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Mainsail shape
Posted: Sun Jul 24, 2016 7:32 pm
by romandesign
I have recently started sailing my 1989 26D, which is my first boat, so I'm learning as I go. It seems to me that my mainsail is too baggy. The sails don't seem to be in a bad shape, previous owner said they were "remanufactured" or "reconditioned" by SailCare, whatever that means. He only knew what first owner told him (he only had it for one season). But compared to a smaller original jib I got with it those sails look relatively new, white, furled genoa has a nice red cover band (is tere a name for it?) and generally look very neat, all sail covers are not faded at all etc. I don't know much about sails but they don't look old or worn to me. But maybe it's baggy because it's old? Boat doesn't have a boom vang, but I added a makeshift boom vang by using MRS blocks and line. Connection point is same as for main sheet (as there is no other) but it seems to be able to do its job. But I still can't get the sail flatter than on the photo. You can really see lazyjacks interfering with sail shape too. Does it look normal to you, or is something wrong?
Mainsail tack is held by a pin on the boom. There is a hole similar to the one for the reefing but close to the reefing hook (whatever it's called) in normal unreefed sail position. Should I attach it to the hook or leave it free? I tried attaching it, not much difference...
How do I make the sail flatter? There is a slight mast bend, and mast rake, as I think there should be. Is there something wrong with my rigging or sail? Any way I can make it flatter? Or does it look normal to you?
BTW the mast bend is not as severe as on the first photo - it's the pincussion distortion from a cheap camera that makes it seem too curved. The real bend is maybe 1 to 2 inch difference between middle and top of the mast. When I raise the mast, after I pin the forestay with furler, I'm then able to pin the backstay by hand without huge effort, I shouldn't be able to create a too large mast bend just by pulling with my hand, I think.
Re: Mainsail shape
Posted: Sun Jul 24, 2016 9:11 pm
by sailboatmike
From the creases I can see in the foot in photo 2 maybe check your outhaul, the foot of your sail seems reasonable but looks like is stretched toward the head, a good 4 to 1 vang may assist in taking some of the twist out of the leech up high.
If the sail has been recut is seems the belly is now pretty high, but Im not a sail maker, maybe Judy can correct me if Im wrong
Re: Mainsail shape
Posted: Sun Jul 24, 2016 9:34 pm
by Judy B
The first thing to do is to ease the lazy jacks. They are much too tight and are distorting the shape of the sail severely.
After you've moved the lazy jacks out of the way, let's see what the shape looks like when you are close hauled (pointing). If you have a windex on the mast head, the apparent wind will be a little less than 30% off the bow, which will correspond to a true wind angle of about 45-50 degrees off the bow.
Take the picture from underneath the boom, looking straight up. Try to get as much of the leech and luff of the sail in the frame as possible. Don't use a cheap camera that distrorts the image.

Re: Mainsail shape
Posted: Sun Jul 24, 2016 9:41 pm
by Judy B
In the picture, the tell tales on the leech at the battens are all flying, so that's good.
Please take that flag off the top of the sail. It's creating turbulence.

Re: Mainsail shape
Posted: Sun Jul 24, 2016 11:50 pm
by delevi
Sight up your sail when sheeted to center line or close to center line and sailing close hauled. You need the sail to be loaded up to determine if it's too stretched out (blown out.) The outhaul will flatten your sail. Get as much tension on the outhaul as possible. With the stock setup, it is easiest to do this before you hoist as you won't have enough power to get any real tension on it under load. If you have an adjustable backstay, you can increase tension on it to bend the mast (mast bend is good when it's windy and when you're sailing up wind.) This flattens out the mainsail and reduces the sag of your forestay, which in turn flattens the jib and lets you point higher. If the sail still looks too baggy, it is probably blown out. Sails don't age by time, but by usage... assuming it's been protected from the sun's UV. All sails stretch over time (use.) Prolonged flogging or improper sail trim (under trimmed) will accelerate the aging process. As most sailmakers will tell you, a sail is gauged by it's ability to hold an aerodynamic shape, not its ability to stay in one piece as an intact triangle. Many people sail with blown out sails and don't mind. It's not a problem down wind. The issue is performance upwind... speed, minimizing heel and pointing ability. Replacing blown out sails with quality new sails will feel like you just turbo charged your boat

Money well spent.
fair winds,
Leon
Re: Mainsail shape
Posted: Mon Jul 25, 2016 1:11 am
by sailboatmike
Being a fractional rig increasing the back stay tension (bending the mast) wont do much for tension on the forestay
Re: Mainsail shape
Posted: Mon Jul 25, 2016 8:30 am
by romandesign
delevi wrote: The outhaul will flatten your sail. Get as much tension on the outhaul as possible. With the stock setup, it is easiest to do this before you hoist as you won't have enough power to get any real tension on it under load.
Thanks Leon, this might be the key. I only tried to tighten the outhaul when already sailing (under load) and couldn't get it any tighter. I tried it few times because visually it does seem that there is not enough tension across the foot of the sail. I will try tightening it before I hoist next time, maybe that will help. Makes sense.
Re: Mainsail shape
Posted: Mon Jul 25, 2016 8:36 am
by romandesign
Judy B wrote:The first thing to do is to ease the lazy jacks. They are much too tight and are distorting the shape of the sail severely.
That may be a problem. How can I ease the lazy jacks? Lazy jacks on my boat are basically two lines with loops at the end, through which a bungee cord is threaded, which is hooked to the mast, and two points on the boom. There is no real adjustment of any kind. Last time I actually didn't use the farthest point on the boom and use the middle point twice, because the sail battens get tangled when hoisting sail, so this moves the whole thing forward enough for no tangles. However they are still tight. If I loose them somehow the bungee line hooks will just fall from attachment hooks. They do it anyway quite often. I'm thinking now how to attach them better. One positive thing is that lazy jack serve as a kind of a topping lift, so the boom doesn't fall down when I drop the sail. If only there would be some easy dynamic adjustment so I can put some slack into lazy jacks while sailing but tighten them before dropping the sail... Maybe I'll think of something...
Re: Mainsail shape
Posted: Mon Jul 25, 2016 8:49 am
by Tomfoolery
romandesign wrote:Judy B wrote:The first thing to do is to ease the lazy jacks. They are much too tight and are distorting the shape of the sail severely.
That may be a problem. How can I ease the lazy jacks? . . . If only there would be some easy dynamic adjustment so I can put some slack into lazy jacks while sailing but tighten them before dropping the sail... Maybe I'll think of something...
Check out this recent thread for some ideas.
http://www.macgregorsailors.com/forum/v ... =9&t=25437
You could splice a bit of line to the bungie(s) so it can be eased for sailing, then snugged back up for dowsing the main. Or just use line. I used to have a 3-legged LJ system on my last boat, which I would slacken and tie to the mast with a short bungie. Easy and quick.
Oh, and for hoisting the main, if you're pointed dead into the wind, the battens should clear the LJ's, and if one gets hung up, just lower a little and hoist when it's clear. Or pull the LJ's toward the mast so no interference, even when sailing, as I mentioned before.

Re: Mainsail shape
Posted: Mon Jul 25, 2016 9:15 am
by romandesign
OK, thanks for the ideas, will try and find one that works for me.
Re: Mainsail shape
Posted: Mon Jul 25, 2016 9:55 am
by delevi
sailboatmike wrote:Being a fractional rig increasing the back stay tension (bending the mast) wont do much for tension on the forestay
Try it. You might be surprised. It is true that on a fractional rig, backstay tension has more affect on the mainsail than on the headsail, but it still adds some tension to the forestay. Conversely, on a masthead rig, backstay tension will have more affect on tightening the forestay than bending the mast. That said, I can still get decent mast bend on my masthead rig with a lot of backstay tension... and my mast is a tree trunk.
Re: Mainsail shape
Posted: Mon Jul 25, 2016 9:59 am
by delevi
Roman. You might consider installing a purchase system for the outhaul. It is really a vital control of sail shape. 3:1 block & tackle will work well which will give you 6:1 advantage as the clew acts like a block, thus doubling your 3:1.
Leon
Re: Mainsail shape
Posted: Mon Jul 25, 2016 11:35 am
by Judy B
delevi wrote:sailboatmike wrote:Being a fractional rig increasing the back stay tension (bending the mast) wont do much for tension on the forestay
Try it. You might be surprised. It is true that on a fractional rig, backstay tension has more affect on the mainsail than on the headsail, but it still adds some tension to the forestay. Conversely, on a masthead rig, backstay tension will have more affect on tightening the forestay than bending the mast. That said, I can still get decent mast bend on my masthead rig with a lot of backstay tension... and my mast is a tree trunk.
Agreed. On a fractional rig, the backstay can tighten the forestay to a significant degree.
Re: Mainsail shape
Posted: Mon Jul 25, 2016 11:38 am
by Judy B
delevi wrote:Roman. You might consider installing a purchase system for the outhaul. It is really a vital control of sail shape. 3:1 block & tackle will work well which will give you 6:1 advantage as the clew acts like a block, thus doubling your 3:1.
Leon
Unless he has a mainsail that was designed to have a loose foot that can be flattened, adjusting the outhaul has virtually no impact on the draft shape or position.
Judy
Re: Mainsail shape
Posted: Mon Jul 25, 2016 11:43 am
by Judy B
romandesign wrote:Judy B wrote:The first thing to do is to ease the lazy jacks. They are much too tight and are distorting the shape of the sail severely.
That may be a problem. How can I ease the lazy jacks? Lazy jacks on my boat are basically two lines with loops at the end, through which a bungee cord is threaded, which is hooked to the mast, and two points on the boom. There is no real adjustment of any kind. Last time I actually didn't use the farthest point on the boom and use the middle point twice, because the sail battens get tangled when hoisting sail, so this moves the whole thing forward enough for no tangles. However they are still tight. If I loose them somehow the bungee line hooks will just fall from attachment hooks. They do it anyway quite often. I'm thinking now how to attach them better. One positive thing is that lazy jack serve as a kind of a topping lift, so the boom doesn't fall down when I drop the sail. If only there would be some easy dynamic adjustment so I can put some slack into lazy jacks while sailing but tighten them before dropping the sail... Maybe I'll think of something...
I think you can unhook the lazy jacks from the boom at mid-boom, and retract them by pulling them forward to hook onto the mast near the gooseneck. Retract them after you hoist the mainsail. Re-hook the bungee onto the mid-boom when you are ready to drop the mainsail.