Re: Anyone have a 14K swinging davit for house?
 

I think it was a good choice adding "BIlge" in your statement. :chimp:

Re: Anyone have a 14K swinging davit for house?
 

Expresscat39,
Here you go, Hi Tide Sales Inc. 4050 Selvitz Road Fort Pierce, Florida 34981. 1-800-544-0735. www.hi-tide.com. I love my lift 16,000lbs. topless, and when I needed parts the people I spoke to were great.

Re: Anyone have a 14K swinging davit for house?
 

Do you have any idea of the massive seawall structure and underground "roots" you will need for a ROTATING crane mount for a 14,000 pound load at a 10' center?

That's a 140,000 (plus crane structure) pound torque load on the base plate.

For example, the 70 foot flagpole at the car lot I'm installing this month, it only has to support the wind load of a 250 square foot flag, yet the hole has to be 8 feet deep and 4 feet in diameter to support the mounting sleeve.

To achieve what you desire will require the entire yard to be excavated probably 30 feet from the edge of the seawall to a depth of probably fifteen feet. Then it will need to be filled with reinforcing steel and concrete before the "yard" is put back on the top 5 feet. This is just a guess.

Re: Anyone have a 14K swinging davit for house?
 

Yes Mcollinstn, that is what I wanted to know. Explains why you don't see many of these.

Thanks Lapse of Reason/NJSONIC, I guess that is the way I'll have to go, much more cost effective but less optimal than the swinging davit. Mcollinstn's calculations indicate it might be cheaper to bury a used destroyer in the yard and use its cargo crane. <gg>

Re: Anyone have a 14K swinging davit for house?
 

I'm going to school designing oil platforms and offshore structural engineering. I don't think it will take as much 'excavation' as previously stated, my dad has a few rotating cranes in his warehouses and they were always so much fun to play with when we were little. I think I might start to design what you are talking about. Maybe the reason they aren't out there is because no one has made one work correctly yet.

Ernie

If you look around there are a lot of them lifting sailboats at regatas.

Re: Anyone have a 14K swinging davit for house?
 

Topspin, I agree. You wouldn't have to have as much substucture if you made one using a counter weight. same concept as a fork lift.

Re: Anyone have a 14K swinging davit for house?
 

Okay,

Assuming you have a really solid sea wall to keep the soil in place, and soil that will compact nicely and hold compaction at 2500 psf, THEN we'll do some math.

#1) No counterweight.
14000 load. Boat beam appx 100"
Square concrete base foundation for jib crane.
Edge of foundation 36" from edge of sea wall.
Crane weight of appx 150% of the max load (just an approximation).
A base foundation of 10 feet square by 8 feet thick will provide an adequate foundation to support and anchor the resultant load (assuming 3000psi concrete with adequate steel reinforcing). You will require a span of 160" from the pivot center to reach the boat (with the boat sitting within 14" of the sea wall).

The max torque load on the structure (which must not exceed the strength of the concrete at the bottom 1" cross section directly under the pivot) will be right at 235,000 lb-ft of torque. This matches safely with the strength of the concrete (3000psi) at 1900psi.

One problem, though. The soil load on the most heavily loaded edge will be 3900 psf. 2500psf is the MAX, and in all honesty, I don't think shoreline dirt will go over 2000 psf.

#2) Counterweighted.
Counterweight figured to offset HALF of the load the boat imposes.
Add 20,000# counterweight at 80" rearset from the pivot (chunk of cast iron about 5' cube).
This reduces the base to 100" square by 48" deep. Concrete tension load drops to 850psi. Boom length drops from 160" to 150" and yields same usable pickup arm length.

The good part here, is that the soil load drops to 1,330 psf.


So I was wrong in my initial reaction.
Looks do-able.
The key is gonna be the stability of the soil near the sea wall.

mc

(I have my quickie Excel sheet I used if you want it)
here it is
mc's boat crane worksheet

Re: Anyone have a 14K swinging davit for house?
 

No, I missed some stuff. Lemme get back to it later and fix it.

Re: Anyone have a 14K swinging davit for house?
 

Not to worry Mcollinstn, you have been very helpful already. I'll employ all you guys you as consulting engineers on this if I am interested again. I kin pay not one, but several six pacs!

I am guessing that if on a solid limestone base that is florida, some steel support beams can be drilled, bolted into the rock. No point in wasting your time until I find out how far down the solid rock is.

Many thanks all!

Re: Anyone have a 14K swinging davit for house?
 

Ya I installed material handling equipment , overhead and jib cranes for years ..
The concrete base for a 2 ton jib was like 4x4x3 and its exponential from there ..
You would have a swimmin pool size chunk of concrete with some serious reinforcement and anchors .
Heres the biggest one I ever worked on , im sure it would fit in your back yard
1,200 tons affectionatly called Goliath