reefing a jib

[casem]

I've got a 15' Whilly Boat rigged as a gunter sloop. I can't find the sail plan online but there is an extremely similar boat The Whilly Tern, that shows the sail plan on this site:

http://www.duckflatwoodenboats.com/mainpages/gallery?KID=34

(Just scroll down and you'll see it. The Whilly Boat is also shown on this site but it is a Yawl rig.)

In strong winds my jib gets overpowered. So I'm thinking about putting a reef line in it. How should I go about doing this? It seems to me that I could just add a couple of reinforcments with grommets and a shackle and I should be able to do it. What problems might I run into? I have no sail controls on the jib except the sheet (fairleads are fixed).

[Kim Whitmyre]

The reef clew needs to be strong! Perhaps a mite stronger than the foot clew. . .And, according to Emiliano of "Sailmakers' Apprentice," the reef cringles should be on a line just above the reef tack. Hopefully Todd Bradshaw will chime in here with actual experience.

[Thorne]

Wouldn't another smaller jib (or flying no jib at all in high winds) be a cheaper solution than modifying the existing one?

Sure seems like a downhaul on the jib and reef points on the main sail would work well on a boat that size.

[Richard Smith]

Yes, the clew patch should be a bit higher . . . there are a number of good reasons.

And, you are going to want some grommets w small patches in the body of the sail to tie/roll up the reefed slab. Otherwise, it floggs in the breeze and you can't see. BTW, I recommend that the reef ties be thin velcro strips - colored red, which will help you remember they are there. That way if for some reason the reef comes out, OR if you forget to remove the velcro strips, you won't tear the body of the sail. The velcro will let go - hopefully. This error/"oops" is a good/steady source of income for sailmakers.

Also know that the added clew patch and grommet is going to weigh down the sail in light air - another justification for Thorne's suggestion.

[ 12-09-2005, 05:45 PM: Message edited by: Richard Smith ]

[Todd Bradshaw]

The measurements I have for the regular Whilly Boat jib are as follows:
Luff - 10.5', Foot - 4.33', Leech - 9.33', L.P. - 3.84', sail area 20.17 sq. ft.

You should check it against the sail you have to be sure it's the same sail, since there are various rigs available for that boat. I'll agree that it's probably easier and better to build a storm jib, especially if you only have one non-movable place to lead the sheets to, than to add a reef. You can probably also dump the normal jib and hang up a little storm jib faster and easier than reefing the present one. It would likely cost a little more to have one built than to adapt the regular jib, but not an awful lot. It's a pretty simple building job. You don't need much shape and two or three panels would do it. I'd probably go something similar to this. The luff curve will be hollow and hasn't been calculated yet, but basic dimensions would be as shown. If you ever wanted to try your hand at sailmaking, this wouldn't be a bad place to start.
http://www.imagestation.com/picture/sraid196/p2d4807302dc5a267dafe9d08ba4593a2/f11ecd0b.jpg

[casem]

Thanks everyone - clearly the consensus is that I need a storm jib for my 15 foot boat.

Todd what you have drawn looks good to me (and those are the dimensions I have for my jib, except I don't know what LP is). But do I really need that much of a reduction in area?

Here is my problem. When it gets real windy, I have a hard time heading into the wind because the jib won't keep its shape. I need to let out the jib sheet because there is too much power but then I have to fall off the wind. I don't like sailing without the jib because the boat really sails much better with both sails up.

Also sometimes I'll be out in fairly rough conditions and I'll double reef just so I can relax, but then I'll have too much lee-helm. So by reducing the jib area, I should maintain my weather helm, right? Maybe if I add some other sail controls to he jib, I might be better off?

[Dave Davis]

The lee helm is caused by having the center of effort forward of the center of lateral resistance--too much sail area forward of that imaginary point consisting of the areas of rudder/board/hull through which the entire boat resists sliding sideways.

So reducing jib area should reduce lee helm with double reefed main. I would think a small furler (like a Wykham Martin (sp?))would work easier than a reefed jib or storm jib. You willing to go all the way forward to reef or shift sails when it's blowing stink? Alternately a downhaul rigged on your usual jib to simply strike it when it blows up.

[John B]

Wykham martins ( and other brand ,non luff spar furlers) don't reef. They furl only.

[Todd Bradshaw]

Other controls - about the only thing I can think of that would make much difference would be jib car tracks, instead of the existing fairleads. Moving the cars aft would put more tension on the jib's foot and less on it's leech. This then would allow the top of the jib to twist off to leeward, reducing the anount of wind it catches and the effect it has on steering, heeling, etc.

How large or small to go on a storm jib depends on what kind of conditions you want the boat to work best in - how much wind, reefed or not, one reef or two. Each combination will produce different helm balance and a different C.E. for the sailplan. With some work, you can actually sit down and do a sailplan that shows all the options and what happens to the C.E. in the process. Ideally, it's usually best to avoid something that makes drastic changes in balance, so some sizes of sail will probably work better than others.

As John mentioned, the little furling systems which use a swivel up top and a spool at the bottom with no structure between them other than the sail aren't designed for roller reefing and they generally don't work well at all if you try it.

[Richard Smith]

LP means "Longest Perpendicular" - the shortest distance, measured from the clew to the luff. (The dashed line in Todd's drawing.)

Yes, IMO, you need that much sail area reduction, and FWIW, I'm not too big on the "twisted off luff with a big sail" as a normal, long term means of sailing in heavy air. In a pinch or "gotta do something" situation, fine. But, the sail and boat will be a lot more efficient sailing up wind and take less of a beating with a proper size sail with appropriate weight cloth set properly, as a whole, for the angle of sail. The boat will sail better, quieter, and with less wear and tear. And, you will be able to relax.

Try it, you'll like it.

[casem]

Okay, I've been putting way too much thought into this. But here is what I calculated in terms of boat balance. Everything is based on the simple balance of geometric centers approach, in which I included my rudder in the determination of CLP (center of lateral pressure). Lead is the distance by which the center of effort of the sail plan leads the CLP, divided by the waterline length.

With the full main and the standard jib up, I have an 9% lead. The boat balances okay in this configuration but I typically find that if I let it heel a little bit I get the "right amount" of wind helm. In spite of this I'll assume this is "optimum" because that is how the designer drew it.

If I put in a single reef (and leave the jib), that lead goes to 12%. If I then put in a double reef, it goes to 19%. This implies that I would induce leehelm which is what I find in real life, especially if I reef when there really isn't enough wind to justify it.

Now with Todd's jib (storm jib) and the full main, my lead goes to 6%. If I then put in a single reef on the main, it goes to 9% (which is what I am calling optimum). If I put in a double reef, it goes to 16%.

Interestingly, when the boat is double reefed with no jib, I also get the optimum 9% lead.

To summarize:

full main -------- standard jib ----- 9%
single reef -------- standard jib ----- 12%
double reef -------- standard jib ----- 19%

full main -------- storm jib ----- 6%
single reef -------- storm jib ----- 9%
double reef -------- storm jib ----- 16%

full main -------- no jib ----- 0%
single reef -------- no jib ----- 2%
double reef -------- no jib ----- 9%

Do these numbers mean anything?

[ 12-11-2005, 03:35 PM: Message edited by: casem ]

[Richard Smith]

It is typical with this type of rig that you want to keep a full main as long as you can - flattening it and reducing the size of the head sail before reefing the main. Your second set of numbers shows that. And, doing so will also provide the weather helm that you say you desire.

One thing that has not come up in this discussion is aspect ratio. Tall and skinny is better (faster) than short and fat. (Birds with long narrow wings fly faster than birds with short wide wings - eagles vs pigeons. Lifting power is another discussion.) This is another part of the argument FOR using a properly designed heavy air jib vs. just shortening (reefing) the AP (All Purpose) jib - and keeping the main tall and flat.

BTW: In light to medium air - if you are consistently finding that your boat is lacking weather helm, you might investigate/experiment with inducing a little more mast rake.

AND: I think it is important to differentiate/define whether we are talking about a "storm jib" vs. a heavy air jib. The design and expectations of each can be different.

[ 12-11-2005, 05:45 PM: Message edited by: Richard Smith ]

[casem]

All good points Richard. I did experiment with mast rake and was surprised at how sensitive the boat is to it.

And I think I am talking about a "heavy air" jib. (Remember, this is for a 15' boat.) I suppose it is all relative, but I guess a true storm jib would be pretty much flat and for use in 30+ knot winds. If I'm ever out in that much wind I'm taking down all the sails and curling up in the fetal position at the bottom of the boat.

[casem]

Question about the boat balance. I am under the impression that I'm not going to point upwind well without a headsail. Is this true? According to these calculations, the boat balances ideally with a double reefed main and no jib (9%). Maybe I really am better off with just the double reefed main and no jib? Of course then I lose a lot of power, but it is power I shouldn't need.

I generally don't sail without the jib because (a) without it I can't tack in any kind of waves without cheating with the oar, and (b) I don't have the jib telltales to tell me when I am pointing too high. But maybe my experience here is wrong. Any opinions?

[Todd Bradshaw]

Don't forget that you are also usually able to make fairly drastic changes in the real, on-the-water helm balance and CLP of small double enders by simply adjusting fore and aft trim. Sometimes just ooching your butt a bit one way or the other can make a big difference in what parts of the hull are getting lateral grip on the water.

[casem]

Yes if I move fwd I definately induce windhelm. But I'm kindof stuck sitting in the aft end just due to the layout of the boat. It is better when I have someone sitting fwd, but usually I am solo. I've always wanted to try to bring along a couple of bags of water (like people use for camping) as water ballast up at the bow.

[Richard Smith]

There a thread going that is discussing a related concern. here (http://www.woodenboat-ubb.com/ubb/ultimatebb.php?ubb=get_topic;f=6;t=005260)

If you want to "get up wind" efficiently in heavy air you are going to want a jib up. If you just want to tool around skip it.

One of my boats is a Rhodes 18, a fractional rig as well. When my wife was pregnant or nursing we used to do a lot of heavy air sailing w just the main or reefed main. It was comfortable and I still got to sail. Now, in the same air, the heavy jib is up and the main is flat and/or reefed and we work it up wind. Depends what you want/have to do.

[Todd Bradshaw]

"But I'm kindof stuck sitting in the aft end just due to the layout of the boat."

Just out of curiosity, how did this figure into your CLP and lead calculations?

[casem]

I didn't. I just used the waterline on the drawing.

[casem]

I checked on www.sailrite.com (http://www.sailrite.com) and I can get the sail that Todd drew (assuming the 8.7' leech was supposed to be a 6.7' leech) for $131 (for a kit). This sounds like a pretty good deal. But, for academic interest, how hard would it be to do it myself (i.e. go through the design of the panels)? And how would I do it? (i.e., please recommend books etc)

[Richard Smith]

Sailrite has books on constructing general types of sails. You might want to order one to see how you feel about the clarity of instructions - for you - and transferring the concepts to dimensions you want for your sail. If you don't feel comfortable doing so I would recommend you get the kit specific to your dimensions AND purpose and weight. The kit will be plenty clear and provide the materials you need -
BUT not tools. You should check to see what the kit is going to require for tools, such as a grommet setter, etc.

If you have a fairly wide zigzag sewing machine you will be ok putting the body of the sail together. That part is not that hard. I would NOT recommend doing it with a narrow zigzag or straight stitch machine. If you ever have to rip a seam to correct a mistake w straight or narrow zigzag you will come to know what I am talking about.

The corners will get 'cha. You will probably run into sewing machine problems in the corner patches, as they can get too thick for a home machine. Corner and luff hardware (rings and grommets) can also be a problem. But, you can web on the corner rings and hand stitch the webbing to the sail. Again, see what the kit is suggesting for the corner and luff hardware.

I've had kit sail builders bring their unfinished sails to me to finish the corners and hardware for them. You might find a sailmaker or someone with a HD machine who would do so for you. Not all sailmakers will do this, OR you will pay an hourly rate that will make you think twice about what you are “saving” in making your own.

Overall, you might be getting the picture that unless you want to have the "experience" of doing it yourself, the cost of a purchased sail might not be all that high. (If nothing else, hand stitching the webbed on rings might get you thinking.) :rolleyes:

[ 12-13-2005, 10:58 PM: Message edited by: Richard Smith ]

[Todd Bradshaw]

"The Stormsail Manual" by Sailrite's founder Jim Grant is probably the least expensive and most to-the-point, nuts and bolts booklet available on building stormsails. Sailrite sells it for about $11. It will give you just about all the info you need to design and construct one. As Richard said, the ability of your machine to sew through multiple layers of stuff may be the determining factor in the success of the project. Storm jibs usually have a wire inside their luffs, though in this case, I'd probably go with a short hunk of high-tech no-stretch line (the sail will stow easier and you wouldn't need to hunt up wire swaging tools).

You were right about the leech length typo above. If you're actually going to build one, I think I'd suggest one small change to the plan. It's a re-adjustment of the clew height and a small change on the sheeting angle. The new plan looks like this:
http://www.imagestation.com/picture/sraid197/pfd33aea91d6ba6dfaaa496ad3654881b/f10ff54b.jpg
(note that the luff curve figures were determined by typical formulas for storm jibs. The curve does need to be fair and that fairness is often best determined on the floor with a batten, using the figures as a guideline. The best final curve may or may not actually match all the figures - especially the top one at the 3/4 height position.)

I added a 4" strop (hunk of rope, webbing, wire, etc.) between the tack fitting and the sail's tack corner, raising the jib up 4" on the headstay. This is because we can't adjust the position of the jibsheet fairleads on the hull and consequently, the sheeting angle of the jib. By adjusting the strop to be either a bit longer or shorter, we at least have the ability to move the jib both up or down the stay a little bit to adjust sheeting angle if sea trials determine that it's needed to get the best sailshape. Sail area stayed the same, and just the leech and foot lengths were altered. Since I'm working from a small. fairly poor quality profile drawing, rather than real measurements taken from your boat, it's just a little safer to build in a little sheeting angle fudge factor.

You'll also notice that a kit for this sail is a bit of an oddity. Sailrite does a great job on their kits. I've known those guys for 25 years and have the utmost respect for them. But - their plotter cost a fortune and there is a certain amount of semi-fixed expense built into every sail kit which helps to pay for the equipment and labor of the guys who run it. On a big sail, the plotting charge is a fairly small portion of the total kit price. The bulk of the price is the fabric and trim hardware in the kit. On a little bitty sail, the vast majority of the kit price is the plotting, not the materials needed to build a 12 sq. ft. sail. For this reason on a sail so tiny, you may find that your local sail loft may be able to come surprisingly close to the kit price and provide you with a finished sail. You do need to be sure that they know you're talking about a storm jib, not just a little jib, and that it needs to be sturdy and well reinforced for high winds, but it's worth getting a bid or two - especially if you can get someone who's willing to double-check the measurements against the real boat.

[ 12-14-2005, 01:33 AM: Message edited by: Todd Bradshaw ]

[casem]

I didn't mention it before but the sails currently on my boat came from SailRite. The kit was top notch, but I definately recall having trouble with my sewing machine with the patches. I think in some places I was sewing through 6 layers of 4 oz dacron. But the sewing machine I was using was able to handle it. It is a good machine, but not designed for sails. I should be able to borrow it again.

Todd - I can't thank you enough for that design. I'm going to order that book and probably try to do it myself, as Richard said, for the experience.

Also, as for my fixed fairlead problem, one solution might be to put a second set of "fixed" fairleads next to the existing one. Maybe later I'll post a picture of how things currently are and get opinions.

[Richard Smith]

Wow. I'm impressed! !

Well, if you are going to make a "habit" of this you might want to consider purchasing a sewing machine from Sailrite. Or better/cheaper yet, a used sewing machine shop might have a low tech zig-zag model that they will mount on a table for you with a motor, clutch pedal and such. Besides the sail(s), you might find it useful for making other things - like covers for the boat, or even the barbcue grill, etc. Also, if you have local sail loft, they might have some used machines they would sell. But, be careful for any that might be too old to get parts for. Good sewing machines tend to outlive parts availability.