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Old 30 July 2003, 19:29   #21
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You are letting your hearts rule your heads. Hypalon is fabric. It's floppy bendy stuff. It can be folded right back on itself and suffer no damage. Unless it is being severely nipped, just let it squidge into whatever shape it wants. The air pressure distributes the load throughout the whole of the tube.
Now, lifting eyes. Let's see, a boat like JK's is likely the weigh about 2 tons. You are going to apply a load of half a ton to each lifting point. Unless the reinforcing plate is very thick, or reasonably thick and carfully shaped to preload the lifting area, almost all of this load is going to applied to the hull over the area of approximately the washer. If it's a U bolt, the 2 washers. At the transom it's a bit different because the load will put the bolt mainly into shear, but you are still carying a load of 1 ton on the transom.
Now, you work out the surface area of the strops under the boat and compare the loads. I know what I prefer.
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Old 31 July 2003, 07:05   #22
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What's this Ovlov engine you've got Jeffrey? Did you buy it in Pwllheli?

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Old 31 July 2003, 09:20   #23
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Oops, must have spelt in wrongly.

Nah, I bought it in Glasgow. Are you nuts?

I did buy my Suzi 200 in Penrhyndeudraeth. Lleyn Peninsular, north east of Pwllheli. Will that do?

What's this Jeffrey thing? That's a hairdresser's name, isn't it? Can't be me then.
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Old 31 July 2003, 12:11   #24
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Oh dear...I had been convinced that fitting lifting eyes was the way I would go.
Now I'm not so sure. I know that my yard won't use a spreader each time so that method's not available to me.
I suppose if I get the manufacturer to fit the lifting eyes and they approve of them for the weight, that should be OK?
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Old 31 July 2003, 12:24   #25
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Lifting points bolted through the hull with sensible backing plates are tried and tested and I am not aware of any reported problems.

I have had two RIBs with this arrangement and there has been no indication of any undue localised stress (gell coat cracking etc).

The backing plates were something like 4mm thick stainless steel, and they were positioned on a flat section of the hull. As far as I can tell they spread the load adequately and this remains my lifting method of choice.

Decisions, decisions!

John
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Old 31 July 2003, 12:30   #26
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Quote:
Originally posted by timw
my yard won't use a spreader each time...
Why not? Do they just use slings up to a hook?
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Old 31 July 2003, 12:35   #27
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yes, they just have slings up to a hook.

This works well on small hard sided boats like my old one and all the ribs they lift have lifting eyes.

I believe the spreader is only brought out when lifting a large yacht.

They haven't the time to use a spreader on the small boats as they are being lifted in and out all day, and I would want mine in and out quite frequently.
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Old 31 July 2003, 12:51   #28
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Lifting points bolted through the hull with sensible backing plates are tried and tested and I am not aware of any reported problems.

JK, I wasn't trying to negate your comments. 'Just indicating the possible loads. I've even seen ribs lifted by a single eye in the wheel-house roof.
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Old 31 July 2003, 14:25   #29
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Quote:
Originally posted by jwalker
I've even seen ribs lifted by a single eye in the wheel-house roof.
That would take a bit of thought in the design stage!

A lot of the "fast rescue craft" and duaghter ships have single point lifts don't they? I've never really looked to see how they do it, but I suppose it may be another option.

John
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Old 31 July 2003, 14:33   #30
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I had my 8.5 craned out today - simply to clean its bum.........

and after reading all the previous, thought i would check up on what was best as the crane does not have spreader bars - by chance i had lifting eyes put on the boat when i bought it and this is the first time i used them.
The reccomendation from the maker was not to crane out unless lifting eyes are fitted??? from the maker, so that is their view??

We put decent size shackles on the eyes, 2 on transom, 2 forward, and lifted it out no bother, all very level and all that.

Personally i think if i was going to do it often, i would have the lifting eyes fitted, not a hard thing to do??
(as long as you do not mind drilliing 8 M10 holes in your hull)

pete f
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