How are my sails doing?

Quantum Sails Annapolis’ Dave Flynn boils down years of industry knowledge into a few easy to check bullet points to help you know when to replace your sails. Here’s the quick list for reference, and read on to get the full explanation and breakdown on structural integrity versus sail shape life.

If you are experiencing any of the following issues, it may be time to consider replacing your sails: you can take an existing tear and extend it with your fingers, difficulty furling or rolling your sail (particularly with in-mast furling mainsails), upwind performance is suffering, particularly your ability to point, excessive heel or weather helm, off the pace relative to your usual competition.

Unfortunately, no sail will last forever. They are consumables. Much like the tires on your car, your sails need to be part of your regular maintenance plan. How long a sail lasts before it needs to be retired depends on the type of sailing you are doing and how demanding you are in terms of optimum performance.

In the high-end grand prix and one design world, sail life is counted in hours. This is not because the sail is falling apart, but because it is the extra boat length or two that make the difference between winning and being in the back of the pack. New sails are always faster, if only by tiny amounts.

Club level racers without unlimited budgets still need to recognize that sail shape deteriorates and plan to replace the most used sails in the inventory on a regular basis. If you start with a new inventory and replace a sail, or two, a year you will be well ahead of the game. For cruising sailors, the answer is more complicated.

In cruising, the sailor should have two main considerations. The first is from a structural standpoint. How long will the sail remain intact as a triangle? The second relates to sail shape. How long will the sail function as a critical airfoil, capable of driving the boat well and being effective upwind? This question is the tougher of the two.

Life of a triangle
As a triangle, sails will last for a surprisingly long time. It is not uncommon to find sails still in use that are 10-15 years old. Structurally, they gradually lose their integrity over time, principally as the materials and stitching fail under the influence of the sun. UV causes woven polyester materials (referred to generically by the trade name, “Dacron”) to gradually lose tear strength.

If you can take an existing tear and easily extend it by pulling with moderate pressure, it is time to replace. You can fix the tear with a patch, but it will keep tearing in other places, often at the edge of any repair. Likewise, if you can run your fingernail across the stitching and pick it off easily, the sail needs re-stitching. It is normal for the stitching to rot before the material in the sail, so it can be re-stitched before a complete replacement is needed and should be periodically during its lifetime.

How long this process takes is heavily influenced by the amount and strength of sunlight your sails are exposed to. Other factors come into play, including the amount of breeze in which they are used, resulting in flogging, chafe, and other abuse. Ultimately, a better way to think of the structural life of a sail is in terms of hours of use.

A reasonably well-treated woven polyester sail that has been maintained regularly will last 3,500-4,000 hours. For the average New England cruising sailor, who uses their boat two weekends each month of a five-month season, with an additional two full weeks of cruising thrown in, for a total of roughly 240 hours per year, your sails will last for 16 years!

At the other extreme, the sailor who lives aboard their boat and cruises the Caribbean extensively might use sails as much as 12 days per month (12 hours per day) all year around, for a rough average of 1,728 hours per year. This sailor will be replacing sails every 2.5 years. Do the math and you’ll get the idea.

Life of sail shape
The shape-life of a sail is more complicated. Since it deteriorates gradually with every hour of use, the effect on performance is much harder to judge than that of a sail which won’t stay in one piece. Sails that stretch too much, become too full, and will not retain a critical airfoil shape (with a distinct rounded entry and flat, straight exit).

This problem will cost you in more subtle ways. Let me read your mind; I know what you are thinking: “I’m just a cruising sailor, I don’t care about performance.” Actually, you do, it’s just that “performance” is based on a different set of criteria. Yours is not the quest for another tenth of a knot of boat speed or one degree of pointing. But it is critical to control heel.

Full, stretchy sails, rob power in light air, but more critically, they create heel and weather helm just when we want control. Also, let’s face it, at some point, we all have to sail upwind (usually at the least convenient moments). After all, a bathtub with a sheet can go downwind. One of the real luxuries of a good cruising boat is the ability to go upwind when necessary, and for most cruising boats this goes against the grain of much of their design criteria.

If sails are not shaped properly, and their materials and structures are not designed well enough to resist stretching, the boat will not be able to go upwind effectively.

So, when do I replace my sails?
Unfortunately, shape-life degrades more rapidly than structural life. Sails will be triangles long after they cease resembling anything like a critical airfoil. Shape-life is very dependent on harshness of use, but good sail shape can only be expected to be half to two-thirds of the structural life of a sail. How much deterioration you are willing to accept is largely a subjective matter. Periodic re-cutting helps. As long as the material is in decent condition, excess shape can be removed and an airfoil shape restored.

The good news is that, relative to much of the gear on your boat, sails last a long time. They do not, unfortunately, last forever. When you make the decision to replace, you will be pleasantly surprised by how your boat will come alive as dramatically as if you had put a new engine in your car.

There will be spring in her step. When the wind is up, there will be a greater sense of control, and going to weather might just be fun again (at least for short periods of time).

Here are a few thoughts to help protect your investment:
• Protect your sails from unnecessary exposure to sunlight and heat.
• Avoid prolonged luffing and flogging.
• Motor with your sails down unless they can be filled.
• Never back a genoa against the spreaders when tacking.
• Use the correct halyard tension. Halyard tension changes as a function of apparent wind velocity. Add just enough tension to remove horizontal wrinkles as the apparent wind increases. Ease when the apparent wind velocity drops.
• Protect from chafe. Make sure spreader and chafe patches are on and in the right place.
• Take sails off the boat when not in use or out of the water for any extended time period.
• Periodically rinse with fresh water. Annual professional servicing and washing is recommended.
• Store sails dry.
• Be sure roller furling sails are well secured when leaving the boat.