Swept spreaders and mainsail shape

[bobbob]

I think the picture exaggerates how far away the luff is pulled from the mast, but there's no doubt it gets pulled away a good deal under a good wind. There isn't a lot of tension on the furler when I attach it to the boom - I'm not sure how I might get any leverage to tension it more though....

Mike, could be Clearly it's not a standard main sail. Maybe this is what is recommended for the CDI furler? As I said its loose-footed by design, there isn't supposed to be a bolt rope in the sail.

[bobbob]

Looking at some pictures online, it looks like the main furler is supposed to be installed to the mast and not the boom? Mine clips onto the boom, meaning I need to disconnect it everytime I lower the mast.

For that matter, I'm not even sure if I have a main furler - it's entirely possible someone used another jib furler instead!

[sailboatmike]

I think the picture exaggerates how far away the luff is pulled from the mast, but there's no doubt it gets pulled away a good deal under a good wind. There isn't a lot of tension on the furler when I attach it to the boom - I'm not sure how I might get any leverage to tension it more though....

Mike, could be Clearly it's not a standard main sail. Maybe this is what is recommended for the CDI furler? As I said its loose-footed by design, there isn't supposed to be a bolt rope in the sail.

Loose footed is fine, but there are no sail slugs to hold the luff to the mast, normally one would have either a bolt rope or slugs into the sail track on the mast to hold the luff in, its got to close to impossible to get correct sail shape if the luff is 6 inches away from the mast and the luff is all curled over

[bobbob]

I see what your saying, but the luff is attached to the furler not the mast. I guess I need to do a much better job of tensioning the furler between its two attachment points, and it will take out most of that bend. I expect it will still flex some under load though. Any sail designed for this furler should expect some minimum amount of luff bend I would think?

[bobflshmn]

OK, I will bite, isnt that a genoa or jib that someone is using as a main???

Notice the UV strips on the foot and leech and no sail slugs or for that matter bolt ropes into the sail slot on the mast, its just held at the head and the tack.

Someone has got it VERY wrong here

I'm with you on this. If it was a furling main shouldn't the UV strips be on the leach and luff, not the foot since it would be the 1st thing to be covered?

[bobbob]

I have no doubt you're correct, but I'm not sure I understand - how would a mainsail furl "differently" than a jib sail?

[Judy B]

I've been looking at the manual for the CDI Mainsail Furler.According to the manual, the system is supposed to be installed with brackets on the mast, top and bottom. If your system doesn't have those brackets, I'd guess it's not the complete system, but rather a DIY modification.

When sailing hard on the wind, the luff of the sail in this system will deflect quite a bit from the vertical, much like a genoa luff will if the headstay tension is too slack. I think some deflection is inevitable, because no matter how much you tighten the wire, there is really no way to prevent the deflection of the luff. Maybe if you fixed the installation so there is alot more tension on the wire inside the extrusion, it would be better. For sure, you should do something about the deflection if you want acceptable sail shape. What you've got right now is not acceptable.

My opinion is that upwind is the biggest challenge for any sailboat, so why compromise the sailshape further? If convenience, cost, and simplicity are your priority rather than optimal upwind performance, maybe this would be a good system for you - but you really SHOULD install it with as little slack as possible.

[bobbob]

Thanks Judy. I am going to spend some time trying to increase the furler tension as you suggest.

To be honest, I admit to being a bit of a duffer sailor - I do find the convenience of the furler is as important to me as performance. That being said, if I can find a regular mainsail at a low cost I might give it a try and see just how much my current performance is compromised!

Cheers

[born2sail]

Bob,

I know I am stating the obvious here, but the luff of the main has not been feed into the track on the mast. The foot of the main is only held on at the clew and tack, but the luff needs to be in the track. Has the "rope" worn off??

I, too have a roller furling main on my 2013 , and I have to start the head into the mast before I can hoist from the cockpit.

Just my 2 cents.

[bobbob]

The luff of the main is attached to the roller furler (a behind mast furler, not an in-boom furler). By definition it cannot be attached to the mast.

Similarly, the design is for the sail to be "loose-footed" - it does not have a rope bolt to attach to the boom, it is designed to only be attached at the clew and tack.

By the way, I confirmed with CDI that this is a jib furler being used as a main furler The main differences between the two are that the main furler has an internal stay and a thicker luff extrusion, both of which are meant to improve the "stiffness" of the furler to mitigate against luff bend. I will be spending some time to see how much I can do to minimize it with this one. Seems to me I can use the boom as a "lever" to increase the tension, and hopefully the vang can keep that tension in place.

[sailboatmike]

Good detective work all round, we knew something was horribly wrong but with input from a few we actually found out what the issue is.

Good luck making a fix

[dustoff]

I got this great information and analysis from Judy B. It should be of great interest to anyone who has used stock sails for more than a couple of seasons.

Hi Rob,

I can appreciate the difficulty of taking pics while sailing. But being head to wind when the pic was taken reduces the reliability of my observations. Never the less, I can tell you that everything you have described is consistent with stretched out sails. So are the pictures. And your attempts to trim out the bagginess aren't working, Every correction you make creates a different problem.

Based on my observations (with the disclaimer about the sail being head to wind), If it were me personally, I would get new sails ASAP if my budget allowed. Those sails look really bad to my eye. I have sailed 26's with sails that looked like that like that and they don't tack, are twitch and heel too much. And your observation that it's okay in light winds but unpredictable in higher winds is a good indication that the sail changes shape drastically with every gust, The cloth has lost its resiliance.

A footed sail is shaped differently than a loose footed sail at the bottom. The draft is permanently built in. There is no way to flatten the draft, even when you pull the foot really tightly. Moving the outhaul aft won't help this sail much. Adding the slides would have made the draft a little, little bit deeper, but not significantly so. Certainly not enough to make the sail as baggy as it looks.

In most cases. using a foot mainsail as a loose footed one doesn't improve the shape - it will probably make it worse.

Pulling the foot tight moves the draft aft, not forward.

I couldn't draw any reliable conclusions about the genoa. I would need pictures looking up to the head from underneath the foot to do that. Sorry.
But if it's the same vintage as the mainsail, I'd guess it's like an old rubber band and stretches and changes shape with every gust.

Regards,
Judy

Hi Dustoff,

I'd like to send you some pictures that I annotated. Please send me your email address.

All in all,
1) It looks to me like the sail could be trimmed better. The leech is too tight, which hooks the battens to windward in those light wind conditions Pull the traveller car up to windward, loosen the mainsheetto allow boom end to rise up a few inches.. This would put more twist in the sail, and (hopefully) flatten the back half of the sail so the leech isn't hooked to windward so hard. (Thank you for showing the picture of how the sail was trimmed., which confirms my observations)
2) The sail looks very stretched out in these pics, It might look a little better if it not stalled and but I suspect it would still look pretty stretched out even if trimmed better, with a very deep draft, much too rounded near the luff, and located too far aft.

* The telltales aren't streaming aft at all; the are folded forward onto the leeward side of the sail. The sail is stalled. According to the telltale at the top of the mast, you are pointed right into the wind. So all the following observations may need to be adjusted. (Also, the picture should have been taken from underneath the mast, looking up. There'a some distortion because the shot isn't visualizing the sail looking straight up.)
*The topping lift might be a bit too tight, which might be forcing the leech to hinge to windward at the top.
* The leech (back edge) is too tight. leech is hooked to windward and the sail has the wrong twist. Pull the traveller to windward and ease the mainsail.
* The upper half of the mainsail has a very, very deep draft, with a "hinge" at the front of the two top battens. The cloth is really stretched out at the front of the batten pockets. The cloth is also distorted due to stretching at the front of the bottom two battens.
* The draft is too far aft, and too deep. It's stretched out.
* The Lazy jacks are impinging on the sail. Loosen them (but maybe they are doing that because the draft looks very dear near the luff
* There's are a couple of shots taken from the bow looking at the mainsail, and they suggest that the sail is very baggy right at the luff. but it's hard to tell that from a picture. A picture taken from under the mast would show it more clearly
* draft stripes would make the shape easier to see, but in lieu of stripes, I drew a spline curve on the reef points.

[sailboatmike]

Emmm not sure about the second picture??

Looks like it needs some trimming

[Judy B]

Emmm not sure about the second picture??

Looks like it needs some trimming

Pic #1 and #2 are the same sail, with different notes on the picture.

He's trimmed like that because otherwise, the sail is hitting the spreaders on a reach. (And Ron was focused on taking the picture, rather than steering, so we have to cut him some slack for momentarily pointing head to wind while he was taking the picture.)

As I previously wrote, the battens are hooked to windward and the leech doesn't have enough twist in it. To correct that, he should pull the traveller car to windward and ease the mainsail to reduce the tension on the leech of the sail. That will twist the leech more to leeward, and reduce the extent to which the battens are hooking to windward. But if he does that, the sail will be against the spreaders, because it's still too baggy.

Honestly, I don't think he will be able to trim that sail so that it isn't "stretched out" with too deep a draft in the wrong place. Pulling everything tight won't solve the bagginess. It will, however, make it look like the picture.

To my eye, this mainsail shows many common signs of having stretched excessively. Even if he trimmed it a bit better, it'll still look very baggy and hit the spreaders. I predict that it will heel excessively in gusts, point badly, and, when eased, hit the spreaders. (and that's what he reports happens).

[sailboatmike]

I dont think your seeing the same second pic as me, on my screen its showing a half naked person, hmm wonder how that works ????