Slab reefing

Davidasailor26 · Jul 11, 2020

The problem with pulling straight down is that it will be hard to pull the new clew back enough to flatten the sail horizontally.

The reef line shouldn’t really run straight from the back of the boom just to the cringle. It should run from the back of the boom through the cringle to a tang on the boom about directly under where the cringle will be when reefed. This way when you pull on the reef line you get 2:1 purchase, and you’re pulling the sail both down and back.

Two other points - take the luff down to the reef point before the leech. Also use the topping lift to hold the boom up while feeding, then release it again after the Sail has been brought down to the boom.

jssailem · Jul 12, 2020

The reefed sail will always be a compromise over the unreefed sail. Fortunately the reason you reef is the wind is blowing stronger so a "perfect" sail shape has less importance.

My system uses a reef line secured to the boom with a bowlin, up to the cringle, back down to a cheek block on the end of the boom, and then through the boom to boom cleat near the mast. The line pulls down and back. The weight of the boom aids in providing adequate tension. The end boomed Main sheet also helps.

When the wind blows enough for me to throw in a reef, the power in the sail after setting the reef is more than I need to drive the boat.

kappykaplan · Jul 12, 2020

@wyctoronto photos would help.

shemandr · Jul 12, 2020

We are talking about the 356? On mine both reef lines come out a pair of blocks that was part of the end plate of the boom. My boat was a roller reefing main, which in retrospect should have switched to slab reefing. Anyway, if you just tie the reef line from the boom end plate block to the leech reefing cringle it will pull the leech back but not down enough. You need the reeve the reef line through the cringle and then either tie it to the boom, or run it to an eye, directly below the cringle. That way when you tighten the reef line the sail will be pulled down and back. Getting the sail flat may be more important than getting the cringle to the boom. A well tied main reed is a beautiful thing. It reduces sail area, flattens the sail and lowers the center of effort for the sail plan. It may not be correct to say it reduces power since in higher wind the power is as much as a full sail in lighter air.

jssailem · Jul 12, 2020

@wyctoronto Have you tried raising the boom to the sail with the topping lift?
Found an image that might help to explain the way I secure the clue reef to the boom.

https://www.uksailmakers.com/proper-reefing-procedure

or instruction from North Sail...

How to Reef a Mainsail | North Sails

There are a number of effective reefing arrangements, but all have two common elements. The first is ease of use; the reef should be easy to set and shake. Second,... Read More

www.northsails.com

Joe · Jul 13, 2020

wyctoronto said:
I find it difficult to effectively reef and flatten the main with the line from the cringle on the leech running aft to the back of the boom. I’m thinking of installing cheek blocks on the boom to pull vertically from the crinkle then aft to the rear of the boom. Any ideas?

The reef line should not be anchored to the cringle. It should be anchored to the boom, then run vertically to the cringle, then diagonally back to the boom end block. jssalem's illustration show's correct rigging.

sailme88 · Jul 13, 2020

Just assisted a friend with this project on Saturday. Luckily his boom has cheeking blocks on slide tracks on the butt end of the boom. In conjunction with the conversion we removed a cleat from the stbd side of the boom at the gooseneck and drilled and tapped to the port side butt end. This allowed the topping left control line to be accessed from the cockpit and not the gooseneck. At the point where the cleat WAS is now a taped in place cheeking block that turns the reefing line up to the luff cringle where it passed thru and descends to a mast base block that feeds to a deck organizer before heading aft to the cockpit. Halyard and reef line are reference marked with a sharpie. This makes the process very quick. Slab reef is at the higher reef point and can be done single handed in about a MINUTE ! The cost was 70' of reefing line...

jssailem · Jul 13, 2020

wyctoronto said:
from the cringle vertically down to th boom to a cheek block

What Joe is saying and illustrated in the image posted, that cheek block is not needed.

Davidasailor26 · Jul 13, 2020

wyctoronto said:
Pic of end result of hardened reef line.

Is that what it looks like reefed? That’s definitely not close to how it should look. But the way the reefing line is run should be able to get you in better shape than that. When you reef, be sure to:
-pull the luff down first
-have the mainsheet slack
-use the topping lift to pull the boom up, rather than trying to pull both the weight of the boom and the sail with the reef line

Also, have you checked that the reefing line runs smoothly and all sheeves are in good working order? Friction in them would make it harder to get enough force on the cringle.

Do you have a picture of the whole foot of the sail when it’s reefed?

jssailem · Jul 13, 2020

Davidasailor26 said:
finitely not close to how it should look. But the way the reefing line is run should be able to get you in better shape than that. When you reef, be sure to:
-pull the luff down first
-have the mainsheet slack
-use the topping lift to pull the boom up, rather than trying to pull both the weight of the boom and the sail with the reef line

@wyctoronto David has repeated the steps.
Your boom needs to move upwards to meet your sail reef. Also how is the stretch in the reef line. My reef lines are low stretch, like my halyards. Once tight they do not move. You will take all that slack out of the reef line and the new clew will sit on the boom or nearly so when you slacken the topping lift after the reef line is tied off.

Slab reefing

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