ASYMMETRICAL SPINNAKERS
A5 Heavy Air Spinnaker — The All-Purpose Storm Chute
A versatile heavy-weather reacher and storm spinnaker that performs across multiple wind angles. Perfect for heavy air reaching (85-130° AWA) and running (up to 155° AWA) in 20-35 knots. Can double as a light-medium air Code Zero substitute.
Why add an A5 Heavy Air Spinnaker?
The A5 is commonly referred to as a “Storm Spinnaker” or “Chicken Chute” because of its smaller, more manageable size. This racing sail is designed to be nearly indestructible—built from heavy 2.2 oz. nylon—and is generally recommended to be paired with a spinnaker net for offshore racing. The sail has no shoulders and features an all-purpose shape that excels as a heavy reacher but can also handle heavy air running.
What makes the A5 incredibly versatile is its ability to be used in place of a Code Zero in light to medium wind conditions (although not as effective). This compromise can be helpful for some rating systems such as IRC where limiting the number of headsails onboard is essential. On fractionally rigged boats with masthead spinnakers, the A5 flies from the hounds. These sails are typically 22% smaller than full-sized spinnakers and are designed to be flatter, making them more controllable in challenging conditions.
Heavy-Weather Performance
Built for 20–35 knots
Handles apparent wind angles from 85-130° as a reacher, and up to 155° when running. The bulletproof construction keeps you sailing when others are down to white sails.
Multi-Purpose Design
One sail, multiple roles
Can substitute for a Code Zero in light-medium conditions, helping you optimize your sail inventory for rating systems like IRC that limit headsail count.
Bulletproof Construction
2.2 oz. heavy nylon
Built to last with robust materials and a flatter shape. Measures 85-90% mid-girth to foot ratio and approximately 22% smaller than full-sized spinnakers for better control.
Understanding Matrix Construction
The key to faster spinnakers lies in their construction. UK Sailmakers uses a Matrix panel layout—a radial design made up of narrow panels aligned with the sail’s primary load paths. Panels radiate from the head, tack, and clew, joined by vertical Matrix panels through the midsection. This layout minimizes distortion and delivers the strongest, most efficient sail for its weight.
Each panel is shaped on all sides to create a smooth, round sail. For one sail to be so versatile, a spinnaker must hold its designed shape without distortion. Distortion is most noticeable when close reaching. Spinnakers made from generic nylon tend to stretch through the middle, which causes the leeches to harden or hook. This reduces driving power, increases drag, and adds heel. The most effective way to prevent distortion, without using a heavier fabric, is to build the sail from performance nylon spinnaker cloth. These materials provide the strength and stretch resistance of standard nylon that is one weight heavier
FAQs
What’s the difference between an A5 and other reaching spinnakers?
The A5 is smaller than a full-sized reaching spinnaker like an A1, with a flatter shape, no shoulders, and heavier 2.2 oz. nylon construction. It’s designed specifically for heavy weather (20-35 knots) with a mid-girth of 85-90% of the foot length.
Can I use an A5 instead of a Code Zero?
Yes, the A5 can serve as a Code Zero substitute in light-medium air, though it won’t be as efficient as a dedicated Code Zero. This versatility is particularly valuable for rating systems like IRC that limit the number of headsails onboard.
Do I need a spinnaker net with my A5?
For offshore racing, an A5 is generally recommended to be paired with a spinnaker net. This provides additional safety and helps prevent the sail from going in the water during challenging conditions.
How do I fly an A5 on a fractional rig?
On fractionally rigged boats with masthead spinnakers, the A5 is designed to fly from the hounds (the sheave just above the forestay). The sail’s shorter luff, foot, and leech are specifically designed for this configuration.
