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Yard sling plate question

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  • 13 Aug 2011 12:08
    Quote
    Reply # 675426 on 671910
    Anonymous member
    Kurt Jon Ulmer wrote:
    Jim Creighton wrote:
    Gougeon Bros.(of West System epoxies) recommend fasteners be fitted to over-sized blind holes in thickened epoxy. I.e.,the threads do not touch the wood.They claim the hold is quite adequate. I wonder, however, what happens in tropical heat. I understand epoxy starts to soften over 120 F.
    I suppose a nut could be fitted in a recessed hole on the underside of the yard but might that weaken the yard?

    A hole drilled horizontally through the yard can be in its neutral axis, if it's being thought of as a beam, so there's little loss of beam strength. A hole drilled vertically, and oversize enough to be a proper epoxy socket, breaks the tension fibres of the beam at the top. The epoxy glue in the hole can't transmit the tension, so the beam is weakened. 

    If there were a glue that could hold a padeye on the top of the yard with 'quite adequate' strength, and no drilling, I wouldn't like that either. Why hold the rig up by the top of the yard, tempting the wood to split?

    And a yard is more than a beam. It bends in all sorts of planes, and bangs around the mast and gets jerked up and down from time to time. Epoxy is brittle and it cracks with shocks, such as sharp tugs on a fastener embedded in it.

    With lashings, the whole intact yard takes the loads. Rope is flexible, absorbs shocks and can line itself up fairly.

    Any of the methods discussed here could hold up a swing for the kids, but what's more confidence-inspiring and obvious and common-sensical than a couple loops of good rope simply wrapped around the branch?

    I'll put a photo of our yard-sling into mehitabel's album. Not because it's the ultimate or anything, but it's one way that certainly 'looks like it should work.'

    Kurt

    I suppose one could mitigate the shearing problem and tensile strength loss by using a horizontal plate and judicious addition of unidirectional fibres to compensate. But now we're getting complicated. Point taken, rope or web lashing is simpler.
  • 12 Aug 2011 12:01
    Quote
    Reply # 674644 on 674091
    Deleted user
    Jeff McFadden wrote:
    Robert Groves wrote:
    TONY AND SALLY SUMMERS wrote:Totally agree with Kurt`s analysis, and solution. On Ron Glas we removed the sling plates as they were all but worn through. we then spliced  a long rope to a large thimble and lashed the rope tails around the yard.  and through a lacing eye on the side of the yard away from the mast. Jock Mcleod sort of gave it the nod! the advantages are cost,  flexible connection, ability to adjust the lifting point, and most importantly you can fix/replace it quickly and easily ,Tony and Sally

    On Easy Go we have round aluminum yards. We use rope slings quite successfully and they are totally adjustable and maintain the strength and integrity of the yard. I can't see any beneficial reason to make a mechanical  fitting when a sling will do the job. Easy to make and easy to repair.

    How do you secure the rope slings longitudinally so they don't slip on your yards?

    I have used Prusik Knots with success and lately am using a knot for securing yards that I found in Ashley's Book of Knots. It has an eye spliced in one end of the rope and a few loops around the yard then thread the rope over and under the loops and no slipping. When leaving on a long passage I put a second rope sling on in this fashion as a backup in the unlikely event of the first failing. Our Atlantic crossings were done with webbing slings and Prusik knots. They performed perfectly and tightened up to the point I had to use a Marlin spike to loosen them up for replacement. The webbing seems to chafe faster than rope.
    Last modified: 12 Aug 2011 12:04 | Deleted user
  • 12 Aug 2011 07:42
    Quote
    Reply # 674554 on 668822
    Anonymous member
    Jerry, your U-bolt looks like it should work, and I'll bet it will work.

    The yard sling is the closest thing we have, in a junk rig, to a genoa clew type of critical, heavily-loaded, knocked-about fitting. And what does it usually have to carry? Maybe, triple the weight of the sail, as a guess? Not very much, really. Not much at all. It's not a helicopter we're building.

    About keeping sling lashing from sliding on the yard, I use a bronze strap with an eye bent into it, screwed on in line with the yard. The rope goes over, over, through, over, over... uh, it's in mehitabel's photos, old rig version and new.

    Cheers,
    Kurt

  • 12 Aug 2011 02:48
    Quote
    Reply # 674400 on 672206
    Anonymous member
    Jerry Stebbing wrote:As for whether an epoxy bonded U-bolt in blind holes will fail on a wooden yard, I'll have to wait and see.

    I've used a 10mm diameter stainless U-bolt with the legs penetrating to within a few mm's of the yard's underside. I was considering drilling right through and backing up with nuts, but from previous experience felt that it wasn't neccessary. As mentioned before I've heavily sheathed the yard in unidirectional glass/epoxy on all four sides, plus a 'bandage' of glass tape/epoxy around the mid point where the U-bolt is mounted, so I doubt if it will break.

    I'll paint the yard white, which, as I noticed previously when cruising the Caribbean, minimizes the risk of epoxy melting. I would also add that my boat is very small, with somewhat overbuilt spars and fittings, and what works for me might not scale up successfully when addapted to bigger boats with much higher loadings and stress. I think a webbing or rope strop arrangement would be my choice for a large boat's yard sling.
    I think your arrangement will be fine. My mooring cleats and stanchion feet are fastened blind with epoxy, and nothing short of dynamite is likely to move them.
    As for epoxy melting - Tystie, wood/epoxy, painted black, has made five crossings of the Equator, and hasn't melted yet!!
  • 12 Aug 2011 02:40
    Quote
    Reply # 674394 on 668822
    Deleted user
    I'm leaving out the long quotes here but still following up.

    Seablossom's yard sling was bizarre, as were some other things. Tonight I replaced it with a block hung on a rope, but I realized afterward that the way I did it the block can swivel. Surely not good.

    So I'm curious to a detailed extent how you have tied on, how you tied your rope(s) to your block shackle and what knot you used to fasten to the yard.

    My yard is wood, very heavy, an inverted "T" in structure.

    Thanks, Jeff
  • 12 Aug 2011 00:12
    Quote
    Reply # 674311 on 674091
    Deleted user
    Jeff McFadden wrote:
    Robert Groves wrote:
    TONY AND SALLY SUMMERS wrote:Totally agree with Kurt`s analysis, and solution. On Ron Glas we removed the sling plates as they were all but worn through. we then spliced  a long rope to a large thimble and lashed the rope tails around the yard.  and through a lacing eye on the side of the yard away from the mast. Jock Mcleod sort of gave it the nod! the advantages are cost,  flexible connection, ability to adjust the lifting point, and most importantly you can fix/replace it quickly and easily ,Tony and Sally

    On Easy Go we have round aluminum yards. We use rope slings quite successfully and they are totally adjustable and maintain the strength and integrity of the yard. I can't see any beneficial reason to make a mechanical  fitting when a sling will do the job. Easy to make and easy to repair.

    How do you secure the rope slings longitudinally so they don't slip on your yards?
    WITH RON GLAS`S WOODEN YARDS, A LACING EYE ON NON MAST SIDE WITH TWO OR THREE TURNS THROUGH SAME ,SEEMS TO DO THE JOB  TONY and SALLY
  • 11 Aug 2011 18:21
    Quote
    Reply # 674091 on 673262
    Deleted user
    Robert Groves wrote:
    TONY AND SALLY SUMMERS wrote:Totally agree with Kurt`s analysis, and solution. On Ron Glas we removed the sling plates as they were all but worn through. we then spliced  a long rope to a large thimble and lashed the rope tails around the yard.  and through a lacing eye on the side of the yard away from the mast. Jock Mcleod sort of gave it the nod! the advantages are cost,  flexible connection, ability to adjust the lifting point, and most importantly you can fix/replace it quickly and easily ,Tony and Sally

    On Easy Go we have round aluminum yards. We use rope slings quite successfully and they are totally adjustable and maintain the strength and integrity of the yard. I can't see any beneficial reason to make a mechanical  fitting when a sling will do the job. Easy to make and easy to repair.

    How do you secure the rope slings longitudinally so they don't slip on your yards?
  • 10 Aug 2011 15:57
    Quote
    Reply # 673262 on 672187
    Deleted user
    TONY AND SALLY SUMMERS wrote:Totally agree with Kurt`s analysis, and solution. On Ron Glas we removed the sling plates as they were all but worn through. we then spliced  a long rope to a large thimble and lashed the rope tails around the yard.  and through a lacing eye on the side of the yard away from the mast. Jock Mcleod sort of gave it the nod! the advantages are cost,  flexible connection, ability to adjust the lifting point, and most importantly you can fix/replace it quickly and easily ,Tony and Sally

    On Easy Go we have round aluminum yards. We use rope slings quite successfully and they are totally adjustable and maintain the strength and integrity of the yard. I can't see any beneficial reason to make a mechanical  fitting when a sling will do the job. Easy to make and easy to repair.
  • 09 Aug 2011 11:59
    Quote
    Reply # 672253 on 668822
    Anonymous member
    My plan has been to use a through bolted eyebolt with 10mm plywood gussets either side of the yard where the bolt will go through.
    As for chaffing I have have quite a lot of 3/4" black poly pipe and softer reinforced garden hose I can use.
  • 09 Aug 2011 09:47
    Quote
    Reply # 672206 on 668822
    Anonymous member
    As for whether an epoxy bonded U-bolt in blind holes will fail on a wooden yard, I'll have to wait and see.

    I've used a 10mm diameter stainless U-bolt with the legs penetrating to within a few mm's of the yard's underside. I was considering drilling right through and backing up with nuts, but from previous experience felt that it wasn't neccessary. As mentioned before I've heavily sheathed the yard in unidirectional glass/epoxy on all four sides, plus a 'bandage' of glass tape/epoxy around the mid point where the U-bolt is mounted, so I doubt if it will break.

    I'll paint the yard white, which, as I noticed previously when cruising the Caribbean, minimizes the risk of epoxy melting. I would also add that my boat is very small, with somewhat overbuilt spars and fittings, and what works for me might not scale up successfully when addapted to bigger boats with much higher loadings and stress. I think a webbing or rope strop arrangement would be my choice for a large boat's yard sling.
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