depowering sail vrs reducing sail

[Franklin]

Something I've been wondering about for a few days and thought I'd ask the expert before I play with it.

Because I have roller furling, my approach has always been to reduce sail, or have the right amount of sail up and keep "normal" trim on it like keeping the vang tight when I want to depower the rig to reduce weather helm. Now I'm wondering if it's better to instead of reducing sail, to loosen the vang to increase the twist. Both methods will move the COE forward, but now I'm starting to think that inducing twist will move it farther forward then reducing sail. Thoughts?

Note: my boat is a tall 7/8ths fractional rig with about twice as much sqr ft in the main sail as the jib, so adjustments to the main is where the performance gains are mostly at. Jib pretty simple....tight jib sheet until inner taletails start flowing (as outters usually start to flow first).

 

[Rick D]

I will induce twist before I reef unless I expect a blow for a long time. in other words, it is a temporary measure when I'm not sure the breeze will stay clocked up or when I am nearing my destination. I do as you suggest with the main (assuming there is no more traveller left) but also move the car back on the jib for the same effect. Not sure if this is the book approach or not but it works for me.

 

[Franklin]

for sake of arguement, lets define the wind as steady blowing 20 knots. On my boat, I start getting overpowered at 15 or 16 knots when I'm by myself and 17 or 18 with a crew.

So in this case Rick, you'd reef because it's not temporary?

BTW: sounds like your answer is based on effort, as it is easier and faster to induce twist than reef. I'm more looking for the performance answer (part of the little perfectionist in me).

 

[Stephen K]

I'm in Rick's camp on this. The order of progression for me is: flatten, then twist, and lastly reef. Why reef if winds are gusty, but not overpowering the rig? Using your situation of steady wind at 20 knots, I would be reefed, because my performance / speed is better when reefed and I have tested that with my GPS. My girl likes to sail on her feet.

 

[Franklin]

my performance / speed is better when reefed and I have tested that with my GPS.

Exactly the type of answer I was looking for. Smaller well trimmed sail beats bigger sail with twist in performance. Thanks. Was actually hoping it was the other way around but oh well, I guess I've been doing it right all along.

 

[Franklin]

One reason I was asking this is because I started thinking that maybe my boat has a lot of helm at max speed because I have the CEO too far back and I need to induce twist instead of reducing sail but I guess not.

It is funny though on my boat. Maybe I have too much mast rake. My boat seems to perform it's best when the helm is about 25 - 30 % over from center to hard over. If I reduce sail to bring the helm back a bit, I loose speed. I do remember one time when I was going almost hull speed on a reach and it didn't have much helm at all, but in most cases, I seem to have a lot of helm.

I remember one time when sailing with a woman at the helm. She complained about too much weather helm but we were doing 7.3 knots on a broad reach with full main and the A-spin up. I took down the A-spin for her. The weather helm reduced and help position was about 10-15%; ideal right? Well, the speed dropped to 6.8 knots.

Total mast rake seems to be about 9 inches including pre-bend. That doesn't seem that bad and considering I did get 7.2 knots one day on a reach without much helm, maybe it is my trim.

Oh yeah....sails are only 1 year old.

 

[Rick D]

Correct, I sail faster for the same wind reefed. However, there are plenty of times I'm not going to reef because the time lost reefing will not make up in efficiency over the short term. I don't like sailing with a bunch of twist but if it gets you through a sundowner or gusty conditions (like near some headlands) then it's a reasonable alternative, especially if you are sailing single or short handed.

 

[Rick D]

One reason I was asking this is because I started thinking that maybe my boat has a lot of helm at max speed because I have the CEO too far back and I need to induce twist instead of reducing sail but I guess not.

Seems to me if you are pushing through hull speed on a reach, you will get some serious helm anyway. I do, but not all the time. I can just edge over hull speed on a beam reach under certain sea conditions without the helm getting crazy. I wouldn't be too concerned about it as you describe (7.3 knots is pushing some) unless you have another reason.

IMHO, the boat is going to behave better balanced rather than sluffed off (reefed vs. a bunch of twist) but that isn't responsive to the question. It still may be better strategy in some conditions to scrape off wind with twist instead of shortening sail.

I did, on another boat, move the CE forward with mast rake and it did improve despite being a tad more forward than the class guys suggested. It may have been my sails or other factor but it worked. Your rig would be pretty easy to play with; give it a try!

 

[Paul356]

Reef for the prevailing breeze; ease sheets, traveler, vang to handle the gusts. It's better to stay on your feet and point high than get knocked over and fight the helm. Do what works. Be flexible. Don't insist that there's one right way. The wind and water are too complex for rote rules.

 

[Don Guillette]

Franklin: Good answers on this thread. Here's my thought on COE. Forget about it as it is too deep into the sail trim thought process where you don't have to go. Concentrate on what happens with each sail trim control for the main and jib when you push or pull it plus how all the controls work together.

For everything to work at 100% efficiency they have to be in balance. In other words, you just can't focus on one sail trim control and not know how the actions of that control effects the others, which it does in almost every situation.

It is like adjusting a 4 barrel carburetor. Some of you younger listers are not familiar with this task so ask your fathers to explain it!!! Anyway you can't just mess with one or two barrels and expect 100% performance. Same with the sail trim controls for the main and jib.

On a fractional rig the engine is the main so it makes sense to conentrate your efforts on that sail. Many masthead rig sailors also concentrate on the main not realizing their engine is the jib.

The boom vang is the primary twist control for the main. Crank on the vang and you eliminate twist. The fairlead is the only twist control for the jib. Move it aft to increase twist and forward to decrease twist.

One other point and again this is what I do and everyone hears a different drummer. In a heavy weather situation, because it is just my wife and myself I do not fool around with conditions. I try the flat sail and then induce twist or vice versa depending where my head is at during this time. I'm a hairs breath from going right past reef to rolling up the jib and dropping the main and motoring. If I had some crew that knew what they were doing I might proceed differently but I'm big on doing what is easy and expediate at the time. On a boat your first thought is always the correct one. pondering get me and you into trouble.

 

[Moody Buccaneer]

I'm in Rick's camp on this. The order of progression for me is: flatten, then twist, and lastly reef. Why reef if winds are gusty, but not overpowering the rig? Using your situation of steady wind at 20 knots, I would be reefed, because my performance / speed is better when reefed and I have tested that with my GPS. My girl likes to sail on her feet.

For most boats, it is heel angle that creates excessive helm (assuming trim is correct).

There is a range of conditions where twisting the top of the sail off will be faster than sailing reefed. The reason is the tip vortex. When fully powered up the vortex and drag are high. Allowing the head of the sails to twist off reduces the vortex, the top of the sail acts as a winglet. Soft sails cannot be twisted off to zero lift, but until the sail inverts the trim can be fast with the top 1/3rd doing no real work. This is a good trim setting for "not quite blowing hard enough to reef".

As noted, the only way to know what is best is to make notes and compare settings. There is a point where reefing for sure produces better boat speed and a range where twist is faster just below that.

If a boat carries more than about 7 degrees of rudder when fully powered up (sails trimmed correctly) reducing rake to require less rudder angle should be faster.

Note that rudder angle and effort to hold that angle are two different things! Some boats (like C30's with the early rudder) require large effort to hold a normal rudder angle "two men and a boy" in a power reach. Other boats have nicely balanced rudders that don't make excessive rudder angles "feel" bad at all ... the knot meter tells the truth.

For masthead boats, with large foretriangles a head sail change is the correct response rather than twist or reefing. Never reef until you are overpowered with the 100% jib up. Granted that is not easy when sailing with roller furling and short handed ... in that case use Don's option ... roll up the head sail and motor sail under main alone ... quite pleasant.

 

[Scott T-Bird]

I agree with Moody about there being a condition when twist is faster than reducing sail. It also should be said that wind speed is normally higher aloft due to less friction. I don't believe that the main sail is always most efficient when less twist is involved. Twist allows you to maximize performance due to the divergence of airflow from the bottom of the sail to the top. In the right conditions, you are actually increasing performance by allowing the top of the sail to twist because the apparent wind at the top is further abeam than it is at the bottom. When you don't have the right amount of twist in these conditions, you are overpowered because the top of the sail is stalled and not performing. When you increase twist, you are not depowering, you are actually increasing performance and relieving that over-powered sensation. Of course, at even higher wind, there is a point when reducing sail is necessary, but I wouldn't be so quick to do that, especially when your engine is the main sail.

BTW, I also find that I get the best speed when I'm heeled close to 25 d, far more than when I have a steady go at about 15 to 20 d. This is despite the noticeable weather helm. I find that above 25 d and especially when we approach 30 d the weather helm makes it too difficult to maintain a course heading.

 

[Cayennita]

I haven't heard about cunningham or backstay adjustments. Move draft forward with cunningham. Weather helm can be eased by cranking back stay. It will open the leach and spill air before reefing is needed.

 

[eberns]

How will these trimming suggestions be affected by rough seas where you need power to punch thru wave action? I have a mast head, tall rig and would appreciate some suggestions with that type of sail plan.

 

[Cayennita]

If you are cruising, ease genoa halyard only enough to get speed wrinkles and or ease back stay to sag the headstay and get more power from the genoa. You might consider runners to keep the mast from pumping.