Rigging Size Inquiry

[Dark and Stormy]

I'm going to purchase wire and line in bulk shortly (to get ahead of myself). What diameter should I be looking at?

I think I've been able to gather that the Venture 25 was originally rigged with 1/8" 1x19 for the standing rigging, and 3/8" for the running rigging.

Ultimately it's important to me to not have to worry about the rigging, but I don't know how much is too much / overkill.

Your guidance is greatly appreciated.

[propnut30]

I'm doing the same thing, The last thing I want to worry about is an aluminum tree trunk falling on me or the kids. I was originally thinking about 3/16" but have opted for 5/32. It still has more strength than 1/8, less weight and less cost too. My fittings are all sta-loc compression fittings and real turnbuckles with toggles at the top. I think 5/32 or 3/16 will be fine. I think before those break something else, chain plates, mast, spreaders, tangs, or even the hull will likely let go. I may be wrong. No matter what you can make a Mac bulletproof, if you do it probly wont float. Defender seems to be a good source for the terminals and wire. I have caught some good prices there. I hope this helps.

Take care
Brian

[Dark and Stormy]

That is tremendously helpful, thank you!

What are you doing for running rigging? I'm leaning towards 3/8" STA-SET.

[propnut30]

Your welcome. I haven't gotten that far yet. Right now my boat is in the garage and back yard, taken totally apart for a refit. I got deployed for a year so Im using that time to buy the parts, paint and epoxy other stuff ill put in her. Ill get the running rigging last. I did target the Ronstan series 40 blocks though. Let me know how it goes.

[Dark and Stormy]

Very helpful again, thank you.

To where have you been deployed?

[propnut30]

Gardez Afghanistan, bout 60 miles from Pakistan. One month left and a i will be home and one wasted year behind me. YES!

[Catigale]

Thank you for your service Propnut.

There are some threads on this but to summarise:

Bigger isn't always better with standing rigging. It has to be tensioned to about 10% of its breaking strength to remove slack, otherwise it fatigue fails. The breaking strength of rigging goes up quickly with size, so your running tension goes up quickly too.

The attachment points on the boat are designed with this tension load in mind, but probably not 2x margins.


On edit ...my bad on next part....3/8 was for running, not standing rigging...

I'm guessing your 3/8 ringing is a typo...the SWL of 3/8 would be about 2000 pounds, the breaking load about 10,000 pounds, and the running tension about 1000 pounds.....this would neatly pull your chainplates off the boat of course.

[propnut30]

Catigale, you're welcome, and thanks. I went back and looked I didn't see a reference to 3/8 standing rigging. I think Dark and Stormy was referring to using that for the running rigging. I still have to find that out myself. I did make a buddy near Shaw AFB where, I'm going that used to sail a Mac 25, He said he would be glad to help me set it up. Thank goodness. Oh I also oreded me a copy of the riggers apprentice so that should be waiting for me when I get home too. Yea!

[Tomfoolery]

Blue Water Yachts supplies 5/32" 1x19 shrouds for the V25 and other boats 24 ft and longer, upper and lower, and 1/8" for the headstay. Just so you know. http://www.bwyachts.com

3/8" running rigging is a little large for a boat this size, IMO, though it is easier on the hands. 5/16" is what I use for everything except small control lines and spinnaker sheets.

[propnut30]

Thanks Tkanzler, I did notice the shrouds were larger than the head stay, I was wondering why that is. Anyone know?

[Tomfoolery]

Probably because the loads are lower due to a more favorable geometry for the headstay. The shrouds have to collectively (two on a side) take all the side loading, and most of the forward loading. Being swept back only a little, the forces from the foward component of the sail force manifests itself as very large tension force in the shrouds, plus the lateral component, which is what's causing the boat to heel.

The backstay will take some of that forward component, but is generally considered more of a sail trim item on a fractional rig boat. My last boat, a Hunter, had a B&R rig, in fact, which doesn't even have a backstay. I don't believe the standard has a backstay, either, but I couldn't swear to it.

Point being, the shrouds normally handle substantial load with relatively poor geometry, whereas the headstay has relatively low loading with favorable geometry, even as a solo member, hence the size difference.

[Sumner]

....Bigger isn't always better with standing rigging. It has to be tensioned to about 10% of its breaking strength to remove slack, otherwise it fatigue fails. The breaking strength of rigging goes up quickly with size, so your running tension goes up quickly too...

Cat do you have some sources for that I can read? I can find sources that say 10% is a normal safe figure to use for a certain wire size, but not that you have to run the wire there to avoid breakage. I talked to the tech guy at Loos & Co., the manufactures of the loos tension gauge, and he said that there was no problem running rigging with less than the 10% tension figure. He said that is normally the figure that you don't exceed. He said run the tension that works or is recommended for your boat and the sailing conditions up to the 10% or sometimes a little more...

http://loosnaples.com/how-tos/tension-gauges

He agreed that having the rigging tensioned properly to avoid pumping is needed, but said that tension is tension. If say 300 lb. tensions the boat rigging to avoid slack then you can use that figure for say 1/8 or 5/32 forestay equally.

We have 5/32 on the forestay and around 300 lb. on it and there is no slack or pumping on any of our rigging. When we had 1/8 for the forestay at first after buying the boat we didn't have noticeable slack at any time in the shrouds, but we still didn't have a high enough tension in my opinion. I increased the tension and it is now about the same with the 5/32 and tighter than probably a lot of Macs out there. If we went back to the 1/8 I'd have the same tension on we do now.

I think most of the Mac rigging failures are usually related to not enough tension to make it easier to pin the forestay regardless of if the forestay is 1/8 or 5/32 (not sure if I've read of any 5/32 failures). The real culprit I believe is people using a furler without toggles top and bottom, especially the top.

Two things will help to remedy this, toggles and a Johnson lever,

Sum

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[SeamanLou]

Noticed some damage on my 70 V22 at the PORT CHAINPLATE. Another "as bought" pic shows the whole thing torn out - plate, deck and hull. I would be careful about this. More important to keep them snug to prevent shock loads as you tack/gibe. They are simply bolted to the hull with 3 large screws - and they point straight up, though the shrouds angle forward.

[Catigale]

Sum...there are quite a few discussions and threads on shock loading of loose rigging, but I'll confess I can't find a good reference on this point for you. This is basic good ME though,....a load that is applied by shock (direct consequence of loose rigging) will fail components at lower loads

I talked to the tech guy at Loos & Co., the manufactures of the loos tension gauge, and he said that there was no problem running rigging with less than the 10% tension figure. He said that is normally the figure that you don't exc

How much less is the question...I don't think anyone would advocate setting it at 5% SWL....how about 7%?

Standard working loads for wire are 20% BL according to my books....