Furling a large headsail vs switching to a smaller one

kappykaplan · Aug 5, 2020

Sail shape is problematic with a partially furled headsail. There are a few things your sailmaker could do to improve the performance of a partially furled sail, but there is still a performance loss. I haven't flown my 150 in many years and use the 110 all the time now. Do you put a reef (or two) in the main in those conditions? :beer:

Justin_NSA · Aug 5, 2020

I was new to sailing when we had our head sail modified for a furler. The sailmaker added luff padding. We never partially reefed the sail so it was probably money wasted.

A headsail is not cut flat like a bed sheet, but with a "belly" in it. When you roll it up on the furler, the end will be tight but the center will be loose, producing a "lousy" shape when reefed. What the luff pad does is add a pad in the center, to make that part a larger circle and take up the sail faster to compensate for the "belly".

Claude L.-Auger · Aug 5, 2020

Same boat, mine being the shoal draft version, i.e. real tender when wind gets around 18 knots. For light winds, I wanted a 150. After discussions with North Sails, including prevailing winds in my sail area, I decided to go with a 130 with a luff pad. That was 18 years ago. I was able to furl it down to about a 110 and still maintain a good shape. Been so happy with it that when time came to replace that sail this winter, I ordered exactly the same thing. Luff pads have progressed quite a bit and my new sail is absolutely great. I added an asymetrical spinnaker which gets used in much lighter winds. Good luck with the decision.

Benny17441 · Aug 5, 2020

It all depends if you are racing or trying to keep a schedule but if you are just pidling around just furl it.

shemandr · Aug 5, 2020

The cloth weight for the 150 is likely lighter than a smaller sail especially if the 150 is “...So great in light wind.” So not only is the shape impacted but you may stretch the sail cloth and degrade it’s shape - even when flown fully deployed. I like the 135 notion, perhaps with a downwind sail. Upwind sails derive most their lift in the first 1/3 of the sail. So with the 135 over the 150 you aren’t losing as much power upwind as you might think. Off the wind you’ll miss the 150 in light air. Your boat will likely feel less tender with a well shaped 135 too.

capta · Aug 5, 2020

Personally, I'd rather not go up to the foredeck and change a jib out in increasingly more wind and seas. We reef our jib by just rolling it up a few turns, but it does have reefing patches on the foot and leech. Honestly, if you are reefing your jib, conditions are getting more severe and I doubt that performance is a big thing to anyone except the racers. In light air and calm seas I can point a lot higher with or with out a reef in the jib than I can in heavy weather and big seas.

dlochner · Aug 5, 2020

The short answer is furling a jib does affect the jib's efficiency. How much it affects it and what difference does it make is a long discussion.

When the sail is furled the leading edge of the sail becomes fatter. This disturbs the airflow across the luff and affects the sails efficiency, especially when close hauled. The further off the wind the boat sails, the less of a problem it becomes.

Which begs the questions, how much of a problem is it? If you are a highly competitive racer, it matters a lot. If you like to go day sailing or cruising, eh, not so much. Yes a furled 150% will lose some pointing ability and that will affect boat speed and VMG, however we're only talking a few degrees and a few tenths of a knot.

In some areas where there is a seasonal variation in prevailing winds, strong in spring and fall and lighter in the summer, sailors will put the smaller sail on in the windier seasons and the bigger sail in the lighter air season.

There is, of course, much more to the story as others have alluded to. How the sail is cut, the weight of the cloth and where it is used, the type of foam luff that is installed and more. For the most part for most sailors, a furled 150% is OK in most conditions.

Kings Gambit · Aug 6, 2020

It really depends on the type and size of Genoa and your point of sail. To "shorten sail" and still have a good sail, the roller reefing Genoa should have a foam luff designed into it. You can shorten a 135% to 120% and still have a sail than can drive the boat upwind well enough but with noticably lower pointing ability. A 120% you can shorten to 105%, the same. Off the wind, even still at a close reach, you can do just fine with roller reefing the Genoas.

Changing a headsail with a double-hand crew after the wind pipes up is a pain in the butt, especially if the headsail is in a track/foil (i.e., not hanked). It's harder to get it down and there is no good way to keep it in place w/o hanks; basically must use sail ties. You expend a lot of energy just trying to control the thing as it comes down in freshening wind, etc. So, if you are going to change headsails, use hanked-on sails IMO. If you are going to roller-reef, use a Genoa with a foam luff. There is not much in between w/o crew work.

Justin_NSA · Aug 6, 2020

You'll want to reset the blocks on the tracks to get a better sheeting angle too

ToddS · Aug 6, 2020

I partially furl my larger sail to reef it... and for that matter, the same on my roller-furling mainsail as well. If I were racing, would I? No. But If I were racing, I also wouldn't have a bimini and dodger up, and wouldn't tow my dinghy around or have a great big anchor on my bow roller... etc. etc. If it's 90% as good as doing it the "better" way, and makes sailing significantly easier and more enjoyable... I'm fine with that. If I had a half-dozen crew members helping me get that last 10% to eek out more speed... sure. But my crew is generally two sleeping (or complaining) teenagers and a wife who is happy to be out on the water enjoying the sea air, but not paying close attention to the knotmeter on our way to explore a beach somewhere. I TOTALLY get the appeal of maximizing efficiency using equipment to its fullest potential in some cases... It all depends on what you're looking for.

I used to be a ski racer, and would measure the temperature of the snow on the hill just before a race to get the best wax for the conditions. And the skis got rewaxed between every race. And I'd freeze my you-know-whats off wearing zero insulation regardless of the air temperature, because you'd never win a race with the aerodynamics of a winter coat. Now? My skis are lucky to get waxed every year or two, and I wear down jackets and smile just as much (or more) despite the added friction.

Kings Gambit · Aug 6, 2020

Roller furling and roller reefing of a headsail are not exactly the same things, any more than furling the mainsail and reefing it would be the same things. To properly reef a headsail on a furling drum you need a foam luff. Otherwise, it is simply partially furled as in, not all of the way in.

Sailfanatic · Aug 7, 2020

I had a 150, 125 and 100 on my prior boat. I would leave the 100 on the furler in the spring and fall, which tend toward stronger winds, then the 125 for the summer. The 150 came out for the accasional race. more than two turns on a genoa, even with the luff padding, and the resulting shape distortions not only reducing pointing but also the fullness increases heeling.

Joe · Aug 7, 2020

YVRguy said:
Hope you can settle something between my boating partner and I. We have a large 150 genoa and a 110 gib. Lately we've been using the 150 because it's so great in light wind but we're easily overpowered with it, particularly considering our boat is quite tender. Is there anything wrong with just furling it back to a more appropriate size as needed rather than going to the trouble of switching to the smaller sail? I heard somewhere that after a few turns on the furler the sail loses its shape and becomes less effective.

This is a question that only you can answer. Go out and test as many configurations as you can. Make notes. Don't for get to re set the jib leads .... if you don't know how, this is a good time to learn. BTW.... the "sheeting angle" is the HORIZONTAL angle created when a line from the bow to the jib lead is compared to the center line of the boat. It tells you how close the sail can be sheeted to the boat's centerline. Unless you have another set of lead car tracks or a barber hauling system the sheeting angle is not really adjustable. Sailmaker will consider this angle when designing headsails for individual boats. Moving the leads forward and aft adjusts the "lead angle" and is critical for getting the right amount twist/power ratio for any given condition.

So... if you feel your headsail is overpowering the boat... before you roll it in... try moving the jib lead aft to give the sail more twist... this means the lower part of the sail will be flatter while the upper leech will be opened up... But lets think about that for a moment. You could move the leads, but would it also make sense that rolling in the headsail a bit without moving the leads would have a similar depowering effect as moving the lead car aft?.... see what I mean.. YOU GUYS need to go out and test... and take notes... that's the only way you get the right answer to your question.

Scott T-Bird · Aug 7, 2020

YVRguy said:
Is there anything wrong with just furling it back to a more appropriate size as needed rather than going to the trouble of switching to the smaller sail? I heard somewhere that after a few turns on the furler the sail loses its shape and becomes less effective.

I think it depends. If you are out in the water and need to furl the 150, then I would do that. If you are going out for the day and you know that you will need to shorten sail, then I would take the trouble to change the sail. I can't find the picture of a race day with my 150 furled and it just looked ridiculously bad and our performance was miserable accordingly.

Here's my very, very old 110 on a day when we knew we would be reefing. I think it actually looks pretty good. It certainly isn't embarrassing like the picture of my furled 150! :huh:

(I'd show the picture if I could find it right now).

Davidasailor26 · Aug 7, 2020

Scott T-Bird said:
I think it depends. If you are out in the water and need to furl the 150, then I would do that. If you are going out for the day and you know that you will need to shorten sail, then I would take the trouble to change the sail. I can't find the picture of a race day with my 150 furled and it just looked ridiculously bad and our performance was miserable accordingly. View attachment 183454
Here's my very, very old 110 on a day when we knew we would be reefing. I think it actually looks pretty good. It certainly isn't embarrassing like the picture of my furled 150! (I'd show the picture if I could find it right now).

I think this is the thread with the pictures you’re talking about Scott - Reefed sail shape not so good ...

In any case that thread has some good discussion that’s relevant here.