Did you know that the average mainsail and headsail only last 8 years? Sails used on a racing sailboat or long distance cruising sailboat break down much sooner. What can you do to prevent sail repairs from eating up a significant portion of your cruising budget? First, take a quick look at how tension control plays a critical role in keeping your boat sails healthy.
A Peak behind the Sailmaking Curtain
Your sailmaker installs a fiber or wire rope luff reinforcement called a boltrope along the edge of the luff. On mainsails, slugs or slides are attached to the boltrope and then inserted into the sailboat mast. Headsail luff attachment depends on the sail type. A furling headsail slides into an aluminum extrusion that wraps over the forestay or replaces the stay altogether. Non-furling headsails use jib hanks to clip on to the forestay.
All of these luff attachment devices have but one purpose: to guide the boat sail up and down the sailboat mast or forestay. They should never come under tension because this could rip or tear the sail.
How Improper Tension Damages Your Cruising Boat Sails
You can compare luff attachment devices to the buttons on a shirt. Conduct this simple experiment to solve the mystery of why sails rip and tear along their luff.
1. Put on a shirt or jacket with buttons. The front of the shirt represents your sail’s luff and the buttons the luff slugs, slides or hanks.
2. Grab the shirt from behind and pull back. This simulates the tension exerted by the clew and sheets. Now, look at the buttons and what do you see? Wrinkles of stress extend into the cloth from each button. With a bit more tension, they’ll pop out or rip the shirt. This represents improper loading along the luff of a boat sail.
3. Next, use one hand and grab both parts of the shirt at the front below the buttons. Pull straight down. With your other hand, grab the back of the shirt and pull back. Look at the buttons and you’ll notice the wrinkles are gone. You have evened the load between the front (luff) and back (clew and sheets) of the shirt.
Three Easy Steps for Perfect Luff Tension
1. Inspect slugs, slides and hanks each time you raise or lower your sails. Replace damaged attachment devices right away to prevent rips and tears.
2. Tension the luff with the halyard rope winch. Stop grinding on the rope winch as soon as you see a single, faint, vertical crease form near the luff.
3. Repeat step 2 whenever you see wrinkles build into the cloth from slugs, slides or hanks. On furling headsails, check all along the luff for wrinkles or bagginess.
Your cruising boat sails will always live their lives under stress. But if you control luff tension, they will reward you with longer life and lower sail repair costs.