SailNet Community - Reply to Topic
Seamanship & Navigation Forum devoted to seamanship and navigation topics, including paper and electronic charting tools.

Thread: main sail blown? Reply to Thread
Send Trackbacks to (Separate multiple URLs with spaces) :
Post Icons
You may choose an icon for your message from the following list:

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

  Additional Options
Miscellaneous Options

Click here to view the posting rules you are bound to when clicking the
'Submit Reply' button below

  Topic Review (Newest First)
07-18-2013 06:28 PM
Re: main sail blown?

I'm seeing two separate questions that have been confused here:

1-Is the trim right?
2-Is the main blown?

And for #2 I would suggest the snuggle test. Rub your cheek on the main. Would you get rug burn if you used it as bedding? If yes, the sail is probably OK. If the sail is too soft to give you rug burn, it is probably blown out.

Odds are that every lo9cal loft will be glad to schedule a visit to your boat, to loan you someone who knows rigging and sails and can put eyeballs on things to give you a better answer. Sure, they're not objective, but a number of them actually know the best long term business is not to sell you a new sail unles you need it, so some of them are likely to say "You don't need a new sail, you need to..." and if you hear the same story from two or more of them, that's probably true.

On the other hand if they all guffaw and offer you condolences, you probably need a new sail.
07-18-2013 02:44 PM
Re: main sail blown?

If you need to de-power the main, you can leave the mainsheet tight and ease the traveller. That way, you don't lose your sail shape, but you change the angle of attack so as to ease pressure on the rudder. This is a temporary tactic I use whne dealing with gusty conditions when i don't want to reef (or reef more).
07-18-2013 02:29 PM
Re: main sail blown?

Yeah I felt there was something wrong when I found it was so easy to push the foot of the sail at dock.

I changed my leech reef line attachment a bit and I also added purchase in the form of an extra block.

That's the only picture I took:

I think the shape looks much better I let the leech rope out a little. The foot is much tighter that it used to and when I tightened it all the way that crease on the leech disappeared. but I will have to try it to be sure. I just need to find the right crew to go out with.

I also feel like I can play with the rope at the luff on the lower part of the sail. If I tension it more, I can flatten the lower part of the sail a little more. Currently it is locked with a knot but I could play with it too.

I do have a traveler I let the cart follow the main to get a little more tension out of it. Just for info I do not expect the vang to change the mast shape. Just to keep the boom from lifting up when I let the main sheet out a little
07-18-2013 02:10 PM
Re: main sail blown?

Draft position, where it should be
07-18-2013 01:59 PM
Re: main sail blown?

Do you have a traveller?
07-18-2013 01:55 PM
Re: main sail blown?

Wow, there are a lot of different opinions on the vang topic.

Lots going on with your videos and photos. First, what was the wind speed? Didn't looks too bad out there, not a lot of white caps. 15 kts? You shouldn't need to reef in those conditions. That being said:

Work on your reefing skills. The sailshape is horrible. You've effectively reduced sail, but have bellied out the bottom of the sail, greatly powering up what cloth you have flying. Take a look at a proper slab reef.

Flat as a board. That is efficient and depowered correctly. There is an extreme amount of fullness in your current main. Try to trim that out first before dropping coin on a recut or new main.

Also, re-set your bolt rope (it's probably shrunk) and check the outhaul bolt rope if you have one for similar shrinkage. This will make a sail seem very blown out. I would also look into bringing out a rigger or sailmaker to make some adjustments to your rig. SF bay in the afternoon is always breezy. Might as well tune for it.
07-18-2013 01:13 PM
Re: main sail blown?

when i read the title of this thread i was expecting something much more scandalous, but thoroughly documented,
07-18-2013 01:02 PM
Re: main sail blown?

The vang is not there to bend back the mast - that's way too much work to ask of it, and more importantly, the fittings that you would be asking to work against that leverage. If you want to bend the mast by pulling the sail down, then crank in on the sheet until it's in all the way, and then snug up the bang, but to try and accomplish that with a rope vang alone in heavy winds is a lot of work for you and your equipment.

The vang is there to reduce twist in the sail. We want to do this, because the lift that is generated by the sail is pretty much perpendicular to the surface of the sail, so when sailing off the wind and the boom lifts, the lower portion of the sail is looking at the water, and that's where the lift is pulling the sail, inducing heeling of the boat. By reducing the twist, that lift is now directed more horizontally, where we want the boat to be pulled. But it's not going to do much for you on a close haul, because your sheet is a more effective lever arm for flattening the sail. At some point, the sheet starts pulling mainly down and not in, and that's where it can be helpful, especially in lighter winds, to switch to the traveller for sail trim, as it's pull is strictly horizontal.

Flo, from your pics, I'd say the sail is pretty blown. One clue is that your leech line is cranked way in, which suggests that the cloth is pretty stretched (if you can loosen it and keep the leech from flapping, go ahead. That curl is making an uphill climb for the wind exiting the sail, and causing lots of turbulent drag. Get some yarn and stitch a couple telltales in there and you'll see what I mean. If the cloth isn't too worn, the sail can be restitched. I'm not sure what your boat is, but I have a pretty decent Catalina 27 main that came with my boat. The problem is that the PO spilled some West Marine resin on the area near the tack, so it's discolored and still a bit sticky, but I can give it to you cheap, and an hour or so with some vinegar or alcohol should cure the stickiness. I'm over in Sausalito, PM me if I can be of any assistance -

07-08-2013 09:39 AM
Re: main sail blown?

The first reef is locked onto the boom at the tack with a hook.

there is a set of slugs on the lowest part of the sail that are attached to the sail through a small rope to create a gap. when I put a reef in, I usually have to let a couple slugs get off the track to be able to bring the tack ring onto one of the two hooks at the gooseneck. I suppose I could try to work on the tension of this rope.

Finally, the boom itself in on a track. I can control how high or low I want it to be using a tensionning line at the bottom of the gooseneck going to a cleat on the mast (before tensionning the halyard).
07-08-2013 02:48 AM
Re: main sail blown?

It does look like the sail is fairly well blown. Look how far aft the point of maximum draft is. If it's that far aft in light winds it must be really aft in heavy ones. Your focus should be on moving it forward.

But something odd is happening to the lower few feet of the sail. You say this is with the first reef? It looks like the lowest ring is not attached to any slide on the mast track.

The second point up is attached but not tightly. I don't think you should have that huge gap between the sail and the mast.

It looks like there is some kind of loose luff line that isn't working or tensioned properly.
This thread has more than 10 replies. Click here to review the whole thread.

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

For the best viewing experience please update your browser to Google Chrome