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Old 14-10-2012, 08:27   #1
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Reefing (furling) Genoa - efficiency?

Advice sought - What is (generally) the loss in sail efficiency by reefing (rolling in) a 150 furling genoa in higher winds, as opposed to taking down the 150 and hauling up a smaller jib? I know this is a very general question, but my wife and I are in our mid-sixties and want to avoid the extra physical work of changing head sails due to changing wind conditions. I have a 130 genoa and a storm jib, but don't particularly want to change sails unless absolutely necessary in the conditions. The 150 genoa is great in winds of 10 to 15 knots and is fine in low winds conditions also. And, of course, we can reef the main also when necessary (that's pretty easy to do). We sail mainly in Long Island Sound and intend to sail to Maine next summer. We do not intend to sail off-shore, except as necessary to get to Maine or possible the Chesapeake Bay area in the future. And, we're not out to break any speed records, but do want to sail reasonably efficiently.
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Old 14-10-2012, 08:36   #2
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Re: Reefing (furling) Genoa - efficiency?

I have a 110 and a 140. AKA Spring/Fall and Summer sails. Rule of thumb is you can furl them to about two thirds of the total (some would say three quarters but it could be even more if you are going down wind when shape matters less). They keep their shape better if you have a padded luff. Your sailmaker can install it if you dont already have it.
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Old 14-10-2012, 09:30   #3
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Re: Reefing (furling) Genoa - efficiency?

As you point out this is a very general question. The specifics of your boat and the cut of your sail will have a lot to do with the answer.

In general a boat is designed so the headsail and the main sail work together. To some extent if you increase/reduce the headsail area you should do the same to the mainsail to keep the COE where it should be. So if you roll up the Genny you should reef the main if the goal is to maintain maximum power from the sails.

Another thing to keep in mind is that the wind is not the only factor to consider. The sea state will often be as important as the wind speed. Things like a confused sea or short steep waves will often require a different sail trim than a flat calm sea or nice friendly rollers.

Another option if you are worried about keeping the speed up with reduced sail is to turn on the motor.
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Old 14-10-2012, 09:50   #4
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Re: Reefing (furling) Genoa - efficiency?

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Originally Posted by BozSail View Post
Advice sought - What is (generally) the loss in sail efficiency by reefing (rolling in) a 150 furling genoa in higher winds, as opposed to taking down the 150 and hauling up a smaller jib?.
Basically you loose some pointing angle when sailing upwind and a little speed when close reaching. On a broad reach or a run there is very little lost from a partially furled jib.

The angle lost when going upwind depends very much on how well the sail is designed to be partially furled. On an excellent sail you might loose only 5 degrees, on a poorly designed (or worn out) sail you might loose 15 degrees (Which basically kills you ability to make ground upwind).

The speed lost when close reaching again depends a lot on the sail design/cut. On an excellent sail it might be almost unnoticeable, while on a poor sail it could be a kt or two.

Typically the sail makers say that you can roll up 25-30% of the sail area and still get decent upwind and close reaching performance. Sailing broad and deep you can roll further than that and still loose nothing. In both cases you do (usually) need to move your jib sheet blocks forward as you roll - up the jib to keep the jib sheet angle/lead correct.

There is not much wind in Maine and the Ches Bay during the summer and a 150 makes some sense. In the spring and fall a 150 might well be a bit big.
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Old 14-10-2012, 11:15   #5
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Re: Reefing (furling) Genoa - efficiency?

All good advise.

I have a well-padded luff on my 150 and I can roll it to nearly any size with good shape. The tack is high enough that I don't generally need to move the jib blocks up wind, but I do have a barberhauler I use off the wind.

Sounds fine to me. You also don't have to sail when sustained high winds (perhaps >25 knots sustained on the nose) are predicted. Just a few lay days can solve the problem when coastal cruising. Thunderstorms are a different problem; just take everything down if it looks bad, since it won't last.
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Old 14-10-2012, 11:37   #6
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Re: Reefing (furling) Genoa - efficiency?

With a furling sail you can re-gain some of the loss by fine-tuning the size of the furled sail - something not possible with a regular sail.

Another aspect is that some sailmakers are better at making furled sails set well than others.

And you must think about the other things too - like e.g. are you sailg up- or downwind? You do not lose much performance downwind where shape counts less that the area.

Other than racing, I would stay with a well cut/designed furling sail.

BTW If there is space, it is well worth to have two furlable sails in a cruising boat. The big genoa on the outer stay and a flat, smaller one on the inner one. Then the big one is usually used all-out only.

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Old 14-10-2012, 12:08   #7
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Re: Reefing (furling) Genoa - efficiency?

Construction of the sail makes a difference. Foam or rope added to the luff will help the sail keep a decent shape as it's furled. Sails are shaped with more curvature in the center. When the sail is furled the foot and head furl tight while the middle bags out. The more the sail is furled, the more it bags. The foam fills up the center keeping it flatter as it is rolled in. That preserves the windward performance of the furled sail.

Another issue with furling sail is cloth weight. Furling sails are often made with weightier cloth to handle the load when furled in higher winds. That hurts the sail performance in light air. It also makes the sail a bear to bag. My 135% percent is very stiff and has to be flaked out on flat ground to fit in a LARGE bag and is quite heavy. I don't ever plan on changing that sail at sea except in low wind conditions.

My local area is light wind, 10k is a hurricane because we are in the lee of the island. If I sail 15 miles north or west, winds will almost instantly go from force 2-3 to force 5 or more. Sailing locally, have a lightish full length 150% that I bend on and remove. If I'm going north, between the islands, or the rare occasion when the wind blows more than 10k locally change to the heavy 135% genoa before leaving the dock. You might think about doing the same in the notoriously light air Sound.
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Old 14-10-2012, 12:30   #8
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Re: Reefing (furling) Genoa - efficiency?

I can tell you that even a 120 furled more than just a little looked like crap.
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Old 14-10-2012, 12:47   #9
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Re: Reefing (furling) Genoa - efficiency?

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Originally Posted by barnakiel View Post
BTW If there is space, it is well worth to have two furlable sails in a cruising boat. The big genoa on the outer stay and a flat, smaller one on the inner one. Then the big one is usually used all-out only.

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The other solution, which we use, is a small (105%) jib (sheeting inside the stays) on the furler, with a code zero for light winds.
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Old 14-10-2012, 18:00   #10
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Re: Reefing (furling) Genoa - efficiency?

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The other solution, which we use, is a small (105%) jib (sheeting inside the stays) on the furler, with a code zero for light winds.
Stellar, IMHO.

Most boats I have been on and seen around have too big and too heavy genoas. All out - they are too heavy for the light conditions, furled - they lose shape and push the SA forward.

A smaller, well furling sail for regular to strong conditions and a light Code-0 generation sail for the light days will sail circles around a typical 150% furling gear boat.

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Old 14-10-2012, 18:49   #11
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Re: Reefing (furling) Genoa - efficiency?

Quote:
Originally Posted by BozSail View Post
Advice sought - What is (generally) the loss in sail efficiency by reefing (rolling in) a 150 furling genoa in higher winds, as opposed to taking down the 150 and hauling up a smaller jib? I know this is a very general question, but my wife and I are in our mid-sixties and want to avoid the extra physical work of changing head sails due to changing wind conditions. I have a 130 genoa and a storm jib, but don't particularly want to change sails unless absolutely necessary in the conditions. The 150 genoa is great in winds of 10 to 15 knots and is fine in low winds conditions also. And, of course, we can reef the main also when necessary (that's pretty easy to do). We sail mainly in Long Island Sound and intend to sail to Maine next summer. We do not intend to sail off-shore, except as necessary to get to Maine or possible the Chesapeake Bay area in the future. And, we're not out to break any speed records, but do want to sail reasonably efficiently.
If you find yourself furling the 150 more than, say 50% of the time I would hang the 130.

I would have no issue, in your conditions, furling the 150 to 100% on a regular basis.

You furl because the wind is strong. Boat speed is not the issue. If you aren't getting hull speed hang a little more sail out.

Pointing will be impacted. The only way to know how you will be impacted is to try it on your boat.

Being in your 60's there is no way I would be changing a 150 to a 130 while underway.

As you said - You aren't racing.

And in confession mode. Last spring we had a very close beat to make in 25knts in a charter boat. It was about 5 miles. I reefed the main and furled the genny. We had plenty of short period swell on the port bow that was wreaking havoc on steady boat speed as I luffed up in the swell and down in the troughs. We weren't racing, I had a medium experienced crew and a couple of noobs that were nervous. I had no issue starting the motor, setting 1800rpm and using the motor to "steady" the boat speed through the swells.

Had we been racing with an experienced crew we would have made other choices. You sail within you boat and people's capabilities and comfort. No shame in that.
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Old 14-10-2012, 18:57   #12
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Re: Reefing (furling) Genoa - efficiency?

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I had no issue starting the motor, setting 1800rpm and using the motor to "steady" the boat speed through the swells.
The motor can solve pointing problems (when cruising).

But do be careful of angle of heel when running the motor. It might get oil starvation at a 'high' angle of heel. The engine shop manual will probably specify a max angle for operation. I personally don't like more than 15 degrees.
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Old 14-10-2012, 19:21   #13
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Re: Reefing (furling) Genoa - efficiency?

The high aspect ratio sail plans get by with smaller headsails. Older bpats with shorter masts just won't move in light air wihout a big overlap headsail. Rigging a code zero with it's continuous line furling will normally require a major refit of the bow to accomodate a bowsprit. I've been very disappointed in the pointing ability of my asymmetric spinnaker. In no way is it a substitute for a genoa in lighter air and seriously overpowers the boat trying to point in heavier air. What works for one type of boat won't work for others.
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Old 14-10-2012, 19:31   #14
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Re: Reefing (furling) Genoa - efficiency?

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What works for one type of boat won't work for others.

completely agree. Specifically with zeros some boats are too crowded at either the bow or masthead to work well without some modification. The bow modifications actually tend to be easier than the masthead modifications.

I've been very disappointed in the pointing ability of my asymmetric spinnaker. In no way is it a substitute for a genoa in lighter air and seriously overpowers the boat trying to point in heavier air.

Not surprised. A traditional asymmetrical spinnaker (say an A2) is a completely different sail from a cruising zero in both cut (the zero will be much flatter, with a straight leach, and probably half the area of an A2) and sail cloth (the zero will be a low stretch cloth). Net net, you might want to actually try a zero before concluding it will not work for you. When we first got Hawk, I got a used one dirt cheap, to experiment and see how it worked with the rig and sail plan.
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Old 14-10-2012, 19:38   #15
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Re: Reefing (furling) Genoa - efficiency?

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Originally Posted by estarzinger View Post
The motor can solve pointing problems (when cruising).

But do be careful of angle of heel when running the motor. It might get oil starvation at a 'high' angle of heel. The engine shop manual will probably specify a max angle for operation. I personally don't like more than 15 degrees.
+1

I was reefed also to reduce heel angle for the "concerned" on board. We were "pretty well" below hull speed. 5.5 kts or so IIRC.

I remember thinking at the time what a blast it would have been with my race crew - especially because the beating we (and the boat) would have taken was on a rental boat - LOL...
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