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Joined 2 年前
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Cake day: 2023年7月8日

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  • I see this so much in so many people that I feel like it’s blown up by the strong streak of magical thinking in American society. Like, I have to worry about it, because if I don’t, it’ll happen. It’s only the anxiety per se (not any actual action based on the foresight gained from it) that stops the bad thing from happening.



  • I’m no expert on whether it’s codified as a work safe practice, nor am I out to convince anybody to get on such a rig. For what it’s worth, I’m just sharing what I’ve learned as a sailor, and what I see here is a lot of folks certain that this is crazy because of their intuition that it’ll tip over easily. With that it of the way…

    Based on my intuition, there was simply no way a 747 could even toodle around the tarmac, much less fly, just by blowing some air out the back. Big ones weigh 500 tons! Then, I learned the power of air and lift intimately by putting a specially-shaped piece of Dacron up a metal pole on top of a boat. Experience updated my intuition, and I’m not even slightly nervous about flying anymore.

    Similarly, from the other direction, my intuition said that there’s no way a boat could stay upright with parts (mast, cabin, tuna tower, stacks of containers, water park and shopping mall deck, etc.) so high above the waterline, and so little hull beneath it. But I’ve learned intimately the effects of primary stability, and ballast. With my intuition changed, this setup looks fine.

    I’ve had the experience, too, of working in a boat yard. At the end of the season, the owner drove the crawler crane onto a barge not much bigger than the one in the image, and we used it to yank boat mooring anchors out of the lake bed. Even a heavy weight on the end of the crane boom barely affected the trim of the barge. I’ve walked on many an EZ Dock section, and experienced that sections like this have immense primary stability, too.

    Indeed, by my back of the envelope calculations, that 20’ by 20’ EZ Dock barge would take in the rough range of 75 tons of force to capsize. (Easier to submerge it!) Even with the 32’ lever arm of the scissor lift, that’s still more than 7 tons of lateral force needed to capsize it. I don’t know the numbers on what it takes to capsize the scissor lift itself, but given that I know that the barge is going to stay quite level, and that there’s no lateral force on the scissor lift platform in this scenario, it seems that they’d be fine even without the straps lashing the lift to the barge.

    Anyway, I did a reverse image search, and did not find an original source. I have no idea how common this is, but I did find a comment thread from 4 years ago on the red site with comments from a user who said he called a local company that rents out Rotodocks (a very similar product) which claimed that they do it all the time.

    Hope that is interesting, and yeah, absolutely, get the numbers from a real engineer before putting yourself in situations like this.








  • No. As noted, it’s a rivet. It was originally a straight piece of metal rod with a cap (visible in the top image) at one end, inserted into the joint, then the other end deformed with a rivet tool to create a lip on the end (lower image) so it stays in place.

    To remove it, use a drill bit about the same diameter as the rivet shaft, and drill it out from the end in the lower image. You usually only have to drill less than a millimeter before the lip breaks free, and you can pull out the rest of the rivet. The trick here is that the rivet is probably hardened steel, that means it’ll take a carbide drill bit, and some time.

    This is obviously a destructive procedure for the rivet, and then you need special tools to put in another. It might be possible to replace with a screw, but it won’t be quite the same.


  • Freaky! For the most part, name a movie, any movie, and I haven’t seen it. But I’m one of the few people who saw Space Truckers in a theater. Stuart Gordon went to school here, so he had screening of the film at the student union, followed by a Q&A session, back in '96.

    Yes, it was a hoot! Gordon was a founder of an experimental theater company here which has the improv mentality of treating goofy ideas seriously and just going with them. That sensibility shows through in the movie, for sure.






  • Simple: Visibility and speed. You look at a parking spot, and if it’s empty, it’s definitely empty. It’s virtually guaranteed to stay that way as you back in, so you don’t need to monitor what’s in it. No cars, cyclists, pedestrians, emergency vehicles, et cetera, are going to enter the parking stall as you back in. That’s not true of a street or lane when you back out into it. It’s often difficult to even see traffic coming, as backup cameras don’t have the wide-angle coverage, and there’s always the possibility that you didn’t see somebody.

    As a result of both of those factors, with practice, backing in can be done in seconds, and pulling out is a breeze. Pulling in forward is a breeze, but for most people, backing out is a slower, more nerve-wracking maneuver. (At least that’s my assumption from watching how long it takes.) On the other hand, the people who just YOLO it back out into traffic are psychopaths.