Any structural engineers in the audience?

[Tim McCrain]

... or anyone who knows beam loads? I need to span 12 feet and lift a V8 from the middle of the span, anyone know what size beam I need? 4x8? 4x10? nail 2 2x10's together?

I used to know this stuff but it's been years and I no longer have my beam spec sheets around.

Thanks!

Tim

[Sammamish1]

here ya go

try this chart http://www.decks.com/article40.aspx

[FINS]

Here is a calculation sheet for either a dimensional beam (4"x) or a Glue-Lam. I assumed a 1500# load at center span. If you know the actual load it will probably reduce the beam size.

[Tim McCrain]

Wow!

Thanks for the prompt response guys! :cool1:

Right now I'm anticipating the max I would lift from the center would be a Chevy small block so a 1500 lb capacity would be more than enough, looks like a 4 x 12 it is.

Tim

[McSkagit Tim Jones]

I'd use a 2X6

I'd use a 2X6. If that breaks, go to a 2X8.

Just kidding! I built one many years ago which I still have. The uprights are galvanized steel pipe, probably 4" with flanges welded at the top and bottom. Initially I used a cedar 6X6 as the cross member...about 12 feet long. I got concerned about cedar, so nailed a 2X8 doug fir to each side. I've lifted Volvo diesels that weigh about 1000 pounds.

So far it has worked....

[BruceDrake]

beam

I was trying to figure out almost exactly the same thing and got some input from a structural engineer but have to call him tomorrow to interpret it. I wanted to create two beams (about 6-8 feet apart) over a 12' space with support posts at the ends. I would like to be able to hoist either 1500 pounds from both to lift a boat totally off a trailer or 750 from just one end.

I got some 2x6 15footers and wanted to know if I nailed three together whether that would be adequate with support posts at 12 feet apart (I could add extra temporary supports in closer to a trailer to reduce the span if needed). Since the span is across the center 12' section of a barn at 8' high the beams would be out of the way unless someone tries to play basketball in the area. I'll add any advice I get in the next couple days.

In the attached picture one beam would go from upper left corner over the metal rail and across to top of room roof at right foreground. Second beam would be further along the rail to the left and further down the room roof at left. Room is 12 wide so second beam could go almost anywhere.
I assume if you are still reading this you have a high tolerance for murky descriptions or are trying to avoid other chores.

[trsexton]

Tim,

If you would like you can borrow my engine hoist.

Tom

[Tim McCrain]

Thanks Tom, I appreciate the offer. I have a hoist, but they won't lift an engine high enough to place it into a '60 Bell Boy.
What I'm building is a boat lift that will lift the boat off the trailer and rotate it approximately 45 degrees either direction for access to the bottom for glass work and paint, and also serve as support when it's time to install the engine.

Tim

[Tim McCrain]

I was trying to figure out almost exactly the same thing and got some input from a structural engineer but have to call him tomorrow to interpret it. I wanted to create two beams (about 6-8 feet apart) over a 12' space with support posts at the ends. I would like to be able to hoist either 1500 pounds from both to lift a boat totally off a trailer or 750 from just one end.

I got some 2x6 15footers and wanted to know if I nailed three together whether that would be adequate with support posts at 12 feet apart (I could add extra temporary supports in closer to a trailer to reduce the span if needed). Since the span is across the center 12' section of a barn at 8' high the beams would be out of the way unless someone tries to play basketball in the area. I'll add any advice I get in the next couple days.

In the attached picture one beam would go from upper left corner over the metal rail and across to top of room roof at right foreground. Second beam would be further along the rail to the left and further down the room roof at left. Room is 12 wide so second beam could go almost anywhere.
I assume if you are still reading this you have a high tolerance for murky descriptions or are trying to avoid other chores.

Bruce,

How do you plan on lifting the boat? If you're using two pick points at each end of the boat, a couple of feet from the posts, then I would think that 2 2x6s stitched together would be fine for that load, but if you're planning on supporting the boat from one point in the middle of the beams you might want something heavier.

I can't supply the correct calculations, (or even explain this in correct engineering terms) but three 2x6s isn't a big increase in capacity over two, as the real increase in load capacity comes from the beam getting "taller", not "wider". In other words, to step up in load capacity from 2 2x6s nailed together to make a 4x6, you should go to a 4x8, not add another 2x6 to make a 6x6.

Tim