Synthetic Sebum Makes Slippery Sailboats 128
sonnejw0 writes "Sea-faring vessels are a major contributor of greenhouse gas production due to a deficit in international laws and inherent inefficiencies at sea, such as barnacle build-up on hulls. Many marine animals avoid the build-up of drag-inducing barnacles through secreting oily residues from their pores or through the nano-molecular arrangement of their skin. Sailors regularly defoul their hulls, removing the barnacles at dry-dock, which requires them to reduce the amount of time they have at sea. Some synthetic chemicals in paints have been used to prevent barnacle build-up but have been found to be toxic to marine animals and thus outlawed by several nations. Now, engineers are trying to replicate the skin of marine animals to produce a slippery hull to which marine bacteria cannot attach, saving fuel costs and improving speeds."
Re:Oh dear lord (Score:3, Informative)
Dude, what what would you do if I told you (truthfully!) that sebum is all over your body? It's all over your hair, your skin, etc.
Yeah. That's because sebum is a term that refers to the natural oils that coat your hair and skin. It's what makes your hair and skin waterproof and what protects them from drying out.
Re:Teflon? (Score:4, Informative)
The glue that barnacles produce will stick to Teflon.
Here is an old 2005 article [nationalgeographic.com] similar to this concept that talks about using a "skin" similar to shark skin to combat the barnacles.
Re:It's a start (Score:4, Informative)
ehm, have you ever studied ships?
Large ships already have extremely efficient two stroke diesel engines (even over 50% which is extremely high if you consider the carnot max) They also have many devices to recover waste heat.
Propeller designs are already very sophisticated, difficult to improve there.
weight: the weight of the ship is very low relative to the amount of cargo it carries (compared to e.g. a truck). Also, the ship sails at relatively low speeds and mostly in a straight line so acceleration/deceleration losses that increase with mass are not really a factor.
All in all cargo ships are already the most efficient mode of transport on a fuel/cargo weight-distance ratio basis.
Re:It's a start (Score:4, Informative)
I know you're trying to make a point about using nuclear energy to power ships rather than burning fuel, but let's not go overboard on the amount of fuel being burned per mile. According to WikiAnswers, if a cargo ship travels at 30 mph (roughly 26 knots), it burns 120 gallons per mile [answers.com].
Granted, as the second item on that page relates, most container ships burn bunker fuel but the calculation is still the same. Even taking into consideration the size of ultra-large cargo ships, they don't use anywhere near thousands of gallons per mile to move across the water.
GP was correct (Score:1, Informative)
It *is* measured in thousands of GPM:
120 gallons per mile == 0.12 thousands of gallons per mile
See?
Re:Teflon? (Score:2, Informative)
America's cup boats typically are hauled out of the water after every days racing. There is little opportunity for stuff to stick to them because they are always moving, and anything that does stick is washed off. Furthermore there is a ton of work done at low reynolds numbers and boundary layers to ensure the boat bottoms are as efficient as possible - including micro-grooving the bottom material. I am not sure about America's cup, but in many racing series it is against the rules to add any shedding coatings other than anti-foul paint. America's cup boats do not use anti-foul.
Re:Oh dear lord (Score:5, Informative)
The sebaceous glands can recalibrate themselves eventually to this increased testosterone concentration, or the testosterone concentration can descrease with age or activity, or the elasticity of the skin can result in increase pore size, allowing greater flow. Massaging of the skin under hot water with soap could be a preventive measure in done regularly and at a young enough age. I would avoid harsh peroxides as they do not attack the underlying cause, even if caused by a bacterial infection it will probably not be entirely effective. The pores need to be cleansed, and peroxides are very effective at damaging DNA resulting in skin cancer later in life.
I am not an M.D., but a Ph.D. student, and I had horrible sebaceous cysts when I was a teenager. So I can commiserate with the issue. Too bad I didn't realize back then that daily fast food was the cause of my problems and not the 'yummy' solution to my psychological needs I thought it was. Now, fast-food makes me sick that I know what is in it and how my teenage years of indiscretion will probably result in a heart-attack in mid-life, not discounting 5 years of misery, physically and psychologically. I bicycle 6 miles a day, now, and cook all of my own foods at home and I love life and social occasions. It's a lot harder to make those kinds of choices as a teenager, though. Peer pressure and the mental cloud of hormones makes it difficult to think for yourself, even when you think you are.
Re:It's a start (Score:5, Informative)
The largest container ships in the word operate on diesel engines with about 114000 HP at 25.5 knots. The engines consume (at peak efficiency, not regular operating conditions) 0.260 lbs/hp/hr of fuel. Diesel is around 7 lbs/gal, so the calc works out to about 144 gals/mile... at peak efficiency.
I saw your claim and thought, "What about superfreighters?" After some back-of-the-envelope calculation, I'm surprised at their relative fuel efficiency...
However, they're still dirty, dirty ships. One superfreighter releases the same SOx emissions as 50 million passenger cars. So even though the fuel usage isn't as bad as it one might think, there are other reasons why nuclear would be better.
What a first sentence... (Score:5, Informative)
Sea-faring vessels are a major contributor of greenhouse gas production due to a deficit in international laws and inherent inefficiencies at sea, such as barnacle build-up on hulls.
Sea-faring vessels are the single most efficient way of transporting goods we have. The reason they're a big contributor of greenhouse gas production is that our global economy requires that a lot of goods are transported around the world. Try transporting thousands of containers across thousands of miles by truck (please, don't actually try this, it's bad for the environment).
The IMO [imo.org] (wikipedia [wikipedia.org]) is one of the most widely acknowledged international authorities on anything. They've made a lot of internationally respected laws, improving sea transport on many levels, including the environmental effects.
It's true that hull fouling is a problem for ships. It's also true that many (especially large) ships burn Heavy Fuel Oil (HFO), which contains a lot of pollutants (like sulfur) and isn't as clean as, say, diesel oil. It's also true that ships burn a lot of HFO, and it's true that ships further pollute the seas by dumping garbage overboard.
However, while the amounts of HFO burned by, say, the Emma Maersk [wikipedia.org], are enormous (about 300 metric tonnes per day at full operation), this is almost nothing when compared to trucks. Assuming 300mt/day at a cruise speed of 25 knots (over 45km/h), that equates to roughly 30 tonnes per 100 km. A semi-trailer truck pulling two TEU containers [wikipedia.org] runs at around 30 liter per 100 km (that's around 8 mpg, anyone that can confirm this number?). This means the Emma Maersk, carrying 14000 TEU, uses 1000 times as much fuel as a truck carrying 2 TEU, which makes this ship about 7 times as fuel efficient as trucks.
And another thing: with HFO costing 300-400 dollars per metric ton, the Emma Maersk burns up about 100,000 dollars per day when running at full capacity (this almost never happens, especially now with the economic crisis, but bear with me). That's about 3 million dollars a month in fuel. The Emma Maersk is crewed by a minimum of 13 seafarers, but let's take 20 for easier calculations, since it's probably closer to reality anyway. Suppose each of those 20 people earn 10,000 dollars a month (which is a lot - maybe the Captain, Chief Officer and Chief Engineer make this much... just maybe). That means total crewing costs for this ship would be 200,000 dollars a month, with fuel costs 15 times higher. What I'm trying to say here is this: it's in the companies' best interest to improve their fuel economy. A 7% increase in fuel efficiency would save them more money than not having to pay the crew. I'm fairly certain there are no cheap and easy ways to drastically reduce fuel usage, or they would have thought of it by now.
All of this is not to say that there isn't room for improvement in the maritime transportation business, far from it. This research and other research like it can and will do great things for the shipping industry and the environment. I just didn't like how the summary made the industry the bad guy here.
P.S. If you want to read more about the IMO's actions on air pollution: go nuts [imo.org].
Re:It's a start (Score:1, Informative)
The Emma Maersk class freighters carry about 154,000 tons of cargo. Given the earlier ballpark of 144 gallons per mile, that works out to about 1070 ton-miles per gallon. Compare that to a F150 which can make 28 ton-miles per gallon...
I'm sure at the fuel expenses the shipping companies have, saving a percent or two would be huge.
problem solved long ago, environmentally approved (Score:3, Informative)
I guess good news travels slowly. ;-)
The private yachters bane. (Score:3, Informative)
It is a constant battle against marine life which wants to live on any part of the hull in the water.
The main antifouling up to now which has been very effective is hard bottom paints containing Tributyltin. wiki: http://en.wikipedia.org/wiki/Tributyltin
This has unfortunately been proven to be fairly toxic to marine life and has consequently been banned worldwide for all craft under a certain length. Not sure of the length but large shipping vessels and somewhat the navy etc are still using it as it really is the only proven way to do a good job keeping that bottom clean.
All modern antifoulings for pleasure yachts are now based one of two things. One is a copper (copper oxide) mixed with various biocides. This is a hard type paint, often merely ground copper mixed with epoxy. This will give you a very smooth finish, and it depends on the copper (which most marine life doesn't like) and the biocides to keep the hull fairly clean. You have to dive under once in a while and scrub the hull down. Small price to pay for sailing around paradise!
The other type used is called an 'ablative' paint which may or may not contain copper/biocides but is meant to flake off itself as the marine life grows on it. This does not work for boats that live more at marinas with little sailing time, and requires bottom-jobs on the boat more often. The upside is that it is much easier to apply and does not require as much hull cleaning.
It all comes down to..if they could invent something that did not require frequent haulouts and kept your hull clean and smooth, they could easily charge $500 per gallon of the stuff and people would be lining up to pay for it.