J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Rig Tune

Just wanted to get an idea of how people tuned their rigs over the Na's. Some I talked too left them tight, some adjusted them alot. We sailed with about 1800 in the heavy air maybe a touch tighter and radically loosened them in the lighter air. Also did the same with the backstay. I thought our speed was good in some breeze but off the pace in the light air. Also what sails did people use? Were most Jibs made out of Kevar or Pentex?

Luke - Rhapsody sailed with a 2008 North Main made in New Orleans with the "Benz Faget" recipe and 2007 North Kevlar #1 made by the finest Sri Lankan sail makers. We used a 2008 Quantum Carbon/Kevlar #3 built by Steve Thurston on Friday when it was blowing.

Rig tune using Loos PT-2 gauge was 1400# on uppers and lowers in heavy wind and 1400/1000 in light wind. Our boat speed and pointing seemed to be as good upwind as anyone else - we just couldn't call the correct side of the course in the light, shifty air :-)

We didn't touch the head stay (class max length), but used some back stay on Friday in the heavy air, which turned out to be our best finish (4th).

My every day main is a 2002 tired Quantum that requires a completely different rig tune to make the boat go. You really need to play around and see what tune works for your cut of sail. The tune on my 2007 North is completely different than the 2008.

Blue Meanie carries all North-main was new last July, purchased from the Annapolis loft. Very happy with that sail, as I am with the #1 from Benz, which is a Kevlar panel sail.

Rig tune on Friday started very tight-first race we had 2000+ on uppers and lowers (40-41 on the Loos). Played backstay to keep the boat flat. The key move in the first race was sticking with the#1 and flattening the hell out of the main. As the breeze dropped, eased everything between each race. In medium, about 1700 outers 1500 inners, in very light-off the gauge, inners softer than outers (probably 900 or so outers, 650 inners).

Fuzzy Wuzzy's sails are made by Bill Draheim @ GUS Sails - main & Genoa was new for last years NA and the spinnaker is new this year. The Genoa is a cross-cut polyester mylar, over the years I found the mylar film to be the weak link in the Genoa and in my opinion exotic (expensive) fibers is just a waste of money.
Our base tune is 37/37 and approx 4" slack in the backstay (adjuster is firmly secured at the top of the lower legs) headstay at max. For the first race Friday we went up to 40/40 and choose the #1, had to use the backstay in a few puffs. For the second race we went back to base 37/37 and never used the backstay, for the third race we backed off to approx 35/35.
Saturday we backed off the rig to 35/33 and eased the backstay to keep the 4" sag - we felt over tuned in that race.
Sunday we started with 32/30 - still too tight in the first race - backed off the rig to approx 27/22 for the last race.
In my opinion this was not a boat speed regatta -it was much more important to find breeze and try to avoid the very big holes scattered over the racing area.
We never figured out the current but I think it played a major roll in the light air races - perhaps some of the local boats can help us with that.

Just to head off the interpretation problem on rig tuning...

There are different model Loos gauges. I believe the numbers Bengt refers to use the Loos Model B gauge. The standard wire size used for J/30 standing rigging is 1/4" diameter. There are conversion charts for settings between different Loos gauge models and absolute tension in PSI at the following links:
Loos & Co. How to use Tension Gauges

Download PDF document with conversion charts between Loos Gauges



[This message has been edited by Rhapsody #348 (edited 10-10-2008).]

So true on finding the wind. We found the holes instead. Not a good strategy at all.

On the current, it wasn't exactly as the current models show in relation to the timing of high and low tide, but they provided a pretty good indication. Look at this web site to see what the currents do with tide over time in the bay: http://www.narrabay.com/empact/bayCurrents.asp

Bill, the #'s are from the PT-2 loos gauge

Thanks for the words of wisdom. not to far off from what we thought it should be. See you next year.

We switched to North main and genoa last year and use their general tuning advice. I see what I believe to be significant back winding on the main caused by the leech of the genoa. Some call it a 'speed bubble' and have advised us to ease the genoa to six inches or more off the spreader. We typically trim to 2-3" and set the jib car so the sail breaks evenly. The backwind is noticeable in all conditions and tune.

Originally I thought the problem could be solved by inducing more pre-bend with tune or backstay to flatten the luff curve of the main. But that doesn't really seem to help and sets us much tighter on the rig than advised.

Bob - I thought it was just me, but I found the same thing with my 2007 North Main & Jib on the "speed bubble". The 2008 Benz designed North Main didn't do that.

Bob - We have the same thing with our North main. I have found that the general rig tune does not work with the main.

Here are my observations (right or wrong):

Strong Breeze: 41 upper 37 lowers tight back-stay (1/2 inch of threads above/below the center bolt) - We found that with the lowers tighter the pre-bend is not carried nicely from the base up, but more from the lower hounds up. But loosening the lowers and tightening the backstay give the rig a better overall arc - which helps to flatten the lower area where the speed bubble is most pronounced.

Lighter Breeze:35 lowers 37 uppers - backstay is much looser - 4 inches of sag (2 inches of threads from center bolt) We then vang sheet the main to keep it from twisting into the slot as it is eased.

So these are somethings that we learned this year - we will try them again next year.

It would be interesting to see your thoughts on these settings.

David
#397

I have not had any issue with the speed bubble with the main I bought this year. I do find that outhaul and halyard tension has a huge impact on draft depth-I've been carrying a little more tension recently, to good effect. On the halyard-I take all wrinkles out of the luff in flat water/almost any breeze.

I have found that overall rig tension helps a lot to flatten the main when breeze is on or building-in the first race at the NA's, I think (judging from photos) that we had the flattest sail on the course.

Like Fuzzy, we used to keep the uppers and lowers at the same tension generally in the 38-41 range depending on breeze. The White/Bartlett tune is much looser shrouds and somewhat tighter headstay. But it might be worth trying, something new since we've been off the pace the last two weekends. Our setup is generally main halyard just tight enough to remove wrinkles, outhaul fairly tight, and no vang or no backstay tension up to 15 knots true upwind.

I can't help it; I have to ask the question:

Is the main is getting back winded predominantly by the 163? Wouldn't that argue better performance by a 155%?

I sail PHRF and I have bought a Dole carbon fiber main this year and have maximized my roach (within the tolerance of Nova Scotia ASPEN rating)...sorry guys. My Mylar 163% is bagged so now I am now faced with a decision that all PHRF sailors face, do I take a hit and sail a 163 or get a 155? My concern, even before I read this post, was the effect the 163 had on back winding the main. Anyone have any thoughts?

Thanks
Jason

Jason - the main with the rig properly tuned works well with the 163 by design and isn't back winded. I had the "speed bubble" issue with my 2007 North main because it took me a while to figure out what the correct tune was for that sail. The 2008 Main I had no problem tuning for at all. Not all sails are cut the same shape even if they have the same sail area, thus the tuning difference.

If you go with a 155, you should find that you sacrifice some light air performance, an area where the J/30 needs all the sail area it can get. For PHRF only racing, the 155 is probably the best compromise if you take the penalty with headsail area from 155 base to 163.

Keep the 163 "bagged sail" as it will help you in real light air. How about you race OD at the NAs in 2009? We had one Canadian boat this year and could use another.

Three races this past Saturday in 15-19 with gusts to 24. Six of eight weather legs were #3. One leg would've been better with the #1, while one of the two legs we did use the #1 was a mistake--way overpowered. Using a tighter rig: 40 uppers/lowers (Using PT-2 and above chart that's 2000 lbs), 15 turns on the headstay, six on each backstay. The 'speed bubble' in the main was gone. We also played the backstay a bit and had it on hard enough to invert the main on the leg where the #1 was a mistake.

Speed and point were good. I'd say we probably had a bit too much tension on the lowers. And, while I'm not going to throw the tuning guide away, I do think I'm going to set the main up to eliminate the bubble.

[This message has been edited by Bob Rutsch (edited 10-22-2008).]

I feel like I'm missing something. I see bills chart that lists the model "B" and the PT-2. However the model "B" doesn't seem to go above 43 for 2000lbs.

I tuned mine with the model 90 in the hyperlink. I also referred to older posts regarding shroud tension and they all concurred on 44/45. Is everyone else using the model "B" which renders a lower (40/41) number? Or am I too tight?

44 for the model 90 is still within range, correct?

http://www.loosnaples.com/how-to-use-90-amp-91-tension-gauges-pg-13.html
http://j30.us/ubb/Forum10/HTML/000356.html

[This message has been edited by MangoMadnesss (edited 10-21-2008).]

[This message has been edited by MangoMadnesss (edited 10-21-2008).]

[This message has been edited by MangoMadnesss (edited 10-21-2008).]

Rob - the conversion chart is direct from the Loos web site. I just deleted the other models so there is less confusion. The PT-2 scale only goes to 40. The Model B (which is the Model 90) goes higher than the PT-2. You'll find the tuning you have is very tight and I think most don't tune the rig that tightly.

Actually, when it's blowing stink, tension of 2000+ (I go up to about 2100) can be very fast.

This discussion would be easier if everyone referred to pounds of tension-trying to reference the various calibrations gets confusing...

I don't do the headstay tightening thing when I have the #3 up-my theory is that keeping the jib with a bit of sag puts more power in the jib to punch through waves, and provides a wider groove.

so these guys are too tight? (hyperlink)
http://j30.us/ubb/Forum10/HTML/000356.html

On a side note I was surfing sailnet and alot of people argued the point that during the americas cup the boats have their rigging as tight as the rigging will allow.
I don't know if its true, I know its a one time race and they're pushing the limits anyway, and I know why we would adjust ours to maximize trim, however keeping it tighter would seem safer.

Rob - If it works for your boat speed use it. The chart on the Loos site suggests that for 1/4" wire breaking strength is 8200 lbs, and there is a warning not to exceed 25% breaking strength (2050 lbs) in the paragraphs below. As long as the pole stays in the hole, you are safe.

As others have pointed out, there is no single "correct" tune. The tension will change as the prevailing wind conditions do. You need to play with it. Go out and try some settings and compare boat speed and pointing angle for conditions of wind speed and chop. Record what you get then make the adjustments based on that knowledge. I would say that for base settings you mention, you are way too tight for light air. You actually want some mast sag at the lowers in light air.

This from the UK tuning guide : Simply stated, the tighter the overall rig tension, the greater the headstay tension; as long as the tension is nearly equal on uppers and lowers. In lighter air, when more sag is desirable, ease both shrouds slightly, and ease the lower shrouds more than the uppers to allow for more pre-bend. In heavier air, use more tension (2000 lbs) on both; the lowers should be as tight or tighter than the uppers to reduce pre-bend.

Another tuning guide for reference:
Banks Sails tuning guide

Just a quick note to let everyone know that the conversion charts to interpret the Loos Gauge readings between the 90 Model B and the PT-2 with equivalent tension in pounds are now posted on the web site with the tuning guides. The chart is readable online, or can be downloaded as an Excel spreadsheet for printing. The numbers come from the Loos website.

The table is organized to show readings being approximately equal listed on the same row. You'll need to interpolate for exact conversion, but it's close enough for dialing in the settings you want.

Go to the J/30 website main menu at the top and mouse over Info, Articles of Interest, then click on J/30 Rig Tuning. It is listed at the bottom of the table labeled "Jump to Sections to read online or download:"

Here is the direct link, but we put the menu structure in place so you can find stuff in the future.

One question I always asked myself,....the wind reference in the tuning guide / is it true wind or apparent wind

Taras

Pretty sure everyone uses true wind speed. Even if you don't have instruments you can probably estimate. I remember reading an article on polars in Sailing World (June 10, 2008) by Stan Honey and Jim Teeters that says, "Most sailors can guess TWS within a knot."

Somewhere (maybe this) I read the Loos PT-2 calibration is 38/1300 lbs (Loos Table 1 seems to support this). Setting the shrouds to that tension initially may help you get more consistent 'turns to tune'.

YIKES. I am reading these tension numbers, wondering if this is part of the reason that my chainplates were broken when I bought my boat! I am using 1300 on the uppers, 1100 on the lowers, and up to twenty knots, the lowers do not slacken, so this base setting may even be too tight. I do not carry my 163 above 15, I found that my 140 is faster, flatter and higher in winds over 15 kts, so that may explain my ability to carry a looser rig. No problem with the bubble in the main either. Maybe this is a carry over from my J-24 days, as the number one in that boat is a 145%. Have not tried the light air settings yet, as central FL does not have much light air in the evenings when we are usually out, but if we have a drifter, will probably try 1000 lbs on the uppers, 800 on lowers. Recommend if you use settings over 1500 to check the rig on cold days, as the tension will increase!

I'm curious. How many of you have shortened the backstay the 3-5 in as recommended in the UK tuning guide. I have the headstay at 35-9.5. and the mast pretty straight. My backstay when released is quite loose. The idea of shortening seems ok.

Yes, I've shortened my backstay. I had the top section cut... only one cut needed there, so it's less expensive than having the legs of the Y cut.

Luke, I replaced my original chainplates with oversize ones. I also replaced the nylon backing plates with SS. I have plans for both if anyone is interested. I will take pictures of the new chainplates and attempt to figure out how to post the pictures on the web site.

I'd love to see the plans - I've thought about redoing mine - I've got a metal fabricator who can turn them out easily if I can give them a drawing, but that means taking them off the boat first which I have not wanted to do.

Be sure to use 316 stainless instead of the cheap 302 that TSP used for the new chain plates. Oversized is GOOD

Dan - I'll send you the drawing off line. After some research,I made mine out of 304ss

Russ - if you are agreeable, I can put the drawings on the J/30 server for people to access. I've been thinking about setting up a web page that includes a list of all the various drawings people have generated as a resource for the class.

I sent you cad drawings via e-mail. Let me know if you have problems opening these. If so, I'll have someone convert them to PDF or jpeg

Attached are files and information Russ Atkinson sent on chainplates he fabricated. These are also referenced on the J/30 Files and Drawing page

Here's a PDF of the drawing for the oversized chainplates. Please note my comments below:

• I had these made at a local fab shop. The plates were cut complete, including all the holes using a waterjet cutting machine. Material used is 1/4" x 304 stainless
• To simplify the drawings and the work required to install these, the overall width of 6.3" should be reduced by .375" and all the material should be removed from the outboard side.
• I did the initial layout for these chainplates on the starboard side of wildcat. I didn't have the sense to compare to the port side. After making the drawings and the parts, I found out that the port backing plate interferes with the cabinet in the head (starboard side backing plate is in the hanging locker and there is no interference). Also, the port side cabin light was in the way of the port chain plate. I had to move the light.
• My company sells complex CNC metal cutting machines so, for me, there was no problem in bringing the port chainplate and backing plate to my business and having my engineers mill off 3/8" from the edge. For me that was a lot easier than modifying the cabinet face in the head.
• Also, I used my old chainplate as a template for where the center 6 holes would go. I cannot guarantee that someone else's chainplates are made identical to my originals. That is important to check making these. To install these I merely removed the old ones, mounted the new ones using the 6 original holes and then drilled the additional new holes through the chianplate and backing plate. (Tip - drill holes half way from both sides).

So OK after 30 years, it was time for us to pull the chain plates off and check them out ... with so many people reporting required action.

Observations:
1. if there is staining on the bulkheads ... it is because the balsa has rotted in the deck around the chain plate.
2. After 30 years there is very minor signs of chainplate steel damage on #505.
3. Butyl rubber is the only way to seal the chainplate at the deck.

I elected to do a simple 1/2 plywood backer plate on the starboard side and bolted it into the hull flange ... only because I had taken the door and closet wall off thinking I would have to replace the existing plywood, but it was OK, not perfect, but not soft at the holes drilled in to it. So I just did a carpenter thing and sistered a 1/2 in. layer on the existing bulkhead. The port side had some staining on the bulkhead but sounded solid.

The birch laminate was stained and unfortunately looked like it would have been a real hassle to restore so I just painted enough to look clean.

Will advise how this program works in another 10 years.

Vic,

I just bought my boat last year, no way of knowing whether previous owner did much maintenance on his chainplates. No staining, bulkheads dry to a moisture meter and solid to the touch. What should I be doing to keep them this way?

Thanks,

Josh

Josh,

Pull your chainplates and check that the area around them in the deck has been epoxy sealed (e.g. no way for water to get to the core). Once that has been done, you can reinstall them. Use a good expandable caulk to fill the void between the plates and the deck with polyvinylsulfide or butyl caulk such as Boatlife, Sikaflex, etc. (not adhesive like 4200).

Josh,
I personally would keep a sharp eye out for any initial sign of clear water leaking especially after heavy rain or winter freeze ... but hold off. With your lack of symptoms in 30 + year boat, I would be afraid of pushing stick in hornet's nest ... Unless of course you are planning a cross Atlantic sometime soon. I am sure there are other things on your list.

I like the black rubber sticky stuff a real lot, if I had known about it 30 years ago ... it would have helped. Actually I did know about it as we used it to seal coax connectors going into radio antennas, but I didn't think.

let me modify this a bit ... take out one bolt and see if it is pitted, if so change all the bolts. A few years ago I did an old J/24 'salvage' and was surprised at the crap quality of the bolts used to hold the stanchion bases to the deck. I was reusing them till a couple broke off on the tightening step and realized they were internally compromised by corrosion.

I did change all the bolts when I put the chainplates back. Six had to be 1/2 in. longer anyway ... and then I added 3 fender washers where they fit over the nylon backer plate.

Thats valuable advice, I'll pull a bolt from the bulkhead and inspect. Thanks