Free 186 More Best Homemade Tools eBook:  
Get tool plans

User Tag List

Results 1 to 5 of 5

Thread: Crane drops vessel into sea - GIF

  1. #1
    Supporting Member Altair's Avatar
    Join Date
    Aug 2013
    Posts
    12,020
    Thanks
    1,365
    Thanked 30,299 Times in 9,998 Posts

    186 More Best Homemade Tools eBook

  2. The Following 4 Users Say Thank You to Altair For This Useful Post:

    carloski (Sep 21, 2022), nova_robotics (Sep 21, 2022), Ralphxyz (Sep 24, 2022), rlm98253 (Sep 21, 2022)

  3. #2
    Supporting Member Frank S's Avatar
    Join Date
    Aug 2015
    Location
    Peacock TX
    Posts
    11,622
    Thanks
    2,178
    Thanked 9,120 Times in 4,364 Posts

    Frank S's Tools
    All too often riggers either miscalculate or don't have the proper sling lengths or capacities for the lift they are tasked with doing. The longer the slings are and the closer to vertical they can be used the lower the stresses each sling will be under during the lift. 2 slings at 90° to a load of 1000 lbs. will each have half the load or 500 lbs but, at 60° each will have 577 lbs of stress. At a 45° angle both slings will have a load of 707 lbs. and at an extreme angle of 30° each sling will have double the loading stresses compared to the vertical loading angle even though the actual weight of the lift remained the same. Whenever possible we always tried to keep our sling angles between 75 and 85°s because the additional loading stresses in any of the slings was negligible. Baring that if there simply was no possibility of using long slings a spreader bar was always the weapon of choice
    Crane drops vessel into sea - GIF-r.png

    2,000+ Tool Plans
    Last edited by Frank S; Sep 20, 2022 at 07:50 PM.
    Never try to tell me it can't be done
    When I have to paint I use KBS products

  4. The Following 4 Users Say Thank You to Frank S For This Useful Post:

    baja (Sep 22, 2022), nova_robotics (Sep 21, 2022), Ralphxyz (Sep 24, 2022), RetiredFAE (Sep 21, 2022)

  5. #3
    Supporting Member
    Join Date
    Sep 2018
    Posts
    2,346
    Thanks
    11,132
    Thanked 1,219 Times in 664 Posts

    nova_robotics's Tools
    Quote Originally Posted by Frank S View Post
    All too often riggers either miscalculate or don't have the proper sling lengths or capacities for the lift they are tasked with doing.
    Yup. Sounds plausible. Lets make the assumption that the lifting lugs are placed roughly square on the deck of that boat. Looking from the side those slings look roughly 45 degrees. But if you work out the angles in 3D, what looks like 45 degrees from the side is actually about 35 degrees with respect to the plane of the rope. Then there's a whole ton of dynamic loads that they almost certainly didn't take into account with that thing sloshing all over the place. And they probably overloaded one of those slings like crazy when they impacted the deck of the crane vessel. It's hard to tell from the video, but I don't see any softeners on that hook either. And what are they in the middle of a hurricane? Ever lift I've ever been on has been shut down if there's more than a stiff breeze.

    So a comedy of errors and incompetence.

  6. #4
    Supporting Member
    Join Date
    Aug 2020
    Posts
    236
    Thanks
    3
    Thanked 25 Times in 22 Posts
    Right U are Frank. That's the first thing I noticed as well, I just didn't have all the specifics along with pics.

  7. #5
    Supporting Member Frank S's Avatar
    Join Date
    Aug 2015
    Location
    Peacock TX
    Posts
    11,622
    Thanks
    2,178
    Thanked 9,120 Times in 4,364 Posts

    Frank S's Tools
    Another thing I noticed it looked like only 2 slings were used for the lift, Maybe I'm assuming too much here but to me logic would tell me if a small cargo craft such as that one had been designed to be hauled from the sea via crane, it would most likely have had 4 lifting lugs for hoisting it out of the water, not 2. All of the work and crew barges I had ever been on or worked around, all had a minimum of 4 lifting lugs. It is very difficult to guarantee a flat lift of anything even if the weight is perfectly distributed with only 2 lifting points



    2,000+ Tool Plans
    Never try to tell me it can't be done
    When I have to paint I use KBS products

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •