per 100,000 houses with swimming pools.

I'll assume that essentially all houses have stairs, ramps, landings, or [more than one] floor. That means the 202,104 deaths/year for 116 million homes equates to 174 deaths/year per 100,000 houses.

Since we have both a pool and staircases, my best estimate is that our stairs are 2.8 times more likely to kill someone than our pool.

The difference may be substantially larger. Our pool will have modern safety features like an automatic safety cover, parallel separated drains, and a properly engineered diving envelope for the diving board, along with a raised-periphery design that makes snapping your neck on the bottom at least very awkward.

Our stairs, on the other hand, are very much like stairs everywhere, and thus should be about as risky. I suspect that a disproportionate number of "Stairs, Ramps, Landings, Floors" fatalities are concentrated in the portion of houses with actual staircases, and so my estimate above understates our staircase risk. The two most used of our three staircases have turns part-way down, which I think makes them marginally safer since you are less likely to fall all the way down the flight, but I doubt that affects the polarity of my argument.

Bottom line: no, I'm not worried about the safety of my kids around the pool, but I have gotten noticeably more nervous about the stairs since running these numbers.

Laminar Fun Group

If anyone reading this is looking for help building a laminar flow fountain, let me know.  I now have a business: Laminar Fun Group.  Reach me at laminarfun@mcclatchie.com.

Too Big Has Failed

I've been wrestling with writing a blog post on how I think we should fix the financial mess.  Happily, it turns out that Thomas Hoenig has written it for me.  Whew!

Mr. Hoenig points out a basic problem we have now:

If an institution's management has failed the test of the marketplace, these managers should be replaced.  They should not be given public funds and then micro-managed, as we are now doing under TARP, with a set of political strings attached.

He reviews past financial crises and the mechanisms used to successfully deal with them:

financial crises continue to occur for the same reasons as always -- over-optimism, excessive debt and leverage ratios, and misguided incentives and perspectives -- and our solutions must continue to address these basic problems.

Then he points out flaws in the existing TARP mechanisms, that can be fixed by using the procedures that were used before.  That is, establish a simple metric for declaring a financial institution insolvent, fire the management of insolvent institutions, bring in new management, allocate losses to shareholders first, and then to unsecured lienholders, and take out all or a portion of the bad assets for seperate disposal.  This isn't new thinking; Mr. Hoenig is just saying we should do it now even though the failing institutions include the largest US banks (you know who you are, Citibank!)

Finally, he looks forward to avoiding our current problems in the future:

One other point in resolving "too big to fail" institutions is that public authorities should take care not to worsten our exposure to such institutions going forward.  In fact, for failed institutions that have proved too big or too complex to manage well, steps must be taken to break up their operations and sell them off in more manageable pieces.  We must also look for other ways to limit the creation and growth of firms that might be considered "too big to fail".

The underlying problem is that when a single entity or network grows to become vital to taxpayer interests, that entity achieves a claim on taxpayer resources.  Firms should have to pay for such a claim.  Many will find it cheaper to break themselves up.  Identification of networks vital to taxpayer interests is an extension of existing antitrust laws.

Mr. Hoenig is the president of the Federal Reserve Bank of Kansas City.

Financial Times opinion piece:

http://www.ft.com/cms/s/0/46e2f784-380b-11de-9211-00144feabdc0.html?nclick_check=1

Fed White Paper

http://www.kc.frb.org/speechbio/hoenigpdf/omaha.03.06.09.pdf

Let me add one thing:

One problem any kind of government takeover and cleanup of a failing bank incurs is that the new entity is unnaturally "clean" compared to the non-failing banks with which it competes.  Folks like Warren Buffet complain that they are penalized for having played well.

First, the complaint isn't entirely true.  As long as the shareholders of the failed institutions get wiped out, the shareholders of non-failing institutions do better in comparison, and so to the extent that shareholders guide bank operations in the future, they will tend to guide away from failure.

The complaint is true, however, for the individuals at the failing banks.  Folks working at Citibank and AIG have made more money than folks working at less spectacular non-failing banks, and they've kept their undeserved gains.  I think we need a better system for aligning the interests of bank shareholders and those who work at banks.  It's not enough to give the folks working at the banks options or shares, because shareholders do not have enough power right now.

Gunite is in

Kathleen is spraying water on the gunite, Anya is directing, while Ava looks on. We're supposed to keep the gunite wet for the next two weeks.

I stayed home for the day to watch the crew shoot the gunite. We used Aqua Gunite (here is their web site), on the recommendation of our consulting engineer Charlie Adams. I found a listing for them here. It's listed as a two-person company, which I suppose would be Jose Aguayo and Sergio Garcia. For a two-person company this place has a lot of assets: at one point I saw three and my neighbor reports five trucks lined up to deliver the sand/cement mix. Those trucks had Aqua Gunite logos and Charlie tells me they cost $260k each. They also had what my friend Wes Grass reports to be the largest air compressor he's even seen (it was all of a large truck). Maybe the company is owned by those two guys.

They got here at 7:30AM and had the gunite going by maybe 8:00AM. That gun was shooting almost continuously until something like 5:45PM, and it took them another 30 minutes after that to finish up. We used almost five truckloads of gunite (our pool is 46 feet by 18 feet, and has a big cover vault at one end). Sergio, the foreman, told me that was 78 to 80 cubic yards of gunite, but I can't see how that's possible:

• The shell surface area is 2015 square feet that average around 8.5 inches thick (53 yards^3).
• We have about 38 feet of internal dam walls that are about a foot thick and average 4 feet tall (5.6 yards^3).
  
• There is maybe 3 cubic yards of gunite in the steps and two pedestals.
• We have a gusset which holds up the diving board that is 2 feet by 2 feet by 6 feet, so that's another yard.
• 10% rebound would be another 6 yards, which is consistent with what I observed getting dumped and hauled away.
• Total: 68 cubic yards.

Those trucks were claimed to hold 15 cubic yards, but they just did not look big enough. Maybe that's the volume of the containers, which they perhaps don't usually fill completely. For comparison, a 10-wheeler holds 10 cubic yards.

The cement and sand is mixed in the truck right before delivery, and the water is only added in the nozzle at the end. As a result, they don't have the usual concrete problem of having to order exactly the right amount of mix. Instead, they have the problem of disposing of "rebound", which is the portion of the stream that does not stick when it hits the wall. Sergio says they usually have 7 to 10% rebound. Aqua Gunite carefully arranges not to have the capability to offhaul the rebound -- they want to dispose of it somewhere on site. We had a nice big hole in which to dump 2 or 3 cubic yards, but after that we piled it up on what used to be our lawn and had some other folks cart it off for recycling the next day. In retrospect it probably would have been a good idea to negotiate this ahead of time with Jose.

It doesn't much matter, we had a fixed-price contract: $13145, $733 of which was for using thicker masonite so that we wouldn't have to strip the forms to make the form edge straight. This last bit is an artifact of our having a bond beam raised 15 inches out of the ground -- the sides have to be straight so that the masons can lay the siding stone properly.

One of the first things Sergio decided when he got here is that we didn't have enough rebar in the cover vault dam wall. The wall is 12 inches thick, and had just a single curtain of #3 rebar on 12 inch centers on the water side, plus four #4 rebar at the top. Sergio added another curtain of #3 rebar on 12 inch centers on the vault side. One nice side effect is that this will make the vault floor even more resistant to cracking from the applied torque should the gravel under the pool settle and leave the pool hanging on the soil under the cover vault.

Here's the top of the gusset that holds up the diving board. You can see the four two-foot bolts that actually go up to the diving board base. In retrospect, I should have had the gusset rebar tied into the vault wall rebar better, as that would help transmit loads between the two.

So now we wait four weeks for the gunite to harden, and shrink, and maybe crack, while we race to get the plumbing, electrical, and solar installations finished, and get the trenches closed up and filled in preparation for the new landscaping. In the meantime, the maintenance crew is keeping the shell wet.

Ready for gunite

We passed our plumbing inspection, so we're ready for gunite. This has been the eighth weekend in a row that I've worked both days on the pool plumbing. Virtually all of that work has been on the hot tub. (Earlier I was working on plumbing too, but I was machining bits and it didn't feel as much like plumbing.)

Picture right is David Kanter, by the way, who was generous enough to come down last weekend and sweat in the 100 degree noontime sun to lay gravel in the trenches around the pool. This is us right before cutting those 3" pipes to make the main drains. Thanks, Dave!

I like this picture because it gives a sense of the scale of this thing. Granted, it will be a smaller hole once 6 to 15 inches of gunite have gone into the sides, and 10 inches has gone into the bottom. But it will still be big enough that, standing on the bottom with no water to buoy you, you will not be able to jump up and touch a string suspended across the waterline. It's significantly deeper than most rooms are tall.

After looking at this thing, the inspector asked me to double the rebar in the hot tub because of all the plumbing. Done in two hours, and the pic is below. [Update, years later: damn good thing the inspector caught this.  The spa dam wall has developed a small circumferential crack. Because the inner layer of gunite has it's own reinforcing, this is not a big problem, but in retrospect I should have inserted rebar that stitched the inside curtain to the outside curtain.]

We tested a fair bit of this hot tub plumbing to 30 psi, and I was amazed that it held. Most of my flexPVC is tested now, and not a single leak.

Unfortunately, the Valterra 4 inch gate valve on the suction side of the fountain pumps leaks. This is an expensive part, and after talking with the manufacturer it seems that it was never going to work right. Finding an alternative is going to be very expensive. If any reader happens to know of a 4 inch valve made of something compatible with ozone (stainless steel, especially 316, and PVC are the big ones) which won't rust and leave stains on my plaster, and which doesn't have a huge flange... please pass along the info. Oh, and it should take 30 psi of internal pressure without leaking. It doesn't have to take 30 psi across the ports when closed, but 3 would be good.

[Update: I've ordered a 4 inch Spears PVC ball valve. It's a very nice valve, very, very easy to turn, but it was crazy expensive: $670. Including the cost of the built-to-fail Valterra gate valve and installation and rip-out of that, this one item has cost $1000. This could have been done more cost-effectively.]

It is now conceivable that we could have the pool open by June 5 (Anya's birthday), but I don't think it's going to happen. Every other aspect of this pool has taken much longer than expected, so I assume that it will be hard to just finish the plumbing over the next four weekends, let alone get the tile, plaster, cover, coping, electrical, solar panels, diving board, rock facing, patio, drainage, lighting, planting, and sprinklers done.

Chickens

I'm amazed by our hens' abilities to eat.

I weigh 215 pounds, and eat something like 2700 calories a day, including about 150 grams of protein. So, about 22% of my calories are protein. Those are rough guesses, not measurements.

Our hens each lay one egg a day, with around 6 grams of protein. I'm going to guess that they must eat 24 grams of protein to deliver those 6 grams, and also run around the yard and make lots of feathers. 24 grams is about 1/6 of what I eat.

The hens eat grass, cornmeal, random bugs that they find, and snails. (Martha has found no snails at all in the last year in the back yard, but clears 10-20 every week from the front.) I don't think their diet is particularly higher in protein than mine. In particular, their cornmeal is almost identical. So, each hen must each 1/6 of the calories I eat.

These animals weigh 5 pounds! (Anya just weighed them.) Per pound, they eat seven times as much as I do. Since I spend at least an hour a day eating, it's no wonder that those hens spend every waking minute pecking at something.