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Shortening Boat Trailer

  1. Nov 18, 2009 #1

    pjm

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    I want to shorten my boat trailer so that it will fit in my garage in the winter, It has to be able to be put back together for the summer. Trailer is built with 5" aluminum I-beams running down each side. My idea is to cut the two beams and splice back together with 4 pieces of aluminum channel about 15" on either side of the joints so two 30" pieces would sandwich each of the I-beams and be bolted together so they could be removed once a year. I beam material is 1/4 " and channel to be used just fits inside and is .29" material.
    Coments or help would be appreciated.
     
  2. jcsd
  3. Nov 18, 2009 #2

    minger

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    They say the two happiest days of your life are the day you buy your boat, and then the day that your boat trailer snaps in half doing 80 mph on I-75 on your way to Lake Erie.

    On all serious though, I would be pretty hesitant to do this. You really don't know what kind of safety factor was used when designing the boat, and you really don't know what kind of stress concentrations will arise from doing this. If you have any loose fit in the connection, it will just amplify the problem.

    If you must do it, then I first advise drawing a free-body diagram. Indicate your trailer as a beam, and apply your load to it. See where your shear and moment forces are minimal and break the beam there. Do not simply break it in middle. Chances are it will be towards one end or the other.

    How much do you need to trim off? Perhaps there's some way to modify the hitch such that it's collapsable or something.
     
  4. Nov 18, 2009 #3
    Or better yet, do some simple trigonometry. What is the longest object that can fit in your garage diagonally? Since I assume you are not thinking about cutting your boat and gluing it back together each spring, there may be a way to fit both boat and trailer in the garage without surgery. Even if your trailer is heavy enough to require a couple of jacks or whatever to get it in place, the overall effort might be much less than reassembling the trailer.
     
  5. Nov 18, 2009 #4

    turbo

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    To add to the above, don't just think in terms of the horizontal plane. If you have rafters to suspend a come-along from you might be able to suspend your trailer in such a way as to make maximum use of the 3-D space. Make a lightweight "T" out of wood to approximate the dimensions of your trailer, and get creative trying to fit that into your available space.
     
  6. Nov 18, 2009 #5

    pjm

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    Ok: Ive actually thought about all the alternatives and short of building a new garage, this seems to be the best option. The trailer already has a hinged tung about 2' ahead of where I want to cut. The trailer has two axles so is pretty well balanced with only about 150 lbs of weight at the cut point about 2 feet behind the hinge and about 12' ahead of the first axle.
    Does this help me, there really isn't much downward force at this cut point because of trailer balance, so most of load will be when pulling and breaking. I'm thinking that the material added due to splice bars is about twice that of original I-beam. Because the two I-beams are coming together about 18" ahead of the cut point we have a triangle between the two beams and the ball connection from the cut point forward. Hopefully this helps share the pulling force on the two splices.
     
  7. Nov 18, 2009 #6

    DaveC426913

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    I would not trifle with these forces.

    It quite likely voids any insurance you might have too.
     
  8. Nov 18, 2009 #7

    DaveC426913

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    This is exactly what I have. Did the trailer come with the boat? What kind of boat is it?
     
  9. Nov 18, 2009 #8

    pjm

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    Yes the trailer came with the boat, a 20' baja outlaw. The boat will fit in the garage with about 6" to spare but the trailer tung sticks out about 2' past hinge point. If I don't lock it up, I'll loose it.
     
  10. Nov 18, 2009 #9

    DaveC426913

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    1] I'd alter the garage before I'd alter the trailer.

    2] The trailer hinges. How far will it hinge? Enough to shorten it if you put the nose on blocks to make it high enough?


    3] Baja outlaw? Where does the mast go? :biggrin:
     
  11. Nov 18, 2009 #10

    pjm

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    So would I but garage is as big as allowed by city. Neighbours turn everyone in if they see something that doesn't comply. Can't go up that high because back of trailer hits ground. As I said, all options have been investigated. Can't find alternate indoor storage, and outside is not an option. I keep coming back to cut and splice. If we can put men on the moon, surely there is some method to splice safely. Kind of sound like a broken record, don't I
     
  12. Nov 18, 2009 #11

    DaveC426913

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    I meant cutting a small hole in the door for the tongue. Since the tongue hinges, you can cut the hole in the bottom edge, kind of like a cat door.

    Or better yet, back wall, where your neighbours won't see it.


    Why is the tail touching ground a bad thing? You know you're supposed to raise your trailer anyway when it's on storage? It's takes pressure off the tires. Unless you like square wheels come spring.

    Build a cradle that supports the trailer off the ground, the rear brace just behind the axles.
     
  13. Nov 18, 2009 #12

    pjm

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    OK I did a scale drawing and rotated the front up to clear the opening. The front of the trailer has to be 11' up which is higher than the ceiling and all four wheels are off the ground with the back of the trailer touching the ground. The back wall of the garage is concrete and has two large conduits inside for 400 amp power service. Don't want to go there. The garage door is a brand new insulated steel rollup so cutting a hole would compromise its integrity and be a shame to ruin. How do I send pictures- I'm new to this
     
  14. Nov 18, 2009 #13

    DaveC426913

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    Even with the hinged tongue? Even if it's in the garage diagonally?


    Your posts have a "Go Advanced" option that will get you more features. Look for the paperclip. It allows you to attach a file.
     
  15. Nov 18, 2009 #14

    pjm

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    Yes even diagonally, thats what I was trying because it minimizes the height requirement. If you get this pic you can see that I have to cut just behind the winch sort of in line with the bow of the boat. The 2x2 seen running down the middle would be unbolted from the crosssmember and pull out with the front being removed. This tube is bolted through the two beams where they terminate and has the hinge piece and hitch connected to it. I hope you can enlarge pic so you can see what Im talking about. Look forward to your comments.
     

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  16. Nov 18, 2009 #15

    DaveC426913

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    What if you moved the position of the boat on the trailer? Moving the boat forward 2 feet would give you the room you need.

    'course now you've got the same problem with the winch post...
     
  17. Nov 18, 2009 #16

    pjm

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    Boat cant go forward enough even with the winch removed mainly because the leg at the back hits the trailer. If I remove the leg, I still have a problem because the beds are designed to support the hull in that position and the hull would then not be properly supported. Ready to cut the i-beams yet?
     
  18. Nov 18, 2009 #17

    DaveC426913

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    Your boat has a leg?

    Well there's yer problem...

    Nope. I'm a thinky guy, not a buildy guy. You'll have to wait around for some buildy guys to come along.
     
  19. Nov 18, 2009 #18

    pjm

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    OK: Thanks for the input, Ive enjoyed the joust
     
  20. Nov 19, 2009 #19
    I would consider cutting. but I would make 2 crossmembers out of channel, wide enough to go over the I beams. trim the web out so that the outside ends of the channel crossmember go over the Ibeam. then weld and bolt both crossmembers to the trailer so they sit back to back and bolt them thru. then plate the I beams, and weld and bolt one side of the plate. that boxes the ends of the frame at the point you cut it at. I would also put a diagnal piece in the rear section between the added crossmember, and any existing one. if no rear crossmember then a pair in a v shape. use large bolts, nylon head nuts and big washers (also preferably welded in place) on both sides of every bolt. and quite honestly, I'd use a dozen or so 6 on the sides of the splices, and 6 to hold the crossmembers together.

    now, insert disclaimer here: I am not a structural engineer, marine trailer engineer, civil (or un-civil) engineer. material composition can vary significantly, and some alloys can NOT be drilled without starting cracking problems that can NOT be stopped. welding should be done by someone VERY GOOD. << deleted by berkeman >>
    be careful, be safe, closed coarse, professional driver, do not attempt this at home, milage may vary with driving style

    dr
     
    Last edited by a moderator: Nov 19, 2009
  21. Nov 19, 2009 #20
    opps you'd need 18 bolts

    dr
     
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