Lifting loads

[johnphilip]

metric/imperial

Are the slings 8m or 16'8"

8M= approx 26' 6"

Crane should come with chain slings to extend the boat slings, spreader less essential.

 

[Lady Campanula]

Are the slings 8m or 16'8"

8M= approx 26' 6"

My mishtook! They're 8 metres.

 

[LittleSister]

Just remember my comment about retaining the forward sling so that it doesn't slide up the keel when the load comes on.

It happened to my old Hurley 22 (long fin), just as it was coming over the quay wall. Bow suddenly dropped, I ran, and when I dared look back the boat was hanging by the bow roller!

The moral of the story is twofold - (1) you can't trust all crane drivers; and (2) make sure the front and back slings are tied together somehow.

This is usually done by means of the strops being suspended from the corners of a rectangular frame (name?) which both spreads the strops to something like the width of the boat (reducing crushing), and restrains the front and back ones (avoiding the front strop sliding up the bow), and this frame is in turn attached by four chains to the crane's hook. Tying the front and back strops together either side with stout lines or straps will also do the latter job.

 

[boomerangben]

Whilst I stand corrected about my maths earlier, I am intrigued as to what your plant hire contractor is going to use to lift the boat: is it going to be a proper crane or is he going to be using something else?

As to the crush loads, I reckon they are still going to be of the order of a 1te and consider your boat laid on its side with a tonne sat on the edge of the deck.

 

[m1nder]

This happened in Galway during the week and amazingly there was a camera crew there to capture it. Watch the video, amazing stuff.

http://www.rte.ie/news/2011/0407/galway.html

 

[Lady Campanula]

This happened in Galway during the week and amazingly there was a camera crew there to capture it. Watch the video, amazing stuff.

http://www.rte.ie/news/2011/0407/galway.html

Now you have me really worried! I must remember to fly off my helicopter ( see vid ) before letting a crane driver near it....

 

[sammie]

13ton

hi my boat was taken out the water with 2 wide spreaders, my boat was in such a bad way structually it was badly pinched below deckline as ther was no deck or any kind of structual support ther at all , this was the same all round the boat,i believe it was the metal straps in the hull that actually stopped her from tearing in half. anyway 6months 40 steamed ribs 6 3inch by 3inch ash frames formed and fitec on site and complete new structure and decks also added and about 300 ft of mahogony planking later. touchwood in about another 2 months she will be back in the water,however i am a bit nervouse as to how to do this the best way,i know the people who do this for a job normally shift glassfibre boats but this one is a 1955 mahogony on oak 39ft twin motor yacht and i could do with a little advice please regards

 

[Lady Campanula]

Boat shift/lift

We managed it!

Lowered the mast ourselves, saving £145 ( much to the chagrin of the lurking Dover Marina yardies ) and had the thing moved to my backyard. A transfer was involved...

I bought 2 x 8m x 4 ton slings and hired a 4-leg lifting chain assembly. Spreader beams were made up from 2 Catapult alloy crossbeam tubes, tied with Kevlar cord to the slings' loops. A crew at my local haulage company effected the lift and transfer to another ( temp ) storage trailer.

Phew! Job done!

Thanks to all contributors of 'the knowledge'.

 

[Billjratt]

Too late I know, but there are other ways.
We lifted 48 (yes) boats last saturday. Spreaders were used twice - the first was for a plywood cat which provided two old bits of aluminium mast section just greater than the overall beam at a cost of SFA, and I had to provide one in order to save my wooden aft guardrails from being crushed - it was the ladder I had been using to climb aboard over winter.
Another issue is toerail/gunwhale capping being damaged by slings - my fix was old carpet with a length of blue plastic water pipe just below and outside the lift point, transferring the strop pressure from the wood to the hull.

Simples.

 

[Avocet]

We managed it!

Lowered the mast ourselves, saving £145 ( much to the chagrin of the lurking Dover Marina yardies ) and had the thing moved to my backyard. A transfer was involved...

I bought 2 x 8m x 4 ton slings and hired a 4-leg lifting chain assembly. Spreader beams were made up from 2 Catapult alloy crossbeam tubes, tied with Kevlar cord to the slings' loops. A crew at my local haulage company effected the lift and transfer to another ( temp ) storage trailer.

Phew! Job done!

Thanks to all contributors of 'the knowledge'.

Ah! You should have said it was a Cutlass! No worries - they're as tough as old boots! They're so narrow in the beam, and thickly laid up that you could probably have managed without any spreaders. Ours has been lifted loads of times (though with longer strops, it has to be said) and no spreaders. The two bulkheads are round about where the front strop is sitting.

How did it tow, by the way? They weigh a good 3 tons, so I've never tried towing ours.

 

[sarabande]

Landrover Defender, and my three axle, rather agricultural trailer.

Please be assured that the gross weight was calculated at 3499kg by the owner


Really, no driving problem even with the rig being a teensy bit nose-heavy, though we were not the fastest vehicle on the roads. I reckon we can get it spot on next time.


(That makes 3 Cutlasses on the forum)

 

[Vara]

Aaah so that was you playing cats cradle on the lift out pontoon.

If I'd been 50m closer I could have shouted helpful tips and proffered advice from my cockpit.

Lovely day for it though, pleased it went so well.

 

[Scotty_Tradewind]

Apologies for the basics employed her and not being mathematically minded....So without the math.. if you put the photo of the boat being lifted onto a large sheet of paper and draw continued angles of the slings up the paper, would this indicate the length of the slings that would be needed if the spreaders were not used?
Accepting of course that the cutlass is as tough as old boots.

 

[Avocet]

Yes, if you continued the drawing of the strops, just extending the existing lines upwards until they met, you'd end up with the same compressive load on the deck.

 

[sarabande]

Vara - thanks

the accuracy of the operation was so great that when we lowered the stick, the spreaders made gentle, but precise, contact with the goalpost on the stern. Bugger . Half an inch either way and all would have been well.

But it was the first time I've been on the lowering team for a mast that big, so it was good to see the theory of A-frames put into practice.

Good cheerful bunch of people on the boats in Dover; a couple of volunteers lent a hand for over an hour, and then one of them then fed us restorative beer .

 

[Lady Campanula]

But it was the first time I've been on the lowering team for a mast that big, so it was good to see the theory of A-frames put into practice.

Down the years, I've been on board when the mast has been 'lowered' on a couple of occasions - each time a darned sight faster than our little 'venture' in Dover Marina.

I'm very pleased to report that, this time, there was a sufficiency of control. I was sufficiently confident of the 'cats cradle' arrangements - which worked exactly as intended - and the only problem came when trying to extract the mast-foot bolt. Despite being pre-checked and loosened, it had bent and jammed under load. A small but useful lesson for next time....

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