The Basics of Jiffy Reefing: A Sailor's Guide

In a Nutshell

Jiffy reefing is a simple, reliable way to reduce your mainsail area quickly and safely. The system uses a series of lines to pull down a "slab" of the sail to the boom, giving you better control and a more comfortable ride as the wind picks up. Whether you’re sailing solo or with a crew, getting a reef in early and efficiently is a fundamental skill.

A Dehler 39 CWS sailing off the wind under a spinnaker and full mainsail

Jiffy reefing works well with a fully-battened mainsail

Getting to Grips with Jiffy Reefing
The Size & Scope of Jiffy Reefing
Is Your Reefing System Set Up Safely?
How Does Jiffy Reefing Actually Work?
Jiffy Reefing vs. The Alternatives
Upgrade Your System & Avoid the Hassle
Safety First: Common Mistakes & How to Avoid Them
Advanced Sail Trim for a Reefed Main
Summing Up
FAQs

Getting to Grips with Jiffy Reefing

Reefing 'slabs'

I'll be honest, jiffy reefing, or slab reefing as it's also known, is my go-to choice for reefing the mainsail. Simple, efficient, and bulletproof - it’s the very definition of a dependable, seaworthy system.

The jiffy reefing system reduces the mainsail area from the foot of the sail in a series of parallel 'slabs'—normally three. This process uses a handful of control lines:

the main halyard
the topping lift
the vang (or kicker)
the reefing line(s)

The whole operation becomes a whole lot easier if all of these lines end up in one of two places: either at the mast or led back to the cockpit. This way, a single crew member can handle the job without needing a second pair of hands.

The Size & Scope of Jiffy Reefing

While jiffy reefing is a perfect solution for most cruising yachts, it's worth noting its limitations, particularly for larger vessels. As a mainsail's size increases, the physical effort required to hoist the sail, set the reef, and manage the bulk of the sail on the boom can become unmanageable. This is especially true for single-handed sailors. On boats over 50 feet, for instance, the sheer weight of the boom and the size of the sail can make it a strenuous and even dangerous operation.

For this reason, yachts over a certain size often opt for more mechanically assisted reefing systems. In-mast or in-boom furling systems, while more complex, offer the advantage of effortless reefing from the cockpit at the push of a button. For a large boat, the trade-off in sail shape is often considered acceptable for the sake of safety and convenience. This is a crucial consideration when you’re planning to buy a larger boat or thinking about how to upgrade your existing one.

Is Your Reefing System Set Up Safely?

The way your reefing system is rigged makes a world of difference to both your safety and how easy it is to use. There are a couple of common setups, and you’ll want to get the right one for your style of sailing.

All Lines at the Mast: This setup is pretty common, particularly on smaller boats. The downside? It means going forward onto the deck when the weather’s already turning sour. In my book, that's a risk you should avoid if you possibly can.

All Lines Led Aft to the Cockpit: This is a much safer alternative. You can get the job done from the security of the cockpit, out of the wind and spray. The trade-off is more friction in the system and a lot more lines to manage in your cockpit, which can look a bit like a rat's nest if you’re not careful.

A Hybrid System (the worst of both worlds): A pretty common, but frankly, less than ideal setup is when the reefing lines are led back to the cockpit, but you still have to deal with the halyard and the reefing cringles at the mast. This means you either need two people, or one person has to handle the luff at the mast, leave the sail flapping, and then scurry back to the cockpit to pull down the leech. I've been there, and it’s a situation you'd do well to avoid.

How Does Jiffy Reefing Actually Work?

The mechanics of jiffy reefing are pretty simple, but the process changes a bit depending on where your lines are.

1. At the Mast

Let's say your mainsail halyard and reefing lines are all at the mast. Here's the drill for putting a reef in:

Before Leaving the Cockpit:

Head up into the wind.
Ease off the kicking strap and the mainsheet.

At the Mast:

Take up on the topping lift to support the boom.
Drop the mainsail just enough so you can hook the reefing cringle over the reefing hook (or cowhorn) on the gooseneck.
Hoist the main again and secure it, making sure the luff is taut.
Pull in the leech reefing line and secure it.
Ease the topping lift.
Tidy up the ropes and get back to the cockpit.
Get back on course and trim your sails. Job done!

Basic jiffy reefing, with everything done at the mast

2. From the Cockpit

With this setup, the mainsail halyard and topping lift are brought back to the cockpit through a series of turning blocks at the foot of the mast. The need to go forward to hook the sail cringles over the reefing hooks on the gooseneck is eliminated, as a dedicated luff reefing line pulls the cringle down to the boom.

Typically, you’ll have two separate reefing lines for each reef; one pulls down the leech and the other pulls down the luff. So, if you've got three reefs, you could end up with a whopping six extra lines in the cockpit. I know, a bit of a "snakepit."

You can sidestep the clutter with a single-line reefing system for each slab, which cuts the number of lines down to just three. A single line runs through a series of blocks inside the boom, so when you pull it, it reefs both the luff and leech at the same time.

A single-line jiffy reefing system

sketch of a double-line jiffy reefing system

A two-line system with reefing lines routed back to the cockpit

Something to remember is that with both of these systems, but more so with the single-line version, the mechanical advantage will be working against you when its time to pull the reef out.

At this point you may well be asking yourself if single-line reefing is all it's cracked up to be, in which case you should take a look at our article Single-Line Reefing: Is It the Best System for You?

Jiffy Reefing vs. The Alternatives

While jiffy reefing is a classic for a reason, how does it stack up against the other options out there? The two main alternatives are in-mast and in-boom furling.

System	Advantages	Drawbacks	Best For
Jiffy Reefing	Simplicity, reliability & excellent sail shape.	Manual labour required; can be dangerous in adverse conditions if lines are at mast.	Performance sailors, offshore cruising & those who prioritise reliability.
In-Mast Furling	Effortless reefing from the cockpit & no lines to handle.	Poor sail shape, expensive to install & can jam at sea.	Coastal cruising, charter boats & sailors who prioritise convenience over performance.
In-Boom Furling	Better sail shape than in-mast furling & sail is stored neatly in boom.	Mechanically complex, prone to jamming & requires a rigid boom vang.	Cruisers who desire a neater solution & can handle the mechanical complexity.

Upgrade Your System & Avoid the Hassle

Reefing at the mast—especially on a wet and windy night—isn’t everyone's idea of fun, so anything you can do to make the job easier is worth a look.

Mark the main halyard: I find it’s a real help to mark your main halyard just below the jammer at the point where the cringle can be hooked over the cowhorn. Do this for each reef position.

Use flying cringles: These are a game changer. Flying cringles are just short lengths of webbing attached to the sail's luff reefing point. They create a larger loop that's much easier to slip over the gooseneck's reefing hook. It'll save you from fumbling around when conditions are less than perfect.

Replace cowhorns with captive hooks: If you can, swap out standard cowhorns for captive hooks. They won't let the flying cringle fall off before you get a chance to haul on the halyard.

Switch to Dyneema lines: Dyneema is a high-strength, low-stretch line that seriously cuts down on friction. It’s a lot more durable than old-school polyester and will make your reefing system run way smoother.

Pic showing how to mark the main halyard at reef points

Main halyard marked at the reefing position. See also the captive hooks and flying cringle on this basic jiffy reefing system

Safety First: Common Mistakes & How to Avoid Them

While the mechanics are important, getting a reef in safely is what really matters. Even the most experienced sailors can get it wrong, but knowing how to spot and fix a mistake quickly can save you from a whole lot of trouble.

Not Dropping the Halyard Enough: This is a classic rookie mistake. If you don't drop the mainsail far enough, you won’t have enough slack to hook the luff cringle. The fix is simple: drop the halyard another metre or so to give yourself some breathing room.

Luff Isn't Fully Tensioned: If you don't hoist the main tightly enough after hooking the cringle, the sail will be lumpy and inefficient. Re-tension the halyard until the reefed luff is firm and flat, getting rid of any horizontal wrinkles.

A Jammed Line: A line can get jammed in a clutch or block in a gust. The most important thing is to stay calm and never force it. If you have a cockpit-led system, head into the wind for a moment to take the load off the line and free it up.

Advanced Sail Trim for a Reefed Main

Putting a reef in is only half the battle; the real skill is in fine-tuning your sail's trim for optimal performance. Once the reef is in, you'll want to use these controls to get the most out of your boat.

Cunningham (or Downhaul): This line helps you flatten the sail. In strong winds, you'll want to use the cunningham to pull the draft (the deepest part of the sail's curve) forward and flatten the sail, which is essential for sailing upwind.

Outhaul: The outhaul controls the foot of the sail. Pull it on tight to flatten the sail and reduce its overall power, which will help reduce heeling and improve your boat's balance.

Vang (or Kicker): After you've hoisted the sail and re-tensioned the reefing lines, remember to put some tension on the vang. It'll help flatten the sail and keep the leech tight, so you're not losing power from an open leech.

By getting to grips with these three controls, you’ll be able to transform your boat into a well-balanced machine that handles gusty conditions with ease.

Summing Up

Jiffy reefing is a tried-and-tested method that offers a perfect balance of reliability, simplicity, and performance. By understanding the mechanics, making smart upgrades, and always putting safety first, you'll be able to master this essential skill. A well-executed reef not only keeps you and your crew safe but also makes your boat a pleasure to sail, allowing you to confidently tackle whatever the sea throws at you. For a broader understanding of sail reduction strategies and safety protocols, you may want to consult our comprehensive guide on the topic: Reefing a Sail: The Ultimate Guide to Control & Safety at Sea.

Article written by Dick McClary, RYA Yachtmaster & Yachting Journalists Association (YJA) member.

FAQs

What's the difference between jiffy reefing and slab reefing?

They're two different names for the exact same system. 'Slab reefing' is the more traditional term, referring to the "slab" of sail area that is removed. 'Jiffy reefing' just refers to the speed and efficiency of the process.

How many reefs do I need?

It depends on the size of the boat and how you plan to use it. Most cruising boats have two or three reefs to handle different wind conditions.

Can I convert my system to single-line reefing?

Yes, you can. It's possible to convert most two-line jiffy reefing systems, but it often requires new lines, blocks, and a more complex setup inside the boom. It's usually a job for a professional rigger.

What's the best time to put a reef in?

The golden rule is to reef before you're overpowered. If you're debating whether to do it, it's probably already time. It's always easier to shake out a reef than to put one in when the boat is heeling excessively and the weather's getting worse.

What is a "flying cringle"?

A flying cringle is a luff reefing point on a sail that has a short piece of webbing attached to it. This webbing creates a larger loop, making it much easier to quickly hook onto the gooseneck's reefing hook.