After four long years in the sun, we’re finally taking our polyester (Dacron) sail repair samples out of the elements for good. Even glued dodger repairs to tenacious Sunbrella material wouln’t be expected to last longer than this. For detail on the earlier portions of this project, see articles Practical Sailor November 2017 and June 2018.
Contact cement
Contact cement and Ailene’s Tacky Glue failed long ago.
Bottom line: Not recommended.
Tear-Aid Type A
The tape just plain fell off, and it wasn’t even on a sail. We had a patch fall off a Sunbrella dodger just weeks after it was applied.
Bottom line: Not recommended.
Polyurethane Adhesives
When applied to either polyester or laminate sailcloth, 3M 5200, Loctite PL S40, and Sika 291 failed completely before two years were up, peeling apart under their own weight. This wasn’t a big surprise, since we have long known that polyurethanes make poor glazing adhesives unless the surface is properly primed with a UV blocker. The UV transmitted through the glazing, or fabric in this case, and attacks the critical bond area.
However, even after four years, the bonds to Pacific blue Sunbrella remain nearly as strong as the fabric. The difference, of course, is that darker Sunbrella colors block greater than 95 percent of ultraviolet rays (white Sunbrella blocks only 90 percent of UV rays).
Bottom line: Recommended for Sunbrella repair and temporary sail repair. Loctite gets the Budget Buy.
Epoxy
West Systems G-Flex was still strong, although it is a little stiffer than we would like. Dr. Sails from Sailing Technologies began failing after one year in the sun, and we had peeling problems within six months on furling laminate sails, while G-Flex repairs on the same tear remained strong for another 6 months, until the sail failed in multiple places.
Bottom line: G-Flex is Recommended for sail and canvas repair.
Cloth Tapes
The polyester and nylon repair tapes in this test were Bainbridge brand, but we’d expect similar results with Sail Rite’s equivalents (#2353 for polyester and
#721 for nylon), based on results in our long-term tests on laminated sails (see PS May 2019). The bond of nylon and polyester sail repair tapes just got better with time. However, the thin nylon tape tore easily, as we’d expect from nylon after four years of UV exposure.
The polyester tape was weakened, but if taped on both sides it was stronger than the sail cloth. We’ve been using these on the boat for decades and have never been disappointed.
Bottom line: Bainbridge Polyester Repair Tape (aka Insignia Cloth) is recommended for working sail repair, and Bainbridge Nylon Repair Tape is recommended for spinnaker repair. These, or their equivalents, belong in every sail repair kit. Apply to both sides and rub down hard.
Sail Rite Laminate Repair Tape
We had some problems with peeling along the edge, which was easily solved by covering the edges with polyester tape. It remained very strong and non-stretch until the sail disintegrated.
Bottom line: Recommended where great strength is required.
TAPES AND ADHESIVES FOR POLYESTER (DACRON) SAIL REPAIR
| MANUFACTURER | MODEL | CONDITION AFTER 4-YEARS | BOND STRENGTH (NEW) | PRICE | QUANTITY | COST PER FOOT REPAIR |
|---|---|---|---|---|---|---|
| TAPES | ||||||
| BAINBRIDGE | Polyester Repair Tape | Good | 82 pounds | 5.95 | 15 feet | 14 cents |
| BAINBRIDGE | Nylon Repair Tape (Insignia cloth) | Fair | 64 pounds | 8.95 | 3 feet | 17 cents |
| TEAR AID | Type B | Poor | 14 pounds | 4.95 | 1 foot | 4.95 |
| ADHESIVE SEALANTS/GLUES | ||||||
| 3M | 5200 | Poor | >150 pounds | 16.99 | 10 oz. | 68 cents |
| LOCTITE | Marine Sealant | Poor | >150 pounds | 12.95 | 10 oz. | 52 cents |
| LOCTITE | PL S40 | Poor | >150 pounds | 5.85 | 10 oz. | 23 cents |
| SIKA | Sikaflex | Poor | >150 pounds | 13.99 | 10 oz. | 56 cents |
| WELDWOOD | Contact Cement | Poor | 55 pounds | 4.97 | 89 ml. | 34 cents |
| ALEENE'S | Multi-surface Adhesive | Poor | 80 pounds | 3.95 | 29 ml. | 79 cents |
| EPOXIES | ||||||
| WEST SYSTEMS | G 5 Epoxy | Fair | 60 | 24.5 | 946 ml. | 16 cents |
| WEST SYSTEMS | G-Flex | Good | >150 | 25.99 | 236 ml. | 22 cents |
| SAILING TECH | Dr. Sails | Good | >150 | 38.5 | 25 ml. | 9.24 |
Application tips
One interesting note: We bought a second-hand sail (laminate with polyester scrim on both sides), and after a few sails, realized that the scrim was failing a few places, pinholes were appearing a few places, and the UV cover (self-adhesive UV Dacron) was shot. We reinforced the foot and leach with large, overlapping patches of Insignia Cloth.
We laid the sail flat, applied the patches carefully and rubbed them down well, and they have proven durable and strong. The problem is, because the sailcloth was wrinkled from years of use (characteristic of this type of laminate), and in spite of our efforts to flatten the cloth first, the long reinforcing patches resulted in excessive tightening of the leach and horrible sail shape problems. We wouldn’t say the sail was ruined, not for testing purposes, but the change was considerable and we are looking forward to a new sail, just as soon as this trial is over. Be very careful not to alter the shape of the sail when applying large patches.
Conclusion
We are done. G-Flex epoxy and polyester (Dacron) tape worked out well on polyester sails, nylon tape for chutes, and polyurethane or G-Flex for Sunbrella. This mirrors decades of field experience.
3M, www.3m.com
ALEENE’S, www.aleenes.com
BAINBRIDGE, www.bainbridgeint.com
DAP (WELDWOOD), www.dap.com
LOCTITE, www.loctiteproducts.com
SAIL-RITE, www.sail-rite.com
TEAR-AID, www.tear-aid.com
WEST SYSTEM, www.westsystem.com
