Please don't use a rope around the limb! There is no way to do that without seriously and permanently damaging the limb. The best way to do what you want to do is by using eye bolts with large washers to suspend the swing.

You will want to make sure the eye bolts have threads longer than the limb is thick because you will need to use a large flat washer, a lock washer, and a nut on both the bottom and top to properly secure the eye bolt to reduce motion that will further damage the tree. Drill a hole just large enough to fit the eye bolt through the limb. Carve the bark and cambium away just under where the washers will touch the tree limb so that the washers are embedded down in the bark and cambium layers. The washers should rest solidly against the sapwood. If carefully trimmed, the cambium and bark will quickly grow around the washers and nuts and seal off the wounds lessening the chance of decay. Tighten the nuts down firmly but not enough to significantly compress the wood.

If properly installed chances are good that little damage will result. I hope I have been clear with my instructions, but if not, or if you have questions, let me know.

Just in case you thought about it, DON'T use any type of sealer. The tree will take care of sealing itself much better than you could. If you really really really wanted to, you could use a liquid copper fungicide (not a powder mix) on the area after a few months when the wound is completly dry to further reduce the chance of decay. Applying this about once a year starting at least a few months after the cuts have been made (when it is completely dried out) and continuing for two or three years (until completely healed over) would be the ultimate in nursing your tree back to perfect health.

Believe it or not, this/that (drilling and using eyebolts - that's how the A-frame originally had it suspended, though those were much shorter) was initially what came to mind. But I became concerned about drilling directly through the limb's layers - through the heart if you will - and that causing the limb to outright die on me. Do you think drilling two holes through the limb would damage it too much initially to survive? My next question about this scenario is on the matter of causing the limb to crack or split or otherwise damage it in a way that would prevent it from surviving or then being too weak to withstand the weight.

The swing isn't likely to be used on a daily basis and I can make it off-limits for some length of time if need be for healing. Would that be of any consequence in aiding the healing or a moot point?

There are 2 ways the limb might be damaged by something like this. The first is mechanical. If the limb was small, the weight of the swing could break the limb, but you said the limb was large enough to support the swing. Drilling the holes will make the limb weaker, but if it's a large limb, the effect of the holes will be negligible and will not significantly effect the limb's strength or cause the limb to break.

The other way the limb might be damaged is by decay setting up in the area around the hole. Trees, in most cases, are able to compartmentalize damaged areas and block decay from spreading. Also, when the damaged area is "healed over", the covering will tend to block further decay. By installing the washers as described in my previous post, the tree will be able to start the "healing" process almost immediately. With clean neat cuts, the area should cover over in 1 to 3 years depending on the type of tree. When the tree grows around the washers and nuts, this will further increase the mechanical strength around the eye bolt and decrease the likelihood of problems. Ideally, not allowing the eye bolts to move any until the healing starts to cement them in place would be a good idea, but I don't know if the small possible benefits would outweigh the lack of being able to use the swing for a year. If you did decide to wait that long, install the eye bolts, but don't install the swing until the following year. Wind could cause the swing to move just as a person swinging.

Two other little details I thought of this morning are...Check to make sure the nuts are tight after a few months and again after about the first year. And, if you do decide to use the liquid copper fungicide (to eliminate possible decay), only apply a small amount. A little won't hurt the tree, but if you caked it on in multiple coats, it might be mildly toxic to the tree. Let me know if I left out any more details or if you have further questions.

As soon as I get a ladder over here (it might not go high enough) or a relative with the tractor with the front-end loader to boost me up there (or someone less inclined to vertigo), I will probably aim to measure the limb in key spots first, and mark it off with ribbon or something. I don't recall exactly what type of Oak it is now - there's several different types on the property, but knowing the type would I think help to discern the strength from whatever data is out there. I'm sure someone has tested this stuff!

I can "easily" wait a year to actually suspend the swing after the limb has been drilled, bolts inserted, boo-boos treated, and testing/tightening as needed. I had the swing for at least a year before I got the idea to look for "just the right spot" WITH "just the right limb" - took me a year or more to find that (because I got hung up on "a perfect limb" that is on a great tree, but a completely lousy location to have a swing unless totally intended for aesthetics alone) and then more wandering around the spot to feel certain I had some idea of how I'd "work" the area/landscape it. There's underbrush and saplings to remove and I need to decide ahead of time if I should go ahead with a different type of fence to replace the field fence that is at the "back" of the area. (Eventually I want to replace the field fence on two sides with something sturdier and possibly more visually appealing, but that's like close to a thousand feet of fencing sooo....) It also gives me plenty of time to pressure-wash the swing, get it well dried, get it to soak up some Thompson's water-seal, possibly replace at least two known broken slats or just repair them with wood glue - who knows, maybe even paint it or "decorate" it - whatever. In summary, it won't kill me to wait a year or more longer.

Now I just wish I had stepped up and asked about this earlier in the year - when I could have done the drilling before the "sap had started to flow".

I wonder if TSC will have bolts long enough for this or if I'm going to have to go searching around one of these old-old tractor/hardware stores in the middle of nowhere. :)

I would think that even Lowes or Home Depot would have the eye bolts you need, but I would never pass up the opportunity to explore an "old-old" hardware store. I get excited just thinking about it.

"Tool Time" Brandon