We Ship Worldwide! Shipping information.

Harken Carbo Racing Foil headsail foils (Units 0 to 3), the complete sets and extrusions we carry, plus sail feeders, prefeeders, spacer tubes, trim caps, chafe guards and mounting spares. Click here to read more.

Headsail Foils: Which Carbo Foil Unit, What to Buy With It, and How to Install It

A headsail foil is a grooved extrusion that slides over the headstay and holds the luff tape of the sail, so you can hoist, douse and change headsails fast. It is a racing and performance item: the foil replaces the bare stay with twin luff grooves, and the sail is fed in through a feeder at the bottom. The foils, feeders and spares are organised in the sections below: Harken Carbo Racing Foil sets, extrusions and parts, plus a few third-party feeders. A roller-furling system is a different product.

What Is in This Section
  • Complete Units (6 products): Harken Carbo Racing Foil sets. Unit 0 in 9 m (29.5 ft), 12 m (39.4 ft) and 15 m (49.2 ft) extrusion length, and Unit 1 in 12 m (39.4 ft), 16 m (52.5 ft) and 20 m (65.6 ft). Start with the Unit 1, 12 m set or the Unit 0, 9 m set.
  • Extrusions (6 products): the same Unit 0 and Unit 1 lengths as the foil extrusion only. The listing notes that this is the extrusion without feeder, end fittings or spacer tube, so it suits replacing a damaged foil on an existing system. See the Unit 1, 16 m extrusion.
  • Sail Feeders (10 products): the Harken Carbo Foil prefeeder and the feeders for Units 0, 1, 2 and 3, plus other makers' feeders: the Schaefer opening pre-feeder (for #5 and #6 luff tapes), the Wichard opening pre-feeder and the Spinlock RF sail feeders for single headsail, double headsail and mainsail. See the Harken Carbo Foil prefeeder and the Schaefer opening pre-feeder; the Spinlock feeders are also grouped in Spinlock Headsail Foils.
  • Tubes (7 products): upper tubes (5 in / 0.1 m) and lower tubes (39 in / 0.9 m) for Units 0, 1 and 2. The listing also holds one trim cap for Unit 3.
  • Trim Caps (3 products): for Units 0, 1 and 2.
  • Chafe Guards (3 products): for Units 0, 1 and 2; the listing describes an aluminum guard for the area where spinnaker sheets wear the foil.
  • Mounting Spares (7 products): the machine screws and barrel nuts that fasten the trim cap, matched by unit.

The Harken parts are also grouped together in Harken Headsail Foils (37 products). In our catalog the complete sets and extrusions are Unit 0 and Unit 1; Unit 2 and Unit 3 appear as spare parts (feeder, tubes, trim cap, screws) for foils that are already installed.

Harken Carbo Racing Foil: What the Listings Say

Harken describes the foil as made from engineering resins, stronger and lighter than the PVC used by other makers, with ultrasmooth, low-friction twin headsail grooves for hoists, douses and headsail changes. It is UV protected so the trimmer can see it, resists impact from loaded spinnaker poles, especially in cold weather, and heat has little effect on its stiffness. For mast-up installation you uncoil the foil and snap it onto the stay.

Choosing the Right Unit

The unit is decided by the headstay wire or rod, the headstay length and the luff tape of your sail. These are Harken's figures from the Carbo Racing Foil installation manual (Unit 0, 1, 2, 3):

  • Unit 0: max wire 1/4 in (6 mm), rod -10; luff #5 (4 mm / 5/32 in). Foil lengths 9, 12 and 15 m for headstays up to 10 m (32 ft 9 in), 13 m (42 ft 8 in) and 16 m (52 ft 6 in).
  • Unit 1: max wire 5/16 in (8 mm), rod -17; luff #6 (5 mm / 3/16 in). Foil lengths 12, 16 and 20 m for headstays up to 13 m (42 ft 8 in), 17 m (55 ft 9 in) and 21 m (68 ft 11 in).
  • Unit 2: max wire 3/8 in (10 mm), rod -25; luff #6 (5 mm). Foil lengths 16, 20 and 24 m for headstays up to 17.2 m, 21.1 m and 25.2 m.
  • Unit 3: max wire 7/16 in (11 mm), rod -30; luff #6 (5 mm) or #7 (6 mm / 7/32 in). Foil lengths 24 and 28 m for headstays up to 25.2 m and 29.2 m.

Harken lists luff rope diameters; the actual luff tape on the sail is larger. The foil length in the table is not a cutting length: Harken says to measure the full foil from the bottom and cut the top end only. Use the wire or rod size and the headstay length together; a foil that is too short for the stay, or a stay too thick for the unit, will not work.

Installation and Care Points from the Manual
  • Feeder height: Harken recommends the feeder 110 cm (42 in) above the deck, with the prefeeder about 300 mm (12 in) below it. The sail's luff tape must sit 15 to 25 cm (6 to 10 in) below the feeder when the sail is raised.
  • Preparation: unroll the foil and let it relax for a day or so before installing, and use a heat gun in cool weather. Liquid soap lubricates the headstay and the foil. Do not use McLube on the headstay or the foil.
  • Halyard lead: the halyard must run parallel to the stay. Harken says an aft-angled halyard pulls the luff tape out and damages the foil grooves.
  • Raising the sail: use the prefeeder, raise the sail completely and tension the halyard before sheeting; sheeting too soon can damage the luff tape and the foil.
  • Noise in wind: the bare foil can oscillate when moored or motoring in high wind. Harken's fix is to wrap the jib halyard around the foil four to six times, secure it to a deck fitting and tension by hand at the winch.
Who It's For

Racers and performance cruisers who change headsails often and want fast, clean hoists and douses; owners replacing a damaged Carbo foil or a worn feeder, tube or trim cap; and boats whose headstay wire or rod falls within the Unit 0 to Unit 3 limits above. Looking for a furling system rather than a foil? See Furlers & Headsail Foils.

Frequently Asked Questions

Which Carbo Racing Foil unit fits my boat?
Match the maximum headstay wire or rod diameter first: Unit 0 up to 1/4 in (6 mm), Unit 1 up to 5/16 in (8 mm), Unit 2 up to 3/8 in (10 mm), Unit 3 up to 7/16 in (11 mm). Then pick the foil length for your headstay length from the table above and check your luff tape size.

What luff tape does a Carbo foil take?
Unit 0 takes #5 luff rope (4 mm / 5/32 in); Units 1, 2 and 3 take #6 (5 mm / 3/16 in), and Unit 3 also takes #7 (6 mm / 7/32 in). Harken's troubleshooting table says a luff tape that is too small comes out of the groove and one that is too large creates friction.

What is the difference between a complete set and an extrusion only?
The set listings are described as complete Carbo Racing Foil sets; the extrusion-only listings are the foil by itself, without feeder, end fittings or spacer tube. Check the listing of the set you are buying for its contents, and buy any missing feeder, tubes or trim cap from the sub-collections above.

Can I install it with the mast up?
Yes. Harken describes mast-up installation: uncoil the foil and snap it onto the stay, using a heat gun in cool weather. Measure the full foil from the bottom before you cut the top end.

Why is my bare foil noisy in wind, and what should I lubricate?
Bare foil can oscillate in high wind; wrap the jib halyard around it four to six times, secure it on deck and tension by hand. For lubrication, Harken says to spray McLube Sailkote on the sail luff tapes, away from the foil and the boat, and never on the foil itself.