The Offshore Voyaging Reference Site

UV Protection For Roller Furling Sails

Several readers have asked how to best protect the exposed part of headsails when they are roller furled.

The traditional answer to this problem is to sew a strip of UV-resistant Sunbrella along the leach and foot. But I have an abiding hate, going back over 40 years to when I was a sailmaker, for this solution. Here is why, along with some better ideas: 


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More Articles From Online Book: Sail Handling and Rigging Made Easy:

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  3. Your Mainsail Is Your Friend
  4. Hoisting the Mainsail Made Easy—Simplicity in Action
  5. Reefs: How Many and How Deep
  6. Reefing Made Easy
  7. Reefing From The Cockpit 2.0—Thinking Things Through
  8. Reefing Questions and Answers
  9. A Dangerous Myth about Reefing
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  11. Topping Lift Tips and a Hack
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  13. Cutter Rig—Should You Buy or Convert?
  14. Cutter Rig—Optimizing and/or Converting
  15. Cruising Rigs—Sloop, Cutter, or Solent?
  16. Sailboat Deck Layouts
  17. The Case For Roller-Furling Headsails
  18. UV Protection For Roller Furling Sails
  19. In-Mast, In-Boom, or Slab Reefing—Convenience and Reliability
  20. In-Mast, In-Boom, or Slab Reefing —Performance, Cost and Safety
  21. The Case For Hank On Headsails
  22. Making Life Easier—Roller Reefing/Furling
  23. Making Life Easier—Storm Jib
  24. Gennaker Furlers Come Of Age
  25. Swept-Back Spreaders—We Just Don’t Get It!
  26. Q&A: Staysail Stay: Roller Furling And Fixed Vs Hanks And Removable
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  28. Rigging a Proper Preventer, Part 1
  29. Rigging a Proper Preventer—Part 2
  30. Amidships “Preventers”—A Bad Idea That Can Kill
  31. Keeping The Boom Under Control—Boom Brakes
  32. Downwind Sailing, Tips and Tricks
  33. Downwind Sailing—Poling Out The Jib
  34. Setting and Striking a Spinnaker Made Easy and Safe
  35. Ten Tips To Fix Weather Helm
  36. Running Rigging Recommendations—Part 1
  37. Running Rigging Recommendations—Part 2
  38. Two Dangerous Rigging Mistakes
  39. Rig Tuning, Part 1—Preparation
  40. Rig Tuning, Part 2—Understanding Rake and Bend
  41. Rig Tuning, Part 3—6 Steps to a Great Tune
  42. Rig Tuning, Part 4—Mast Blocking, Stay Tension, and Spreaders
  43. Rig Tuning, Part 5—Sailing Tune
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  48. Cruising Sailboat Running Rigging Inspection
  49. Cruising Sailboat Rig Wiring and Lighting Inspection
  50. Download Cruising Sailboat Rig Checklist
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bill koppe

Hi John,
I had a sleeve on a 45 ft cruising yacht with a short mast.
The sleeve needed the sheets tied around the sail so it could go over them.
With the sheets bent on with bowlines this was a problem and often need a boat hook to assist .
The sleeve was tightened by a line passing through alternate loops.
With high winds the sleeve would flap, even after retightening.
There was an area at the head and foot that still was subject to sunlight, partly as a result of the large diameter mentioned above for the sheets.
I would not recommend sleeves.
For a genoa I would have a strip and like you would stick with dacron.
For a staysail there is a lot to be said for a hanked on sail and a deck sail bag.
Bill Koppe

Marc Dacey

This is what we have, a nanked-on stay sail. Lives in a knotted bag in the anchor well and seems in good shape. I am considering either replacing our yankee-cut jib topsail (with the dreaded Sunbrella trim in Nova Scotia next fall, so it’s good to have an implicit endorsement for area around Halifax. The 303 spray tip is most welcome, and easily done.

Dick Stevenson

Hi John,
Good advice, nicely put. We do as you do for the reasons you describe.
Another thing about Sunbrella, for the use you describe and especially those who use it for a mainsail cover, is that it loses its capacity for UV protection over time, usually less time than one supposes. Hold a few-year-old piece of Sunbrella up to the sun and it will become apparent. If the piece has been in the tropics, you might get a sunburn through it and your mainsail will certainly suffer. A few-year-old Sunbrella will also allow water through making the sail sit soggy and wet and allow dirt through. Dan Neri in his excellent book, “The Complete Guide to Sail Care and Repair” (although it may be dated now) speaks to Sunbrella breakdown in more detail as well as do other authors.
For the last 13+ years or so I have used vynilized Sunbrella for my mainsail cover (no longer available, I believe). It has been bulkier and heavier, for sure, but even as ratty as it is, it remains perfectly opaque and so does the job of keeping sun off the mainsail. It is falling apart at the edges, so I am getting a new one made and will go with Sunbrella Plus: a fairly new product in the Sunbrella line which promises better attributes for UV and waterproofness. It will be easier to handle and lighter and I will see how it holds up. I plan to “303” at least yearly: maintenance un-necessary with the vynilized Sunbrella.
303 is a great product (although not inexpensive) with many uses on a boat and has served Alchemy well.
When I last had sails made, the Gore-Tex thread came up as an option (not sure now whether it was the same thread you refer to), but the sailmaker reported that the thread was so abrasive and tough that it ate up his machines and needles, so we went with more conventional thread. This has been fine as we have been up north.
I had never seen the “sleeves” until sailing in Europe. Watching skippers putting on the sleeve, especially in a bit of the late afternoon breeze, was always entertaining. And, not infrequently, the top few inches were left exposed.
My best, Dick Stevenson, s/v Alchemy

Marc Dacey

Having a newish mainsail cover, I wonder if there’s a way to, post-purchase,”vinylize” the inside of it to preserve the opacity? Some sort of “mackintosh” process, which was essentially rubber-coated cloth that didn’t crack. Like you, I’m not so concerned with the ratty-looking part as I am about keeping the mainsail sequestered from mould and sun when stowed away.

Dick Stevenson

Hi Marc,
Some I know have, after a few years, sewn an extra layer of Sunbrella on the inside of the mainsail cover just on the top 2/3rds of the cover that gets the most intense sun. I know of no vinylizing that would work (but have never looked into it). I do know that the vinylized Sunbrella was mostly used for Bimini tops and full enclosures for the most part. I believe they have a new product to meet these demands but it felt too much like plastic to me, so I am going with the new Sunbrella Plus which has some coating on the inside (polyurethane, I believe) which is modest enough to allow the material to be handled like regular Sunbrella.
My best, Dick Stevenson, s/v Alchemy

Marc Dacey

Dick and John, thanks for the replies. A “petticoat” of more Sunbrella makes sense…and avoids the mildew aspect.

Dick Stevenson

Hi John,
Agree, especially if the sails are laminate. One of the considerations when I went for HydraNet radial cloth was that it was a woven product and would do more breathing, With the vinylized mainsail cover, when the sail was damp/wet, I just draped the cover over the sail leaving the whole underside un-attached and open. In this way, over 3-4 seasons now (mostly in damp & wet UK) I have not had any mold or mildew. I think laminate sails would have a harder time.
My best, Dick Stevenson, s/v Alchemy

Brian Smith

No, it doesn’t need to cause mildew. I (and now several of my sailing friends) have been using 100% vinyl boom covers for about 30 yrs, what’s more I weld the seams making them completely air and water proof. The trick is to make them sit like an inverted U. I attach quick release plastic buckles along the inside equator which firmly hold the cover in place but leaves the bottom of the sail open to the air and breeze, thus well ventilated but out of sun and rain.It’s a little heavier to fold away than brella etc but very quick and easy to deploy.It also lasts years, and years, and years.

The boat right next to mine in the marina ( hadn’t been used for 12 months ) removed his conventional boom cover last week to reveal a mass of mould, so the climate here is far from dry……

Philip Waterman

I had my “sacrificial” protection replaced with a vinyl coated acrylic weave last year. I don’t know the brand but it wasn’t Sunbrella. The sailmaker said is will outlast the sail – even in the vicious Southern Med. sun and heat – time will tell. It was expensive compared with an acrylic only fabric and is a fairly stiff material. This seems to help the sail shape but does add bulk to the furl.

I have used Tenara thread (which is suposedly UV/heat stable) for my spray-hood, sail covers, etc. It is too early to see if it does what it says on the tin and outlasts the Sunbrella. I would expect Gore Industry’s to be pretty honest with the spec. so it bodes well. There are fabrics woven with Tenara. I have only seen heavy weaves for use as a stuctural fabric, for example in the roofs of sports facilities where there is a desire for minimal weight and maximum transparancy to daylight. A lighter woven Tenara fabric might be an interesting prospect for UV protection. Now if the fabric was suitable to make a sail they would really be on to something.

Ted Scharf

I raced on a boat that used a sleeve and it worked well. It had a zipper so had no open spots. I also liked that there was no way a sail was going to open in the wind with it on. With 2 people it was easy to put on and one person could do it. Just a little more work. Each to their own.