Turnbuckle choices

[Peter]

I'm slowly going over my standing rigging (all metric, but I'll keep this in inches), with the intention of replacing the whole works sometime in the future. All my wire is the same size (3/16") and is probably the original stuff. No sign of cracks in the swage terminals, and not a hint of corrosion on the wire ... just nice shiny stuff with no meat hooks, so I'm not rushing this.

I plan to use Dyform wire and Hayn Hi-Mod compression fittings.

Meanwhile, I'd like to carry a spare wire and two compression eyes and a compression stud in case of a failure anywhere. This would work well, as all my stays have eye terminals and are connected to jaw-jaw turnbuckles ... except the head stay which has a 3/8" - 24 turnbuckle stud on the lower end.

On measuring wire sizes, thread sizes, and pin sizes, I discovered all the eyes at the end of the wires have 3/8" holes. At the top of the shrouds/stays there is a corresponding tang or toggle with matching 3/8" pins.

However, at the bottom of the stays all the jaw-jaw turnbuckles have 5/16" holes and 5/16" pins through the 3/8" eyes.

The lower end of the turnbuckle is pinned to the chainplate, which is a 5/16" rod bent in a loop. (See picture).



My dilema is whether to up-size my turnbuckles to 3/8" pins to match the 3/8" eyes, or stay with 5/16" pin turnbuckles and downsize the new eyes to 5/16". Is there any sense in up-sizing when the chainplate is only 3/16"?

Also, most newer boats I see have a toggle at the bottom of the turnbuckle and a turnbuckle rod swaged at the top of the turnbuckle. Is this better than the jaw-jaw turnbuckle, or just a cheaper way to do it?

As always, I'm open to all opinions and suggestions :-)

[LazyGuy]

Peter,

As a minimum I would replace the upper portion of the turnbuckle so that you are matching the 3/8" eye with a 3/8" turnbuckle and pin. A pin that is smaller than the hole creates a point load on the rigging. All of the load that is normally distributed over the surface of the pin is concentrated at one point on the pin. If you don't have a catastrophic failure of the rigging, you will elongate the holes in the terminals and make additional weak points.

As far as the prudence in up-sizing the rigging, my opinion is to not do it. The mast, rigging and chain plates are a system. If you up-size the rigging, you take a chance of over stressing the other components and it is easier to replace a shroud than a chain plate or a mast.

[kristian]

Why Dyform?

If using Hi Mod fittings, be aware that they don't yet make a comp. eye fitting for 3/16" wire with a 5/16" (MS) pin. You can get a swaged aircraft eye for that, but that kind of defeats the self sufficiency aspect. So I would think 3/8" turnbuckles are a better fit.

It looks like those are 5/16" studs in the turnbuckles, which rules out an easy swap of the forks for 3/8" size.

If this were me I would replace with 3/8" size turnbuckles, and more importantly go with a toggle at the bottom end, as forks tend to bind when articulated. That would be an even bigger concern for me, although I'm not sure how much side/side play that loop chainplate gives you. You could use a turnbuckle like Hayn's 38TFBJ.

[Figment]

3/8" screws on the cap shrouds for an Albin Vega?

Are the 1/4" on my Triton grossly undersized?

[Peter]

It looks like those are 5/16" studs in the turnbuckles, which rules out an easy swap of the forks for 3/8" size.

They are actually 3/8" 24 studs.

3/8" screws on the cap shrouds for an Albin Vega?

It's the "One size fits all" philosophy .... good sense for the spare parts department.

Why Dyform?

316 stainless with 30% more strength and less stretch for the same size wire, at about $1 a foot extra. And the peace of mind when I finally get the time to circumnavigate ... Vancouver Island, that is :-)

[kristian]

Since the turnbuckle body is 3/8" you can swap out the ends for threaded toggle jaws. These would give you the 3/8" pin size and a toggle instead of a fork. IIRC the hayn part is 38TJRH or LH (right and left hand threads) and each costs around $14. A new toggle/toggle turnbuckle would cost you around $45. Either way, this way you get the right pin size and interchangability between parts.

Only caveat would be to check the new ends length to the old. I get the feeling that the toggle jaw is longer than the fork you have now, so you'll have to take that into account when making your stay.

By the way, if you haven't already, I would pick up a couple good bimetal fine tooth hacksaw blades for cutting the dyform. They make a flatter cut than wire cutters, and don't affect the metalurgy like a cutoff wheel. It's amazing how fast these blades cut through a well taped and clamped wire rope.

[Peter]

Kristian: Good idea on swapping out the toggles on one end of the turnbuckle.
However, I'm going to replace the turnbuckles when I replace the wire, as the old ones are ... well ... old!
The existing ones are ss, the new ones will be bronze.

Using all Hayn hardware, my plan (today) is to replace the stays, starting from the top, with:
3/8" pin compression eye
5mm Dyform wire
3/8" compression stud
3/8" jaw-body open turnbuckle

Using the compression stud instead of an eye and a jaw-jaw turnbuckle saves about $20 a pop, and simplifies the system a bit.

Defender has the best prices I could find.

[David]

Your turnbuckles appear to be Hasselfors. For the Hasselfors 3/8 thread size (#174-473-xx) the pin diameter is 9.5 mm. For the 5/16 thread size (174-472-xx) the pin diameter is 8 mm.

David

[Peter]

Thanks, David. The depth and bredth of knowledge on this forum is awesome!

My threads are definately 3/8" and the pins are 8mm (5/16") so I appear to have a conbobulated version. Maybe I'll re-measure those pins

(Edit) .... unless, 38 years ago, they mixed pin thread sizes ... who knows?