Most mainsail reefing involves a tack hook and clew line to secure the reefed foot of the sail. Reef hooks are very secure and strong and offer little risk of allowing the sail to slip off.
The way they work is you slip the tack cringle over the hook and then haul in on the halyard to secure it. This works well on small light sails, but heavy sail cloth and/or high winds can make it nearly impossible to reach the hook. For this reason, tack straps have become a wonderful solution, aiding the sailor in securing the tack. A webbing strap with a ring hangs down and can easily be hooked onto the rams horn. Once secured, the halyard is hauled in and the sail is raised. This secures the tack in its reefed position.
While tack hooks are a standard, they do have a significant problem: they are hooks!
A flaked mainsail can easily lie under the tack hook, and if raised quickly, it can be pierced by the hook. This will create a puncture in the luff if you stop instantly, or a large tear if you raise the sail before you realize what is going on.
I personally pierced my old sail three times on my old tack hook. The last thing I wanted in my new laminate mainsail were luff punctures, so the hook had to go! This led to my current and very sail friendly tack setup, a tack line.
I used a length of dyneema (regular, not heat set SK75) for my tack line, and another length tied to the reefing tack points on the sail. The length of dyneema is tied to the goose neck on a strong attachment point with a bowline ready to connect to the sail.
On the sail, I tied a very fancy series of knots to the reefing tack points. The first set of knots is an interlocking double fishermans knot. This keeps loops from coming apart when the tack is loaded. The tails are then further knotted into the loops to ensure that these knots will never come undone!
I did not make grommets for these locations because grommets bulk up the loop considerably and I was concerned that they would be overly stressed passing through the tack ring and decided to simply tie a strong knot and keep the bulk of line passing through the ring reduced.
I tie the tack line tail to the loop via a sheet bend with a slip. If you do not include a slip, you will be hard pressed to untie the bend knot after a stormy sail. The slip gives you the ability to pull the knot apart if you are unable to untie it in a timely manner.
The sheet bend has a tendency to slip out, which is why considerable care should be taken to make sure that it becomes fully tightened as the sail is raised. If you see the knot slipping, simply tighten it a bit more and continue raising the sail. It will become incredibly tight as the winch pulls the sail into position and will not come untied under any situation!
Shaking the reef out literally becomes a matter of shaking the knot out, and raising the sail all the way.
This method makes reefing hardware very safe for your sails and provides a very secure method to attach your reefed tack point.
