Gin pole top/front end attachment

[tbodine88]

Hello

I used some u-bolts from lowes for attachment points. They seem insufficient.

What would a better attachment be?

[Spot]

Hi Tom, what size hardware and what size wire?

Question to the group: Would it be a matter of just matching safe working loads (SWL) or doing the math for load then yield and tensile? When does one apply yield and when to apply tensile? My math and engineering skills are not rigging-approved...

On my boat, wire is .125" (3.2mm) 1x19 SS which would be breaking at 1780lbs and safe working 40% 712lbs according to Hayn. The major hardware is 1/4" pins and bolts and pieces heavier. The minor hardware is strap pad eyes and #8 fasteners.

My major hardware seems to exceed yield and tensile as compared to SWL of the wire except my pad eyes and their bolts taken as each do not.

What has failed on me during a mast stepping is an old 1/4" forestay turnbuckle which was replaced by a quick release lever.

[tkeithlu]

Not enough information, as Spot says.

Is that an eye bolt holding the hook and block?

Are you suspending from the U bolt?

What's the load? As is, I don't think that I would use it, period. They are insufficient, as you've concluded.

Tell us more about the task, and I think any number of us could come up with a usable design for simple lifting.

[Spot]

If someone is good with their physics and trig...here is a schematic for my boat. Mast is normally stepped from a raised crutch and not from dead horizontal:

[Jammer]

Originally Posted by tbodine88

Hello

I used some u-bolts from lowes for attachment points. They seem insufficient.

What would a better attachment be?

A pad eye, I guess, if you want a strong attachment.


But you can drill a fore and aft hole through the gin pole and put a loop of rope in it and use that and you'll transfer the load better. The big load is fore and aft and you just want to connect them, rather than trying to pull the piece of wood apart. Or use a soft shackle.





https://marine.wichard.com/en/stainl...dels/part-6635

[Jammer]

Originally Posted by Spot

Question to the group: Would it be a matter of just matching safe working loads (SWL) or doing the math for load then yield and tensile? When does one apply yield and when to apply tensile? My math and engineering skills are not rigging-approved...

It's a gin pole. Figure out the actual load on it and use that, if some components are stronger so what. Mast raising goes sideways when the mast goes sideways (literally) creating excess loads on the hinge/tabernacle and other hardware, not usually because the lifting tackle itself is weak. Or you break turnbuckles because they got stuck. For boats under 30' the idea usually is that a strong individual can raise the mast with a four-part and no winch which limits the load to around 150 pounds.

[Jammer]

Originally Posted by Spot

If someone is good with their physics and trig...here is a schematic for my boat. Mast is normally stepped from a raised crutch and not from dead horizontal:

The load on the jib halyard is equal the the weight of the mast system (including shrouds etc) that rests at the point where the jib halyard comes out of the mast when the mast is horizontal, probably a little more than half the overall weight (the rest is on the hinge) -- then divided by sin 18 degrees. Figure 30# divided by sin 18. Works out to 97 pounds. The load on the 4:1 is the same as the jib halyard. The compressive force on the gin pole is 60# (2x30#).

[Spot]

Thanks Jammer!

I don't think my hardware will fail abruptly at approx 100# load but the current system has a flaw in that the strap pad eyes are too wide for the toggle and pin so I was using them 'off to the side' so to speak with a piece of double braid acting like a soft shackle to the snap cleat on the mainsheet block. The quick release is helping the overall rigging and I am trying to be more aware as I handle things but I should figure out something for a straighter pull. Many small things on this boat that were done by previous owners, but not done well..