Some Things I've Learned About Sail Trim Recently

[cwyckham]

Originally Posted by Dockhead

I'll stand by and get flamed right with you. But that's the whole point of the jib car -- to balance the tension of leech and foot. Certainly that's how I use it. If the foot is tight but the leech is loose, for example, then the car needs to go forward. That's pretty basic, isn't it?

I would say, more precisely, the purpose of the car is to control the twist of the headsail. You can either choose to twist the sail to match the wind gradient of the day (by having all of the telltales lift simultaneously), or you can choose to pull it further back to intentionally depower the head of the sail, reducing heel angle and weather helm.

[sailorboy1]

Is it any wonder that people say they can not figure out how to trim a larger boat with a B&R rig? Seems a lot of people can not figure out how to trim a modern boat with a "standard" rig (whatever that is now days)

Overall I just think too many sailors try to sail modern boats too hard, which is just starting a fight with your boat that you wouldn't win.

[DoubleWhisky]

Originally Posted by Dockhead

I wish I had polars for my boat.

I think it is well worth to e-mail the designer and ask for them

bill@dixonyachtdesign.com

[Jammer Six]

Originally Posted by cwyckham

I would say, more precisely, the purpose of the car is to control the twist of the headsail. You can either choose to twist the sail to match the wind gradient of the day (by having all of the telltales lift simultaneously), or you can choose to pull it further back to intentionally depower the head of the sail, reducing heel angle and weather helm.

Weather helm, by definition, wants more power in the headsail, not less.

[StuM]

Originally Posted by Jammer Six

Weather helm, by definition, wants more power in the headsail, not less.

Not if the weather helm is the consequence of heel angle and more power in the headsail increases that angle.

[Snowpetrel]

Originally Posted by Jammer Six

Weather helm, by definition, wants more power in the headsail, not less.

Trying to dispel this sort of simplistic thinking is what this thread is all about. Different boats respond very differently to sail trim and heel.

[cwyckham]

Originally Posted by Jammer Six

Weather helm, by definition, wants more power in the headsail, not less.

Most people, even most instructors, don't really understand how important heel angle is to weather helm.

Imagine that the force of the wind on the sail is from a large rope that goes through the center of effort of that sail. The rope pulls out (heeling force), but also forward (driving force).

There are two ropes, one for each sail, so the amount of pull on each rope will certainly effect the rotational (yaw) force on the boat, otherwise known as weather helm.

However, also notice that when the boat is heeled over, the rope is no longer centered over the boat. In fact, it is way off to leeward. Now if you pull forward on the rope, it will twist the boat around to windward.

This effect is even more important than asymmetric hull forces, etc. that most people talk about when it comes to why a heeled boat rounds up.

So now, if you can stand the boat up, it will have less weather helm. Moving the center of effort down (by twisting off the jib and/or main) will both decrease the heel and decrease the yaw force lever arm, so you get a double benefit.

I like to try twisting off the jib first, since the performance of a rolled jib is so bad. Only later will I start to roll the jib.

[Jammer Six]

With weather helm, I usually just reef the main, not the jib.

Originally Posted by Snowpetrel

Trying to dispel this sort of simplistic thinking is what this thread is all about.

Good luck with that.

When I see a thread on the internet, on any subject, I pay at least if not more attention to who is posting as I do to what they say.

[Ex-Calif]

Originally Posted by OldFrog75

Not sure I understand this comment. In an extreme case with the car all the way forward, the foot would be loose, the leech tight, a wide angle of attack, and the draft rounding way out to leeward.

Without a genoa Cunningham you can't impact draft with cars or sheeting. You may impact it with halyard and or backstay. You are only impacting twist and a twisted genoa has less power.

In 14 knots the halyard should be "medium" tight. In high winds hard on halyard and hard on backstay. In light winds you may even have a loose halyard with wrinkles in the luff (for hanked sails).

I still think if you have 5-6 people on the rail hiking in 14kts on a 32 foot boat it "must" be flatter than 20-30 degrees. We'd have 5 people on the rail of a 41 Benne and whether they hiked or not impacted heel by a couple of degrees.

BTW - A well trained crew knows how to hike - lean out in gusts, straighten up in lulls and if severe lulls they even will automatically scooch back towards the coach roof. They call the gusts, they call traffic etc. Some are thinking this is a bit anal and yes not required for cruising but I feel if one is going to do something why not do it well.

Training can be fun and interesting thing to do on a boat. When we raced J24s we'd practice backing the boat, holding position on the start line, hoists, drops, tacks etc... OK thread drift, sorry.

I just find this stuff fascinating.

Originally Posted by carstenb

At the risk of being flamed by those who know a lot more than I do about sail trim. I was taught (a long time ago) that you set the genua car so that the leech and foot exhibit the same arc, meaning that the arc the foot describes (no matter how loose or tight it is) should be mirrored in the leech.

Now you have the car set correctly and you can get on with tightening/loosening the sheet.

No need to flame this is exactly the "starting" position. Car position is often set by experience before a race for example based on conditions. The Benne had car pulleys to easily adjust if conditions changed while racing.

Originally Posted by Dockhead

I'll stand by and get flamed right with you. But that's the whole point of the jib car -- to balance the tension of leech and foot. Certainly that's how I use it. If the foot is tight but the leech is loose, for example, then the car needs to go forward. That's pretty basic, isn't it?

There are conditions when you might want to close the leech on the genoa.

Choppy seas for example. If the leech is closed the foot opens and the bottom of the sail gets "rounder" and drafty. This can help acceleration out of chop. Chop is often accompanied by higher winds so boat speed need not be sacrificed. Pointing is affected.

[OldFrog75]

Originally Posted by Ex-Calif

I still think if you have 5-6 people on the rail hiking in 14kts on a 32 foot boat it "must" be flatter than 20-30 degrees. We'd have 5 people on the rail of a 41 Benne and whether they hiked or not impacted heel by a couple of degrees.

How many degrees is this...

[StuM]

I just rotated the image 33 degrees to get the horizon about horizontal.


1. At about 33 degrees of heel like that, the crew should be hanging out a lot further than they are. Get them to stick there heads under the top lifeline and belly up to the bottom one with their backsides up to the toerail! I'd also get them to bunch up together further astern.

2. Judging by the angle of the pennant on the stern, it looks like you are on a close reach and if so your headsail is cranked on far too tight.

[Dockhead]

Originally Posted by StuM

Not if the weather helm is the consequence of heel angle and more power in the headsail increases that angle.

I wish someone had told me that five years ago!!! The grief I went through to learn it on my own!

I even started a thread on here on weather helm years ago -- dozens of posts, and not one person suggested this

[Dockhead]

Originally Posted by Jammer Six

Weather helm, by definition, wants more power in the headsail, not less.

That was true on the boats I learned on years ago, but not anymore. Moving the center of effort of the sail plan fore and aft was what determined helm balance, more than anything, in olden days. Because of the shape of the hull (long keel, narrow beam, old fashioned boat), heel angle didn't matter much, but sail plan balance did.

Now on my new boat, although the hull form is quite conservative by today's standards -- forefoot not flat, aft sections not flat, beam not carried aft -- sail plan balance doesn't do anything at all to helm balance. Nothing!!! I proved it yesterday sailing in a pretty good blow with my mainsail completely unreefed, traveler centered, and no headsail on except the little staysail. No weather helm!! I was gobsmacked. Goes against everything I learned.

[Jammer Six]

Speaking of old boats, some instructors, who shall remain nameless, at least until they reach forty, don't remember boats that don't care about heel.

I've heard instructors teach what they were taught, as if it were always true, without question or reason. I've heard them preach the party line, that if you reef, you'll go faster, have whiter whites, brighter colors, grow taller and have more sex. The party line may be true for them, but not for everyone. Or every boat.

Then they're surprised when they lose.

As a result, I never listen to anyone who preaches that there's only one way-- that always indicates lack of experience, and has never indicated that there's only one way.

Good on you, Dockhead, never stop learning. I intend to die of old age, in class. I've said for years that if I win the lottery, I'll travel, build a boat, then go back to college.

And that all said, this isn't class, and while the good thing is that anyone can post here, the bad thing is that anyone can post here. And they do. Just consider: you post here, Stu posts here, Ex-Calif post here, Snowpetrel posts here, and I post here.

That should convince anyone that the problem isn't the question, the problem is which answer.

[Ex-Calif]

Originally Posted by StuM

I just rotated the image 33 degrees to get the horizon about horizontal.


1. At about 33 degrees of heel like that, the crew should be hanging out a lot further than they are. Get them to stick their heads under the top lifeline and belly up to the bottom one with their backsides up to the toerail! I'd also get them to bunch up together further astern.

2. Judging by the angle of the pennant on the stern, it looks like you are on a close reach and if so your headsail is cranked on far too tight.

Exactly - the rail meat should be sitting with their butts uncomfortably square on top of the toe rail. Everyone can be 12 inches closer to the rail - their tummies should be touching the lower lifeline for sure. Everyone should be leaning out over the lower lifeline and with this heel angle (believe it or not) some crews will extend their arms upwind. You should be shouting, "Hike you B!tches!" in a gruff skippery voice...

Hard to tell on the pennant but I agree this boat is not yet on a close hauled course and the genoa is over sheeted. The main is depowered causing some of the nose low attitude of the boat.

When the heel angle is excessive like it is in this photo the lift angle on the sails (and especially the genoa in this picture) is "towards" the water exacerbating the plowing that you see.

Sea state is pretty flat so a flat main would be fine (tight steering angle low acceleration). Hard to tell but it looks like this loose footed main's outhaul is not on hard enough.

Depending on where the mark is this boat can be pointing higher. I am guessing this is a buoy/can race and not a true windward leeward course. So close reach is probably what you need to the next mark, presuming you are pointed at it, and you are oversheeted.

I am attaching a couple of photos of hiking. I could not find one of any of my crews but the blue boat is a TP52 that sailed a couple of seasons here and this crew is well trained. These are pretty powered up conditions. Note the guy up forward really leaning out.

The white boat Tikki Tavi is also a competitive crew around here. They aren't hiking as much as they should but at least everyone is on the high side.