Ronstan Series 40 Auto Ratchet Swivel Orbit Block

The Ronstan Series 40 Auto Ratchet Swivel Orbit Block is made for mainsheets and fine-tune systems where extra holding power is useful under load but a free-running sheet is still important during maneuvers. Its load-sensing ratchet engages automatically as sheet tension rises and releases when the load comes off. That behavior lets the trimmer ease quickly through a gybe or tack without stopping to switch the ratchet on and off. Ronstan targets the block at dinghy mainsheets and fine-tune systems on sportsboats and small keelboats.

A machined hard-anodized aluminum sheave provides the gripping surface that gives the ratchet its holding assistance. High-compression carbon-black Acetal ball bearings keep the sheave moving smoothly when the ratchet is not heavily loaded. The Orbit structure concentrates support around the sheave, helping the block stay compact and light for a moving sheet system. A swivel shackle head lets the block rotate with the sheet lead instead of forcing the rope against a fixed cheek angle.

• Automatic load-sensing ratchet engagement
• Up to 14:1 holding assistance
• Hard-anodized machined gripping sheave
• Swivel shackle head for changing lead angles

Ronstan specifies line up to 9mm (5/16 in), a 385 lb maximum working load, and a 1,100 lb breaking load for this block. At about 1.5 oz, it adds very little moving weight to a dinghy mainsheet. Keep the ratchet sheave clean and confirm that the automatic engagement releases freely before relying on it in a high-load trim. For more ratchet blocks and mainsheet controls, browse more Sailing Hardware.