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Rig tuning advice

Alan Gomes

Sustaining Partner
In a previous thread I mentioned some gelcoat cracks I was seeing at my port side U-bolts, apparently caused by improper tensioning of the tie rod that takes the load of the upper and forward lower on that side. After confirming that the plywood (not balsa) core was dry and that the gelcoat cracks were superficial only, I overdrilled, filled, and then re-drilled those holes and reinstalled the U-bolts.. Then I set the tie rod to one full turn beyond hand tight, which is what the Ericson documentation calls for.

Now I am tensioning my rig, and I'd like to get some feedback from those of you who are knowledgeable about such things.

The Ericson tuning instructions (see attached) are a bit vague in my opinion. I tried an initial tune following those somewhat seat-of-the-pants guidelines, and I think the result was a rig that was too loose when I took the boat out under sail. So now I'm using a Loos gauge to tension my shrouds as a percentage of the wire's breaking strength. This gives me some actual numbers to work with.

My question is about the uppers and lowers. My rig has a set of inline lowers and aft lowers, besides the uppers.

Right now, I've set my uppers to about 15%, my forward lowers to 11%, and my aft lowers to 8%. Based on the Ericson document, I'm probably tighter than what they have in mind, especially on those aft lowers. According to the Loos gauge documentation, I'm (possibly) a bit too tight on the uppers, correct on the forward lowers, and loose on the aft lowers. And then, per one of Brion Toss's videos on rig tuning, I'm at the low end of what he would think is acceptable for the uppers--he calls for 15-20%--about right for the forward lowers, and loose on the aft lowers.

What do you all think? I've not yet been able to take the boat out since I reset the rigging with the Loos gauge. It will be interesting to see what the leeward shrouds look like when going to weather in a bit of a breeze. Given what Ericson says about the purpose of the aft lowers and how they suggest adjusting them, I'm thinking I might want to loosen those even a bit more, even though I don't have them all that tight if I were going by the other authorities

Thoughts?
 

Attachments

  • E26_Mast_Tuning_Specifications.pdf
    72.3 KB · Views: 13

Dave G.

1984 E30+ Ludington, MI
Every boat is a bit different but I think you are right in the ballpark with those numbers. You may have to tighten your lowers a wee bit if you keep the uppers @ 15% but you'll find out more when you take the boat out in some wind. I agree Ericson's rig tuning specs are open for interpretation & somewhat vague. Before I bought a Loos Gauge I just tightened them up with standard length open end wrenches and found it was very difficult to overtighten them without causing pain in the palms and they were pretty close to "tuned".
 

Alan Gomes

Sustaining Partner
Every boat is a bit different but I think you are right in the ballpark with those numbers. You may have to tighten your lowers a wee bit if you keep the uppers @ 15% but you'll find out more when you take the boat out in some wind. I agree Ericson's rig tuning specs are open for interpretation & somewhat vague. Before I bought a Loos Gauge I just tightened them up with standard length open end wrenches and found it was very difficult to overtighten them without causing pain in the palms and they were pretty close to "tuned".
Thanks for this.

Is your rig the same as mine, with a set of aft lowers? I’m curious how much tension you put on those, if you have a way of describing or quantifying it.
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
I think you're right that Ericson instruction for rig tuning is not too helpful, though it is a starting point.
When you head out for a sail, I would watch for and try to avoid any sideways curve or falling off to leeward in the mast. I would also want the shrouds tight enough to avoid shock loading the shrouds as you tack. The headstay should be tight enough so the furler (if you have one) doesn't bounce around as you furl the sail. The backstay adjuster should be able to be fully deployed to flatten your sail in a breeze.
I'm sure others will chime in, but these are my initial thoughts, as I sip a glass of wine. :)
Frank
 

Dave G.

1984 E30+ Ludington, MI
Is your rig the same as mine, with a set of aft lowers?
Yes I have aft lowers but they are too big for my loos gauge. let's see if I can quantify the tightness...I tightened them with a open end wrench until it became difficult to turn(kind of relative I guess). Then first time out I check for leeward slack and adjust accordingly. I like them not to show any slack in up to 16 knots but a lot of folks leave them looser. I just don't understand what good a loose leeward shroud is ? That just means your mast is leaning, out of column, or both .
 

Alan Gomes

Sustaining Partner
Yes I have aft lowers but they are too big for my loos gauge. let's see if I can quantify the tightness...I tightened them with a open end wrench until it became difficult to turn(kind of relative I guess). Then first time out I check for leeward slack and adjust accordingly. I like them not to show any slack in up to 16 knots but a lot of folks leave them looser. I just don't understand what good a loose leeward shroud is ? That just means your mast is leaning, out of column, or both .
OK. Thanks.

I think Ericson‘s point in that document is that the fwd lowers are there to limit the forward bend of the mast at/below the spreaders rather than attempting to keep the mast in column, which the in-line lowers would help to do. I’m supposing that is why they say they are not concerned about those going slack, whereas the uppers and the forward lowers should not be so loose on the leeward side. At least that is how I am reading it. But I am not certain what that translates into exactly as far as a specific tension goes.
 

Alan Gomes

Sustaining Partner
Yes I have aft lowers but they are too big for my loos gauge. let's see if I can quantify the tightness...I tightened them with a open end wrench until it became difficult to turn(kind of relative I guess). Then first time out I check for leeward slack and adjust accordingly. I like them not to show any slack in up to 16 knots but a lot of folks leave them looser. I just don't understand what good a loose leeward shroud is ? That just means your mast is leaning, out of column, or both .
Also, I’m curious as to why your after lowers would be too large for your gauge when apparently your other shrouds are not. If anything, I might expect your uppers to be larger than your lowers.

On my boat the shroud diameter is the same throughout, with the exception of the backstay bridle. That is to say, 3/16 of an inch.
 

Dave G.

1984 E30+ Ludington, MI
Also, I’m curious as to why your after lowers would be too large for your gauge
My aft lowers are 9/32, Upper 1/4", Intermediates 3/16". Unfortunately I would need a second Loos to cover all which I'm probably not going to buy. Also most of the info available out there is for masthead boats and fractionals are a different animal.
 

Alan Gomes

Sustaining Partner
My aft lowers are 9/32, Upper 1/4", Intermediates 3/16". Unfortunately I would need a second Loos to cover all which I'm probably not going to buy. Also most of the info available out there is for masthead boats and fractionals are a different animal.
That's interesting! I wonder why your aft lowers would be so large? 1/4" sounds right for the uppers for that size boat.
 

Dave G.

1984 E30+ Ludington, MI
Here is a document from Ericson I found in the books I got when I purchased my boat. It's pretty specific and talks about a pretty "loose" rig. I did try this method and did not like the result at all. Problem with all these is what is or who is defining loose and tight. It's good read though.
 

Attachments

  • E30+Rig Tune.pdf
    221.1 KB · Views: 8

Alan Gomes

Sustaining Partner
Here is a document from Ericson I found in the books I got when I purchased my boat. It's pretty specific and talks about a pretty "loose" rig. I did try this method and did not like the result at all. Problem with all these is what is or who is defining loose and tight. It's good read though.
Thanks!
 

Alan Gomes

Sustaining Partner
I can see it for a headstay. But for an aft lower?
My curiosity got the best of me so I took a look at Standing Rigging Specifications for the E30+.

They did indeed call for 9/32" on the aft lowers. (I didn't doubt that yours had them, but was wondering whether that might have been the result of a previous re-rig rather than factory spec.) Interestingly, though, your rig differs from mine as far as the lowers go in that those are the ONLY lowers on your rig. That is, it shows "none" both for Fwd. Lowers and In-line Lowers. My rig has both inline and aft, so the tuning for our boats would differ. I wonder if the single set of aft lowers is what accounts for the larger diameter?
 

Brad Johnson

Member III
Alan, do you have a backstay adjuster?? If so I would keep the rears fairly loose , I pretty much stop once the stay straightens with tension, this allows the midpoint of the mast toned forward flatting the main, I inly tighten the uppers and inner stay for racing in 15 knots true or more , I also have running backstays for upwind in 10+ knots of true wind
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
I sent a thread link to a friend and professional rigger for comments.
His comments seem useful and even a bit wry, and do indicate that tuning is not, IMHO, completely a science.
There seems to be some 'art' in it, too!

"That is one convoluted discussion. As usual the manual that comes with the boat seems to be lacking some information.

From what it sounds like I think he's best sticking with the higher percentages as suggested by Mr. Toss. Shape, balance and the ability to keep the mast in column when hard on the wind in about 15-20 kts. of breeze are the final guiding factors in rig tune. It can be difficult to tune when you don't have directly opposing lower shrouds and various wire sizes, ask R___(a mutual friend) how much I love tuning his rig. Even professional riggers disagree on how tight the rig should be, as long as everything stays in column athwartship, and you get a little tip fall off to leeward in the big gusts, there is some discussion as to how slack the leeward side should be.

I tend to go with higher tensions, as long as the boat's structure can take it. I prefer to not have the rig subjected to the shock loading that can happen when tacking in higher winds. I also prefer to have a little bit of a bend in the mast that can be adjusted with backstay tension. When you have a rig with "in-line" aft lowers it can be difficult to control the bend and they don't really contribute that much to the fore and aft shape of the mast. Single spreader, fractional rigs are tricky; in my opinion they're best left to trailerable boats.
Just my $.05 worth of comment (inflation values) "
 
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