You’re familiar with basic mainsail running rigging, right? The halyard hoists it up the mast and the main sheet adjusts the angle of the sail to the hull. Both lines are important but they don’t adjust the aerodynamic shape of the mainsail, which can make a big difference if you want to get the best performance out of your mainsail.
There are three potential control lines for your mainsail to adjust its shape. Each line controls the tension on one of the three sides of the mainsail. To control luff tension, you need a Cunningham or boom downhaul like I describe in Control Mainsail Draft with a Boom Downhaul. To control leech tension, you need a boom vang like I describe in Control Your Mainsail Shape Better With a Boom Vang. In this post, I describe a trimmable outhaul to control the foot tension.
Most first generation C-22s and similar sailboats came from the factory with a simple loop of line between the mainsail clew and an eye strap at the end of the boom similar to the picture below. It holds the sail in place but that’s about all. You can’t easily trim it while sailing. If it’s loose enough to make connecting the clew easy, then it isn’t tight enough for moderate to heavy winds. If you take the time to cinch it up tight, you’ll have to untie it to take the sail off if you trailer sail. By then, the knot could be hard to loosen.
The solution is to replace that crude loop of line with a trimmable outhaul that consists of:
- (2) Harken 085 double blocks or equivalent, one with a becket
- Fixed eye snap shackle or halyard shackle
- (2) Harken 072 3/16″ shackles or equivalent
- Ronstan small V-Cleat Fairlead or equivalent
- 5′ x 1/4″ New England Ropes Sta Set or equivalent
The pictures in this post show a five part (five line segments) outhaul only because those were the blocks that I had on hand when I rigged the outhaul. You could use fewer parts. I recommend at least two. The line is white with blue flecks in keeping with the color scheme that I describe in Choose Your Running Rigging Colors Logically. Notice in the picture below that I spliced an eye in the end of the line where it attaches to the becket. You could also use a bowline knot there but I prefer the neatness of spliced eyes, particularly here at the end of the boom where four lines are attached (main sheet not shown).
Size does matter
The challenge in this setup is to get the overall length of the outhaul as short as possible. On a C-22, there’s only about 10″ from the mainsail clew to the eye strap at the end of the boom. If the combination of blocks and other hardware is too long when you tighten the outhaul, the blocks will meet in the middle before putting enough tension on the foot of the mainsail. To solve the challenge, use the shortest shackles you can find. You might also need to shorten the becket on the one double block. Another option is to attach the working end of the line around one of the sheaves of the block itself, but that will result in less mechanical advantage.
To make the outhaul as easy to attach as possible, add a snap shackle to the working end of the outhaul for hooking to the mainsail clew. Install the fairlead cleat on the same side of the boom as where the line exits the outhaul blocks (port side in the picture below). The fairlead keeps the line captured at the boom if it gets out of hand. A foot of slack on the end makes the setup easy to trim while under sail and to loosen when removing the sail to head home.
The two lines that you see hanging down from the aft end of the boom in the pictures above are the working ends of the topping lift and jiffy reefing lines that I’ve installed on Summer Dance. They’re held out of the way in the pictures for simplicity. I describe them in Make Your Boom More Useful with a Topping Lift and Single Line Jiffy Reefing Made Easy, respectively. To see how all four systems (including the main sheet) fit on the boom, see the pictures below.
Keep It Simple, Skipper (KISS)
If the outhaul shown above seems too complicated or expensive for you, a simpler version is even easier to set up.
For a three part (three line segments) outhaul, you’ll need:
- Harken 083 single block with a becket or equivalent
- Ronstan small V-Cleat Fairlead or equivalent
- 4′ x 1/4″ New England Ropes Sta Set or equivalent.
Install the block on the boom eye strap, the fairlead cleat on the side of the boom, and reave the line as shown in the picture below.
In this system, the line runs through the clew grommet itself. The line isn’t as easy to trim as with multiple blocks, but it’s still easy enough.
For the complete collection of rigging projects like this one, purchase my ebook Do-It-Yourself Small Sailboat Rigging.
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