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I am wanting to replace the shroud tensioning with turnbuckles, as the boat is new to me, and the PO had the mast reversed when trailering, none of the shrouds were connected . i can do a guesstamate of the length of the turnbuckle, but would appreciate a seasoned response. what length and size of turnbuckle should i be looking at for my Mac 25.

thanks

I know I'm going to get some flak for saying this, but I use the 5/16" turnbuckles from E-rigging for my 26C and in some cases I use the 1/4" ones. Like these:
https://www.e-rigging.com/five-sixteent ... turnbuckle
The reason I'm reluctant to advise you to use them is because I "had to." The PO took the stock plate adjusters off, cut them into pieces, then used the pieces in conjunction with these turnbuckles to get the correct length on the shrouds. Yes, the result is part metal plate adjuster, turnbuckle, then another cut off piece of plate. I have since replaced them with the turnbuckles in the link exclusively (I cut away all the remnants of the plate adjusters), but there is more trouble. The locknuts on the threads not only add unwanted tension to the turnbuckle threads and can weaken the link, but the nuts back themselves off CONSTANTLY while trailering and even on the water! And yes, I lock them down using pliers and a wrench and it still happens.
The solution is to use turnbuckles that are strong enough (look at the WLL) and that are secured in length with a pin or something. I'm guessing you are like me and that you want to be able to adjust the tension of the standing rigging on the fly (or at least on the trailer). I should buy new plate adjusters and live with it, but that would also mean buying all new standing rigging since the stock plates are seized in the thimble of the necopress and cannot be added after the crimps are made.

Is there any reason you could not double nut the turn buckle? Tighten the first nut to lock the turn buckle on each end the turn a second nut against the first nut to lock the first nut and turnbuckle overall. I did that with my steering tie bar on my M years ago after the lock nut walked off the tie bar bolt. Now I use a combination of Nylock followed with a lock nut against the nylock to neither can walk off.

I don’t adjust the rig on the water, or on the trailer; other than the annual check.

I would set it up like you like it and try some Loctite on the jamb nuts.

Seems a waste to go get all new standing rigging to go back to plate adjusters.

I would make sure you have good quality turnbuckles with adequate WLL and stick with the turnbuckles. Plate adjusters aren’t really as user-friendly as turnbuckles - in my opinion.

1st Sail wrote: ↑Sat Apr 22, 2023 8:38 am Is there any reason you could not double nut the turn buckle? Tighten the first nut to lock the turn buckle on each end the turn a second nut against the first nut to lock the first nut and turnbuckle overall. I did that with my steering tie bar on my M years ago after the lock nut walked off the tie bar bolt. Now I use a combination of Nylock followed with a lock nut against the nylock to neither can walk off.

That's a great idea! I never thought about that. I'll have to buy some SS nuts at the hardware store just for that. One drawback is that the turnbuckle body would potentially have the ability to loosen itself independently of the nuts. Although the nuts would stay locked to themselves. Honestly, a tiny amount of tape would be enough to prevent the vibrations of trailering from loosening them.

Another advantage of turnbuckles is that you can loosen them to make pinning the headstay a lot easier. Then go back and tension the shrouds before sailing. My jib furler has a turnbuckle (with cotter pins) that is so deeply buried in the mechanism of the furler that its all but impossible to adjust the headstay. Turnbuckles on the shrouds are a big help.

There is a good reason why turnbuckles on stays have cotter pins in them. I have to believe that the folks that came up with that idea were well aware of the concept of a jam-nut and decided to do something else. Just sayin'.

Of course, my reference point is different. The M boat stays and shrouds should not be as tight as the other boats due to the rotating mast. So, I can see how being able to add a little slack for pinning the forestay might come in handy.

Just for chuckles, here are some shots from my neighbor’s 31 Island Packet. The back stay turnbuckles (typical of all), just have Cotter pins to keep them from backing out entirely. There are no jamb nuts (atta boy Bill). The rig tension keeps them in place (and the salt water atmosphere corrosion probably helps, too). Unfortunately, not much rig tension on the Mac when she’s on her trailer….





You could always work a Johnson lever (or two) into the rig somewhere to give you slack for pinning the forestay. That would allow you to leave your turnbuckles at the same position all of the time. Plus, it would get rid of some of that pesky extra cash that accumulates between boat projects.

https://defender.com/en_us/c-s-johnson- ... ver-14-205

For what it’s worth …

While the plate type are originally “locked on” via the thimble swag there isn’t any reason one couldn’t simply drill out/cut the plate pin if one wanted to…. A shanked bolt and by lock nut can replace the pin.

I’ve also seen turn buckles secured with circle clips through the threaded adjuster and around the turnbuckle body… it keeps the adjuster pretty much in place (within a 1/4 turn or less), avoids the sharp edges of a cotter pin tangs, are reusable and if done right can remain in the turnbuckle body so they aren’t lost or misplaced.

I’ve been told by several people that the plate adjusters are somewhat superior to turnbuckles in that once set they don’t wander like turnbuckles and are actually much stronger.

Hopes this helps some…

Best Regards
Over Easy

I've used that Johnson lever on my old trailer sailor headstay and it was a huge help. No furler on that boat though. And that boat had only two shrouds. The shrouds had turnbuckles you had to tighten by hand with a smooth body thumbscrew...it was an awful design. With the Johnson lever, I had to get a custom headstay made and it needed to be precise! The Johnson lever has only a tiny amount of tension adjustment available.

Considered adding side shroud turnbuckles, but found the stock setup was enough after adding a lever tensioner to my forestay. (same as is on the backstay)
This forced me to move the forestay connection higher up the mast to compensate for the longer forestay.
This then changed the angle of the forestay making the foresail come to the boat at a different angle.
At the moment I have pulleys shackled to the rear lifeline mountings, with the sheets outside of the shrouds, thus the closest I can sheet the foresail is at the shrouds.
Even at full deploy it looks reefed.
A whole bunch of trade-offs.