With the variety of options of mainsail furling systems available, including slab, in-boom, and in-mast systems, it can be challenging to determine which one best suits your needs. In this comprehensive guide, we will explore the pros and cons of each system, enabling you to make an informed decision that aligns with your sailing requirements.
The majority of yachts, specifically over 75%, utilize the slab-reefing technique as their preferred method for reefing the mainsail. However, as the size of the boat increases, there is a noticeable trend towards adopting systems that allow the sail to be furled within the spar itself. In-mast furling systems, in particular, are more prevalent in larger yachts with a length overall (LOA) of 50 feet and above. For craft measuring 65 feet and beyond, in-boom furling becomes the more commonly employed method.
In essence, as yacht size grows, there is a shift towards the use of in-mast or in-boom furling systems instead of the traditional slab-reefing method. This transition is influenced by factors such as ease of use, convenience, and the desire for improved sail control. Larger yachts often opt for in-mast furling due to its ability to reef the sail at any point of sail, while in-boom furling offers advantages in terms of sail shape and incremental reefing positions.
Slab (AKA ‘Jiffy’ Reefing) System
The slab-reefing method has stood the test of time and remains the most prevalent choice, with over 75% of yachts utilizing this system. Over the years, jiffy reefing lines have replaced the traditional reefing points stitched into the sail, offering a more convenient and efficient solution. There are variations of the jiffy system, including single lines and continuous lines, each with its advantages.
When it’s time to reef the mainsail, the crew releases the halyard tension to allow the sail to be lowered. Reefing lines, which are pre-attached to the sail, are then pulled through reefing cringles (sturdy metal rings) along the luff of the sail. These lines are used to gather and secure the excess sail material in a folded position. By pulling the reefing lines, the sail is gradually reduced in size, creating a smaller and more manageable sail area.
Once the desired amount of sail area is reefed, the reefing lines are secured, typically by tying them off to designated reefing points or reefing hooks on the boom. This ensures that the reefed portion of the sail remains securely in place. After the reefing lines are secured, the halyard tension is adjusted to raise the sail back up, taking into account the reduced size of the reefed area.
Advantages of Slab System
Disadvantages of Slab System:
In-Boom Furling System
In-boom furling is a method used to reef the mainsail on a yacht by rolling the sail inside the boom. When it’s time to reef the mainsail with an in-boom furling system, the process begins by activating the mainsail furling mechanism. This mechanism is typically located inside the boom and is connected to a mandrel, which acts as a spindle for rolling the sail. By operating the mainsail furling control, the mandrel rotates, causing the mainsail to be gradually rolled up inside the boom.
As the sail is rolled up, the excess material is neatly stowed within the boom. In-boom furling systems often feature full-length battens that help maintain the shape and stability of the reefed sail. The mainsail furling process continues until the desired amount of sail area is reefed, adjusting to the prevailing wind conditions.
Once the sail is fully rolled up inside the boom, it is securely held in place. In-boom furling systems usually incorporate a locking mechanism to prevent any unintended unfurling of the sail. This ensures that the reefed sail remains tightly furled and ready for use when needed.
Advantages of In-Boom:
Disadvantages of In-Boom:
While the in-boom system offers several advantages, it’s important to consider its limitations and potential drawbacks before making a decision. Here are some disadvantages associated with the in-boom mainsail furling system:
In-Mast Furling System
When utilizing an in-mast furling system, reefing the mainsail is a straightforward process. The mainsail furling mechanism, typically located inside the mast, is engaged to initiate the mainsail furling operation. As the furling control is activated, the sail is rolled up around a mandrel positioned within the mast.
As the mainsail is furled, it is neatly stored inside the mast, reducing the exposed sail area. The mainsail furling process continues until the desired amount of reefed sail area is achieved, providing better control and stability in stronger winds. In-mast furling systems often allow for infinite reefing points, enabling precise adjustments to match the prevailing conditions.
In-mast furling provides sailors with a reliable and user-friendly solution for reefing the mainsail. Its versatility, ease of operation, and streamlined cockpit contribute to a more enjoyable and efficient sailing experience, particularly for cruisers and those seeking simplicity in sail handling.
Advantages of In-Mast:
The in-mast mainsail furling system is widely favored among larger offshore cruising boats for its convenience and ease of handling. It offers several advantages that make it a popular choice for many sailors. Here are some advantages associated with the in-mast mainsail furling system:
Disadvantages of In-Mast:
The in-mast mainsail furling system is widely popular, particularly among larger offshore cruising boats. It offers several advantages, but it’s also important to be aware of its limitations and potential drawbacks. Here are some disadvantages associated with the in-mast mainsail furling system:
When considering the various mainsail furling systems available for yachts, it’s important to evaluate the advantages and disadvantages of each option to determine which system best suits your sailing needs. Here’s a summary of the main points discussed for the three common mainsail furling systems: slab, in-boom, and in-mast.
The slab system is widely used and offers several advantages. It provides excellent sail shape and a larger sail area when fully set. It is relatively simple, cost-effective, and lightweight compared to other systems. However, it requires the yacht to come head to wind for reefing or setting the sail, which can be challenging in adverse weather conditions. Additionally, it requires more crew members for sail maneuvers and has a higher sail stack on larger yachts.
The in-boom system keeps the furled sail low down and allows for good sail shape. It offers more reef positions and reduces weight aloft, contributing to a better righting moment. However, it also requires the yacht to come head to wind for furling and setting the sail, which can be time-consuming. The system tends to be more expensive, often requiring a powered vang for boom lifting. There is a propensity for the sail to stack forward, necessitating the use of a preventer on all points of sail.
The in-mast system is favored for larger offshore cruising boats due to its convenience. It eliminates the need to come head to wind for reefing or furling, allowing for easier sail handling at any point of sail. It can often be operated by a single crew member and has fewer ropes in the cockpit, enhancing safety and reducing clutter. The system offers more reef points, allowing for incremental adjustments to the sail area. However, it compromises on sail shape, has a larger mast profile, and results in a smaller sail area when fully set. Sail jamming is a potential concern, but can be mitigated with proper sail tensioning techniques.