in light winds should I still be flattening slightly?

[danstanford]

My question is related to the use of my outhaul and Cunningham in light airs. My tendency is to like the look of a nice smooth flat sail and to likely overuse these controls when I could use a little more power in the sail. Should I be using the two controls to just remove wrinkles and leave the maximum depth in the sail possible in light winds or since this seems to take some depth out should I be leaving them alone? Though I am working on it, my main halyard will not take the main all the way up for some reason so I feel I need to use the Cunningham to pull the tack down some.

After the telltales, I next look to remove wrinkles in my jib as a way to get good trim on the foresail so it is tempting to start hauling on the main too!


Thoughts?

 

[Jackdaw]

In light airs your cunningham should usually be OFF.

You always want a powerful sail. In light airs, this means a full draft. The trick is that as it gets lighter the flow must stay attached to the back side (in particular) all the way to the leech. If the tell tails stop flying, this usually means that the flow as detached, and the best way to get it back is to start flattening the sail, This makes it easier for the flow to back it all the way around the sail. You start to see this (depending on your sail) in less then 4 knots.

Luff tension is used to pull the area of max draft forward. It usually goes aft when a sail is flattened. More important in heavy air. Cunningham the best way to do this on the main.

 

[danstanford]

Thanks Jack, just to confirm I read you correctly...In light airs I should use the boomvang and or traveler position to flatten the sail when I see detachment. Would the outhaul be used in conjunction when I see some vertical wrinkles?

I should resist changing luff tension until the wind increases and I need speed more than power.
Do I have it?

Dan

 

[rardiH36]

... If the tell tails stop flying ..

I've truncated the above "quote" from Jackdaw's advice. Certainly sound.

But we are talking about "light air". I've got standard material tell tails. That would be a light yarn of some sort. In light air, (fortunately not frequent in San Francisco Bay and when so, often one can't really sail because the water tidal current overwhelms any wind driven boat speed), the tell tails won't fly. They just don't stop flying. They might never have flown! Just not enough wind velocity for them to "stand to" and give guidance to the crew as to sail trim.

So in that case, how does fine tune the sail trim? Must be a standard convention for very light air sailing. Like maybe turning on the motor!

I remember several years ago, I was on the shore at Crissy Field in San Francisco having a picnic. A few hundred yards out, a marker had been placed for a J-boat race. The leaders approached and turned with a light but noticeable wind. And transited back into the central bay where the wind was still happening. Then the wind died right along the shore. The other boats, which were only a couple of minutes behind, barely made any headway against the current. And eventually started to drift backwards. 10 minutes later, the leaders were almost out of sight across the bay and were probably near the next mark. Where I was, the main pack hadn't moved at all except mostly backwards. Quite amusing to watch. Probably infuriating though to the racers.

 

[Jackdaw]

Thanks Jack, just to confirm I read you correctly...In light airs I should use the boomvang and or traveler position to flatten the sail when I see detachment. Would the outhaul be used in conjunction when I see some vertical wrinkles?

I should resist changing luff tension until the wind increases and I need speed more than power.
Do I have it?

Dan

On a fractional boat, outhaul and backstay control the flatness of the sail.

 

[Chris Blubaugh]

...Though I am working on it, my main halyard will not take the main all the way up for some reason so I feel I need to use the Cunningham to pull the tack down some....

Thoughts?

When you raise your mainsail, is your main sheet completely free? If the main sheet is pulling the boom down, it can interfere with raising the sail completely.

 

[danstanford]

Hi Chris, I have insured the sheet is free and the outhaul as well. In fact, I start with the topping lift set to bring the boom up a bit till I get the main up. With the big roach my main has you need to be careful the sail isn't caught on the topping lift line going up though. I am going to add a little Sailkote to things tonight and see if that helps.
I have been known to have the boom vang set on tight a couple of times though.
Do you Guys normally leave the vang quite loose till you need it on a broad reach?

Dan

 

[Don Guillette]

danstanford: Please check out the topic on "observations" -- the traveler has nothing to do with flattening the sail.

If a mate can sail in very light (just before the wind dies) to light wind he can sail in anything. Jackdaw was speaking about keeping the wind "attached" to the sail. Here's why the wind can't stay attached in these conditions -- it lacks the power to get around the sail. I don't know the scientific reason but that's what's happening. How many times have you seen beer can racers in very light conditions induce a ton of draft in both the main & jib? The answer is "all the time". What they're mistakenly trying to do is catch what little wind there is and they're action are counterproductive.

 

[danstanford]

danstanford: Please check out the topic on "observations" -- the traveler has nothing to do with flattening the sail.

Don and others, I tried the method of setting twist first using the main sheet and then trimming with the traveler rather than trying to set boom angle first then using the traveler and sheet to massage the twist and I really found it easier. Thank you.

This is a follow up. I notice that several of the new cruisers are not being shipped with travelers and use some kind of bridle instead. In each case they use a solid boom vang, do you think the intent is to use the vang to set twist/flatness and the sheet for boom angle?

 

[Don Guillette]

The boom vangs primary use is to control twist. It is also one of the controls that are used to adjust draft position. If a boat doesn't have a traveler then the only control they can use to adjust angle of attack is the mainsheet. Both the outhaul and the boom vang are used to flatten mainsail.

Again, the traveler has nothing to do with setting twist.