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Old 04-05-2015, 06:41   #1
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Hidden downside in beefing up new shrouds?

I'm working on replacing the shrouds and backstay on my Pearson 26 and I'm wondering if it makes sense to go up one diameter for overall strength and longevity, from 3/16 to 1/4. It has nearly twice the breaking strength but it's not that much more expensive.

A friend advised against it on the theory that you don't want the "weakest link" to move elsewhere on the boat, like the chainplates or bulkheads. I get this, but standing rigging is not like a shear pin and losing a rig is not exactly a small deal. Additional weight aloft and windage seem like they would be relatively insignificant on a rig this size.

I sail my boat a bit harder and farther than most P26s probably are. The original designers wanted 3/16 for a reason of course, but if part of that reason was cutting costs, would it make sense to beef them up bit now?

Any thoughts? Thanks in advance.
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Old 04-05-2015, 06:48   #2
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Re: Hidden downside in beefing up new shrouds?

I would be cautious about adding extra weight aloft.
While the weight increase may seem small, it has a big effect due to the leverage effect of the mast.

Someone else may be able to post real figures of the effects of added weight aloft.
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Old 04-05-2015, 07:03   #3
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Re: Hidden downside in beefing up new shrouds?

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Originally Posted by Wotname View Post
I would be cautious about adding extra weight aloft.
While the weight increase may seem small, it has a big effect due to the leverage effect of the mast.

Someone else may be able to post real figures of the effects of added weight aloft.
1/4" wire will be about 70% heavier than 3/16".
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Old 04-05-2015, 07:04   #4
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Re: Hidden downside in beefing up new shrouds?

Keep in mind that when you go up a diameter in rigging, other components change size too. larger turnbuckles = larger pins = changes to tangs and chainplates. its system. changing just 1 component moves the weak point somewhere else.
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Old 04-05-2015, 07:11   #5
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Re: Hidden downside in beefing up new shrouds?

...adding extra weight aloft...


I'm betting that you will hear/see (probably theoretically correct?) this comment a lot, as with the requirement to keep the rigging as the weak-point; however:


On our first boat (a 27' Albin Vega) I had exactly the same thoughts/concerns as yourself and for exactly the same reasons; the boat's rigging was due for replacement and it was 'standard' rigged with 5mm wires and a 6mm forestay (actually, I think even the forestay was originally 5mm, but increased to 6mm when the roller-reefing had been fitted?) Anyway, I chose to ignore the nay-sayers and re-rigged the whole boat using 6mm wire and new bottle screws; we never noticed any difference whatsoever, due to the increased weight/windage (I doubt the weight increase was more than about 5kg anyway!) But we did feel a lot more secure on those days when we were well offshore (indeed inshore too) and taking a battering from the wind and seas.

As part of the re-rigging process, do make the effort to check all the chain-plates too and replace any of those that look even vaguely suspect; we found one (a very minor water leak, but 30 years old and in exactly the wrong place).


In conclusion, I would report that I have no 'formal' qualification whatsoever for giving this advice, other than 'having done it myself'!
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Old 04-05-2015, 07:45   #6
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Re: Hidden downside in beefing up new shrouds?

Personally I would not upsize, and not because of the weight issue per se.

Your boat is only 26'. I'm going to wager that, if the spec'ed rigging is in good shape, that your boat will get knocked down before you'd have a wire failure. 1/4" on that boat seems like serious overkill for no real benefit. Rigging that you have confidence in, provided it's properly designed for the boat, is more a matter of it being in good shaped and replaced on a conservative schedule than it being oversized, IMO. Save your money now and put it towards refreshing the rigging when it needs it.

And what does "a bit harder" mean, in your case? Offshore in squalls? More frequently than the average weekender? Frequently over-powered because you like heeling a lot?
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Old 04-05-2015, 08:21   #7
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Re: Hidden downside in beefing up new shrouds?

I own a P26. Hull #49. The rigging on her is original to 1970.

I have noticed that on later P26s, the standing rigging was much smaller in diameter. The forestay on #49 is of such a diameter that one could lift the whole boat by just that stay.

So all these comments about extra weight and windage are from people that never owned a Pearson 26 or didn't know that the early models had much beefier rigging.

Don't know about the "weakest link" theory, if Pearson didn't downsize the two chainplates, there shouldn't be any issues with a upsize in the standing rigging.

I always thought that Bill Shaw authorized smaller stays, 1. to save production costs and 2. the rigging was overspeced to begin with.

These boats are pretty indestrucible. I always apologize when I hit a rock...to the rock.
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Old 04-05-2015, 08:34   #8
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Re: Hidden downside in beefing up new shrouds?

Aside from considerations of weight, bigger diameter wire will need more tension applied toit achieve the same mast support result I believe, thus putting more strain on the hull. I'm not an engineer but that was what I was told many years ago when I too considered upping the dia on a re-rig. Atthat time it was suggested I used same diameter but dieformed wire which was much stronger with no increase in weight or diameter. Is dieform wire even available now?
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Old 04-05-2015, 08:48   #9
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Re: Hidden downside in beefing up new shrouds?

For reference, the rigging on my 30 ft 10K lb. Pearson Wanderer is 7/32. 1/4 is what you would find on an even bigger boat. It's massive overkill for a 26. Just stick with the 3/16, it'll be cheaper and you will avoid any number of complications, minor and otherwise.
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Old 04-05-2015, 09:09   #10
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Re: Hidden downside in beefing up new shrouds?

One 3/16 wire will lift 90% of your boat's entire weight. That's several times more tension than you will ever see while sailing. I'd stay with that. Do check the chainplates.
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Old 04-05-2015, 09:10   #11
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Re: Hidden downside in beefing up new shrouds?

I don't think the extra weight or windage should be an issue as the difference is so small in these diameters.

But, there is something very important to consider:

The shrouds should be tightened to 15 % of their max. breaking-strength. In general the max. breaking-strength of 1x19 stainless wire would be:
3/16 at 2.100 KG
1/4 at 3.020 KG

Because they have to be tightened to 15 % of their max breaking-strength, beefing up the shrouds from 3/16 to 1/4 increases the pull between the mast-fitting and the chainplates by 138 KG on each side and, increases the pressure of the mast itself on the keel by 276 KG.

You need to find out if the fittings on your mast where the shrouds are attached, your chainplates and the step for your keel are built heavy enough to be able to cope with these extra forces.

Cheers Dody
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Old 04-05-2015, 09:18   #12
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Re: Hidden downside in beefing up new shrouds?

Sounds like we're nearing a consensus here, thanks guys.

When I say 'harder and farther' I'm mainly referring to some near-coastal passages from Boston across the Gulf of Maine, and at least a couple thousand sea miles per year. I'm just assuming that most P26s don't do this, but I reef early and often and I don't race the boat, so maybe there is nothing out of the ordinary here as far as demands on the rig.

I replaced the chainplates a few years back and I don't plan on doing so again, so making sure all the pin sizes are correct could indeed be an issue with larger shrouds.

If they were considered undersized to begin with or if there weren't any weight/compatibility considerations it might be worth it, but as it is I guess I'll stick with the 3/16th. Thanks!
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Old 04-05-2015, 09:27   #13
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Re: Hidden downside in beefing up new shrouds?

Quote:
Originally Posted by Dody View Post

Because they have to be tightened to 15 % of their max breaking-strength, beefing up the shrouds from 3/16 to 1/4 increases the pull between the mast-fitting and the chainplates by 138 KG on each side and, increases the pressure of the mast itself on the keel by 276 KG.

Cheers Dody
Yes this is a big issue that I had not really considered; thanks for doing the math. (that's why I love this forum)

The mast is deck stepped and the deck is supported with wooden compression posts, so at some point I would indeed start caving in the deck.
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Old 04-05-2015, 09:42   #14
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Re: Hidden downside in beefing up new shrouds?

Quote:
Originally Posted by Dody View Post
I don't think the extra weight or windage should be an issue as the difference is so small in these diameters.

But, there is something very important to consider:

The shrouds should be tightened to 15 % of their max. breaking-strength. In general the max. breaking-strength of 1x19 stainless wire would be:
3/16 at 2.100 KG
1/4 at 3.020 KG

Because they have to be tightened to 15 % of their max breaking-strength, beefing up the shrouds from 3/16 to 1/4 increases the pull between the mast-fitting and the chainplates by 138 KG on each side and, increases the pressure of the mast itself on the keel by 276 KG.

You need to find out if the fittings on your mast where the shrouds are attached, your chainplates and the step for your keel are built heavy enough to be able to cope with these extra forces.

Cheers Dody
Can you provide a source for the 15% breaking strength?

While we have a much different boat, the manual for ours states a load in pounds of tension, not a percentage of breaking strength.

Are you maybe confusing an idea that you don't want to "exceed" 15% of the breaking strength?

To the origianl question: It sounds like the original spec was overbuilt and no one has brought up a history of failures on these boats, so it's likely a waste of money.
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Old 04-05-2015, 10:07   #15
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Re: Hidden downside in beefing up new shrouds?

I would not worry about the rigging size, unless you increase the sail area. Then the compression forces increase drastically. To the point that you can pull the bulkheads off the boat bottom. Additional tabbing would be required. BUT the shaft for the rudder on a number of those 26's were aluminum. Have seen quite a few that have sheared off. And while the Pearson 26 is a true coastal cruiser, if you can't steer her, well you know !!!
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