Tag Archives: ships

Sailors, boaters, and motor sailing at the hull speed.

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I’ve gone sailing a few times this summer, and once again was struck by the great difference between sailing and boating, as well as by the mystery of the hull speed.

Sailors are distinct from boaters in that they power their boats by sails in the wind. Sailing turns out to be a fairly pleasant way to spend an afternoon. At least as I did it, it was social, pleasant, and not much work, but the speeds were depressingly slow. I went on two boats (neither were my own), each roughly 20 feet long, with winds running about 10-15 knots (about 13 mph). We travelled at about 3 knots, about 3.5 mph. That’s walking speed. At that speed it would take about 7 hours to cross Lake St. Clair (25 miles wide). To go across and back would take a full day.

Based on the length of the boats, they should have been able to go a lot faster, at about 5.8 knots (6 mph). This target speed is called the hull speed; it’s the speed where the wave caused by the bow provides a resonance at the back of the boat giving it a slight surfing action, see drawing.

This speed can be calculated from the relationship between wave speed and wavelength, so that Vhull = √gλ/2π where g is the gravitational constant and λ is the water line length of the boat. For Vhull in knots, it’s calculated as the square-root of the length in feet, multiplied by 1.34. For a 20 foot boat, then,

Hull speed, 20′ = 1.34 √20 = 1.34 x 4.5 = 6.03 knots.

While power boats routinely go much faster than this, as do racing skulls and Americas cup sailboats, most normal sailboats are designed for this speed. One advantage is that it leads to a relatively comfortable ride. There is just enough ballast and sail so that the boat runs out of wind at this speed while tipping no more than 15°. Sailors claim there is a big increase in drag at this speed, but a look at the drag profile of some ocean kayaks (12 to 18 feet, see below) shows only a very slight increase around this magical speed. More important is weight; the lowest drag in the figure below is found for the shortest kyack that is also the lightest. I suspect that the sailboats I was on could have gone at 6 knots or faster, even with our current wind, if we’d unrolled the spinnaker, and used a ‘screecher’ (a very large jib), and hung over the edge to keep the boat upright. But the owner chose to travel in relative comfort, and the result is that we had a pleasant afternoon going nowhere.

Data from Vaclav Stejskal of “oneoceankyacks.com”

And this brings me to my problem with power boating. Th boats are about the same length as the sailboats I was in, and the weight is similar too. You travel a lot faster, 20 to 25 knots, and you get somewhere, but the boats smell, and provide a jarring ride, and I felt they burn gas too fast for my comfort. The boats exceed hull speed and hydroplane, somewhat. That is, they ride up one wave, fly a bit, and crash down the other side, sending annoying wakes to the sailboaters. We crossed lake St. Clair and rode a way down the Detroit river. This was nice, but it left me thinking there was room for power -assisted sailing at an intermediate speed, power sailing.

Both sailboats I was on had outboard motors, 3 hp, as it happened, and both moved nicely at 1 hp into and out of the harbor, even without the sail up. Some simple calculations suggest that, with I could power a 15 to 20 foot sailboat or canoe at a decent speed – hull speed – by use of a small sail and an electric motor drawing less than 1 hp, ~400 W, powered by one or two car batteries.

Consider the drag for the largest, heaviest kayak in the chart a move, the Cape Ann Double, going at 6.5 knots. At 6 knots, the resistance is seen to be 15 lbs. To calculate the power demand, convert this speed to 10 fps and multiply by the force:

Power for 6 knot cruising = 10 fps x 15 lbs = 150 ft lbs/s = 202 W or 0.27 hp.

Outboard motors are not 100% efficient, so let’s assume that you need to draw more like 250 W at the motor, and you will need to add power by a sail. How big a battery is needed for the 250 W? I’ll aim for powering a 4 hour trip, and find the battery size by multiplying the 250 W by 4 hours: that’s 1250 Hrs, or 1.25 kWh. A regular, lithium car battery is all that’s needed. In terms of the sail, I’m inclined to get really invovative, and use a Flettner sail, as discussed here.

It seems to me that adding this would be a really fun way to sail. I’d expect to be able to go somewhere, without the smell, or the cost, or being jarred to badly. Now, all I need is a good outboard motor, and a willing companion to try this with.

Robert Buxbaum, Sept. 9, 2024

Prosperity guardian; whose prosperity are we guarding?

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The Houtis, a Shia Islamic group, have been attacking ships in the Red Sea, hitting European ships, mostly carrying goods going between China and Europe. They use ballistic missiles plus cheap drones with great effect, targeted by an Iranian spotter ship in the Red Sea narrows, the Bab el Mandab. The US response is “Prosperity Guardian.” We’ve sent four missile destroyers. and the British one. These are arrayed along the entire coastline, too much coast for 5 ships to protect, and we try to shoot down drones and missiles. We manage to shoot down most of the missiles and and drones, but some always get through, and they mostly hit US and British targets. Recently the Maersk Detroit, a US flagged ship and 3 days ago, the British tanker, Marlin Luanda, shown below. It was carrying Russian naphtha headed for China. Some months ago, The Houtis kidnapped a British ship (Jewish owned) and took it to Yemen, as described previously.

British oil tanker, Marlin Luanda, on fire in the Gulf of Aden after being hit by an Iranian missile fired by Yemen’s Houthis. The tanker is hauling Russian naphtha, headed for China.

Iran supplies the missiles, and helps choose targets. According to Kissinger the aim of their attacks, and of the attacks on Israel, is to delegitimize Sunni Moslem countries like Egypt and Turkey that have made peace with Israel and the west. Whatever the motivation, Chinese and Russian ships are not targeted, but our ships are. We don’t attack the Iranian spotter for fear of starting a war. Instead we bomb Yemen, and protect ships carrying Chinese good and Russian oil. Currently 80% of the oil tanker transits of the Suez carry Russian oil (see below).

Most of the oil trade in the Suez is Russian — yellow line. Everyone else is shown in blue-black. It’s down to 0.5 ships per day, on average.

I don’t mind helping European countries get cheap Chinese goods, but I think the the main folks to pay should be the Europeans. We’re firing expensive anti-missiles and we’re showing the strengths and vulnerabilities to the Iranians, Chinese and Russians. Currently it’s our sailors who are at risk. The US trades with China too, but our China trade is not benefitted by ‘Prosperity guardian. Mostly our China trade avoids the Suez Canal, and comes around Africa to Savana or NY, or it comes across the Pacific, directly to Los Angeles. Our India trade most goes the same way. Some used to go through the Suez before the Houtis started attacking.

France and Japan have not joined prosperity guardian. Instead they have chosen to convoy their own flagged ships, even allowing the occasional stringer to tag along. Doing this, they use fewer ships, and it seems to work better than our approach. The picture at left shows a French courvair-escort escorting two French container ships. Note how much bigger the container ships are than the French warship. Should the Houtis’s missiles get too close to a French ship, I suspect that the French would retaliate hard. I think we should switch to following the French model and convoy-protect our shipping, plus whoever wants to tag along.

Map of Yemen and the Red Sea narrows.

Shipping, insurance rates have risen to about 1% of the cargo value. It’s now so expensive that no US cargo carrier will transit the area except when needed to supply our troops. At this point it’s worth asking, “Whose property are we guarding?” Also, is this really worth the lives of US sailors? If it is, why not hit the source of the problem — The Iranian spotter. The behavior of the French and Japanese makes sense to me. Biden’s behavior here does not.

Robert Buxbaum, February 6, 2024. Iran also funds and arms Hezbollah, a group that killed 3 US soldiers two months ago, and who killed several Kurdish allied troops in Syria just yesterday, and have shelled Israel intensely for months. IMHO, you want a few, well defended bases, not in harms way in Syria, but close enough to come back fast, in force.

Ferries make more sense than fast new trains.

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Per pound mile of material, the transport cost by ship is 1/4 as much as by train, and about 1/8 as much as by truck. Ships are slower, it is true, but they can go where trucks and trains can not. They cross rivers and lakes at ease and can haul weighty freight with ease. I think America could use many more ferries, particularly drive-on, fast ferries. I don’t think we need new fast rail lines, because air travel will always be faster and cheaper. The Biden administration thinks otherwise, and spends accordingly.

Amtrak gets $30 Billion for train infrastructure this year, basically nothing for ferries.

The Biden administration’s infrastructure bill, $1.2 Trillion dollars total, provides $30 Billion this year for new train lines, but includes less than 1% as much for ferries, $220 million, plus $1B for air travel. I think it’s a scandal. The new, fast train lines are shown on the map, above. Among them is a speed upgrade to the “Empire Builder” train running between Chicago and Seattle by way of Milwaukee. I don’t think this will pay off — the few people who take this train, takes it for the scenery, I think, and for the experience, not to get somewhere fast.

There is money for a new line between Cleveland and Detroit, and for completion of the long-delayed, and cost-over-run prone line between LA and San Francisco. Assuming these are built, I expect even lower ridership since the scenery isn’t that great. Even assuming no delays (and there are always delays), 110 mph is vastly slower than flying, and typically more expensive and inconvenient. Driving is yet slower, but when you drive, you arrive with your car. With a train or plane, you need car rental, typically.

New Acela train, 150 mph max. 1/4 as fast as flying at the same price.

Drive-on ferries provide a unique advantage in that you get there with your car, often much faster than you would with by driving or by train. Consider Muskegon to Milwaukee (across the lake), or Muskegon to Chicago to Milwaukee, (along the lake). Cleveland to Canada, or Detroit to Cleveland. No land would have to be purchased and no new track would have to be laid and maintained. You’d arrive, rested and fed (they typically sell food on a ferry), with your car.

There’s a wonderful song, “City of New Orleans”, sung here by Arlo Guthrie describing a ride on the historic train of that name on a trip from Chicago to New Orleans, 934 miles in about one day. Including stops but not including delays, the average speed is 48 mph, and there are always delays. On board are, according to the song, “15 restless riders, 3 conductors, and 25 sacks of mail.” The ticket price currently is $200, one way, or about as much as a plane ticket. The line loses money. I’ve argued, here, for more mail use to hep make this profitable, but the trip isn’t that attractive as a way to get somewhere, it’s more of a land-cruise. The line is scheduled for an upgrade this year, but even if upgraded to 100 mph (14 hours to New Orleans including stops?) it’s still going to be far slower than air travel, and likely more expensive, and you still have to park your car before you get on, and then rent another when you get off. And will riders like it more? I doubt it, and doubt the speed upgrade will be to 100 mph.

Lake Express, 30 mph across Lake Michigan

Ferry travel tends to cost less than train or plane travel because water traffic is high volume per trip with few conductors per passenger. At present, there are only two ferryboats traveling across Lake Michigan, between Michigan and Wisconsin, Milwaulkee to Muskegon. They are privately owned, and presumably make money. The faster is the Lake Express, 30 mph. It crosses the lake in 2.5 hours. Passenger tickets cost $52 one way, or $118 for passenger and car. That’s less than the price of an Amtrak ticket or a flight. I think a third boat would make sense and that more lines would be welcome too. Perhaps Grand Haven to Racine or Chicago.

Route of the Lake Express. I’d like to see more like this; St. Joseph to Milwaukee say, and along Lake Erie.

Currently, there are no ferries across Lake Erie. Nor are there any along Lake Erie, or even across Lake St. Clair, or along the Detroit River, Detroit to Toledo or Toledo to Cleveland. These lines would need dock facilities, but they would have ridership, I think. New York’s Staten Island ferry has good ridership, 35,000 riders on a typical day, plus cars and trucks. In charge are roughly 120 engineers, captains and mates, one employee for every 300 passengers or so. By comparison, Amtrak runs 300 trains that carry a total of 87,000 passengers on an average day, mostly on the east coast. These 300 trains are run by 17,100 employees as of fiscal year 2021, one employee for every 4 passengers. Even at the slow speeds of our trains the cost is far higher per passenger and per passenger mile.

The Staten Island ferry is slow, 18.5 mph, but folks don’t seem to mind. The trip takes 20 minutes, about half as long as most people’s trips on Amtrak. There are also private ferry lines in NY, many of these on longer trips. People would take ferries for day-long trips along our rivers, I think. Fast ferries would be nice, 40 mph or more, but I think even slow ferries would have ridership and would make money. A sea cruise is better than a land cruise, especially if you can have a cabin. On the coal-steam powered, Badger, you can rent a state-room to spend the night in comfort. Truckers seem to like that they cover ground during their mandatory rest hours. The advantage is maximized, I think, for ferry trips that take 12 hours or so, 250 to 350 miles. That’s Pittsburgh to Cincinnatti or Chicago to Memphis.

New York’s Staten Island ferry leaves every 15 minutes during rush hour. Three different sizes of boat are used. The largest carry over 5000 passengers and 100 cars and trucks at a crossing.

A low risk way to promote ferry traffic between the US and Canada would be to negotiate bilateral exemption to The Jones Act and its Canadian equivalent. Currently, we allow only US ships with US crews for US travel within the US.* Cabotage it’s called, and it applies to planes as well, with exemptions. Canada has similar laws and exemptions. A sensible agreement would allow in-country and cross-country travel on both Canadian and US ships, with Canadian and/or US crew. In one stoke, ridership would double, and many lines would be profitable.

Politicians of a certain stripe support trains because they look futuristic and allow money to go to friends. Europeans brag of their fast trains, but they all lose money, and Europe had to ban many short hop flights to help their trains compete. Without this, Europeans would fly. There is room to help a friend with a new ferry, but not as much as when you buy land and lay track. We could try to lead in fancy ferries going 40 mph or faster, providing good docks, and some insurance. Investors would take little risk since a ferry route can be moved**. Don’t try that with a train.

In Detroit we have a close up of train mismanagement involving the “People Mover.” It has no ridership to speak of. Our politicians then added “The Q line” to connect to it. People avoid both lines. I think people would use a ferry along the Detroit river, though, St. Claire to Wyandotte, Detroit, Toledo — and to Cleveland or Buffalo. Our lakes and rivers are near-empty superhighways. Let’s use them.

Robert Buxbaum, January 2, 2024. *The US air cabotage act (49 U.S.C. 41703) prohibits the transportation of persons, property, or mail for compensation or hire between points of the U.S. in a foreign civil aircraft. We’ve managed exemptions, though, e.g. for US air traffic with Airbus and Embraer planes. We can do the same with ferries.

** I notice that it was New York’s ferries, and their captains, that rescued the people on Sullenberger’s plane when it went down in the Hudson River — added Jan. 6.

Modern piracy and the gate of tears.

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Piracy is illegal throughout the world, but has become increasingly popular. Over the last 3 weeks, perhaps 15 ships have been attacked by pirates (or privateers) in the narrow entrance to the Red Sea between Yemen, Somalia, and Djibouti, the “Bab el Mandab,” In Arabic, this means “the gate of tears”. Most of the ships attacked are large commercial vessels operating between Europe and Asia. The US destroyer, Carney has been attacked as well. Three of the attacked ships have been boarded, and two have been successfully hijacked, the car-carrier Galaxy Leader was taken to South Yemen, while the MV Ruen a Bulgarian owned dry bulk (grain) ship was brought to Somalia. The last of the hijacked ships, the Strinda, was recaptured by the US and Japanese navy. The other ships were attacked, at a distance, by Iranian ballistic missiles, cruise missiles, and drones, all fired from Yemen. All of these acts are defined as piracy under the UN Charter, Law of the Sea, UNCLOS. The punishment is 10+ years in prison, assuming you catch the pirate.

Bab al Mandab = Gate of tears, where the pirates operate.

All of these ships are European except for the Carney and a Chinese container ship flagged in, Hong Kong. You’d think that the European navies would protect their own ships here, but they do not. Neither did the Chinese navy, though they are stationed in Djibouti. It’s clear that Iran is organizing the attacks, and that they are using a spotter ship to help direct the missiles. My guess is that the European countries don’t want to annoy Iran here, nor do they like to use their $1 million missiles.

In theory, these attacks are in response to the Israel – Gaza war. The hijacked Galaxy Leader was registered in the UK, but owned by an Israeli Jew (see a video of the attack). Another ship that was attacked, the Strinda, was not directly associated with Israel, but was going to go to Israel at some point in the future. While it’s possible that the other attacked ships had Jewish or Israel connection, a simpler explanation is that this is economic terror. Israel-based Zim shipping has elected to avoid the straight and redirect around Africa instead, a much longer route that is sure to damage the shipper and Israel’s economy. I suppose that was an intent, but the damage is spreading.

Commercial vessel attacks in Bab al Mandab, chart from “What the Ship” video blog.

The European shippers have demanded that the US protect their ships, and perhaps Biden will agree. My sense is that Trump would have said no, or at least demand something in return. Personally, I see no reason to defend trade that doesn’t involve us, with no obvious payback. Yesterday, British Petroleum BP announced that it would avoid the Bab. Four major European container freight firms, MSC (Swiss), Maersk (Danish), Hapag-Lloyd (German) and CMA CGM (Italian, French). Currently Maersk supplies our troops, but has threatened to stop unless we defend their whole fleet. I consider this an offensive, a breech of contract. They European press seems to think it’s clever. We used to have a US company that supplied our troops, Landsea intermodal, but Maersk bought them out. Personally, I think it’s time to look for a company that doesn’t play these games.

As of two days ago, the economic damage has been minimal, except to Israel. Only 55 ships had diverted around Africa, or begun to. This is a small fraction of the 2,128 ships that have gone through the Bab since November 15. In the last day or so, European oil prices have started to rise, while ours fell. The thought is that Saudi oil will now flow to the US, not Europe. I think this is the beginning of a serious problem for Europe and that they should defend their own shipping. A few, million dollar missiles are a lot cheaper than the billions of loss to their economies that rerouting will cause. At present, Europe expects us to save them while they do little or nothing. I think we should say no. They think Biden will cave.

Robert Buxbaum, December 19, 2023. I’d like to call out my admiration for the “What the Ship” video blog, and Marine Link.

I’d like to expand the Jones act so more ships can do US trade.

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If you visit most any European port city, you’ll see a lot more shipping than in the Midwestern US. In Detroit, where I am, your’ll see an occasional ore boat from Wisconsin, and an occasional tourist cruise, but nothing to compare to German, Belgian, or Turkish ports. The reason for the difference is “The Jones act.”

The port of Istanbul with many ships

The Jones act , also known as “The Merchant Marine Act of 1920”, requires that all ships depositing cargo or people between US ports must be US owned, US built, US captained, US flagged, and at least 70% US manned. This raises costs and reduces options. The result is that few ships can move people or cargo between US cities, and these ships are older and less efficient than you’ll see elsewhere. World wide water traffic costs about 1/8 that of rail traffic per ton-mile, but in the US, the prices are more comparable. The original justification was to make sure the US would always have a merchant marine. The Jones act does that, sort of, but mostly, it just makes goods more expensive and travel more restrictive.

The port of Detroit — we rarely see more than one ship at a time.

Because it does some good, I don’t want to get rid of the Jones act entirely, but I’d like to see US shipping options expanded. Almost any expansion would do, e.g. allowing 50% US manned ships delivering along US rivers, or expanding to allow Canadian built ships or flagged, and ships that are more than 50% US owned, or expanding to any NAFTA vessel that meets safety standards. Any expansion of the number of ships available and would help.

The jones act increase the price of oil transport by a factor of five, about.

Currently, the only exceptions to the Jones act are for emergencies (Trump voided the act during several storms) and for ships that visit a foreign port along the route. This exception is how every cruise ship between California and Hawaii works. They’re all foreign, but they stop in Mexico along the way. Similarly, cruises between Florida and Puerto Rico will stop in Bermuda typically, because the ships are foreign owned. Generally, passengers are not allowed to get off in Puerto Rico, but must sleep on board. This is another aspect of the Maritime act that I’d like to see go away.

Because of the Jones act, there is some US freight-ship building, and a supply of sailors and captains. A new, US ore-ship for the Great Lakes was launched last year, so far it’s been used to carry salt. There is also a US built and operated cruise ship in Hawaii, the “Pride of America,” that makes no stop in Mexico. I’d like to see these numbers expanded, and the suggestions above seem like they’d do more good than harm, lowering prices, and allowing modern container ships plus roll-on-roll-off car transports. Our rivers and lakes are super highways; I’d like to see them used more.

The port of Antwerp – far busier than Detroit.

Another way to expand the Jones act while perhaps increasing the number of US-built and operated ship would be through a deal with Canada so that ships from either country could ply trade on either countries rivers. As things stand, Canada has its own version of the Jones act, called the Coastal Trade Act where Canadian vessels must be used for domestic transport (cabotage) unless no such vessel is available. Maybe we can strike a deal with Canada so that the crew can be Canadian or US, and where built ships in either country are chosen on routes in either country, providing they meet the safety and environmental requirements of both.

Robert Buxbaum, June 14, 2023.

Rotating sail ships and why your curve ball doesn’t curve.

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The Flettner-sail ship, Barbara, 1926.

Sailing ships are wonderfully economic and non-polluting. They have unlimited range because they use virtually no fuel, but they tend to be slow, about 5-12 knots, about half as fast as Diesel-powered ships, and they can be stranded for weeks if the wind dies. Classic sailing ships also require a lot of manpower: many skilled sailors to adjust the sails. What’s wanted is an easily manned, economical, hybrid ship: one that’s powered by Diesel when the wind is light, and by a simple sail system when the wind blows. Anton Flettner invented an easily manned sail and built two ships with it. The Barbara above used a 530 hp Diesel and got additional thrust, about an additional 500 hp worth, from three, rotating, cylindrical sails. The rotating sales produced thrust via the same, Magnus force that makes a curve ball curve. Barbara went at 9 knots without the wind, or about 12.5 knots when the wind blew. Einstein thought it one of the most brilliant ideas he’d seen.

Force diagram of Flettner rotor (Lele & Rao, 2017)

The source of the force can be understood with help of the figure at left and the graph below. When a simple cylinder sits in the wind, with no spin, α=0, the wind force is essentially drag, and is 1/2 the wind speed squared, times the cross-sectional area of the cylinder, Dxh, and the density of air. Multiply this by a drag coefficient, CD, that is about 1 for a non-spinning cylinder, and about 2 for a fast spinning cylinder. FD= CDDhρv2/2.

A spinning cylinder has lift force too. FL= CLDhρv2/2.

Numerical lift coefficients versus time, seconds for different ratios of surface speed to wind speed, a. (Mittal & Kumar 2003), Journal of Fluid Mechanics.

As graphed in the figure at right, CL is effectively zero with sustained vibrations at zero spin, α=0. Vibrations are useless for propulsion, and can be damaging to the sail, though they are helpful in baseball pitching, producing the erratic flight of knuckle balls. If you spin a cylindrical mast at more than α=2.1 the vibrations disappear, and you get significant lift, CL= 6. At this rotation speed the fast surface moves with the wind at 2.1 times the wind speed. That is it moves significantly faster than the wind. The other side of the rotor moves opposite the wind, 1.1 times as fast as the wind. The coefficient of lift lift, CL= 6, is more than twice that found with a typical, triangular, non-rotating sail. Rotation increases the drag too, but not as much. The lift is about 4 times the drag, far better than in a typical sail. Another plus is that the ship can be propelled forward or backward -just reverse the spin direction. This is very good for close-in sailing.

The sail lift, and lift to drag ratio, increases with rotation speed reaching very values of 10 to 18 at α values of 3 to 4. Flettner considered α=3.5. optimal. At this α you get far more thrust than with a normal sail, and you can go faster than the wind, and far closer to the wind than with any normal sail. You don’t want α values above 4.2 because you start seeing vibrations again. Also more rotation power is needed (rotation power goes as ω2); unless the wind is strong, you might as well use a normal propeller.

The driving force is always at right angles to the perceived wind, called the “fair wind”, and the fair wind moves towards the front as the ship speed increases. Controlling the rotation speed is somewhat difficult but important. Flettner sails were no longer used by the 1930s because fuel became cheaper and control was difficult. Normal sails weren’t being used either for the same reasons.

In the early 1980s, there was a return to the romantic. Famous underwater explorer, Jacques Cousteau, revived a version of the Flettner sail for his exploratory ship, the Alcyone. He used aluminum sails, and an electric motor for rotation. He claimed that the ship drew more than half of its power from the wind, and claimed that, because of computer control, it could sail with no crew. This claim was likely bragging, but he bragged a lot. Even with today’s computer systems, people are needed to steer and manage things in case something goes wrong. The energy savings were impressive, though, enough so that some have begun to put Flettner sails on cargo ships, as a right. This is an ideal use since cargo ships go about as fast as a typical wind, 10- 20 knots. It’s reported that, Flettner- powered cargo ships get about 20% of their propulsion from wind power, not an insignificant amount.

And this gets us to the reason your curve ball does not curve: it’s likely you’re not spinning it fast enough. To get a good curve, you want the ball to spin at α =3, or about 1.5 times the rate you’d get by rolling the ball off your fingers. You have to snap your wrist hard to get it to spin this fast. As another approach, you can aim for α=0, a knuckle ball, achieved with zero rotation. At α=0, the ball will oscillate. It’s hard to do, but your pitch will be nearly impossible to hit or catch. Good luck.

Robert Buxbaum, March 22, 2023. There are also Flettner airplane designs where horizontal, cylindrical “wings” rotate to provide high lift with short wings and a relatively low power draw. So-far, these planes are less efficient and slower than a normal helicopter. The idea could bear more development work, IMHO. Einstein had an eye for good ideas.

A new, higher efficiency propeller

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Elytron biplane, perhaps an inspiration.

Sharrow Marine introduced a new ship propeller design two years ago, at the Miami International Boat show. Unlike traditional propellers, there are no ends on the blades. Instead, each blade is a connecting ribbon with the outer edge behaving like a connecting winglet. The blade pairs provide low-speed lift-efficiency gains, as seen on a biplane, while the winglets provide high speed gains. The efficiency gain is 9-30% over a wide range of speeds, as shown below, a tremendous improvement. I suspect that this design will become standard over the next 10-20 years, as winglets have become standard on airplanes today.

A Sharrow propeller, MX-1

The high speed efficiency advantage of the closed ends of the blades, and of the curved up winglets on modern airplanes is based on avoiding losses from air (or water) going around the end from the high pressure bottom to the low-pressure top. Between the biplane advantage and the wingtip advantage, Sharrow propellers provide improved miles per gallon at every speed except the highest, 32+ mph, plus a drastic decrease in vibration and noise, see photo.

The propeller design was developed with paid research at the University of Michigan. It was clearly innovative and granted design patent protection in most of the developed world. To the extent that the patents are respected and protected by law, Sharrow should be able to recoup the cost of their research and development. They should make a profit too. As an inventor myself, I believe they deserve to recoup their costs and make a profit. Not all inventions lead to a great product. Besides, I don’t think they charge too much. The current price is $2000-$5000 per propeller for standard sizes, a price that seems reasonable, based on the price of a boat and the advantage of more speed, more range, plus less fuel use and less vibration. This year Sharrow formed an agreement with Yamaha to manufacture the propellers under license, so supply should not be an issue.

Vastly less turbulence follows the Sharrow propeller.

China tends to copy our best products, and often steals the technology to make them, employing engineers and academics as spys. Obama/Biden have typically allowed China to benefit for the sales of copies and the theft of intellectual property, allowing the import of fakes to the US with little or no interference. Would you like a fake Rolex or Fendi, you can buy on-line from China. Would you like fake Disney, ditto. So far, I have not seen Chinese copies of the Sharrow in the US, but I expect to see them soon. Perhaps Biden’s Justice Department will do something this time, but I doubt it. By our justice department turning a blind eye to copies, they rob our innovators, and rob American workers. His protectionism is one thing I liked about Donald Trump.

The Sharrow Propeller gives improved mpg values at every speed except the very highest.

Robert Buxbaum, September 30, 2022

Global warming and the president’s Resolute desk

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In the summer of 2016, the Crystal Serenity, a cruse ship passed through the Northwest passage, going from the Pacific to the Atlantic above the Canadian arctic circle. It was a first for a cruise ship, but the first time any modern ship made the passage, it was 162 years ago, and the ship was wooden and unmanned. It was the British Resolute; wood from that ship was used to make the President’s main desk — one used by the last four presidents. And thereby hangs a tale of good global warming, IMHO.

President Trump meets with college presidents at the Resolute desk. Originally the front had portraits of Queen Victoria and President Hayes. Those are gone; the eagle on the front is an addition, as is the bottom stand.

President Trump meets with college presidents at the Resolute desk. Originally the front had portraits of Queen Victoria and President Hayes. Those are gone; the eagle on the front is an addition, as is the bottom stand. The desk is now 2″ taller than originally. 

The world today is warmer than it was in 1900. But, what is not generally appreciated is that, in 1900 the world was warmer than In 1800; that in 1800 it was warmer than in 1700; and that, in 1640, it was so cold there were regular fairs on the frozen river Themes. By the 1840s there were enough reports of global warming that folks in England thought the northwest passage might have opened at last. In 1845 the British sent two ships, the Erebus and the Terror into the Canadian Arctic looking for the passage. They didn’t make it. They and their crews were lost and not seen again until 2014. In hopes of finding them though, the US and Britain sent other ships, including the Resolute under the command of captain Edward Belcher.

The Resolute was specially made to withstand the pressure of ice. Like the previous ships, and the modern cruise ship, it entered the passage from the Pacific during the peak summer thaw. Like the ships before, the Resolute and a partner ship got stuck in the ice — ice that was not quite stationary, but nearly so, The ships continued to move with the ice, but at an unbearably slow pace. After a year and a half captain Belcher had moved a few hundred miles, but had had enough. He abandoned his ships and walked out of Canada to face courts martial in England (English captains were supposed to “go down with the ship”). Belcher was acquitted; the ice continued to move, and the ships moved with it. One ship sank, but the Resolute, apparently unscathed, passed through to the Atlantic. Without captain or crew, she was the first ship in recorded history to make the passage, something that would not happen again till the Nautilus nuclear submarine did it under the ice, 100 years later.

 

The ghost ship Resolute was found in September 1855, five years after she set sail, by captain Buddington of the American whaler, George Henry. She was floating, unmanned, 1200 miles from where captain Belcher had left her. And according to the law of the sea, she belonged to Buddington and his crew to use as they saw fit. But the US was inching to war with Britain, an outgrowth of the Crimean war and seized Russo-American property. Franklin Pierce thought it would help to return the ship as a sign of friendship — to break the ice, as it were. A proposal for funds was presented to congress and passed; the ship was bought, towed to the Brooklyn Navy yard for refitting, and returned to Britain as a gift. The gift may have worked: war with Britain was averted, and the seized property was returned. Then again, Britain went on to supply the confederacy early in the Civil War. None-the-less, it was a notable ship, and a notable gift, and when it was broken up, Parliament decided to have two “friendship desks” made of its timbers. One desk was presented to President Hayes, the other to Queen Victoria. One of these desks sits the British Naval museum at Portsmouth; its American cousin serves Donald Trump in the Oval office as it has served many president before him. It has been used by Coolidge, Kennedy, Carter, Reagan, Clinton, Bush II, and Obama before him — a reminder that global warming can be good, in both senses. If you are interested in the other presidents’ desks, I wrote a review of them here.

As for the reason for the global warming of the mid 1800s, It seems that climate is chaotic. ON a related note, I have proposed that we make a more-permanent northwest passage by cutting thorough one of the islands in northern Canada. If you want to travel the Northwest passage in 2017, there is another cruise scheduled, but passage is sold out.

Robert Buxbaum, March 16, 2017.

Thinking the unthinkable

Do you know how you go about thinking the unthinkable?

 

With an ithberg, of course.

 

Robert Buxbaum. April 12, 2016. I thought it was time for another “dad joke.” Besides, the Titanic sank on April 14th. I spend a fair about of time thinking the unthinkable. On a vaguely similar note:

After Boris died, everyone gathered at his funeral.

The minister started to speak: “He was a model husband, a decent man, a terrific father..”

The widow then makes a motion for her son to come to her.

“What is it mother?” he whispers.

“Dear, go check the casket, I think we’re at the wrong funeral…”

The future of steamships: steam

4 Replies

Most large ships and virtually all locomotives currently run on diesel power. But the diesel  engine does not drive the wheels or propeller directly; the transmission would be too big and complex. Instead, the diesel engine is used to generate electric power, and the electric power drives the ship or train via an electric motor, generally with a battery bank to provide a buffer. Current diesel generators operate at 75-300 rpm and about 40-50% efficiency (not bad), but diesel fuel is expensive. It strikes me, therefore that the next step is to switch to a cheaper fuel like coal or compressed natural gas, and convert these fuels to electricity by a partial or full steam cycle as used in land-based electric power plants. 

Ship-board diesel engine, 100 MW for a large container ship

Diesel engine, 100 MW for a large container ship

Steam powers all nuclear ships, and conventionally boiled steam provided the power for thousands of Liberty ships and hundreds of aircraft carriers during World War 2. Advanced steam turbine cycles are somewhat more efficient, pushing 60% efficiency for high pressure, condensed-turbine cycles that consume vaporized fuel in a gas turbine and recover the waste heat with a steam boiler exhausting to vacuum. The higher efficiency of these gas/steam turbine engines means that, even for ships that burn ship-diesel fuel (so-called bunker oil) or natural gas, there can be a cost advantage to having a degree of steam power. There are a dozen or so steam-powered ships operating on the great lakes currently. These are mostly 700-800 feet long, and operate with 1950s era steam turbines, burning bunker oil or asphalt. US Steel runs the “Arthur M Anderson”, Carson J Callaway” , “John G Munson” and “Philip R Clarke”, all built-in 1951/2. The “Upper Lakes Group” runs the “Canadian Leader”, “Canadian Provider”, “Quebecois”, and “Montrealais.” And then there is the coal-fired “Badger”. Built in 1952, the Badger is powered by two, “Skinner UniFlow” double-acting, piston engines operating at 450 psi. The Badger is cost-effective, with the low-cost of the fuel making up for the low efficiency of the 50’s technology. With larger ships, more modern boilers and turbines, and with higher pressure boilers and turbines, the economics of steam power would be far better, even for ships with modern pollution abatement.

Nuclear steam boilers can be very compact

Nuclear steam boilers can be very compact

Steam powered ships can burn fuels that diesel engines can’t: coal, asphalts, or even dry wood because fuel combustion can be external to the high pressure region. Steam engines can cost more than diesel engines do, but lower fuel cost can make up for that, and the cost differences get smaller as the outputs get larger. Currently, coal costs 1/10 as much as bunker oil on a per-energy basis, and natural gas costs about 1/5 as much as bunker oil. One can burn coal cleanly and safely if the coal is dried before being loaded on the ship. Before burning, the coal would be powdered and gassified to town-gas (CO + H2O) before being burnt. The drying process removes much of the toxic impact of the coal by removing much of the mercury and toxic oxides. Gasification before combustion further reduces these problems, and reduces the tendency to form adhesions on boiler pipes — a bane of old-fashioned steam power. Natural gas requires no pretreatment, but costs twice as much as coal and requires a gas-turbine, boiler system for efficient energy use.

Todays ships and locomotives are far bigger than in the 1950s. The current standard is an engine output about 50 MW, or 170 MM Btu/hr of motive energy. Assuming a 50% efficient engine, the fuel use for a 50 MW ship or locomotive is 340 MM Btu/hr; locomotives only use this much when going up hill with a heavy load. Illinois coal costs, currently, about $60/ton, or $2.31/MM Btu. A 50 MW engine would consume about 13 tons of dry coal per hour costing $785/hr. By comparison, bunker oil costs about $3 /gallon, or $21/MM Btu. This is nearly ten times more than coal, or $ 7,140/hr for the same 50 MW output. Over 30 years of operation, the difference in fuel cost adds up to 1.5 billion dollars — about the cost of a modern container ship.

Robert E. Buxbaum, May 16, 2014. I possess a long-term interest in economics, thermodynamics, history, and the technology of the 1800s. See my steam-pump, and this page dedicated to Peter Cooper: Engineer, citizen of New York. Wood power isn’t all that bad, by the way, but as with coal, you must dry the wood, or (ideally) convert it to charcoal. You can improve the power and efficiency of diesel and automobile engines and reduce the pollution by adding hydrogen. Normal cars do not use steam because there is more start-stop, and because it takes too long to fire up the engine before one can drive. For cars, and drone airplanes, I suggest hydrogen/ fuel cells.