How much can I lift with mast/boom

[colinstone]

Hi,

Just finished having a steel barge built, but it does have a douglas fir mast and boom!! Mast is hollow 6m tall 6 inch diameter, tapering to 5 inch over final meter. Boom is solid, 4m long and 4 inch diameter. Can be seen here www.rmstone.screaming.net. (http://www.rmstone.screaming.net.)

I am trying to work out what load I can lift with the boom - the weight that I am interested in is 360Kg - www.micro-car.co.uk. (http://www.micro-car.co.uk.)

TVMIA

[colinstone]

Should be www.rmstone.screaming.net (http://www.rmstone.screaming.net) - no full stop!!

[outofthenorm]

Can't comment on your lifting question - but I can sure comment on the Vessel. In a word - WOW!

Very, very smart little ship!

- Norm

[Dan McCosh]

How much weight is a bit different that safely loading a car over the side. That rig doesn't appear to have been designed as a working crane, hence it raises all kinds of questions about fittings, angles, wire, blocks, as well as wood dimensions. The wood dimensions sound adequate in compression, marginal in bending, but that's only an estimate. I wouldn't try it myself. A reasonably designed system to bring the car aboad shouldn't be too difficult. To begin with, ramps are probably easier to use. A proper crane wouldn't be that expensive to fabricate, even in steel.

[Ian McColgin]

I'm no wiz on compression loading wood. I know it's quite strong but would I really want what could get to almost 500 kg compression on a 4" that boom?

You'd also need a different hallyard arrangement to ensure that the strain on the boom comes all at the point holding the car and the strain on the mast is right where all the stays come. You'll certainly want very serious chainplates where the shrouds land, not just a cabin top attachment, as they will be subject to strains over 1,000 kg.

Were I you, I'd just have a couple of nice long planks to roll it on. You could then safely use the gin pole to lift one end of the car and rotate it to a fore and aft position by pivoting on the other two tires.

Take a look at the sort of highfield lever style of axel tie-down used on ferries for thoughts on how to secure this.

Sure will obstruct the view and the very pleasing line of the vessel. Why not a couple of nice folding bikes with cargo carts?

[nedL]

WOW! You guys on that side of the pond sure can form steel plate nicely. I don't think you'd find to many yards around here wanting to put compound curves in like that. Beautiful. smile.gif

[mmd]

Nice looking yacht, Colin. Not many of that type over here.

To your question: More info, please...

What is the distance from gooseneck boom pin to

a.) lower block on mast
b.) upper block on mast
c.) inner block on boom
d.) outer block on boom

What is the wall thickness of the hollow mast? Is there solid blocking in way of the goosneck fitting?

How are the blocks attached to the mast/boom? (mast bands or through-bolts?)

[Gary E]

An engineer would be able to use the plans and spec's of the components to determine the safe load on each.

Since you got what you got, now comes a test that I like to call a FatAlbert test, you may not know FatAlbert but he is one of Bill Cosby's kid friends... Anyway, FA is a heavyweight, so what I would do is get a pallet or skid and round up as many FatAlbert look alikes as needed to make up more than your cars weight, rig up a lift so that all of them can stand on that platform and start lifting, get them a few inches off the ground then tell them to start bouncing, if that works, it will lift your load.

If it dont, there's a Plan B somewhere... smile.gif

[Venchka]

Originally posted by Gary E:
...Since you got what you got, now comes a test that I like to call a FatAlbert test, you may not know FatAlbert but he is one of Bill Cosby's kid friends...

If it dont, there's a Plan B somewhere... smile.gif OK, we do that test all the time. Only we use steel plates on a pallet. Sorta. Let's say the load you want to lift is 400kg, since things vary a lot. A reasonable test weight would be 500kg.

BUT! Where are going to put the itty bitty toy car? On the deck where the dinghy is? How the heck are you going to attach rigging to the car? I suppose you could have a pallet built and rig to the pallet. BUT! You don't have any head height for the car.

MAYBE? Build some lightweight ramps and drive the car on the deck?

Get a bicycle? With a trailer? You can tote a week's groceries and ale that way.

Here's how you rig for lifting...

http://www.imagestation.com/picture/sraid127/p50c232770e4f0fa7f4806f54d31ff4f6/f7e596ed.jpg

Concept...

http://www.imagestation.com/picture/sraid150/pf40d8fa0b4c0204db8f6bcc2d6d8067f/f5d7dfd5.jpg

Fact...

http://www.imagestation.com/picture/sraid152/pfa2bd8ff139680b9abd2fe36b44fa5bd/f5a2a2e1.jpg

Your gear isn't near tall enough to lift your car.

In my very unexpert opinion.

Upon further searching...

http://www.euroshipservices.nl/afbeeldingen/2300-lux-fuhr-43.jpg

The builder knew what would work. Get one of those.

Dan, sorry. You said it all first. Shame on me for not reading more carefully.

Wayne
In the Swamp. :D

[ 07-15-2005, 03:05 PM: Message edited by: Venchka ]

[Venchka]

And another thing...

I don't know enough to answer this myself. Assuming the deck will handle an additional 400kg load (maybe, maybe not-looks like a stout boat), what happens to the stability of the vessel when you put the toy car on deck? Assuming you get the car on the deck.

The builder offers an "AUTO" version with a cargo hold in the bow. That seems like the safest way to do it.

Wayne
In the Swamp. :D

[ 07-15-2005, 04:16 PM: Message edited by: Venchka ]

[Gary E]

Are you thinking a Eye Bolt in the car roof and a coil of line with marker buoy?

[colinstone]

Thanks for all your thoughts. The idea to use the mast and boom only recently came about as we discovered that the dinghy is light enough just to chuck over the side, and pull back up the side.
Original idea is to have a small scissor lift on aft cabin roof and a pair of alloy ramps - I may well stick with that.

Mast/boom dims are:

Gooseneck to lower mast block 4.2m
To upper mast block 5.2m
Gooseneck to inner boom block 3.4m
To outer boom block 4m
Mast hollow is approx max 70mm mm diamter in centre.
Gooseneck is a 1 inch ss316 pin sent into socket set into cabin roof.
All blocks on mast bands.

The auto version is attractive - but looses quite alot of interior space. Micro car is amazing though - 4 seats, 3m long and only 360kg - same as 4/5 people sat on deck enjoying a drink.

Agree that the compound curves are excellent, particularly those in the lower hull at the bow where the steel plate is 10mm - and they also been achieved with very little jacking and pulling - designer calculated the stretch in the steel and mostly relies on the welding heat to pull the metal into the curves.