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

David Tyler wrote:The PJR yard sling is intended to be in line with the pull of the halyard, to avoid bending loads on "U" part, and unnecessary extra shear loads on the fasteners of the side plates.

I seem to remember using a boom bail as a yard sling, back in the days when I was working for a mastmaker, and had access to such things. Being able to rotate, it avoids both of those two unfair loadings. The "U" shaped bail rotated on two side plates that were riveted to the tube. 

With both, some fendering over the fitting on the mast side is a good idea, so as not to damage the mast as the yard pitches forward in a seaway. The U-bolt into the top of a wooden yard neatly avoids that possibility.

Of course, to provide an "in line" pull. (What was I thinking?)
But then, when reefed down to one panel, the canted yard sling would no longer be in line.
What about a substantial eye-bolt, instead of a U-bolt?
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?

The PJR yard sling is intended to be in line with the pull of the halyard, to avoid bending loads on "U" part, and unnecessary extra shear loads on the fasteners of the side plates.

David Tyler wrote:

Jerry Stebbing wrote:I've just finished building the yard for my new 18 ft boat. Dimensions are as per page 152 of PJR, built from laminated pine, and, to increase the stiffness, strength and durability, I sheathed the whole thing in unidirectional glass/epoxy.

I don't have access to stainless welding gear, nor the cash to pay for professional welding so I'm looking for alternatives to the fabricated yard sling plate as shown on page 154 of PJR. I like Arne's use of webbing for a mast cap but his photos don't show how webbing is used to attach a block to the yard. I presume it's just a simple strop around the yard held in place by pads or eyes screwed to the yard?

Alternatively I was considering using a large stainless U-bolt epoxy bonded in place with the hoop arranged fore and aft rather than athwartships. I've wrapped multiple layers of glass/epoxy around the yard's mid point so the U-bolt wouldn't significantly weaken the yard. Arne's Johanna seems to have a yard attachment plate running fore and aft so I guess an athwartship sling plate isn't vital.

Any suggestions would be gratefully received.

Also, would I need any fendering on the yard, bearing in mind that the mast is aluminium and the wooden yard has a generous glass sheathing, and I'll be attaching the sail with rope lashings rather than slides and track.

I'd go for the large U-bolt, bonded into blind holes by the WEST method, Jerry. I think this is probably the easiest thing to do on a wood/glass yard. The webbing loop method will be preferred on an alloy tube yard, where it's more difficult to fix strongly to the metal tube wall. 

You'll need some yard fendering, to protect the lashings, and to protect the mast finish - avoid scuffing the surface of an alloy mast, if you possibly can. PJR recommends dinghy fendering. A piece of flat or half-round plastic bar would be my favourite, screwed down over the lashings; with lashings, it's not possible to bond on a fender of leather or thin plastic.

Many thanks David,

I've previously had great success using the epoxy bonding technique for attaching all sorts of metal fittings, winches etc to wood decks and spars, so I'll have no worries about the U-bolt pulling out or creeping under strain.

Thanks to the internet there are now several engineering plastics suppliers in the UK happy to accept small orders, and at very reasonable cost, so sourcing the yard fendering will be easy. A bit different to the old days where your 'friendly' local engineering shop charged a fortune for an offcut of nylon that cost them pence.

I've just finished building the yard for my new 18 ft boat. Dimensions are as per page 152 of PJR, built from laminated pine, and, to increase the stiffness, strength and durability, I sheathed the whole thing in unidirectional glass/epoxy.

I don't have access to stainless welding gear, nor the cash to pay for professional welding so I'm looking for alternatives to the fabricated yard sling plate as shown on page 154 of PJR. I like Arne's use of webbing for a mast cap but his photos don't show how webbing is used to attach a block to the yard. I presume it's just a simple strop around the yard held in place by pads or eyes screwed to the yard?

Alternatively I was considering using a large stainless U-bolt epoxy bonded in place with the hoop arranged fore and aft rather than athwartships. I've wrapped multiple layers of glass/epoxy around the yard's mid point so the U-bolt wouldn't significantly weaken the yard. Arne's Johanna seems to have a yard attachment plate running fore and aft so I guess an athwartship sling plate isn't vital.

Any suggestions would be gratefully received.

Also, would I need any fendering on the yard, bearing in mind that the mast is aluminium and the wooden yard has a generous glass sheathing, and I'll be attaching the sail with rope lashings rather than slides and track.