Don...In your Sail Trim Chart page 1, for Main Sail in 15-18 Knots, in the chart at the top it says to place heavy tension on the vang to eliminate twist. Same page at the bottom on the right under "Quick Reference" under "Heavy Air Trim," it says to increase twist. The chart on page 2 is no help. I'm confused, the above gives conflicting information...in heavy air do we want twist or not?
Sail Trim In Heavy Air
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Heavy Air
Increase twist(spill air out of the top of the main) and lower the travler to leeward as necessary. If that doesn't do it, reef. Regards, Jim.
Increase twist(spill air out of the top of the main) and lower the travler to leeward as necessary. If that doesn't do it, reef. Regards, Jim.
Bert: I'm not back on line yet and am writing this from a Starbucks!! Hopefully, our phone line will be installed tomorrow and Ill get my computer up and running . Thank you Alan and Rick for helping me out with the answer, Part of the problem is as Rick stated - the chart could be as long as the book and it is not designed to cover every situation in detail. It would make sail trim a lot easier if that were possable. There are two ways to kill the power in your main and jib. The first is with a flat sail and the second is with twist. Both work almost equally as well. Part of the problem I had with the development of the chart was the space limitation. I needed more space to explain myself but it was not availbale. In the example you brought up I wish I could have said to kill the power make the sail flat or twist it off but that probably would have confused everyone,
Flatten vs twist
Bert, the basic controls for flattening the mainsail are the halyard, cunningham/downhaul, backstay/mastbending, and outhaul. Mainsheet twist is controlled by the vang and mainsheet. The traveller works with the mainsheet and vang also, but its primary function is to control the sail's angle of attack to the wind. You can twist a flattened main. As the boom eases out past the traveller track the mainsheet has less influence on twist and the vang becomes the primary control. I'm posting this explanation because your last post indicated some confusion.
Bert, the basic controls for flattening the mainsail are the halyard, cunningham/downhaul, backstay/mastbending, and outhaul. Mainsheet twist is controlled by the vang and mainsheet. The traveller works with the mainsheet and vang also, but its primary function is to control the sail's angle of attack to the wind. You can twist a flattened main. As the boom eases out past the traveller track the mainsheet has less influence on twist and the vang becomes the primary control. I'm posting this explanation because your last post indicated some confusion.
Depowering
I am under the impression that both work and the the two concepts: Flatten (flatter=less sail depth= less power) and twist (twist=more spilling of air aloft=less power) CM
I am under the impression that both work and the the two concepts: Flatten (flatter=less sail depth= less power) and twist (twist=more spilling of air aloft=less power) CM
Skinny vs Fat
One of the aspects of this topic which tends to confuse me is the word 'flat'. When referring to a sail, 'flat' means something a little different from regular english. Generally, we use 'flat' to mean things like 'not curved' or 'level in a single plane': it's impossible to be flat and twisted at the same time. Not so with sails which can definitely be simultaneously 'flat' and twisted. It might help to think about fat/thin instead of flat. Thin means take the belly/bulges out; fat means put them in. Even a thin sail can be twisted. So: to depower - thin the sail down to get the bulges out, then let it twist at the top. If I have it right, fat/thin controls include cunningham (gets vertical bulge out: thins front of sail) and outhaul (gets horizontal bulge out: thins bottom of sail). Twist controls include mainsheet (best directly upwind) and vang (best when reaching). I'm probably making it worse, aren't I. Dick
One of the aspects of this topic which tends to confuse me is the word 'flat'. When referring to a sail, 'flat' means something a little different from regular english. Generally, we use 'flat' to mean things like 'not curved' or 'level in a single plane': it's impossible to be flat and twisted at the same time. Not so with sails which can definitely be simultaneously 'flat' and twisted. It might help to think about fat/thin instead of flat. Thin means take the belly/bulges out; fat means put them in. Even a thin sail can be twisted. So: to depower - thin the sail down to get the bulges out, then let it twist at the top. If I have it right, fat/thin controls include cunningham (gets vertical bulge out: thins front of sail) and outhaul (gets horizontal bulge out: thins bottom of sail). Twist controls include mainsheet (best directly upwind) and vang (best when reaching). I'm probably making it worse, aren't I. Dick
A small correction
Not a bad way to think of it, Dick. "Flat", when used to describe a sail, just means trimmed out so that it is flatter than if it were allowed to 'bag out' - it doesn't mean the sail all lies in a single plane. By the way, the cunningham doesn't flatten or as you say, 'thin out' the front of the sail unless it is eased. When the cunningham is tensioned, the luff of the sail becomes more rounded (draft forward). This decreases power, but also decreases drag. Additionally it makes the "sweet spot" a little easier to find for the helmsman.
Not a bad way to think of it, Dick. "Flat", when used to describe a sail, just means trimmed out so that it is flatter than if it were allowed to 'bag out' - it doesn't mean the sail all lies in a single plane. By the way, the cunningham doesn't flatten or as you say, 'thin out' the front of the sail unless it is eased. When the cunningham is tensioned, the luff of the sail becomes more rounded (draft forward). This decreases power, but also decreases drag. Additionally it makes the "sweet spot" a little easier to find for the helmsman.
Maybe
RE: "fat" vs. "skinny": I find the terms "shallow belly" and "deep belly" of a sail to be the common terms in almost any literature I read from How To Sail primers to voyage logs of famous circumnavigators. Other sailors I talk too immediately comprehend the concept when put in these terms. Adding twist as a second dimension yields the phrase "shallow belly with induced twist," a mental image which is quite clear and readily understandable. Fair Winds, AD
RE: "fat" vs. "skinny": I find the terms "shallow belly" and "deep belly" of a sail to be the common terms in almost any literature I read from How To Sail primers to voyage logs of famous circumnavigators. Other sailors I talk too immediately comprehend the concept when put in these terms. Adding twist as a second dimension yields the phrase "shallow belly with induced twist," a mental image which is quite clear and readily understandable. Fair Winds, AD
Vang on hard; traveler down.
Bert, I don't what kind of a rig you're sailing, but here is what works best for for my Hunter 30, which is a fractional rig with a large main and 110 jib--this might not work for a masthead rig like a Catalina (which Don sadly still sails). I can delay reefing considerable by flatting the sail as much as possible with the vang (a rigid vang rigged to the cockpit really helps) and dropping the traveller leward as far as possible. I may ease the main a little to let the boom out further if needed, but it will take a winch to get it back in. This decreases the angle of attack, decreases heel, and keeps the sail from luffing. Easing the main sheet and vang to obtain more twist often results in the main luffing, getting backwinded by the jib (which is called a "fisherman's reef" and is not a bad strategy in big puff of wind), or the main too hard up against the spreaders (if you have swept back spreaders, like I do). With "vang on hard, traveler down" I can sail with full canvass to 20 kts of wind, point higher, keep heal at about 20 degrees, and fly at 6 1/2 to 7 knots.
Bert, I don't what kind of a rig you're sailing, but here is what works best for for my Hunter 30, which is a fractional rig with a large main and 110 jib--this might not work for a masthead rig like a Catalina (which Don sadly still sails). I can delay reefing considerable by flatting the sail as much as possible with the vang (a rigid vang rigged to the cockpit really helps) and dropping the traveller leward as far as possible. I may ease the main a little to let the boom out further if needed, but it will take a winch to get it back in. This decreases the angle of attack, decreases heel, and keeps the sail from luffing. Easing the main sheet and vang to obtain more twist often results in the main luffing, getting backwinded by the jib (which is called a "fisherman's reef" and is not a bad strategy in big puff of wind), or the main too hard up against the spreaders (if you have swept back spreaders, like I do). With "vang on hard, traveler down" I can sail with full canvass to 20 kts of wind, point higher, keep heal at about 20 degrees, and fly at 6 1/2 to 7 knots.
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