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Help With Lumber Capacities for Engine Hoist Gantry

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  • Help With Lumber Capacities for Engine Hoist Gantry

    Building a gantry to use for a hanging a chain hoist that will be used to pull my boat engine. I tried some online calculators but most go into too much engineering details needed and I can't seem to concentrate long enough to glean useful information. Thought maybe some here could help me shortcut this.

    I need at least 1k lbs capacity, first and probably only use will be a 4.3MPI bobtail. Just want to have a good safety margin for the beam. It will be maximum 10 feet between supports, but probably have gussets that will reduce that to 8-9 ft.

    So, questions like: Will one 6x6 beam work. Or do I need to build a beam from 3 2x6 or 2x10 or 2x12, these are my ideas. Vertical supports probably 2 2x6 each side with some spacing between them, and appropriate floor stand gusseting.

    What are y'alls thoughts, thanks!
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  • #2
    I used a pair of 10' 2x10s bolted together to form the beam. The vertical supports were two 2x8s. Cross bracing for the vertical supports were 2x4s and, for the beam, 2x6s. It was plenty strong to lift my 350 Mag (5.7) V8.

    Location: West Central Illinois, USA 1997 Larson 186 SEi Bowrider I/O Mercruiser 350 #0F747565 Mag Alpha One Gen II #1A270120 Transom and Deck Restoration Project on my '97 Larson Bowrider

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    • #3
      I'm with JAS on this . . . a 6" beam is not strong enough, tripling the width (to a 6 x 6) will add a lot of weight high up (not good) See if you can get a 2 x 12 or two 2 x 10's
      Best regards, Ted . . . . Cape Cod, MA

      Formula 330 Sun Sport, O'Day Mariner Sail #3224, Sunfish
      Past Boats: Catalina 22 Sail #10531, Formula 242 Sun Sport
      Twin Mercruiser 7.4 LX MPI (0F802036, 039), Bravo 3's (0F806198, 199), Mercury 7.5 HP (1969), Johnson 4.5 HP (1980)

      My Boating Web Pages: http://www.tpenfield.com

      Member of the Month - February 2013

      Comment


      • #4
        what I have done. for 10' wide.....3 2x8's as the cross beam, 3 2x4's as the vertical posts, and 2x4's as kickers. will hold a big block for 13' wide, use 2x10's

        for the 4.3, you can get away with two as JAS indicated

        the 2x8's and 2x10's are easy enough to raise up one at a time by yourself. I used ratchet straps around them to secure them together until I was able to shoot bolts thru.

        if doing this in a storage unit, I used the walls as the kickers and simply had the post to support the beam

        another thing you can do, check craigslist for A-frame gantry cranes. a buddy found one with an electric hoist, used it for a month to put his motor in his car, sold it for what he bought it for. net cost $0
        1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - http://forums.iboats.com/forum/owner...988-rogue-2420

        Past Boats
        1970 Wooster Hellion - Merc 9.8
        2002 SeaRay 190BR - 5.0 - A1G2 - "Cheasheads in Paradise"
        1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

        What’s behind you doesn’t matter.Enzo Ferrari

        Comment


        • #5
          Very good guys, thanks. I tend to overbuild and really do not want to this time as I do not want to have to rent a forklift to get it in and out of the garage!

          The 2 2x10's scenario is what I had been gravitating towards for the main beam, just wanted some comforting collaboration. Thanks for the pic JASinIL2006 that is exactly what I had envisioned.

          Scott, thanks for that tickler to look into the a-frame gantry. I only have 9 feet height to work with but could be just the ticket.

          We had a really cool DIY garage here real close with hoists and all, and only $30 charge for overnite, would have been perfect but the couple had a bad divorce just about the time I was ready to book them for this, sigh.

          _

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          • #6
            Oh yeah, I am R&Ring the coupler and hope I will be able to get at it with engine still inside the boat so I do not have to lift any more than a foot or so. Lift, move boat back, maybe turn engine, set down on thick plywood, do the work, reinstall then get out the alignment bar and see how many times I have to crawl in and out to get it right.
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            • #7
              if you pull the wheels off your trailer, does that lower it enough to use a standard engine hoist?
              1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - http://forums.iboats.com/forum/owner...988-rogue-2420

              Past Boats
              1970 Wooster Hellion - Merc 9.8
              2002 SeaRay 190BR - 5.0 - A1G2 - "Cheasheads in Paradise"
              1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

              What’s behind you doesn’t matter.Enzo Ferrari

              Comment


              • #8
                I have seen some taller engine hoists, but I'm not sure how readily available they are. With places like Harbor Freight, it might be easier to buy a hoist than to build a gantry.
                Best regards, Ted . . . . Cape Cod, MA

                Formula 330 Sun Sport, O'Day Mariner Sail #3224, Sunfish
                Past Boats: Catalina 22 Sail #10531, Formula 242 Sun Sport
                Twin Mercruiser 7.4 LX MPI (0F802036, 039), Bravo 3's (0F806198, 199), Mercury 7.5 HP (1969), Johnson 4.5 HP (1980)

                My Boating Web Pages: http://www.tpenfield.com

                Member of the Month - February 2013

                Comment


                • #9
                  All good ideas, and some have been contemplated, but alas, not feasible in my situation. I am oppressed with an HOA and that complicates the logistics some. Leaving the boat sticking out of the garage or in the driveway for more than a few hours can cause a fine-quake. That DIY garage would have been perfect dangit.

                  Do you think I will run into issues trying to work on it inside the boat? Boat is pretty standard Bowrider layout, small sunpad at stern, bench seat then buckets for cockpit. Current pics did not make it to my new phone, but here are a couple pics from happier days of the layout, and the engine from a relative side angle. Right now the sunpad is off, all partitions have been removed, and it is all open from the engine up to the buckets. Thanks guys!

                  General layout...:
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                  Engine placement relative to top opening...
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                  • #10
                    Gantry construction went well. Used double 2x10s for the beam, with double 2x6 uprights each side, single 2x6s for footing on each leg, legs are 8' tall on the nose. Added 2x6s angled beam gussets bolted to legs and toe-nailed to beam for easy removal of legs. Smaller 2x4's for upright to footing gussets. Ended up having to make a "porch" at the top for the hoist to hang from in order to get enough travel for the hoisting effort.

                    I built the simple beam, then drilled and prefitted the legs to the beam on the flat. I put eye rings in the top of the beam so I could lift just the beam up the the ceiling where I put hooks in for it. Then installed the legs. Then lifted it up slightly to get it off the hooks. This way I could leave it half assembled by putting just one end up on the hook and taking that leg off so we could navigate with a vehicle in the garage if this effort goes on for very long. I did all the boat work with engine suspended in the boat, moved truck/trailer in and out as needed to R&R engine. Was plenty of room in the boat, biggest challenge was getting in and out.


                    Overall config...

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                    A 5/8" bolt thru-bolted for the hoist to hang from...

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                    "Driver's side" left hanging with no leg...

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                    • #11
                      I'm not liking the 5/8" bolt idea . . . I'm thinking it will bend, if not break. But it actually held up

                      Usually folks go with a chain around the top of the gantry to connect the hoist.
                      Last edited by tpenfield; October 2nd, 2017, 05:43 PM.
                      Best regards, Ted . . . . Cape Cod, MA

                      Formula 330 Sun Sport, O'Day Mariner Sail #3224, Sunfish
                      Past Boats: Catalina 22 Sail #10531, Formula 242 Sun Sport
                      Twin Mercruiser 7.4 LX MPI (0F802036, 039), Bravo 3's (0F806198, 199), Mercury 7.5 HP (1969), Johnson 4.5 HP (1980)

                      My Boating Web Pages: http://www.tpenfield.com

                      Member of the Month - February 2013

                      Comment


                      • #12
                        I tried that first. The boat is so high up on the trailer that with the hoist on a chain like I had it at first would have been inside the boat, with no upward travel left. I needed to get at least a foot lift or more. The chain I was going to use had 1.5k capacity, and the 5/8 bolt could not go through a link so I equated that into nominal. I have not taken that bolt out yet to see if it is still true! Might be a good thing to know how close it is. The washer did not deflect any. I only needed the 860 lbs capacity on this one though.
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                        • #13
                          That bolt would make me nervous, too... but I understand about the height and clearance problems. When I built mine, I forgot to include the lost lift height due to the hoist and the chain holding it to the gantry. First thing I thought when I saw your first picture was, 'that isn't tall enough...'

                          Glad it worked out for you. Are you going to keep the gantry or repurpose the wood?
                          Location: West Central Illinois, USA 1997 Larson 186 SEi Bowrider I/O Mercruiser 350 #0F747565 Mag Alpha One Gen II #1A270120 Transom and Deck Restoration Project on my '97 Larson Bowrider

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                          • #14
                            I better keep it, so I won't need it again
                            _

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                            • #15
                              Sign up today
                              Just checked...That bolt held ok, did not bend any, was a thicker washer and it is still flat. I drilled the hole a little down hill, was on a 3 step stool and a little unsteady. That may have actually helped. The bolt will not hold at near the capacity of that hoist or the gantry for sure. That is a stout little hoist, did not need much effort going up. Had to work on the engine while it was suspended, nothing wiggled or even creaked while jockeying it around. Most lookups said 860lb for the 4.3 bobtailI. It did not "feel" that heavy, and I did a few big block MoPars for myself and friends late last century. This hoist was there for a couple of them!

                              Just need anyone looking at this in the future to realize the bolt is scoped only for the 860lbs from the little 4.3 bobtail
                              _

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