Repairing Non-Skid Deck Patterns

If the patterned non-skid on your production-built fiberglass boat needs repair, you may be interested to know flexible molds are available for making professional looking repairs. Gibco Flex-Mold™ produces the non-skid patterns used to mold the non-skid on fiberglass boat molds. They also produce flexible molds designed for repairing existing non-skid patterns used on hundreds of production fiberglass and one-off boats. You can call them to see if they have the pattern you are looking for. If the damage to the deck is more than cosmetic, repair it prior to continuing.

The Flex-Mold is designed to lock into the existing molded pattern on your boat and works best if the pattern has not been painted over. If paint has been applied or if debris has accumulated in the pattern, the fit will be poor at best and the repair will be harder to blend in. Mold release is applied to the Flex-Mold at the factory so epoxy or the polyester gelcoat used to make the repair will not stick to it.

1. Apply mold release wax to existing non-skid prior to beginning the actual repair. Spread wax well beyond the actual repair because gelcoat will migrate. Use wipe on/wipe off method to apply wax.
   
   
2. Use a router to remove the damaged non-skid. Remove only the thickness of the pattern, no more. If you grind through the opaque white gelcoat or you can see the dark substrate through it, you must then fill the dark low spots with gelcoat so that after molding a new non-skid you do not see the dark laminate through the thinnest, lowest parts of the gelcoat pattern.
   If the damage went beyond the base gelcoat thickness, or you are finishing a structural repair, you will have to router a void to fill with a thick enough layer of gelcoat to make an opaque base for the pattern. This layer of gelcoat is then machined with a shallower pass on the router, to level the opaque layer and establish the base of the non-skid pattern. Break the corner of the routed area with sandpaper.
   
   
3. Position the Flex-Mold over the area to be repaired, moving it around until it locks onto the pattern. Tape one end down securely and roll back the Flex-Mold until the repair area is accessible.
   
   
4. Pour catalyzed gelcoat (you can use epoxy but it will require painting) near the Flex-Mold.
   
   
5. Slowly flex the mold forward while continuously engaging the non-skid pattern. Use a stiff rubber or plastic spreader to uniformly apply pressure to the backside of the Flex-Mold, effectively squeezing out the excess gelcoat. Allow the gelcoat to cure before removing the mold. Clean up excess gelcoat film (surrounding the repair) with an air nozzle or by brushing the area with a stiff bristled brush. When done correctly, the repair will not be detectable.
   If you are interested in doing your own non-skid repairs, contact Gibco Flex-Mold at 817-236-5021 or click here to download their PDF repair process brochure .

Gelcoat (polyester) over Epoxy; A Synopsis

Most production fiberglass boats are made with polyester resin.  Epoxy is a wonderful material for repairing polyester fiberglass boats. One reason for this is the ability of epoxy to form a stronger mechanical bond to a damaged laminate than polyester resin. Epoxy also provides a better moisture barrier than polyester resin.

Our customers' fiberglass repairs range from filling a minor screw hole to completely rebuilding the bottom of a boat that ran aground. In most cases, a final finish needs to be applied over the repair. If the repair is above the waterline, high-gloss paint or gelcoat are often used to reproduce the original appearance. If the repair is below the waterline, antifouling paint is most often applied over the repaired area. However, customers often want to restore the original gelcoat finish to below-waterline repairs where the boat is kept in the water and no antifouling paint is applied. These customers are concerned about the gelcoat's long term ability to adhere to the area repaired with epoxy. There are good reasons for this concern, but if you understand the materials involved and follow recommended repair procedures, you can successfully apply a gelcoat finish to a boat bottom repaired with  epoxy.

In repairs above the waterline, gelcoat applied over properly prepared  epoxy has a great track record. Many boats have been repaired this way and are performing well in a variety of climates. Boats that are dry sailed or trailered have also had good success with gelcoats on underwater epoxy repairs. Concern about adhesion occurs in situations where boats are in the water constantly and need to have a high level of finish on their bottoms that requires gelcoat. Such a situation might occur with a boat kept in a pristine lake where antifouling paint is often not used. Since the polyester gelcoat is not very good at preventing moisture from permeating through to the laminate, there has been a concern that, over time, the gelcoat will detach from the more moisture resistant epoxy layer.

Understanding the materials
Polyester resin laminates achieve their highest strength when the bonds between layers of fiberglass are chemical or primary bonds as opposed to mechanical or secondary bonds. The manufacturing process for polyester boats has been developed so that a chemical bond exists between the gelcoat and the laminate. When a polyester boat is built, polyester gelcoat is first sprayed onto the mold surface. The first layer of the laminate is then applied to gelcoat, which has not completely cured. The two layers eventually cure together with a chemical bond between them.

Applying gelcoat to a cured laminate relies on a mechanical bond. Because of the difference in curing chemistry, it is not possible to achieve a chemical bond between epoxy and polyester gelcoat. We developed some tests, to determine whether or not the mechanical bonds achieved between gelcoat and properly prepared, cured epoxy were strong enough to achieve a durable repair.

Testing
The test program we developed was designed to determine the effect of moisture on the adhesion of polyester gelcoat applied over fully cured epoxy. The tests were done on a gelcoat finish over a simulated repair made with epoxy. The test included a variety of finishing processes. In addition, we varied the length of time the epoxy was allowed to cure before being subjected to high moisture conditions. For comparison, we also tested gelcoat adhesion to a polyester laminate using West Marine Boaters Resin™.

Two popular gelcoats were used, Minicraft™ and Evercoat™. Interestingly, Evercoat states on their can that it is not to be used over epoxy. Although we often suggest following the manufacturer's instructions, we believe, in this particular case, the manufacturer is overly conservative. As with many products, the surface must be prepared properly; if it is not, then poor curing and adhesion may result. Polyester materials can be affected by amines in the epoxy hardener. If the hardener has not fully reacted with the epoxy resin or the amine blush is not removed from the cured surface, problems can occur. Proper surface preparation will prevent these problems.

Preparing the test panels
The test panels were laminated from three layers of 738 Biaxial Fabric (15 oz biaxial with .8 oz mat) wet out with 105 Resin and 205 Hardener. Panels were covered with 879 Release Fabric and allowed to cure. This laminate provided a stiff panel that simulated a patch used to repair the bottom of a fiberglass boat. After the Release Fabric was removed, a variety of finishing processes were applied to the panels. These included using 742 Glass Fabric (6 oz), 407 Low-Density Filler, and 410 Microlight™. All of the test panels had a sealer coat of 105 Resin/206 Slow Hardener to fill the weave and seal the scratches in the sanded fairing compounds. Slow Hardener was chosen because its slower reaction time would be more likely than 205 Fast Hardener to reveal any adhesion problems.

The gelcoat was applied using a pressure pot type spray gun. It was thinned using 10% Acetone by weight catalyzed at 1% with MEKP (Methyl Ethyl Ketone Peroxide). After the gelcoat cured for two weeks, PATTI (Pneumatic Adhesive Tension Testing Instrument) studs were applied to the surface.

One set of PATTI studs were pulled for a baseline value. Panels were then placed in our 100% humidity/100°F environment room. The conditions in this room accelerate any effect that moisture will have on the laminate. The remaining PATTI studs were pulled at three, six and nine weeks to determine the long-term effect of moisture on the bond.

Figure 1 (right) lists the different material combinations that were sprayed with gelcoat. The graph for each combination shows the tensile load required to pull the stud off the panel at four time intervals, illustrating the trend of the bond strength when the gelcoat is applied after allowing the laminate to cure for 36 hours and 7 days. Each data point represents the average of five stud pulls.

Conclusion
The overall effect of moisture on the gelcoat's bond to both the polyester and epoxy panels was negligible. The graphs show very little change in the adhesive strength, and much of the variance is within the tolerance of the test method. When the studs were pulled, the failures occurred in the fairing compound, cohesive failure of the gelcoat, or in the bond between the gelcoat and laminate. Since these three modes of failure occurred under similar loads, it indicates that the strength of the bond is close to the cohesive strength of both the gelcoat and the fairing compound. The nine-week exposure may not simulate what could happen after many years, but it does indicate that the gelcoat bond to epoxy laminates is a good bond and should perform well.

Our test clearly demonstrates that polyester gelcoat will bond to a properly prepared  epoxy as well as to a cured polyester laminate. This test confirms that polyester gelcoats can be applied over cured  epoxy on repairs below the waterline.

 

Forestay Installation

When we purchased Solace it didn't have a forestay and yet we had running back stays. A pad eye was on the foredeck where perhaps a forestay should attach to, but that was just attached to the deck with no support from below such as a bulkhead. We decided we wanted a forestay, but with suitable support from below to take care of loads; as we intended to use it for a storm jib. Here's what we did.

The padeye was above our anchor locker which had no convenient bulkhead to attach to. So we created  and glassed in a false bulkhead in a "V" shape to allow the anchor chain to continue to lay down. This was then finished off with a coat of "Flowcoat"; an air cure gelcoat.

Two rods were shackled to the new bulkhead. These had turnbuckles for adjustment of tension and PVC tube placed over for protection from the anchor chain.

Shackle to bulkhead

Finally, the padeye on the deck was replaced with a folding padeye which matched the one seen here under the deck. Reinforcing between the padeye and underside of the deck was also undertaken. The two padeyes where then secured through the deck with countersunk bolts and nuts. The two rods where then shackled to the underside padeye to provide the support need for the forestay. We finished with installing our forestay and used a quick coupling cam lever to attached and remove the forestay from the padeye when not needed. Perhaps unluckily, one storm has proved it's effectiveness and I'm convinced our mast stands today because we had the forestay and running backs attached when a shroud broke. 

Fiberglass Repair

The people at the questforwindandwaves.com have completed a re-glassing of their cockpit sole. Here's how he did it, but read the comment at the end.

As part of the current section I am working on (engine room/cockpit area), the biggest job is completing the repair of my delaminated and waterlogged cockpit sole.  In the first post on this subject, I cut out the bottom layer of glass and removed the wet core.  If you haven’t read the first post, check it out here: http://www.thequestforwindandwaves.com/?p=137
This past week I finally finished the repair work and am excited to have it done.  Aside from the hull blisters, this is probably the biggest repair job on the boat.  This is what the sole looked like before the repair job:

The next step was to grind down the remaining core and get a fairly smooth surface to glue in the new core.  Here is the surface post grinding:

I purchased some end-grain balsa to use as the replacement core. Here is the first piece measured and cut. The board underneath it is the backing plate I will use to hold the core in place while the epoxy dries. I covered it in wax paper so epoxy wont stick to it.

After measuring and cutting the core, I painted both contact surfaces (core and sole) with unthickened epoxy to penetrate, then slathered on a ton of thickened epoxy to the core:

Next I smushed it up against the sole undersides, put on the backing plate, then used shower curtain rods to snug it up.


I filled in the edges with thickened epoxy and let the first piece cure.  Here it is after it dried:

I then performed the same tasks on the second piece of core.  Here are both pieces in place, with the edges sanded round:

Next up I applied a few progressively larger layers of biaxial cloth to the undersides.  I used smallish (1 ft or so) strips to keep it manageable while laying up the glass overhead.


Job finished!  I will sand it down and paint it along with the rest of the engine room ceiling.  I stood on the cockpit sole for the first time in a while and it is solid as a rock!
Lessons learned: doing the job from the underside was a mistake.  My initial idea was that working from the underside would ensure the top skin is undamaged and finish/fairing work would be minimized.  The glass underneath is rough and unfinished, so the repair work need not be super neat.However, I underestimated the effort it took to glue in the core overhead with gravity working against me.  It was extremely messy, with epoxy getting all over me, in my hair and everywhere.  My arms were noodles after each work session working overhead.  If I had to do this again I would definitely go from the top and just take my time with the finishing work, particularly since I am fairing and painting the decks regardless.  Gravity working for you is a good thing.  All in all, I am happy with the repair and glad to be moving forward!