Not a simple matter of new for old

[ribbony]

Ummmh, it now gets tricky. Have found our supplier of wire and was about to get some turnbuckles. However we discovered that we had old sized Ronstan Sealoc turnbuckles that are not made any more, they only make the matching swage/thread ends for the wire with 9/16th UNF threads.

We have two choices, if we go up in turnbuckle size without changing the wire size, then we get a really heavy body on the TB with a 5/8" clevis pin that is too big for the holes in the chainplates. If we go down in size to the body with the smaller pin 1/2" then we will have some gap between the pin and the chainplate holes, the old pins were 14mm, the large option is 15.7, the smaller option is 12.4mm.

These turnbuckles are used for the cap shrouds, the lowers x 4, the forestay and the backstay.

The heavier body turnbuckles are a lot more expensive (+ 60%), the chainplates would have to be drilled out, that is not ideal as some can not be got to with a drill.

If we used the smaller pins than perhaps we need to use shims on them to fill the gap in the chainplate.

Or we could use the small pins in the big holes, however from what I could find googeling was that option is not recommended.

Other option is to use the old turnbuckles with new wire and swaged/threaded attachments.

All the upper attachments (eye swages, toggle swages, etc) are 1/2" clevis pins with appropiate holes to match.

[GordMay]

Presuming your original rig (chainplates, turnbuckles, & pins) were adequately sized, you should be able to safely reduce the diameter of the piins in the larger turnbuckles, provided you install bushings to pick up the hole diameters.

I don't recall ever seeing a turnbuckle which could recieve a pin, but not be accesible for drilling. Notwithstanding, I don't generally recommend overdrilling chainplates.

[johneri1]

If it were me, and I was faced with all of what you describe, Iwould seriously consider synthetics: www.dynexdux.com
Good luck.

[ribbony]

The original rig is probably a little oversized.

What sort of material should the bushings be made from, a local yachtie suggested brass/bronze.

The bow attachment is a set of three SS plates welded in parallel to contain bow rollers for rope and chain, the inner plate has the chainplate holes for the forestay and to enlarge those holes I would need to drill holes in the outer plate first so the drill could get to the central plate. Not impossible to drill, just not ideal.

[Stillraining]

If it were me I'd drill..

However I would rather use my old TB and swaged fittings then cobbled togather with thin unreliable bushings..but I would magnaflux my TB to make sure they pass the mustard before I made my decition...If one was bad I'd drill..

IMHO if a chain plate can't be uped one miesily hole size with out ruining its integrity its the wrong chain plate in the first place.

Magnaflux/Itw SK-416 Dye Penetrant Kit

[ribbony]

Dye Penetrant testing is certainly prudent, I will have to see what is available in Oz for this sort of testing.

[ribbony]

Here is a link for dye penetrant supplies in Oz:
::: Russell Fraser Sales Pty Ltd :::

[harlaken]

Not knowing anything else about your boat I'm going to assume you have 5/16" wire. The convention would be to go with a 5/8" pin but it's not absolutely necessary. If your forestay carries a 1/2" pin at the masthead then you gain absolutely nothing by going bigger at the bottom so I'd say go for the smaller less expensive and rig-consistent 1/2" turnbuckle. Now to address your stem-fitting. The point of a closely fitting pin is to provide as much surface area to surface area and distribute that load evenly. A bronze bushing will achieve that goal nicely IF you can find one that fits both your 1/2" pin and your (probably) metric hole. If not, you can make your own bushing or shim from a thin piece of stainless that you trim to shape with tin-snips and then bend around your pin. Set the seam on the bottom. Once it's loaded up in place nothing will move.

[ribbony]

It was 5/16 wire that we will replace with 8mm.

I like the thin SS shim idea. That we can do.

I had not though about the 1/2" at the top relevant to the hardware at the bottom, I see you point.

[delmarrey]

Thin SS 316 or 304 bent would just work it's way out or even squash. I'd recommend a full bushing made of 17- 4 or 18-6, much more durable to wear and stress (aircraft SS).

But I'd drill out the chain plates. If there's a will, there's a way!

[ribbony]

Is there a need to use the largest turnbuckles on all the rig or select items.

The rig is dual spreaders. Boat 6.5 ton 35' steel cutter, about a 12mt mast.
All wire is 5/16" except for the inner forestay and upper shrouds - they are 1/4". The forestay, backstay, cap shrouds and 4 x lowers are all 5/16".

For example I would think that the caps, forestay & backstay are all needing the heavier turnbuckles, but do the 4 x lowers need such heavy gear. How much load is there on those 4 wires ?

[harlaken]

Originally Posted by delmarrey

Thin SS 316 or 304 bent would just work it's way out or even squash.

Is this theory or experience? I have some first hand with this technique, I have a bushed/shimmed merriman type toggle at my masthead (backstay) and have had no issues over 5 years now. Experience to the contrary though would be valuable. If you've had bad experiences please let me know and I'll reconsider the practice.

[delmarrey]

Being a Repair/Maintenance Machinist for more then 40 years I can visualize a thin piece of metal bent around a shaft and shoved into a hole and then applying several thousand pounds of stress with multiple back-lash. Remember, stays are not always under a constant load. They are on and off every time one tacks and literally F**k'n the hole that the pin goes threw.

I've seen it many times before where people jury rig machinery to just get a job done or out of ignorance and then later come back having to do more repair then if they had done it right the first time.

Maybe I'm reading you wrong but my experience says it's a no-no to use any thin walled bushing for a side load, especially a split bushing. What's to hold it in place. One would have to have washers tight up against each side of the hole around the pin for me to even consider a jury rig. ☠ IMHO

[harlaken]

Your shrouds should always carry some load. If your leeward shrouds are slack then your rig isn't adequately tensioned and you are shock loading those stays. The exception to that is a racing boat where sail shape takes precedence over rig longevity. As for washers holding the shim in place, that is the function of the two sides of the toggle. I'm not advocating something simply wedge in to place and not held there. What I'm describing (or at least attempting to) ends up being a captive piece.

Keep in mind also, the whole point of a bushing is to distribute load and avoid a point loading scenario which causes deformation over time. Even if the completely captive shim some how works its way out it in no way affects the integrity of the rig.

[delmarrey]

I'll bow out now!