Overhead trolly crain / wood beams

Having a problem moving my hull halfs out of the female form. Decided I need to make two overhead beams from which I can hoist up the hull from and roll it.

Because of the span (28 ft), steel wide flange beams are too heavy.

Decided to try self-made, twin, wood I-beams. Anybody have an idea if the attached design will come close to supporting the weight?

Thanks in advance

 

I doubt it, not at 28' long. You might be OK if you placed a temporary vertical support under that beam on each side of the hull as you lifted and turned it. I have a solid fir 6" x 12" beam 14' long over my work area with a trolley system similar to the one pictured and feel safe lifting 3000 lbs. Big difference between 14' and 28' however. Also that boxed beam design would not do well if your load gets lively while you are turning it IMO.

 

What Bob S. is saying is real important. If there is ANY sideways pressure on the beams they have a good chance of rolling, parallelogramming and collapsing like a deck of cards. Really fast with no warning.

 

The beams will be anchored at both ends, so rolling will not happen with out the beams splitting apart.

Parallelogramming, each box/joist beam will have internal framing to keep them from doing this. It is true that this will be the most dangerous type of failure! No warning or flex, just crash.

Thinking back to the last house floor I framed with manufactured I-joist, they were very flimbsy sideways. Was thinking that plywood sheeting on top and bottom of two parallel I-joist would effectively resist sideways movement. Hope the barn withstands the loads. smile

Since I am rolling the trolly across the top there is no physical way to cross brace the two beams against swaying forces. So each beam will have to resist small swaying forces. Will move things real slow.

Thanks for pointing this out SamSam.

The max loads will be applied when I am moving assembled hulls fully glassed. Planning on using temperary supports to reduce the spans to 16'. At that stage, I can even use beams and support from the bottom to carry the load and abandon the overhead system.

On a different approach to this problem, I can use steel profiles to weld up two truss bridges to span the 28'. It will cost a bit more, take more time, but still light enough to push up into position. This is engineering 102 ... brings back bad memories of math.

Continued thanks for helping me think thru this.

 

Even with the beams anchored at both ends, it could still be possible. Bob S. pointed it out, I just kind of made sure you realized what he said. I hadn't even thought of it until I saw his post. My first thought was, you wanted to know if the beams would support the weight you wanted to lift, but you should ask if the beams will support at least twice the weight you wanted to lift. Safe workload, blah, blah, yadda,yadda, etc, etc. My second thought was to not touch the thread with a ten foot pole. It's all Bob's fault. sam

 

Okay, I realize now that forces coming from the side will cause a quick failure. I am working on another idea that will allow cross bracing between the two beams.

Thanks again

 

Advancements

After months of stress, thinking, drawing, and scrounging around for material, a good-old-boy suggested using the steel beams out of a mobile home chasis.

These beams are Junior I-beams. They are light at 9lbs per foot for a 10 inch tall beam. (sorry I am going to mix metric and english units in this post)

Using Vectoworks CAD, I designed a gantry crain that would span the distance, clear the roof trusswork, and work with the lengths of steel that came out of the frame.

I downloaded a free program called Structurix X. (It had some problems a year ago, but, now all is fixed and stable.) Using the points out of the middle of each beam in the Vectorworks drawing, I set up the Structurix file. Added loads and crossed my fingers.

The structure bent like a noodle. So, I partnered two beam cross sections, in Vectorworks. Got the engineering info to plug into Structurix. Crossed all my fingers. It worked .... in theory.

At present I am welding up the pieces. This is taking far longer than using a wood box beam. But the cost is (will be?) less.

 

There's a homemade boat trailer down the road that's made from mobile home beams. Apparently 1 beam wasn't strong enough so they doubled the I beams, one on top of the other, so instead of being 10" high they were 20" high. How much weight are you lifting? Sam

 

why waste all your time and cash trying to rig something up do what i do hire a crane and if some thing goes wrong they have insurance there not as much as you think .

 

The load is 3,000 kg. Maybe the weight will be split 60/40 between the two beams. So each beam I ran the FEA at 3,000 kg load straight down and another 500 kg pushing sideways. I had a torque load also, but forgot what the load was.

Doubling the beams side by side is better ... for my situation. They are welded at the flanges (non continuous weld) so they act together. This also gives some torsional resistance. I beams are weak in this sense. Secondly, since I am running a trolley across the top, the down length needed to clear the bottom of the beam is at a minimum.

So why not use the flange for the trolley? The flanges on junior beams seems thin and week. Also there were a lot of cross supports welded (poorly) at one time that I cut off. The flanges are not smooth on the insides.

I have one more flat to weld across one of the joints tomorrow morning. I'll take a picture and post it afterwards.

Hire a crane. Cut a few holes in the barn roof. Call them back everytime I need to pull a hull half from the forms or rotate one? Kinda expensive. Also, it envolves someone else. When it is just me, I am responsible for me. No insurance (dislike giving away money to the mafia)

 

photos of gantry hoists

Welded all but the top and bottom flange reinforcement strapping. Some photos.

 

Standing Tall ... but still not tested

Here are the photos of the results. It doesn't look clean but it should do the trick. I will test load it in a month. That will be just before I pull the second hull half from the mold.