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Old 28-01-2012, 05:53   #61
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Re: Sailors don't know how to set sails ?

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Originally Posted by s/v Jedi View Post
Oh, hold on... in-mast furling... I don't know for sure but think that changes things. I know very little about how to make that work best, so you're better off with the sailmaker for advice

A laminate should survive longer when furled inside a mast instead of dropped on top the boom and covered with Sunbrella. While sailing, the laminate should be better with support from full battens. I don't even know if in-mast furling can be tri-radial cut but think it can.

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Yes, in-mast furling is good for laminates, and laminates are good for in-mast furling. They roll up tighter inside the mast, so the furling system works better. The ideal protection inside the mast, and the crease- and wrinkle-free storage provided by in-mast furling help a lot with useful life of laminates.

As we know, in-mast furling comes with a big performance hit but you make the best you can out of what you have . . .

Until I have some windfall (I would say "win the lottery" but I don't play) and can afford a carbon mast set up for a regular fully battened main
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Old 28-01-2012, 06:04   #62
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Yes, in-mast furling is good for laminates, and laminates are good for in-mast furling. They roll up tighter inside the mast, so the furling system works better. The ideal protection inside the mast, and the crease- and wrinkle-free storage provided by in-mast furling help a lot with useful life of laminates.

As we know, in-mast furling comes with a big performance hit but you make the best you can out of what you have . . .

Until I have some windfall (I would say "win the lottery" but I don't play) and can afford a carbon mast set up for a regular fully battened main
Yes, I did not have in-mast in mind with my earlier advice for Hydranet. If they can make a tri-radial laminate for you, the many seams will help against delamination too.

cuao!
Nick.
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Old 28-01-2012, 06:35   #63
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Re: Sailors don't know how to set sails ?

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How about those that do know, post up some tips, as Bash did, on how to trim, at least the basics. A bit of time passing on your knowledge to others could help somebody with extreme weather helm etc. Maybe even a thread just for it. Now someone will tell me there is one.


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Study Hall: Correcting Weather Helm
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Old 28-01-2012, 07:09   #64
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Re: Sailors don't know how to set sails ?

Yes. I too think that a boat sailing too slow will wallow.

Earlier in our adventures we sailed very conservatively. Then I spent some time in NZ and was lucky enough to see (and do) the way the kiwis do their racing. So, on the home run, I sailed the boat more aggressively. She sailed direr, more under control and was way more comfortable.

So, my advice to young skippers is always: break nothing. But once the skipper is no longer young and they know how to break things I say keep her going and you will break fewer things ;-)

Off course, a fasssst light boat must be slowed down when upwind. But downwind (which is most often the case with cruising people) all boats seem to benefit from sailing them in the upper range of their hull speeds.

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Old 28-01-2012, 09:31   #65
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Re: Sailors don't know how to set sails ?

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And remember that 90% of weather helm is caused by the underwater profile being asymmetric... which is caused by heeling. So reducing weather helm most relates to reducing heeling, and not to balancing sails etc.

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Old 28-01-2012, 12:27   #66
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Re: Sailors don't know how to set sails ?

I don't care about others sail trim as long as they give way or stand on as necessary.
I went to a coast guard rules and regs refresher class for a large group of sailors. They would present scenarios of crossing boats and I was amazed how many stated that they had the right of way over all power boats even with there sails down. when they were corrected, several indigent people stood and shouted "but we're sail boats!" some refused to understand that if the boat is under power they are a power boat.
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Old 28-01-2012, 12:42   #67
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Re: Sailors don't know how to set sails ?

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I don't care about others sail trim as long as they give way or stand on as necessary.
I went to a coast guard rules and regs refresher class for a large group of sailors. They would present scenarios of crossing boats and I was amazed how many stated that they had the right of way over all power boats even with there sails down. when they were corrected, several indigent people stood and shouted "but we're sail boats!" some refused to understand that if the boat is under power they are a power boat.
just do not INSIST on ypur right of way. also--if passing me, be aware that YOU are responsible to avoid collision while overtaking another boat.
while you insist on your right of way, you are making a bad choice as to results.
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Old 28-01-2012, 12:43   #68
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Re: Sailors don't know how to set sails ?

And your point? Most cruising boats have furling mains that do not set well regardless what you do, My light air gennys are at home and I have a heavey 130 on the rollerfurling jib. The mast will only bend when I hit a bridge. Sure we move the cars on ocasion. Even have snach blocks. Remember ....cruisers like the concept of " Honey..... do you want to tack today?" We are not all Farr go fasters out here. Besides, when you have somewhere you want to go the wind is always on the nose.
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Old 28-01-2012, 13:21   #69
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Re: Sailors don't know how to set sails ?

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(...) " Honey..... do you want to tack today?" (..)
Bravo! That's the spirit!

Cheers,
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Old 28-01-2012, 13:28   #70
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Re: Sailors don't know how to set sails ?

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And remember that 90% of weather helm is caused by the underwater profile being asymmetric... which is caused by heeling. So reducing weather helm most relates to reducing heeling, and not to balancing sails etc.

ciao!
Nick.
Very good point. All the other stuff, like letting the traveler down to depower the main, is mostly trying to counteract the huge weather helm created by heeling over.

I wonder, though, whether the weather helm is really less about the underwater shape of the boat (undoubtedly part of the picture), and more about the fact that the sails are pulling forward at their CE which is about a third of the way up the sails. When you heel over, this point is off center. The more you heel, the more lever arm you get. If you pull a boat from a point off its center-line, it will rotate.

So, even if you had a magic underwater profile shape that induced no turning, regardless of angle of heel, you'd still get massive weather helm when you heeled over. (almost said, "even if you had a magic bottom..." but knew where that would lead us!)
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Old 28-01-2012, 13:44   #71
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Re: Sailors don't know how to set sails ?

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just do not INSIST on ypur right of way. also--if passing me, be aware that YOU are responsible to avoid collision while overtaking another boat.
while you insist on your right of way, you are making a bad choice as to results.
Absolutely!
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Old 28-01-2012, 13:49   #72
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Originally Posted by cwyckham

Very good point. All the other stuff, like letting the traveler down to depower the main, is mostly trying to counteract the huge weather helm created by heeling over.

I wonder, though, whether the weather helm is really less about the underwater shape of the boat (undoubtedly part of the picture), and more about the fact that the sails are pulling forward at their CE which is about a third of the way up the sails. When you heel over, this point is off center. The more you heel, the more lever arm you get. If you pull a boat from a point off its center-line, it will rotate.

So, even if you had a magic underwater profile shape that induced no turning, regardless of angle of heel, you'd still get massive weather helm when you heeled over. (almost said, "even if you had a magic bottom..." but knew where that would lead us!)
How do the sails pull forward when that is where the apparent wind comes from? Remember that the forward vector is the result of two other vectors that do not pull forward.

ciao!
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Old 28-01-2012, 14:49   #73
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Re: Sailors don't know how to set sails ?

jedi, if you fire your starboard retro's only then your craft will spin fast enough to apparently disappear, who knows where.
Centre of aero pressure also moves aft along the sail/wing making it so necesary for you to trim continually in pitch on re-entry.
More heel and boat speed also each add to this facter. More speed with constant heel will cause the hull to turn to the high side of the boat.
All these act with together. By having a reasonable balance before the gust hits will leave the boat a good bit unbalanced but still in control.

Cats are different. The hulls are narrow so heel has little effect. The lee hull is pressed deeper turning the boat (gently) down wind. Mine still had a distinct turn into the wind when hit by gusts, including a big down-burst that had the boat chosing to leap from dead in the water to hull speed or above, turning forcibly into the wind because of the rearward pressure shift on the sails. Fortunately the coarse it chose was a safe one, and in the direction I wanted. I was not in control until the hull speed gave the rudders a lot of authority.
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Old 28-01-2012, 15:11   #74
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Re: Sailors don't know how to set sails?

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I used to deliberately annoy a racer friend of mine when he came with me. He would say that the sails are not set for maximum performance and i would ask him which way do i have to steer to make them right.,

Coops.
Hilarious Coops.

In my home waters, I have to sail as close as I can to make my marks and stay off the shoals.... with frequent course changes. I don't have a depth sounder right now, and I make it a policy not to cut corners. I am often challenged by the same day markers, and nearly collided with one last spring -- misjudging my leeway and having to claw my way out of there with the diesel.

So, yeah, I suck, but I'm getting better. If you use your sails to get you places, you simply get better at it. I would like to do some ocean racing sometime, east coast US to Bermuda sound perfect. I could learn a ton, I'm sure....on a long-legged thoroughbred.
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Old 28-01-2012, 15:16   #75
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Re: Sailors don't know how to set sails ?

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How do the sails pull forward when that is where the apparent wind comes from? Remember that the forward vector is the result of two other vectors that do not pull forward.

ciao!
Nick.
I got a little lost in your response, so I'll just explain my point a little more and hope it answers your question

I think we agree that we can approximate the forces on the sails as a single force located at the combined center of effort (CE) of both sails. This is a single force. Let's say that we're sailing upwind (otherwise we wouldn't have much of a heel). Close hauled, on port tack, the force vector from the sails will be pointing off to starboard, somewhat forward of the beam.

The exact angle of the force will depend on the lift to drag ratio of the sails, which is what we're trying to improve on with good sail trim. With well trimmed sails, the angle will be further forward of the beam.

You can split this one force into vectors, one pointing forward and one abeam. The latter is causing the heeling force. The former is the reason that the boat sails forwards as it is counteracting the drag force.

Both vectors will impart a turning motion (yaw) to the boat. The heeling force will yaw the boat if it isn't aligned with the center of lateral resistance (CLR) of the boat's underbody. This is pretty well understood by sailors and is the reason that people think a lot about balancing the sail area fore and aft, letting down the traveler, etc.

However, the forward drive of the sail is also imparting a yawing motion since the boat is heeled over. Even if some clever tweaking of the sails can exactly align the CE and CLR, and the boat has an underbody that won't introduce much yaw force when heeled, there will be a significant yaw force due to the misalignment between the forward drive at the sail's CE and the drag force.

So, heel will create weather helm. Heel will also rotate the plane of the rudder, so that more rudder angle is required to provide the same amount of yaw force. The rest is wasted as lift. So, more heel makes more yaw force, which requires more rudder force to counteract it, and the heel itself means you needs even more rudder force. Rudder force causes drag.

So sailing with a large heel and lots of sail feels fast, but it's often faster to sail with less sail and therefore less heel. It's also easier on the gear and the crew.

Our rule of thumb is 25 degrees of heel and a quarter turn of the wheel. If we go over either one of those, we need to make a change to the sails.
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