Forestay Sag

 

Home Forums General Olson 30 Discussions Forestay Sag

This topic contains 22 replies, has 6 voices, and was last updated by  Skip Danesi 3 years, 10 months ago.

Viewing 23 posts - 1 through 23 (of 23 total)
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  • #1904
    Bruce Hubble
    Bruce Hubble
    Participant

    What am I doing wrong? I can’t seem to get that last bit of forestay sag out when the wind is up. Full on backstay is not doing it.

    With the backstay off..I have about 5″ of deflection. Is that too soft a starting point?

    #2950

    Ray
    Participant

    I know I’m one of the least experienced O-30 owners, but I can’t for the life of me figure that one out unless you have a disfunctional backstay. I had 2 feet of sag when I bought my boat (no lie), then went about tightening the turnbuckle up there to get it down to 5 or 6″ and have no sag when I haul on the backstay. It’s amazing how noticeable it depowers and powers up the boat compared to my J24. Maybe a picture of your backstay set up?

    #2954

    Ray
    Participant

    Bruce- we raced last night, and I finally got a rigger on the boat this morning to see what’s up with our forestay. We had good moderate wind (7-8 kts) and on the upwind legs we had quite a bit of sag as well. I can’t quite quantify it (wish I’d taken a photo), but it was easily 6″ or so. Backstay was pretty much maxed out, but I’m guessing this is just the way these boats are sailed. The rigger suggested that these boats are so flexible, that you’ll never get all the sag out, especially in heavier air, and there is a reason we have 36:1 purchase for that backstay and that is about as good as it gets. If anyone here knows, please correct me if I’m wrong, but my crew is just amazed that we can’t achieve the knife edge we’re used to on J24’s. Apples:oranges, I know…

    #2955
    Bruce Hubble
    Bruce Hubble
    Participant

    Tuesday night I made an adjustment. I don’t want forward rake, so I put on about 15% of backstay and went up to the forestay and tightened it until I had only a couple of inches of deflection. I expected that I might get some lee helm, but I didn’t. 8-13 true kts of wind, #1 and still had a nice minor angle of helm. Jacked on the backstay and YAHOOOO…. a pretty darn straight forestay. Out ran a Tripp 33 scratch that beat me with hcp last week, so the boat was fast.

    Flex boat? My cabinets say that is spoof. My new mast step is probably the real cure.

    Maybe it is my ‘left over’ J/24 tuning that was my issue. If others don’t know, the J/24 sails with a bunch of sag up to medium wind. I mean negative Loos gauge on the forestay by two fingers. I removed a toggle in my forestay..about 2″, so this was my concern with tuning without it. All seems fine now.

    I didn’t max out the backstay Tuesday, so I feel I’m now set for 20+ kts apparent with no issues.

    Do you have a below deck attachment of the mast to the bottom of the deck? Make sure that is tight. If you don’t have one…get one.

    #2956

    Ray
    Participant

    I do have jockstraps, and they are plenty tight.. I probably couldn’t turn them without a screwdriver, but I haven’t tried. I think that’s ok, but I still have room to further tension the forestay at that turnbuckle. I still have no forward rake (and no lee helm, for sure), so I think I can shorten it some more. I know where we stand amongst our phrf fleet, so I should be able to assess the effect of any changes.. We’ll see.

    #2969

    Ray
    Participant

    Ok- we took off cruising today (so please ignore the horizontal wrinkles in the main!), and I took a few photos of the jib with backstay full on and backstay off. I clipped the spare spin halyard to the tack horn on the bow and tensioned it for a straight line reference point and from photo 1 (backstay on) you can see about 5 or 6 inches of sag in the forestay. This was sailing close hauled in about 8-9 kts of breeze. Then for comparisons sake, I took a photo with the backstay completely off and you can see the extra heel induced and maybe 10-12 inches of forestay sag. So- should I shorten the forestay more at the turnbuckle? Yanking on the backstay gets pretty tough beyond this point, but I could possibly manage another inch or so. This is fairly light breeze for around here, so I don’t think that’s the answer.. imagine what it would be like in 15-20– rather tough.. although I could spend more time in the gym…

    Edit: you know on second view- the jib isn’t fully trimmed in, but I think the forestay sag would be even a little worse.

    #2970

    Jim Saylor
    Participant

    Ray,

    What kind of and how much purchase do you have on your backstay?

    #2971

    Ray
    Participant

    Hey, Jim- here’s a photo of my setup. It’s quite a bit different from the usual split arrangement. All of it comes down to a custom plate mounted on the transom that is about 6 inches wide, has 3 blocks and two fixed lines (and spliced with thimbles) attached. I’m not sure if this is a 36:1 or the conventional 48:1, but it’s a lot of purchase.

    #2972

    Ray
    Participant

    By the way- that image attached (3185.jpg) isn’t the current configuration- that was an experiment, but it spreads things out so you can see all of the blocks. I’ve put everything on that single plate, which is the way the boat was sold to me.

    #2973
    Bruce Hubble
    Bruce Hubble
    Participant

    How is your helm? Balanced or have to tug much? If you are tugging much, then yes..shorten the forestay until you are only getting a slight pull on the tiller at 15 degrees helm. If you are pretty balanced..shorten the backstay. Take out that long toggle. That will give you more travel. You don’t need a turnbuckle either! That is a remnant of an old wire setup. Just adjust your rope lengths.

    #2974
    Bruce Hubble
    Bruce Hubble
    Participant

    You have the same setup I have. You have the triple blocks wrong. The exits should be at the deck. I don’t have the center deck attachment. My lines terminate at the two backstay plates.

    #2975

    Ray
    Participant

    Bruce- can you provide a photo of your setup? It would make things a lot clearer..

    #2976

    Ray
    Participant

    by the way- here’s our current arrangement-

    #2977
    Bruce Hubble
    Bruce Hubble
    Participant

    That’s better on the bottom exits of the green lines. Still looks like you could take out the toggle. That would give a few more inches.

    #2978

    Ray
    Participant

    I think if I take out that toggle, the double block would rub on that line spliced with the thimble attached directly to the plate and wouldn’t run as freely. I forgot to answer your question about my helm. I have no other O-30 boats to compare, but the helm isn’t what I’d put in the difficult to handle category. I think in normal conditions like we had yesterday (7-10) I have maybe 4 or 5 deg of weather helm sailing upwind. Even when the boat heels to upward of 35 or 40 degrees (I’m estimating) I still have control, which surprises me with the shorter stock rudder. On a J24, we’d round up or even auto-tack. I’m just learning to live with it, and reduce sail when shorthanded if it’s blowing > 10. The real issue for me is to figure out if that 4 or 5″ of forestay sag is anything to worry about. I have one more option, and that’s to get our local Quantum guy on the boat (John Bowden) and go out for a sail to see what he thinks. I just might do that anyway- I’m sure John will point out all sorts of idiosyncrasies.

    #3409
    Bruce Hubble
    Bruce Hubble
    Participant

    I’m doing a bit of retraction here on my previous comments on shortening the forestay.
    1. Neutral helm is bad for speed. You need some helm in 10 degrees of heel. Not much; some.
    2. Shortening the forestay might have helped sag, but it induced neutral/lee helm and possibly too straight a mast for the main to work.

    I have since lengthened the forestay back to original position and reworked the backstay to get enough travel to pull the backstay and get a firm forestay. I now have the rake needed to fit the main luff.

    Could I get a favor from someone that is FAST and happy with their tune? Please get a 100′ tape and measure the forestay with the jib halyard at the forestay attachment. I know this is a bit crude, but it is a starting point for all. Better yet, next time someone is up the mast, measure the forestay itself. Having this measurement gives a starting point for pre bend. If someone has this measurement in an archive, point the way!

    Thanks!

    #3410

    Ray
    Participant

    Hey, Bruce- I could possibly take that measurement, since I have the tape (and have been regularly going up the mast installing all sorts of stuff lately…). I’m pretty happy with my current setup, and have not lengthened it back. There is plenty of sag, but my mast is straight as an arrow. I have a double-spreader rig, so it’s not as bendy maybe as the single, but I can readily de-power with just a touch of backstay and keep going until the backstay blocks are about 6″ apart (which is fine, I think). In my local fleet (phrf against J120’s, several different kinds of Beneteaus’s, but no other Olson’s), I can outpoint everybody in light air (<6 or 7 kts), and pass them going upwind- I've done it a bunch of times. I regularly sail short-handed, so I have little weight to put on the rail, and when the breeze goes into the medium-heavy range, they all pass me back again (even sailing ddw). Most people use a-kites around here, so I just get out-canvased. Right now, I'm not tempted to adjust anything..

    Ray

    #3464

    Jonathan Pollak
    Participant

    Bruce, just seeing this. My 2-cents here. A couple years ago I completely ripped out and rebuilt my mast step. This improved boat performance dramatically. However, all of a sudden I had far more headstay sag and the whole boat was flexing more. In other words the mast step was solid and all of the forces were being directed elsewhere. At this point my foredeck is not as I would like it to be. I think that I need to pull the rails and redo the hull deck joint at the very least and maybe do some stiffening. The sag, resulting from the front of the boat flexing up more than it used to, is not something I have completely solved as of yet.

    -Jon

    #3465

    Zeke Wolfskehl
    Participant

    Head stay 37′ 6-7/8″ with center halyard two-blocked to centerline stem head stay pin
    Stemhole to top of turnbuckle 13-1/2″
    Also have about 6″ of mast rake measured about 6″ above the gooseneck
    Trying to figure out how to get the boat to point.

    #3466
    Bruce Hubble
    Bruce Hubble
    Participant

    Jonathan and all:

    I’ve had more racing experience with my backstay mod since I last wrote. Jon, strength is not needed at the deck joint. Unless it has come apart (you would see that inside via cracked at the joint), your hull is intact.

    I too have a strengthened mast base. I have a turnbuckle from the underside of the deck just forward of the mast opening and it attaches to the front of my mast. This ‘fixes’ the deck height and does not allow the chain plates or hull sides to flex inward. It also offsets halyard tensions at the deck. I eliminated the toe rails from the chain plates aft.

    Want a tight forestay? One solution: You need more travel in your purchases. It takes a huge amount of backstay to tighten the forestay. My old setup was two blocked way too early compared to what I have now. Want to point…straighten your forestay!!! Right Jim Saylor? I would suggest shortening the backstay to raise the block as high as you can reach from the cabin top. Then get a diagram/setup to give you 48 to 1 purchase, remembering the triples will travel a huge distance for very little pull.

    My forestay is sloppy eased and straight when on hard. You can’t pull enough on. Pointing relies on this. Also, it flattens the main when it pipes up.

    #3467

    Ray
    Participant

    I’m not clear on something, Bruce- if you shorten the backstay so that you can just reach it when standing on the cabin top, how are you going to reach it when you walk back to the stern to attach it? I’m confused a bit..

    #3468
    Bruce Hubble
    Bruce Hubble
    Participant

    I meant shorten it so you can just reach the block. Your tackle will attach easily, you just have to thread it over that block before fixing the rest.

    #3494

    Skip Danesi
    Participant

    Hey guys, had the Haarstick sailmaker on board last night and after a couple minor tweaks, she was pulling real nice. The numbers – 7-10knots true, although it looks like more from the picture, we kept it about 3-4″ off the spreader – single spreader mast. About 8″ of sag under this condition. Kept her running between 5.4 in the lulls and 6.4 knots in the puffs. More lulls then puffs unfortunately but can’t complain, had to lee bow the J-111 near the windward mark. Usually we’re not that close at the mark. So either we were dialed in or he was spacing out. I’d prefer to believe the former.

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