Which is more important, straight mast or balance shroud tension?

[Vtonian]

Ignoring that there's possibly/probably an underlying problem that needs to be solved, I'm learning to tune my E38 rigging, which was pretty loose as bought. Going with a blend of the Ericson docs, Loos gauge suggestions, a consensus of rig tuning YouTubes, and tempered with consideration for age and a careful visual inspection, I'm at a point where there appears to be a slight "S" in the mast, even though the shrouds are already slightly tensioned to counter it.

If I take the S completely out, the tension will be significantly more unbalanced. If I balance the shroud tension, the S will be more pronounced. I feel like I’m at a ‘good’ compromise set/tune, but I have never seen anyone suggest to compromise rig tune.

The PO put a new boot on the mast, and I don't know if the E38 (1985) has adjustable wedges or has a fixed position collar, so I don't want to start dismantling that until I know if there's anything to adjust there. It’s my first thought though, he wasn’t a sailor so maybe ignored/hid a correctable problem there.

FWIW, I started with the more commonly recommended procedure of loosening all shrouds first, then setting the masthead for center, rake and tension, then working from mids, down. Oddly, Brian Toss (only very briefly) mentions working lowers, up, and I’m contemplating starting over trying that.

Obvz, a professional should be consulted but it’s a beautiful day, I’m enjoying the process and keeping this side of harm.

Side note: the port chain plate, the one that angles forward to the head bulkhead after penetrating the deck, has a little crazing and lifting around it, but the deck taps out sounding solid. I’m hoping it’s a common ‘feature’ of the design that just needs maintenance and not a bug that needs repairs, although I do intend to rebed everything ASAP.

Input and comments appreciated...

 

[Vtonian]

Pic, with string, although camera angles...

 

[Frank Langer]

Pic didn't show up.
If the deck is raised in one place, that can be adjusted on many models by reducing/adjusting the tie rod in the cabin to get the deck level.
I think it's more important to have the mast straight, and without any S curve, even if that means the shrouds are not tensioned exactly equally-- it may be that the shrouds are not exactly the same length due to the way they were made or stretch.
I would continue to tune, both at dock and under sail until you get the mast as straight as possible.
Frank

 

[Vtonian]

Thanks Frank. I'll take a look at that adjustment, sounds like a fix.
After tinkering a bit more and then deciding to wait and see what it'll look like after a little sail tomorrow when the wind comes back, I put the genny back on and now I'm cleaning up the jobsite, I can't see the S anymore.

Maybe it was just my stigmatism arguing with my cataract...

 

[ConchyDug]

Yeah if the deck is lifting tighten the below deck turnbuckle. You may have to roll back on whatever shroud it's attached to. Use a straight edge on deck to verify it's flat. I'd also check if that's the original below deck hardware, I've seen them cracked before.

I'm in the straight mast at the dock and on the water camp. I do top down Caps, D2s, D1s, you can go bottom up but it's the same result. I've tuned a lot of masts the same technique works on all of them. I'll touch up the tune on the water if it needs it. Cable rigging isn't as touchy as rod rigging, a half turn on rod is equal to one to two full turns on cable. Just throwing that out there in case you somehow have rod rigging on a 38. Your tensions may not be exactly the same side to side but they should be pretty close. I also use a PT-3 tension gauge, it's much faster to un-noodle a mast with a gauge. I like seeing the numbers, it allows me to periodically check the rig. I had a swaged fitting slip on me a couple years ago, so I check the rig now.

Here is my tuning guide I use, don't get confused with the wind speeds at the top. I have a lot of tunes saved on this app for boats I race but the ericson is pretty much set it and forget, but I have played with the backstay some in different winds, it's a turnbuckle so a pain to change. Eventually gonna slap a racheting adjuster on it and maybe check stays.

Here is photo of a sight up my mast.

Here is the angled below deck section where the cracked turnbuckle was, then later the swaged fitting the rigger made slipped ripping the deck open. In the image is the heavy duty version 3.0.
In my opinion the angled tie rod to the chain plate is a poor compromise in design. I would definitely inspect that part well if the deck was lifting.

 

[Christian Williams]

Get the S out of the mast. Look up the sail track in 10 knots and 20 knots and adjust stays accordingly.

The leeward stays will be slightly loose in heavy air, but the mast should still be straight. On both tacks.

 

[Vtonian]

Yeah if the deck is lifting tighten the below deck turnbuckle...

...Cable rigging isn't as touchy as rod rigging, a half turn on rod is equal to one to two full turns on cable...

Here is my tuning guide I use...

Here is photo of a sight up my mast...

Here is the angled below deck section where the cracked turnbuckle was...

Thanks ConchyDug.
I will definitely check that turnbuckle.

I don't have rod rigging but a friend does and that's good to know.

What do those numbers represent? The Loos chart recommended 1000lb for the uppers, I went 850, 700 for the mids, I'm at about 500, 850 for fwd lowers, I'm about 750, and about 700 for aft lowers.
The mids and lowers are harder on the starboard side which needed to be pulled over.

The whole rig was loose before, leeward shrouds were flopping in 15kn, so I figured I'd sneak up to proper tension a bit at a time, make sure nothing was going to give before going all the way.

My opinion from inspections is, the rigging is all 'fine', no visible cracks or frays, but also probably toward the end of its lifestyle, so I'd rather it was a little looser than spec and suffer a little extra bending fatigue than be at its limits and pop something.

I forgot to sight up the main track again, good reminder.

Interesting angled rod solution. I agree it's an odd design choice, when it seems like 10" of cabin layout modification would have made a much better structure.

 

[bgary]

IMHO, loos gauges are ... somewhere between subjective and useless. It is very difficult to get reliable/repeatable readings, and the fact that it generates "a number" tends to distract from whether or not the adjustments are meaningful.

Best advice is above, from Christian: adjust things until there is no S-curve, and the mast is straight on both tacks

(my own approach is to loosen everything a touch, and then use a 100' tape on the main halyard to see if the masthead is centered between the chainplates. Adjust the upper shrouds until it is, then snug each of them up slightly. Then sight up the mast to see if the sail track is straight between the lower spreaders and the masthead. Adjust the intermediates until it is. Then sight up the mast to see if it is straight between the gooseneck and the upper spreaders. Adjust the lowers until it is. When all is straight, snug things up evenly and go sailing. When the rig *stays* straight on both tacks, you're good.)

Edited to add: You may also want to check the blocking where the mast comes through the deck. If the mast is off-center there, it could easily explain why you are having to tighten the lowers more on one side than the other.

 

[Pete the Cat]

Lots of good advice here. a little aft bend at the top is not a problem. But I concur with the general view of straight mast that Christian and Frank have outlined. Aft lowers slightly less tension than forward to the touch. This is not true on all types boats FWIW. I once had a professional rigger retune my old Folkboat rigging before an important race and I thought the stuff was so sloppy I might lose the mast in the SF Bay winds. For reasons I still do not completely understand, the boat accelerated in a way I had never experienced before. But these production, rigid fiberglass boats are simpler to rig and tune.

 

[Christian Williams]

E38 factory tie rods at right. They also looked odd to me at first glance. The surveyor shrugged and said something like, "inner stays always need some solution." My engineer friend examined them and declared the angles made sense.

...

 

[ConchyDug]

Loos Gauges/tensiometers are subjective and useless? I'll remember that next time I rig a 30000lb business jet using cable tensions. Measuring tension is a methodical process and requires consistency. The "numbers" represent tension, you have to use the chart on the gauge to determine what your tension is. Is a sailboat Loos Gauge calibrated every year... no but Loos makes a lot of instruments for determining tension so it's accurate enough for a boat. I've seen general aviation guys using sailboat Loos gauges on small Cessnas... which is wild, but general aviation is amateur hour.

I've fixed a couple masts people just arbitrarily went out sailing and started rolling turnbuckles trying to get the "S" out. You can crush the mast foot on a boat if you do not know what you are doing. A boat I race against C&C 38-2 tightened their rig up without using a gauge and cracked the hull causing the boat to start sinking(C&C uses sandwich core below the water so not really comparable to an Ericson). I've seen a J130 with almost 4000lbs on the rod cap shrouds and stress cracking on the deck where someone used the breaking strength rule and "just sailed it to tune", I rolled it back off to 2300ish lbs(base tune) using a rod gauge and now he has appropriate headstay sag and the backstay actually bends the upper mast and opens the mainsail leech properly. Also fiberglass boats are far from rigid and adjusting rigging bends the boat. Yes you need to verify the tune by sailing, but the numbers get you close.

Vtonian here is the table from the PT-3, I can't remember my wire sizes but I think my caps are 9/32", inters 1/8", backstay is 5/16". You'd have to extrapolate from the hand written image. I see the leeward shrouds start to slacken in about 18-20kts but the upper mast section above lower spreaders
starts to pump beating to weather in 5-6 foot waves. An adjustable backstay and check stays would stop that but that's a project for this fall or winter.


The original rigging you are showing Christian I've personally seen the rod cracked 3/4 of the way thru on the diagonal tie rod, it was above the vinyl and wasn't noticed until I dropped the headliner. I misspoke earlier and said the turnbuckle cracked. It's a compromise for sitting room/bulkhead placement the Ericson is the only boat I've seen this way.

Here is what happens when improper rigging is used on that diagonal. Pardon the upturned t-toggles it was the only fitting that'll fit over the big Garhauer U-bolts we could find during supply chain shortages a few years ago. But the below deck tie rod slipped 30 miles offshore in a race due to an improper swaged fitting. The rig could've easily been lost but we depowered and used a spare halyard to stabilize the rig.

 

[Dave G.]

+1 on using a Loos gauge. Totally reliable and wouldn't tune a rig without one.

 

[Dave G.]

As far as what's more important I think they go hand in hand unless the mast is physically bent. When you loosened all the shrouds was the mast straight ? If so then the tensioning process is the issue. IF your turnbuckles are of equal condition in that they rotate with the exact same thread friction(not very likely) you can in theory tighten them by hand until they are all snug then start the process of equal turns on opposite sides until the wrench(small open end type) starts to become hard on the hands. That should ne about 10% ish of breaking strength. should be a good dock tune at that point, next step is to go sailing in about 12+ knots and fine tune. The problem is no 2 turnbuckles are the same. So you either have to use a tension gauge or the rule and caliper method to know your tension for sure. I tune my shrouds to 15% on the Loos gauge and generally don't have to make any adjustments under sail. I guess my big question here is the mast straight with the rig loose ?

 

[Vtonian]

You may also want to check the blocking where the mast comes through the deck. If the mast is off-center there, it could easily explain why you are having to tighten the lowers more on one side than the other.

This was my first thought but I didn't know if there was any adjustment possible there. Do you, or anyone, know if there are wedges or some other adjustable feature/function there, on the E38? I've seen that on some boats there is not.

 

[Vtonian]

I once had a professional rigger retune my old Folkboat rigging before an important race and I thought the stuff was so sloppy I might lose the mast in the SF Bay winds. For reasons I still do not completely understand, the boat accelerated in a way I had never experienced before.

I've seen enough YT's to get that optimal tuning can be different for each rig/boat, and the only marginal consensus was tuning to percentage of breaking strength or looser. Except racers, because there have to be exceptions.

 

[Vtonian]

E38 factory tie rods at right. They also looked odd to me at first glance. The surveyor shrugged and said something like, "inner stays always need some solution."

This is oddly assuring, thanks.

 

[Vtonian]

Vtonian here is the table from the PT-3, I can't remember my wire sizes but I think my caps are 9/32", inters 1/8", backstay is 5/16". You'd have to extrapolate from the hand written image. I see the leeward shrouds start to slacken in about 18-20kts but the upper mast section above lower spreaders
starts to pump beating to weather in 5-6 foot waves.

Thanks, CD. I agree, the gauge is more accurate for me than 'feels', although I also do a round of yanking after setting. Very much appreciate the pics and numbers, that makes me think I'm on the right track.

Here's my sloppy chart, but in my defense, my intention was to do this first iteration and sail it, see how it felt, then go back over it and do a 'final' set:

Desc	Size	Rec lb	Initial Port	Final Port	Initial Stbd	Final Stbd
Upper	9/32	1000	460	850	-400	850
Mid	7/32	700	-300	480	-300	560
Fwd Lower	1/4	850	370	700	630	840
Aft Lower	1/4	850	750	630	680	630
Backstay	9/32	1500	750 rake ok, no adj	forestay sag ok

As I was trying to get the S out more than meet recommended numbers, with some compromise for what felt too imbalanced, I wasn't too bothered for this initial set by the variances.

I had the opportunity yesterday to trial it, beautiful day, 10kn, gusty/twisty beating out of the harbor, steady in the sound, then beat a modern sailboat back in DDW, so happy for a first trial. On the beat, mast was pumping (if that's the correct term for a feel of oscillating/throbbing that can set in at about 3 per sec) way less and leeward shrouds only wavered slightly when a slewed gust would heel her 30deg.

Have to wait for the retest and adjust and I still have to remember to sight up the mainsail track but was having way too much fun, sailed too late to have time when I got back.

 

[bgary]

Loos Gauges/tensiometers are subjective and useless?

Sorry, I didn't mean to give offense or create drama. I retract the over-generalization.

...but will make three personal observations, as a former professional rigger who has tuned a lot of rigs.

1) in my experience, and in my observations among DIY owners, the numbers one gets from a Loos Guage are highly dependent on technique. Perhaps with airplanes there is a specific process but, I've seen people use a Loos Gauge at different points in a span of wire (e.g., 3 feet above turnbuckle, eye-level, or mid-span) and get VERY different numbers. Makes it hard to know which one is meaningful.

2) Especially with DIY owners, in my experience that ^^^ leads to a phenomenon known as "chasing a number". It's easy - lacking other context - to decide to keep tightening things until the numbers reach some % of listed breaking-strength for the wire. The problem with that is two-fold... one, it's completely possible to have all the numbers perfect and the rig nowhere near straight-and-in-tune. And two, it's completely possible to chase a number until the rig is over-taut and at risk of (e.g.) deflecting the deck. IMO, "a number" - in isolation - is not the answer.

3) rather, in my experience, if the question is "is the rig tuned properly?", the rig will tell you the answer. It's not a quantitative thing - it's qualitative (*). Is the rig centered in the boat? Is it straight side-to-side? Is the mast rake where I want it for the anticipated conditions? Are the mast-blocks set up for the pre-bend I want? Etc. I can get a rig in "pretty good" tune in about a half-hour with nothing other than a 100-foot tape, some wrenches, and a couple of original-equipment Mark-1 eyeballs. And then to complete/refine the tuning we'd go out and do some upwind sailing to check the mast on each tack and adjust as needed - based on what we see the rig telling us. It works. Maybe it's not the only approach, but I'd offer it's an effective one.

I've *never* seen a top-level big-boat racing team use a Loos Gauge to prepare their boat (maybe they do, don't know, I've never seen it). Snipes and Lidos and Etchells and Solings and J24s? Sure. But having raced on (e.g.) Schock-35s, J-35s, ID-35s and 48s, Farr-40s, IOR-50s, IMS-50s, etc, I've never seen it. What I *have* seen, countless times, is teams working to ensure the mast is in-column at the dock, and then going out sailing and making adjustments as needed to ensure it is still in column on both tacks. (heck, when I was racing Schocks - a fleet of 30+ identical 35-foot boats - we'd (re)tune the rig every morning before leaving the dock, and then check/adjust/refine on the water before that day's start in order to ensure it was right for that day's conditions.)

So my answer to the original question is: get the mast centered and straight first. Then go sailing and make adjustments as needed to make sure it remains that way on both tacks. And if one wants to use a gauge to see if the shroud tensions match side to side, have at it... but seeing that the mast is straight under load on both tacks is far more meaningful (to me) than seeing a number on a gauge.

$.02
Bruce

(*) there are two places I do think quantitative measures are super useful. One is with an adjustable backstay. If you know (e.g.) that a reading of 4200 pounds on the hydraulic meter produces the amount of mast-bend you want in 18-22 knots (or whatever), there's great benefit in being able to reproduce that setting. And, two, many race-boats use a hydraulic "mast-jack" under the step of the mast so that they can unload the rig when not racing. Knowing how much pressure to put on the jack to get the rig back in race-mode tension is useful - although, frankly, most of those boats pump up the jack then put blocks under the mast to make sure a jack-failure can't cause problems on the race course

 

[Vtonian]

@Bruce, FWIW (very little), my impression from trying to study up on it was as you say, it's both art and science: of course it has to be based on the engineering numbers but also has to work in the dynamic real world of unique boats sailing in organic environments. I was a little surprised to find how many knowledgeable/professional people recommended eye/feel tuning with no gauge. I just wasn't comfortable starting out 100% clueless without some objective data as a starting point.

It did occur to me in the process that readings would be different at different heights and to be consistent about where I took them. I thought it was odd that no one had mentioned that, but then, a friend leant me Brian Toss' rigging book and in the whole thing, he only spends a couple pages on tuning, and that mostly just loose theory, nothing like how to, so apparently the rig tuning teaching industry is not yet quite the open book I was hoping for. So, yay for EYO!

As an infant racer, the one thing I know for sure is, amazing differences in relative performance can come from the seemingly most subtle tweaks. I'm still a long way from knowing what/when to apply them myself. My sense is that so far, I'm only getting maybe 75% of the boat's capabilities.

 

[bgary]

addendum to my rant... I'm aware that Loos makes "professional" gauges and "economy" gauges (perhaps there are even calibrated/certified gauges for use on airplanes. Don't know). I've never seen or used a professional guage around boats, no insights to contribute as to their efficacy.

My opinions above are with regard to the economy models one can find at (e.g.) West Marine, and that are commonly in use around most marinas....




B