In-mast furling is a system where the mainsail rolls into the mast instead of being hoisted and lowered like in traditional slab reefing. Some sailors love its convenience, others criticize its complexity. Here's a balanced look at the pros and cons:

✅ Advantages

• Ease of Use: Reefing and unreefing can be done quickly and safely from the cockpit — especially helpful for short-handed or solo sailors using an autopilot.

• Flexible Sail Area: Unlike slab reefing, where you’re limited to set reef points, in-mast furling lets you adjust the sail area precisely to suit changing wind and sea conditions.

❌ Disadvantages

• No Weight Reduction When Reefed: The sail remains furled in the mast and doesn’t lower, so the boat's centre of gravity isn’t improved like it is when a slab-reefed sail is physically lowered.

• Complex Mechanism: The furling system has multiple moving parts — which means more potential for failure and extra maintenance.

• Reduced Sail Shape & Performance: Most in-mast sails lack horizontal battens, which help maintain sail shape and performance over time.

• Potential for Damage: The sail can chafe against the inside of the mast while furling or unfurling, causing premature wear — though this depends on the system and technique.

• Risk of Jamming: If the sail jams midway, especially in rising wind or sea state, it could leave the yacht exposed and cause damage.

Conclusion

In-mast furling offers real convenience and safety, but it comes with trade-offs in performance and reliability. It’s ideal for cruisers who prioritise ease over racing performance — but it’s essential to know the system well and maintain it properly.