When is rigging too big?

[hellosailor]

I suspect that Ericson properly sized the rigging, and has been noted, the real problem is that you are trying to get 30 years out of standing rigging. The rule of thumb is ten years, no more, and some insurers will cut you off at some point after that.


if you stick to a conventional rig instead of trying to "penny wise pound foolish" get away with extending the life by allowing heavier rigging to corrode longer...you'll probably do just as well with the conventional rigging.
And hey, maybe in ten more years, one of the fibers (dyneema, etc.) will be so highly competitive and superior in strength that wire will be obsoleted anyway.
You know. What's the long term difference in annual expense if you "only" get ten or fifteen years off the next rig? A killer?

[Adelie]

Upsizing the rigging a small amount would be pretty reasonable provided you can do so without wholesale replacement of related hardware: tangs, turnbuckles, chainplates.

1). If your boat was designed for inshore or protected waters and you are now sailing offshore then you are exceeding the designers assumptions when the rig was designed.

2). Going up one size the change in weight of the wire is minuscule.

3). Even if the change in weight of the wire et al is significant (5% or so of total mast weight) the affect on the boat will be a mixed bag. The boat will be slightly more tender, you might have to reef in several knots less wind than previously. On the other hand it will be somewhat more resistant to breaking wave capsize via the increased roll moment of inertia. This is a bit counter intuitive but the science is pretty clear the boat will be slightly safer in that regard.

4). If you do roll the boat you are more likely to come back up with all or part of the rig.

5). If you do upsize, the preloading of the rigging needs to be to the same absolute loads ( pounds or newtons of force) as the original not the same relative load (percentage of wire capacity) or you will start overloading other parts of the boat.

6). Upsizing will allow you to change to A316 SS which will last better in warm climates.

7). Most importantly upsizing will give you peace of mind.

First thing to check is whether upsizing the wire will require upsizing the tangs, pins, turnbuckles and chain plates. Anything evenly matched to the wire will need to be up sized too. To check you will need to get a micrometer to check thickness of tangs and chainplates and how much meat there is around pin holes. Then you need to research capacities of the materials used. Various design books have the relevant charts.

If you do wind up needing to replace the other hardware then it become a matter of how much needs to be replaced and what can you afford.

[UncleIroh]

Originally Posted by hellosailor

I suspect that Ericson properly sized the rigging, and has been noted, the real problem is that you are trying to get 30 years out of standing rigging. The rule of thumb is ten years, no more, and some insurers will cut you off at some point after that.


if you stick to a conventional rig instead of trying to "penny wise pound foolish" get away with extending the life by allowing heavier rigging to corrode longer...you'll probably do just as well with the conventional rigging.
And hey, maybe in ten more years, one of the fibers (dyneema, etc.) will be so highly competitive and superior in strength that wire will be obsoleted anyway.
You know. What's the long term difference in annual expense if you "only" get ten or fifteen years off the next rig? A killer?

Actually I'm not trying to get 30 years out of the rig. The last few owners were. I'm trying to replace it and get 5 years give or take. The only reason I didn't replace it all when I bout it is because I got the boat for such a steal I just figured I would have as much fun with it as I could before the mast went into the drink and then give it away. I had no idea I would fall in love with it. Now I would like to get 30 years out of the chainplates and tangs. And I think that is achievable with frequent enough polishing to keep rust away. And 10 years from the turnbuckles and pins would be nice. But I really wouldn't mind changing the wire or synthetic every year or two. Cost is not even an issue here I'm going to be redoing everything on this boat this year. I'm not looking for the cheapest way I'm looking for the best way. I have no intention of letting a heavier rig corrode longer... That sounds plain stupid. If my rig starts to corrode it will be replaced

[UNCIVILIZED]

Brion Toss's book, which I, & several others have been steering you towards, will explain a Lot; about rigging, & especially, as you say, how to "do it right".
And regarding the book, as it relates to your rig, & upgrading things. You'll really only need to read a few of the chapters, targeted towards what you're doing. For it to be a big help.

Also, if you want "The Full Monty", then pick up the Dashew's books. At $70 for the set, it's a pretty good deal. Especially given that when their Offshore Cruising Encclopedia, vol II first came out, it cost over $100.
SetSail » Products
The Cruising Encyclopedia alone, is almost 1,300 pages... chock full of knowledge on boats. The kind of stuff which it' take you 20yrs of sailing full time, professionally, to learn. And you can find it, by it's self, for like $15-$20 on Ebay, etc.
That, & you can download several of their books, in PDF, for free.

The reason I'm mentioning them, & their books. Is that they go into a Lot of detail about boat design, rig design, sizing components, how everything on a rig also is an integral part of the boat's design, & vice versa. Plus a lot more. So it'd likely be of help to you.

Though I'd suggest getting Brion's book now, ASAP. Such that you can have a reference on hand which covers how to build a rig, & the why's behind everything.

[roverhi]

Originally Posted by Jim Cate

Re use of 3/8 " chainplate stock: be sure that the bottom fittings (fork or toggle usually) will fit over the thicker material.

And the suggestion to stay the same size but to go to Dyform or Compact strand wire is a good one. The fittings are all the same size, but the wire is significantly stronger.

Jim

His boat is only 25' so 3/8" chainplates are way overkill.

Dyform wire is actually almost the same strength as 1x19 in smaller than 1/4" wire IIRC. Was going to go with 1/4" Deform wire which was the OEM size size on my boat but wasn't worth the cost or hassles to get it for the small difference in strength. Dyform is also heavier per foot than 1 x 19 because it's lay doesn't have the voids and is so compact.

As others have said, it's not visible corrosion that is the achilles heel of stainless but the areas where salt water but no air can live next to the SS like where chainplates pass through the deck and the swages. Swages are a no go for me on a serious offshore boat. They are too prone to failure and there is no way to be sure of them short of destructive testing. Mechanical terminals can be disassemble regularly to inspect the wire and reused practically forever with new wire.

[Jim Cate]

Originally Posted by roverhi

His boat is only 25' so 3/8" chainplates are way overkill.

Dyform wire is actually almost the same strength as 1x19 in smaller than 1/4" wire IIRC. Was going to go with 1/4" Deform wire which was the OEM size size on my boat but wasn't worth the cost or hassles to get it for the small difference in strength. Dyform is also heavier per foot than 1 x 19 because it's lay doesn't have the voids and is so compact.

first, I agree that 3/8 is way overkill, but he said he had the stock and was thinking about using it for fabrication, hence my warning.

And I'm not aware of the lack of strength advantage in small diameters with Dyform. From their website:

"Dyform has significantly lower stretch and a modulus value around 30% higher than conventional wire strand. Dyform strand compaction gives a guaranteed breaking load around 30% higher than conventional wire strand.

Dyform's smooth surface is attractive, and corrosion resistant.

Reels hold 100m, 250m, 500m, and 1000m lengths depending upon weight."

So I question your statement (didn't want to do all the research) since the mfg does not make that distinction. And the reason that it is a bit heavier is from the extra s/s mass in the wire... and that's why it is stronger for a given diameter.

So, I think it is worth his thinking about.

Jim

[Snowpetrel]

Originally Posted by Adelie

Upsizing the rigging a small amount would be pretty reasonable provided you can do so without wholesale replacement of related hardware: tangs, turnbuckles, chainplates.

1). If your boat was designed for inshore or protected waters and you are now sailing offshore then you are exceeding the designers assumptions when the rig was designed.

2). Going up one size the change in weight of the wire is minuscule.

3). Even if the change in weight of the wire et al is significant (5% or so of total mast weight) the affect on the boat will be a mixed bag. The boat will be slightly more tender, you might have to reef in several knots less wind than previously. On the other hand it will be somewhat more resistant to breaking wave capsize via the increased roll moment of inertia. This is a bit counter intuitive but the science is pretty clear the boat will be slightly safer in that regard.

4). If you do roll the boat you are more likely to come back up with all or part of the rig.

5). If you do upsize, the preloading of the rigging needs to be to the same absolute loads ( pounds or newtons of force) as the original not the same relative load (percentage of wire capacity) or you will start overloading other parts of the boat.

6). Upsizing will allow you to change to A316 SS which will last better in warm climates.

7). Most importantly upsizing will give you peace of mind.

First thing to check is whether upsizing the wire will require upsizing the tangs, pins, turnbuckles and chain plates. Anything evenly matched to the wire will need to be up sized too. To check you will need to get a micrometer to check thickness of tangs and chainplates and how much meat there is around pin holes. Then you need to research capacities of the materials used. Various design books have the relevant charts.

If you do wind up needing to replace the other hardware then it become a matter of how much needs to be replaced and what can you afford.

+1 this is a great post. I think upsizing the rigging is a good idea, just not oversizing it stupidly (as 1/4" would have been), which can have unintended consequences as have been pointed out.

I don't 100% trust the manufacturers and designers to always get it right, especially if you are using the boat for offshore cruising, where it might be heavily loaded in rough water and the consequences of failure are high. In this case a little bit of overspecing give good peice of mind.

Adele is right about the pretension. Say you have it currently around 10 or 15% then if you go up to a wire 3 times stronger you end up with it somewhere around 3-5% pretension. This is getting a little bit low to be sure that all the constructional stretch is out, and things might start getting wobbly.

From memory Brion Toss talks about a quick and dirty rule of thumb that the windward shrouds should have a combined breaking strain around 3 times the displacement. Very crude but it would be interesting to see some numbers.

As far as books go the best at the moment that I've found is Principles of yacht design by Lars Larson and ??... This has the full Nordic method and workings for rig design that is about as good a system as any except full FEA analysis.

It was pointed out that plastic coating can cause corrosion. Very true, don't go plastic coated wire, terrible stuff, but a loose split plastic tube that can rotate on the rig doesn't seem to cause any issues, and saves a lot of sail and sheet chafe, as well as reducing the cheese wire effect.

I like the sound of your new 3/8 chainplates, if the bottlescrews fit. If not it might be possible to grind down a taper so the toggle fits.

If the rig is that old you are probably also going to need new rigging screws, also replace the gangs and the tang bolts.

[meirriba]

Originally Posted by UncleIroh

Hello all, I just registered with this website finally but I've been getting help from everyone else's answers the past 2 years. I'm ready to replace all of my standing rigging as I have a few busted strands. The boat is an Ericson 25 fin keel. 3'8" draft 2500lbs of lead in her belly and 33' tall from waterline. She has the original size rigging of 5/32 which has been ready to go for a long time but I've still managed to abuse it and had several knockdown. I'm wanting to beef it up a lot because it scares me with the way I sail it. a lot of coastal cruising in the gulf of Mexico and tend to go out in bigger seas than I should. My question is this, is 1/4" standing rigging too big for a 25 foot boat? I don't race but maybe windage would be an issue? Anyways I unstepped my mast today to get all my measurements and will be ordering all that I need sometime before February. 3/16 seems like a more reasonable size but 1/4 feels better on the hands. Would this be too big? Also I'm still debating between 316 ss and dyneema. But either way I like 1/4. Most likely dyneema to save the weight of upsizing what do you guys think? I'll go down to 3/16 if need be but want some opinions first.

3/16 is already a 20% up from 5/32.
Check the area of the cross cut.
It will be more than enough.

[UNCIVILIZED]

Originally Posted by meirriba

3/16 is already a 20% up from 5/32.
Check the area of the cross cut.
It will be more than enough.

5/32 = 2,800lbs breaking strength
3/16 = 4,000lbs breaking strength

Thus, it's a 43% increase in strength, assuming we're talking plain 1x19 stainless. So, yeah, it should be more than enough of a step up.

[UncleIroh]

Thanks all of you so much for your help. I will definitely be buying at least a couple of the books mentioned. Also I took all my old tangs and chainplates of today to see if I could polish them out since the 3/8 is overkill. But the pitting was too bad I would have to take off too much metal. The micrometer says they are 3/16. I went ahead and ordered some 1/4 x 1 1/2 flat steel which will fit in the toggle end turnbuckles. I'll make them up when it comes in. I haven't actually ordered the cable as I need to put some more thought too it. You've all talked me out of going 1/4 but seems half of you say 3/16 will be an ok step up. I want to but I may just stick with original. I'm going to go back finishing another boat project of mine (building a power dory for bay fishing faired the frame and just stopped after that) and get back to this one after I make the new chainplates. I'll also read a book or two at work before I decide. Don't expect me to reply much very soon but I will be back on to check on activity and will definitely post what I decide on. Thanks again everyone !

[DMBOS]

So, the person, probably well educated, involved in the design of said boat - enough to be selected in the first place - and I am guessing that that the present specs of 5/32" lasted longer than others will suggest you replace your rigging anyway is somehow second guessed ??? Just replace your rigging - it obviously is appropriate. Don't over think it.

[Adelie]

Originally Posted by DMBOS

So, the person, probably well educated, involved in the design of said boat - enough to be selected in the first place - and I am guessing that that the present specs of 5/32" lasted longer than others will suggest you replace your rigging anyway is somehow second guessed ??? Just replace your rigging - it obviously is appropriate. Don't over think it.

Just because the designer may have been educated, and was SELECTED by some 'higher authority' doesn't mean they didn't make mistakes. As a construction inspector I periodically see design mistakes, some of which would have killed people. If you want an example of such a design mistake that did kill people, I35W in Minneapolis, the undersized gussets worked for 46yr then they didn't and 13 people died and 146 were injured. Something a little more current would be the water managers in Flint, MI. They are educated in what they do, were appointed by a appropriate authority and yet managed to let 15,000 people be poisoned with bad water, and for more than 1 year ignoring folks that were telling them there was a problem with what they were producing.

If the OP is concerned why shouldn't he upsize to acheive peace of mind? Is his questioning the design of his boat causing you to question yours? Is that sort of ambiguity/uncertainty something you can't live with?

[jamhass]

Originally Posted by neilpride

This question is a clasic in our rigging shop, can we upsize the gear? wire, furler, rod or whatever ... and the answer is the always the same... stick with the OEM specifications unless the change is not to big, saying that , jumping from 1/8 to 5/32 or from 5/16 to 3/8 is not a big deal on chainplates and other gear , but to much and you can overstress chainplates, tangs, etc... the turns in the screw to keep proper tension change with wire size ... Cheers.

I believe it was Brion Toss who pointed out that (assuming the original design was adequate) rigging loads are limited by the righting moment of the boat. Thus, going up in wire size does little but add weight aloft (and complexity as already stated.) Any load "over" righting moment just makes the boat roll faster.

[Jim Cate]

Originally Posted by jamhass

I believe it was Brion Toss who pointed out that (assuming the original design was adequate) rigging loads are limited by the righting moment of the boat. Thus, going up in wire size does little but add weight aloft (and complexity as already stated.) Any load "over" righting moment just makes the boat roll faster.

While I have great respect for Brion, his point of view is likely different from a "frugal" yottie. In particular, having oversized (reasonably) rigging wire can mean that they will remain serviceable longer than the canonical 10 years. Not important to Brion (in fact, interferes with his selling of services) but possibly important to the OP. Further, while the static loads on rigging are limited by the righting moments of the boat, peak loads are from a combination of righting moment loads plus inertial shock loads from falling off waves. Many rig failures have been reported when driving hard to windward in big "hollow backed" seas, and crashing down on their windward sides. A bit of extra strength could help there IMO.

However, I agree that in the OP's case, I see no need to upgrade. The long term success of the stock wire is a pretty good testimonial to the design.

Jim

[Adelie]

Originally Posted by jamhass

I believe it was Brion Toss who pointed out that (assuming the original design was adequate) rigging loads are limited by the righting moment of the boat. Thus, going up in wire size does little but add weight aloft (and complexity as already stated.) Any load "over" righting moment just makes the boat roll faster.

Assuming you got your authority right Brion is correct up to the point that the mast OR BOOM hits the water then he's wrong, all of a sudden impact loads and solid water loads get added to the equation. That also assumes the original design was adequate which again is an assumption that is not guaranteed.

Increasing wire size does not make the boat roll faster, in fact it makes the boat roll slower which is safer in breaking waves.