[Andy Carson]

I don’t know if I can really defend the economy of my feeding practices, but I think it might have evolved from two factors. First, I only have one draft horse so the cost of the increased feed is not as painful as it could be. Secondly, only having one biases me towards making sure she is as strong a fit as she can be so I can squeeze the maximum power out of a single. Maybe it also makes me feel like I am working an athlete and helps me to expect an athletic performance. You are definitely right though, Erik, this is probably not a pathway to self sufficiency. I’m not sure that it’s truly practical now, but am pretty sure it wouldn’t be practical if there weren’t huge tractor farms churning out great gobs of pretty cheap grain. I like to think that I’m going to trade small amounts of carefully made crops suitable for humans for larger amounts of not very carefully made crops suitable for animals. I think there is some truth this this…

[Andy Carson]

Awesome site. It is great to see all the things we have been learning laid out in roughly translated german. Amazing! Apparently, both my spring buffer and the rope buffer are not new in concept, but are simply modern versions of the 1880 “horse-saver” that improved draft efficiency by about 14%. One of the pictures looks, uh, pretty familiar… Very interesting read.

[Andy Carson]

Tim,
Where did you get that rope from and do you have an additional information about it? I have been reading a little about rope and have found it fascinating how many difference ways rope can be put together and how many different things can be accomplished by this. Particularly important here is that some types of rope are designed to absorb shock and not return that energy. This is particularly important for climbing rope when if the energy was returned a fallen climber would bounce up and down the mountain side as if on a bungee cord. Ouch! Apparently, this property is sometimes designed into tow ropes as well, so that a jerky pull is smoothed without slingshotting the towed car into the tow vehichle. It seems that pure rubber has nearly the same resilience as spring steel and would likely return most of the energy. Pure synthetic ropes are more likely to absorb and dissipate the energy rather that return it. They are also subject to a phenomon called “creep” where the rope under constant tension slowly elongates without energy storage or return. The rope you showed is somewhat of a hybrid between the two and I am not sure if it will act more as a “rope,” a “bungee,” or something inbetween. Do you have a better idea?

[Andy Carson]

Right now, mine gets about 12 pounds a day performance feed (low NSC, 12% protein, 10% fat). Over the winter, she was up to about 15 pounds a day with some added oil and supplemental alfalfa hay, but I worked her through the winter months. Some people say this is alot, but she works hard and isn’t getting fat in the least bit. The horse I had before her ate probably 1/3 of this and no alfalfa, but was always kinda slow and never put out the effort of the one I have now. In my limited experience, the most important thing is the quality of the hay and how much work they are doing.

[Andy Carson]

Taking into account the animals ability to adapt, I am not sure I believe the buffering effect either… I wonder if the best way to test starts would be to vary the load between starts enough that the animals really don’t know what to expect. Tim, I wonder if you might remember how long it would have taken to transfer between the chain and the tow rope. I wonder if the oxen would remember and expect the same load if the changeover took several minutes. I am pretty sure if I walked my horse away from the sled to change over and then brought her back, she wouldn’t expect the same load. On the other hand, if I left her to stand in place while I switched the traces, she would likely expect the same load (especially if I was quick about it). If the changeover took a while and the oxen really didn’t know what to expect, the most fair comparisons would be the first few pulls. This is where the differance in power is huge, with the rope reducing the total power required to start by nearly half.

[Andy Carson]

Geoff,
The worms actually do eat the oil as described in the article. I was suprized too. The following article calls them “wildcat worms.”
http://www.theworld.org/2009/11/23/life-in-the-deep/
You are right that the worms are not on the surface or in wetlands, and I am concerned about these areas too. Still though, the existence of natural seepage and worms that feed on seeping oil demonstates that nature has been exposed to oil for a long time and evolved ways to tolerate and even benefit from “some” oil. To give an idea of the scale, the following article estimates the world total of oil seepage in a year to be 706 million gallons, which dwarfs even the highest estimates of the spilage from the deepwater spill.
http://www.waterencyclopedia.com/Oc-Po/Oil-Spills-Impact-on-the-Ocean.html
I think your point about the amounts and locations of the oil due to seepage versus spillage is a good one. I do think that this spill has the potential to cause more damage than natural seepage, especially if it hits land, but do not know how much more damage it will do… I do not doubt that oil is more toxic in some locations and to certain species, but it is at least partially an issue of scale, and I think the whole question deserves careful and detailed study. I really do not think the question of “just how toxic is this?” has an obvious answer and I think it is a good question to ask.

[Andy Carson]

Geoff, did you look at the article I posted??? I am refering to tube worms and clams that were trawled from a cold water area of heavy seepage. I do believe natural seeps are relavant to this discussion because even though the oil is released deep, it does float. This is the same mechanism that brings the oil from the deep in the current spill.

[Andy Carson]

Again, I am not saying this oil spill is a good thing, but I am willing to entertain the possibility it’s not that bad. If oil was a new thing to the gulf, than I would have more of a zero tolerance policy about it, but it seems that oil leaks out of the ocean floor all the time as isn’t nearly as toxic as I would have suspected. I found an interesting article describing natural seepage and the discovery of the strange and fastastic creatures that live in and near the oil seeps. These creatures obtain thier energy from oil and gas rather than conventional foods. Substantial amounts of oil must have been leaking for a long, long time for a whole several species of animals to evolve to eat it!http://www.rense.com/general63/refil.htm

[Andy Carson]

Yes, controlling this system is tough. One might be tempted to simply repeat the starts many times, but I would speculate the animals learn quickly how to most efficiently start and move this particular test load and starting and stopping over and over again might not represent a “real world” situation. If you look closely at the data, you can see the first 3 starts with the chain were horribly innefficient using almost twice the power of any other starts. The last 3 starts with the chain were much more efficient, and I would speculate the oxen learned exactly how much force was required to start this load and exactly how fast to apply it. This lesson may or may not apply to the next load they start and it is highly possible that thier timing or force will be off if the load is increased or decrease by 25%, leading to several more inefficient starts. With the nylon rope, there was much less variability and they seemed to be learning over time that they could start with a heavy push and the energy wasn’t wasted. Every start with the rope had a higher peak force, although they were all of very short duration. This is similar to what my horse learned with the buffers. It is amazing the physical techniques animals can learn without really being taught, but they complicate data analysis… Tim, in the data set you sent me, I can see hints of harmonic oscillations in the nylon rope (especially between starts 1 and 2) with a time interval of between 0.8 and 1.2 seconds. Did you see harmonic oscillations in the 1500 ft pull? That seemed to be a limitation in some of the buffer set-ups…

[Andy Carson]

Thanks for the raw data Tim,
I focused in on the power expenditude over the first 0.8 seconds for each start (most very high draft points are in the first 0.6 seconds), so four data points for each start. To calculate total energy expenditure during the start, I added up all the draft forces for these data points and divided by the time interval (0.8 sec). The nylon rope was very consistant in the force required to start the load at 1645, 1605, 1570, 1845, 1795, and 1805 lbf/sec (average = 1711 +/- 118). The chain was a lot more variable with 3170, 3095, 3150, 1555, 1645, and 1930 lbf/sec (average = 2424 +/- 792). This represents about a 30% decrease in power required to start the sled with the rope. The p value (unpaired two tailed t test) between these groups is 0.05, which is statistacally significant with 95% confidence (although just barely). An unpaired two tailed T-test is a pretty strong test in biological systems (at least in my hands), so I am convinced this reduction in power required to start is a real phenomenon.

[Andy Carson]

Tim,
Were the average peaks taken from the graph shown or from a different set of data? On the graph shown, I see a max peak force of ~775 with the chain and ~725 max with the rope… Also, I calculated an average peak force of ~670 with the chain (775+750+725+525+575+675/6) and ~580 with the nylon rope (475, 350, 575, 650, 700, 725/6). There are some rounding errors here, I’m sure, because I am estimating numbers off the graph, but these numbers give about a 13% difference in peak force… Maybe this matters, maybe not… More importantly, I notice a difference in the duration of the forces needed to start a load with a chain versus a nylon rope before returning to the low forces needed to maintain forward momentum. In the data set shown, the oxen with the chain had to maintain a pull of over 400 lbs for an average of 0.6 seconds ((4+4+4+2+2+2/6)*0.2) while the oxen with a rope had to maintain a pull of over 400 lbs for only 0.3 seconds ((2+0+2+2+1+2/6)*0.2). As power expenditure is best estimated by the area under the curve, this is a pretty big differance! Even if the peak force was similar, maintaining that heavy starting pull for only half the time cuts the power required by half. Although I can’t make heads or tails of the maintainence draft, I think this data does show a beneficial effect of the nylon rope on starting draft.

[Andy Carson]

Actually, I think that Ixtoc is a pretty good spill to compare to (although the volumes are very different). Both were caused by blowouts on underwater wells in the same body of water. Ixtoc was in shallower water 150 ft, but was drilling much deeper than the Deepwater Horizon (11,800 ft). They also had troubles capping the Ixtoc well and the spill continued for many months. I still don’t know what the environment impact of the current spill will be, but do not trust the media to produce an accurate and scientifically supported prediction. I think it is overly simplistic to say “oil is gross and that’s alot of oil.” I was reading a little about what the impact of Ixtoc was and mostly found data on how much tourism revenue was lost, the monetary impact on fishing, the numbers of wildlife cleaned (without giving the numbers of wildlife NOT cleaned!), and the amount of money the cleanup cost the US. From these measurement the impact was not great, but I am skeptical that this captures the whole picture and don’t really know what the proper way to measure the environmental impact of something like this ought to be. I remember alot of concern about the Valdez and the impact (at least by some measures) seemed greater there. Perhaps the percieved impact was greater because people are more environmentally aware than they were in 1980, or perhaps the effects of an oil spill are easier to see in Alaska versus Mexico. It seems that an important factor in determining the environmental impact is how close to land and wetlands the oil gets. Maybe this is simply because these are areas we can measure, but I am pretty sure these are also areas with more life than in the deep ocean.

[Andy Carson]

I reported a less than 1% failure rate because I figured there has got to be more than 100 offshore oil and gas platforms in the gulf. Actually, there are 3,858 just for the US(http://en.wikipedia.org/wiki/Oil_platform), making the failure rate 0.026%. Perspective, to me, means comparing the thing of interest to similar things. If it is an oil spill, it seems fairest to compare it to other oil spills. Again, I am not saying this is good, or even OK, but I think there is so much spin in the media it is hard to figure out how much this matters. Which story would sell better:
“Oil spill grows to 3.5M gallons as BP scrambles”
or “Oil spill might be larger than the median oil spill over the last 70 years”
or “Oil spill might be the largest in the gulf of mexico if not stopped in the next 3 months”
Also, which story furthers someones political agenda more? I hate that I have to filter news stories though this spin apparatus, but I like to just look at the facts and historical precendent.

[Andy Carson]

As much as I generally don’t like oil, I think I have to side with OldKat here. Media seems to like interesting stories and they rarely put things into proper perspective. How many offshore oil rigs do not spill? If there is less than 1% failure do we say the whole concept is wrongheaded? I don’t think so… Check out this link that lists the top oilspills in history. http://en.wikipedia.org/wiki/List_of_oil_spills
The current spill ranks, but not high (at least so far). Ixtoc (2nd worst in history) was in the same body of water and looks to be at least 10 times higher in total oil spilled. I would be curious to know what the environmental fallout from Ixtoc was… It’s hard for me to believe that Deepwater Horizon will be worse…

[Andy Carson]

Another report from the leaf spring buffer…
I tried a variety of different lubricants for the spring ends where they rub the angle iron. I found that the spring ends really don’t need much lubrication to increase efficiency quite a bit. The biggest problem is figuring out a lubricant that doesn’t attact and hold alot of dirt. Heavy grease, for example, works great but grabs dirt really fast and the efficiency starts to fall fast once it’s dirty. Lighter lubes (WD-40 and similar) tend to get dried up by dust and quit working pretty fast as well. The best by far (at least from what I’ve tested) is the silver anti-sieze lubricant. It’s plenty slick, stays slick when dirty, and though some miracle of chemistry tends to move the dirt out from between the contact surfaces. When efficiently lubed, the leaf spring buffer appears to be just as efficient as the coil spring at starting loads, smoothing forward speed (the boatlike feeling is back), and easing the strain on the front quarters. It still doesn’t need a preload to prevent harmonic oscillations. Perhaps there is still enough friction with lube to prevent these… Or, perhaps harmonic oscillations are not possible (or more difficult) on a variable rate spring. At any rate, I tried a variety of loads on the sled with and without the buffer and the buffer seems to help decrease the total effort by about 12%. This is an EXTREMELY subjective measurement based on how comfortable and tired my horse was pulling these different loads (815 lbs on sled without buffer required about the same effort as 920 lbs with buffer). It’s definetly not something I want to hang my hat on, but it gives me some sort of idea on if this is even worth measuring. I think it is. Tim has forwarded some directions on how to put together a simple pull meter, so that’s the next step. I’m not sure if you all are still interested in the “play-by-play” but this still seems like a good place to report my findings and hear about others…

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