Crane Launch - Hardware Questions

Crane Launch - Hardware Questions

Postby RRaedeke » Sat May 12, 2012 3:39 pm

I am a new owner and a bit if a rookie. Looks like I've jumped into the deep and now need to learn to swim.
I have a couple questions about launching this boat - specifically about the hardware.

I understand there is an eyebolt that attaches to one of the keel bolts but beyond that I'm not sure how else this is supposed to work.
I was told I'd need this eyebolt, and a extended nut that I thread onto the bolt. But I wondered if I could buy an eye nut of the proper dimension and achieve the same thing?
There has also been talk of straps, but again I'm uncertain as to where these are going to attach. I understand they are used for balancing the boat out as it is lifted from the single point.

Lastly, the bolts on this boat are a bit rusty. Anyone want to take a look at them and see if you think I should even chance it?
This is hull #79 - not in my possession yet - but hope to have her home in few weeks.

By chance is there any good videos on the subject or perhaps some photos?
Trying to get prepared as best I can for her arrival.

Guess I'm getting a little excited about the new boat.
Thanks
Richard
Attachments
IMG_0736.JPG
twin bolts w/ some SS plate?
IMG_0736.JPG (167.95 KiB) Viewed 3602 times
IMG_0735.JPG
Single bolt aft
IMG_0735.JPG (198.17 KiB) Viewed 3601 times
RRaedeke
 
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Re: Crane Launch - Hardware Questions

Postby mckeever » Sun May 13, 2012 7:56 am

Hi, Richard

Some boats apparently came with the lifting tab (that bent piece of metal with the hole in it) and some didn't. It's kinda hard to see how thick yours is from the picture. If it's thicker than say 3/16", you're good to go. The eye bolt and extension nut are used if you don't have one.

The keel bolts are way below the CG of the boat, so if lifted from there the boat will attempt to invert and things will get very ugly.

Most harnesses that I've seen consist of a 4'-5' chain or strap good for >3000 lbs shackled to the keel bolt eye and having a sufficient eye on top to accommodate the crane hook.

This is stabilized with longitudinal lines that attach to the mast base and somewhere at the back of the boat and lateral lines that attach to the main winches.

All of these are adjusted so that the place that they all come together is laterally centered and longitudinally approximately in the plane of the "vertical" hatch boards. This location is aft of the bolt you are lifting and is intended to lift the boat bow-down so that the mast does not hit the crane (much).

I know this sounds pretty complicated. I invite you to come down to Cherry Creek some Wednesday night from 4:00 to 6:00. You'll see as many different implementations and choreographies as there are boats...

Concerning the rusty bolts, I have no experience with this. From an engineering standpoint, a single, new 3/4 inch thread has a ultimate tensile strength in excess of 18,000 lb. That's a 12X factor of safety when lifting this boat with one bolt. That could make up for quite a bit of rust. In the end, it will be your comfort zone that rules.

Mike
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| Mike McKeever - Santana 20 #713 "Feisty!" - Boulder, Colorado
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Re: Crane Launch - Hardware Questions

Postby RRaedeke » Sun May 13, 2012 9:23 am

Thanks Mike
I was down last Thursday and sailed with Joe and Kim.
I watched Emesis go in from Santana Row, but clearly need to be right there to get a better view of how it's done.
Thanks for the great explanation, I can now visualize how it's supposed to work.

Kim mentioned yellows traps from Harbor Freight... Not sure your explanation would use straps, but rather 3/8" line...assuming you are spooling onto the winches. But I assume everyone has their own method.

Thanks again and I will be down on Wednesday.
Richard
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Re: Crane Launch - Hardware Questions

Postby mckeever » Sun May 13, 2012 1:08 pm

Hi, Richard

I actually currently use a chain with a pear-shaped ring on the top to fit the crane hook. I have 5 lengths of retired ~1/4 dia line tied onto the chain at the height of the top hatch slide. One goes forward to a spring shackle connected to the mast butt plate, two aft to sprin shackles on the pushpit bases, and two to loops over each main winch. These five are all adjusted with trucker's hitches and are left permanently adjusted. I leave this whole mess under the floor board when not being used unless I extra-paranoid about weight...

Mike
+---------------------------------------------------------------------
| Mike McKeever - Santana 20 #713 "Feisty!" - Boulder, Colorado
| mijamck@gmail.com
| 303.530.4503 Home 303.589.0815 Mobile 928.447.1168 Fax
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Re: Crane Launch - Hardware Questions

Postby JoshE » Wed May 29, 2013 5:03 pm

Ditto what mckeever said. I have a big piece of Dyneema with an eyesplice in each end, one of which has a thimble in it. The thimble end has a big Wichard shackle rated about 10x the weight of the boat, so I know I'm safe there. The upper eye extends just above the top of the companionway.

From there, I have a 4 pieces of 6mm line attached to the line at the upper eye. Two go around the aft cabintop winches and are cleated off, one goes to the mast base and another goes to the rudder post. The one going to the rudder post is adjusted with a trucker's hitch, as it needs to be tightened just a bit before hoisting so that the main lifting line is leaning slightly aft. This makes sure that the boat goes into the air slightly bow-down to avoid the mast striking the boom of the crane. I'm still playing around with how much is right - I'm a recently minted (this month) S20 owner, and I've only hauled it three times to date. Then, I just have my bow/stern lines (which are 19' long each) tied together so that I can singlehandedly hoist/launch the boat. By having the continuous line from bow to stern, I can control the "spin" of the boat with one hand like you would a kiteboarding kite while I operate the crane with the other. It's worked well so far - haven't dropped the boat yet. :) Knock on wood...
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