A Guide to Inner Forestays by Jimmy Green Marine

An inner forestay can enhance a yacht’s sail plan, particularly for offshore, ocean and heavy-weather sailing. Set aft of the main forestay, the additional support offers increased versatility in sail configurations while improving the structural integrity of the rig. 

What is an Inner Forestay? 

An inner forestay is a secondary stay running from the mast to a point on the deck, located behind the main forestay. It serves as an attachment point for additional headsails, typically a storm jib or staysail. The inner forestay may be permanently fixed or detachable, depending on the yacht's design and intended use.

Inner Forestays: Structural Advantages, Performance Benefits and Practical Uses 

• Steadier Heavy-Weather Performance: Allows the use of smaller, high-cut headsails such as a storm jib or staysail, improving sail control in strong winds, particularly useful for offshore and ocean sailing 
• Increased Rigging Stability: Helps to reduce mast movement and minimise excessive mast bend, particularly in high-load conditions. 
• Sail Plan Versatility, Improved Balance and Reefing Options: Facilitates a cutter rig configuration, allowing for a broader range of sail combinations and a smaller, more manageable sail area without relying solely on furling systems. 
• Backup Rigging Support: Provides an alternative attachment point for a jury rig in case of forestay failure 
• Heaving-to or Heavy-Weather Manoeuvres: Improves stability when seeking to slow or stop the boat in challenging conditions 

Inner Forestays: Important Preinstallation Checks 

Before installing an inner forestay, conduct the following checks: 

• Mast Structural Integrity: Verify that the mast is designed to support an additional stay without undue stress or bending 
• Chainplate Positioning: Ensure that the deck attachment point aligns with a substantial, reinforced area to handle the load without flexing 
• Load Distribution: Check that the new stay will not interfere with the main forestay or cause unwanted mast deflection 
• Rigging Compatibility: Ensure that the new running rigging won’t interfere with the existing sheets, halyards, control lines, and furling systems 
• Sail Compatibility: Confirm that your intended sail wardrobe includes appropriately cut and sized sails. 
• Survey and Professional Advice: If unsure, consult a rigger or marine surveyor 

Inner Forestay Installation Tips 

• Placement: Position the attachment point on the mast according to manufacturer specifications, typically around two-thirds of the way up the mast, depending on the rig design. 
• Deck Reinforcement: Ensure the deck attachment area is structurally reinforced with adequate backing plates. Another option is a dedicated chain plate fitting on a reinforced bulkhead. 
• Adjustability: If opting for a removable stay, consider a Highfield lever or threaded pelican hook to allow for easy detachment and stowage when not in use. 
• Tensioning: Apply sufficient tension to make the stay effective under load and avoid undue stress on the mast or the surrounding rigging  
• Stay Selection: Use KOS stainless steel 1x19 wire to prevent sag and ensure load capacity and durability 
• Mast Fittings: Adhere to the mast manufacturer's recommendation if possible – options include a T-terminal backing plate, an eye or fork tang, or a specialist hounds fitting 
• Deck Fittings: Consider only recognised top-quality branded hardware with assured load capacity – options include Deck Pad Eyes, U Bolts or Eye Bolts/Plates. Pad Eyes can also be folding to present a low profile when not in use – ideal for trip prevention on the foredeck 
• Wire Terminal to Fitting Compatibility: Ensure that Holes and Clevis Pins are matched for a snug fit to avoid point loading. T-Terminals and Backing Plates should ideally be from the same manufacturer, but otherwise, great care should be taken to ensure a proper seated fit 
• Top and Bottom Wire Termination: Wire terminals can be Swageless for DIY fitting in situ or roller swaged by a Professional Rigger. N.B. Swageless versions are not a suitable option for T-Terminals 
• Bottom Wire Fitting Options: These will depend on the anticipated frequency of removal; see below 

Removable Bottom Fitting Options 

• Highfield Lever: Simple to deploy, tension and disengage - ideal for intermittently used stays that don’t require fine-tuning. 
• Turnbuckle with integral pelican hook or snap shackle: Quick-Release for convenient removal and stowage with added tension adjustability 

Permanently Fixed Bottom Fittings

A fork and toggle fork rigging screw (aka a turnbuckle) allows articulation and enables precise tension adjustment and control, ensuring the rig remains accurately tuned.  

Conclusion 

An inner forestay can be a valuable addition to a yacht’s rigging system, particularly for yachts venturing offshore or likely to encounter heavy-weather conditions, providing increased rig stability, enhanced safety, and a more flexible sail plan.
However, careful consideration should be given to whether the installation may affect the rigging's structural integrity and optimal performance.