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Old 31-07-2012, 19:05   #1
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Can You Identify This Davit/Crane?

Hi!

This is on our new-to-us Chris Craft 480. It's on the top of the sundeck hardtop with a 4" standpipe below, fastened with a flange on the sundeck. The pipe is aluminum, the diameters are 4", 3-1/2" and 3". There is no strongback, but there is a 3/8" flat plate welded at the back of the crane "turn".

The winch on it is a Dayton(Grainger) rated at 1000#, but I doubt the crane can handle that.

Previous owners have all shrugged off my questions. Before I buy a fancy dinghy to match our fancy boat I'd like to know my limits.

Thank you for any help you can supply.

OG
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Old 31-07-2012, 19:53   #2
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Re: Can You Identify This Davit/Crane?

Quote:
The winch on it is a Dayton(Grainger) rated at 1000#, but I doubt the crane can handle that.
A safe working load of 300 lbs would be fair. The blocks won't hande as much are the crane arm can. The block adds a 2:1 advantage. The working load of the winch is not the same as the working load of the blocks and line. If you are lifting more than 300 lbs you'll not be happy with this crane even if it would handle it fine. In a breeze going that high I would not feel safe. Given you have to manulaly swing the arm to nest the dinghy you don't want a heavy dinghy. A nice 12 ft center console dinghy would be quite nice but you would need a real powered davit to swing it that high. I think you have seen the types of davits that swing the larger dinghys. This isn't like those.
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Old 01-08-2012, 05:27   #3
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Re: Can You Identify This Davit/Crane?

Paul,

Thanks for the reply. But what about a manufacturer? I can find NO data plate except on the winch, so I'm stymied as to what the full capabilities are here. 300# for a dinghy isn't all that much, and I'd like something in the 11' foot range with a steering station and a bimini. Let's see if there are any other ideas out there.

OG
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Old 01-08-2012, 05:45   #4
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Re: Can You Identify This Davit/Crane?

Any pictures without the stuff blocking the view of attachment points?
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Old 01-08-2012, 06:32   #5
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Re: Can You Identify This Davit/Crane?

Cat Man Do,

I'll provide whatever photos I can. What exactly would you like to see? Base of crane? Standpipe base? Details of the pile sections? Backing plate at the curve? Which Attachment points?

OG
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Old 01-08-2012, 06:53   #6
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Re: Can You Identify This Davit/Crane?

This may have been custom made in a boatyard, therefore no data plate. I agree with Paul that the capacity is very limited. Also, a heavy dingy carried that high up will increase the roll of your boat. Perhaps you should consider the sundeck roof as a good place to store a couple of plastic kayaks, and mount your dingy off the swim platform.
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Old 01-08-2012, 07:04   #7
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Re: Can You Identify This Davit/Crane?

Having seen the type of Dinghy you want I'm very sure the crane you have is not up for the task. Your basic 9 ft inflateable with a small outboard is about what it would be rated for. Its not only the lifting capacity but you need to have a longer arm. Your height is WAY up there and controlling the arm laterally unassited isn't easy.

I can understand why you want the dinghy you want and know people that have them but they all use a much larger powered crane to manage them. They usually have a corded remote so you can see what you are doing. It's not an issue if your crane arm would break but the base may not be up to the stress and thus detach fom the deck or at least stress it.

You have to lift from the center point of the dinghy and swing 180 dgrees to deploy it. You may need to swing the dighy freely so it does not hit the lift to complete the maneuver too plus clear all the things that stick out beyond the upper deck. That means the arm has to be about half the length of the dinhy. Even longer if it has to center the dinghy on the upper deck. You won't be able to slide this dinghy around once you get it aboard. It has to land where is needs to be exactly.

I wouold work with who ever you are acquiring the dinghy from to be sure you have the right rig. The requirements for "liftIng" and "manuevering" are not the same as other things and the standards are more exacting for something safe and effective. Both size and weight of the dinghy need consideration.
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Old 01-08-2012, 17:27   #8
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Re: Can You Identify This Davit/Crane?

Quote:
Originally Posted by OldGeek View Post
Cat Man Do,

I'll provide whatever photos I can. What exactly would you like to see? Base of crane? Standpipe base? Details of the pile sections? Backing plate at the curve? Which Attachment points?

OG
Yes please

More to see how the load is spread.
Is it just a pipe welded to a 100mm base with a 1/4 inch screw in each corner
or is it a heavily gusseted pipe welded to a 1000mm base with a 1/2 inch bolts in each corner with backing plate under.
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Old 02-08-2012, 07:49   #9
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Re: Can You Identify This Davit/Crane?

Cat Man Do,

I've uploaded 9 photos of this davit/crane. Six in this post and three in the next.

Some details:

1. The first three photos show attachments to the boat. The sundeck roof, the sundeck underside, and the standpipe base attached to the sundeck.
2. The winch on this is rated at 1000#, it's 110VAC powered with a corded up/down control box.
3. The other photos show details of the construction, i.e., the "backing plate", the winch base, the telescope joints and the pulley at the end.

With no info in hand we have tried to lift a 1996 12' Renova Dinghy with console, handrails and 40 HP Honda engine. It almost got this rig out of the water, with only the lower unit still in the water. But all the onlookers "suggested" what with the list to port and the deflection of the crane that prudence should prevail and that we wouldn't be buying this dinghy.

Thanks for your perseverance with me on this issue.

OG
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Old 02-08-2012, 07:50   #10
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Re: Can You Identify This Davit/Crane?

More Photos:

OG
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Old 02-08-2012, 07:56   #11
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Re: Can You Identify This Davit/Crane?

This looks like an old " Nautical Structures " davit but many of that vintage looked similar.
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Old 02-08-2012, 13:17   #12
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Re: Can You Identify This Davit/Crane?

Ahoy!

This is an older Marquipt davit as identified by the recessed bolt on the end pulley. Capacity is about 500#. To be safe it needs a new cable and re-rigging to be a single cable lift.

Thanks to all the respondents and especially Rick Thomas at Nautical Structures in Ft. Lauderdale.

OG
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