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Crane Barge 1

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280474

Mechanical
Aug 18, 2001
35
Dear All,
I have a bidder's document to be reviewed regarding the subject. They offer a barged mounted crane with the following specification :
Barge Dimension = 150' x 50' x 10', draft=4.5' completed with ballast system
Crane = Crawler Manitowoc 4100 (Serial 41383) with LaticeBoom 200T capacity (Boom Length = 150ft and 180ft)

According to its load chart, the crane barge is able to lift safely 42 Tons of load at 45' working radius (150 ft boom length and 76.8 deg angle)with crawler extended.

Looking to the layout of crane barge, actualy the crane is not located at the center of barge. In fact, it is located 1.6 meters from barge center line.

What I need from you guys, if you ever have experience using such as barge mounted crane, please share to answer my question.... is it possible to lift 42T of load at 45’ working radius with that specification and layout..?

Looking forward for your response
 
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I would have to say yes if the
ballast system works to keep the
deck level. You could also
check with Manitowoc. I think
they are still in business.
 
Placing the crane off center is intentional. To pick up the heaviest loads the barge may be oriented to provide maximum floatation resistance to overturning.
A fringe benefit - for lighter loads it allows the crane to reach a longer distance from the barge.
 
SlideruleEra is absolutely right.

I've worked around many such barge/crane configurations that you have noted and in no case has the crane been centered on the barge.

Also keep in mind that for ordinary conditions, the bulkhead compartments may be filled to balance out the crane and ballast weight being off center.

The 200T sounds a tad high but its definitely in the ballpark.

Is this a ringer crane configuration? If so, then the 200T is very likely a doable pick. Otherwise I would expect something around 100-150T.

Regards,
Qshake
[pipe]
Eng-Tips Forums:Real Solutions for Real Problems Really Quick.
 
280474...ditto on the off-center comment. It does usually limit the swing to 1/2 the circumference, 'cause you don't want to swing the load over the long side because of the reduced overturning resistance when you do that (you're adding the overturning moment and reducing the overturning moment resistance).
 
A 4100 seems a little big, but the barge does have a lot of draft. IT is not uncommon to have the barge be able to walk along the longtiudinal axis. Walking transversely is more exciting and generally not done.
For barge crane lifts you can not use the land based crane charts. The crane charts are limited to 1 deg out of level. The problem with a barge is that as you boom out he barge lists and the radius increases. If you are using a 4100 on a 150 by 50 barge, the contractor should have had a naval architect develop lifting charts for the barge. Use those for the locations of the crane shown on the chart.
 
Do you have reason to doubt the contractor?
Ask them to document the capability, they don't just pull these things out of thin air. They should be glad to oblige.

JTMcC.
 
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