Marine Fiberglass Woes

Most of the nicks, chips and spider-webbing on a boat are found in fiberglass. They’re annoying because they ruin the appearance of the boat’s hull or interior. Service providers on Mariner Exchange know for a fact that, sometimes, they move beyond annoying and into the realm of real trouble as the spiderwebs and cracks continue to get worse and eventually allow water to seep inside the hull. That can spell big trouble. Most boats manufactured today are made with a fiberglass or fiberglass laminate hull and deck, and fiberglass components like the console.

Marine fiberglass maintenance and repair is as important as marine engine repair or sailboat canvas repair because it’s no fun watching your boat sit in a boatyard when you could be cruising the open water. It’s common to look at minor flaws in the fiberglass and think, “No big deal. I’ll fix it later.” In the real world, that can prove to be an expensive mistake. You’ll understand better why after reading all about marine fiberglass.

Typical Issues that Develop with Fiberglass

Fiberglass is an essential material in most boats. It offers many wonderful advantages, including making nice boats affordable. But there’s one fact in a fiberglass boater’s life – the gelcoat and fiberglass will get damaged in some fashion. Typical issues boat owners deal with include:

  • Blisters – gelcoat blisters are due to osmosis in which water is drawn through the gelcoat by the laminate’s water soluble materials Warping – when boats are subjected to intense heat for prolonged periods of time, causing the foam and plastic materials in the fiberglass to deform
  • Fatigue – hull loses its strength due to impact of waves and vibration (boat drags in the water)
  • Stress cracks or spider cracks, hairline cracks and crazing – though not structurally damaging, they can eventually lead to water seepage into the laminate; often found around a stanchion base or other hardware items installed in the fiberglass
  • Gouges – damage that goes deeper than the gel coat
  • Dings – small dents that are confined to the gel coat
  • Delamination – the wood between upper and lower layers of fiberglass pulls away from the fiberglass or the wood breaks down; a common cause is water allowed to pool in the bilge for a long period of time
  • Stringer damage – remember that stringers are supportive structures and are prone to wear and tear from fatigue, bilge water, impacts, quality of the wood and aging; sometimes, the stringer core material disintegrates

Marine gelcoat repair goes hand in hand with fiberglass repair. Some of the issues are due to water seeping through the gelcoat. For example, osmotic blistering is a process in which water moves through a semipermeable membrane as it attempts to equalize concentration. In this case, the gelcoat is the membrane. Small water molecules pass through the gelcoat, and the gelcoat traps the large water soluble materials (WSMs) in the laminate. The water flows into the laminate and creates pressure which leads to the gelcoat detaching from the laminate.

Voila! Blisters form.

Most gelcoat blistering occurs in polyester boats, seldom in vinylester boats and never in epoxy boats. The elements in polyester are a major source of water soluble materials. The factors influencing gelcoat permeability include the gelcoat’s thickness, the amount of laminate voids and the temperature. As the resin degrades, the laminate is losing strength. This is one reason some people promote the use of vinylester or epoxy.

Fiberglass breakdown is due to more than water damage, impacts or vibrations. The sun’s heat and ultraviolet rays can eventually cause fiberglass to get brittle. Periodic waxing is important to slow this process. If salt from seawater is deposited in fiberglass, the salt can create undue pressure that eventually causes damage.

How is Fiberglass Repaired?

Many boaters are do it-yourselfers (DIY) when the damage is minor. Let’s use blisters as an example. A small number of blisters may lead you to try the repair process on your own. You can grind out the blisters, use alcohol to remove the water soluble materials and fill the void with thickened epoxy. After that, you must sand and paint the epoxy.

The last step is standing back and wondering why you didn’t try to find a marine fiberglass repair specialist because it just doesn’t look very good.

Even more troubling is the fact that blister re-occurrence is often due to the DIY repair job not being done right. Either the compromised laminate with a high level of WSMs was not fully removed, or the barrier coating was not thick enough, to name just two common issues.

A major repair is needed on a hull that has a lot of blisters, is partially hydrolyzed and has a high WSM content. Hydrolyzed means a compound has undergone a chemical breakdown due to a reaction with water. A major repair involves removing the laminate, removing the water and drying the laminate to 2-3% moisture content, removing WSMs that rise to the surface as the laminate dries and installing a water barrier coating to slow water migration.

If delamination occurs, you will need a professional repair. No discussion needed. The fiberglass surface has to be removed so the wood is accessible for repairs.

Warping needs professional repair because, once deformed, the core of the fiberglass substrate needs replacing. No discussion there either.

Stress cracks and crazing is sometimes a DIY job, but it depends on whether it is surface damage (cosmetic) or a deeper problem. If the cracks reach the laminate, a serious problem is developing. If it’s cosmetic, you can thicken the area with more fiberglass, and then use a Dremel tool with a conical bit to remove the gelcoat along each of the paths of the cracks. Next, you’ll clean the channels with a solvent, fill the channels with gelcoat or epoxy. Once dry, dry sand and then wet sand to get the area nice and smooth. Wax the repair area, and you’re good to go (until the cracks reappear!).

Stringers in smaller boats can be replaced by removing the damaged stringer, making a new core, sanding the surfaces, and applying resin-hardener mix. Then apply a thickened epoxy at the stringer joints and replace the fiberglass skin.

Hull fatigue eventually leads to the purchase of a shiny new boat at a boat dealership or boat brokerage!

The descriptions of these repairs are simplified for purposes of discussion. The point is that some repairs can be made by the DIYer, and others have to be completed by a marine fiberglass repair specialist. If uncomfortable doing even a small job yourself, then it’s better to let someone with experience do it. The problem is that ANY crack or damage to the gelcoat, fiberglass or fiberglass laminate and core can lead to major expensive repairs.

A complicating factor that makes a professional repair the only option is when the boat must be lifted out of the water for a repair. You’ll likely have to work with your local marina to get the boat hauled out so that the fiberglass repair guy doesn’t have to do a balancing act on your dock’s boat lift.

When DIY Repairs is Not Advised or Possible

Do you know about the need for resin and fiberglass fabric compatibility? For example, fiberglass mats need a polyester soluble binder because epoxy can dissolve the mat. Epoxies are good for adhesion purposes. Do you have the right tools, like saturation rollers and mechanical sanders or grinders?

There are situations which scream “professional marine repair only.”

  • Boat owner does not have the knowledge to know things like the thickness of resin to apply or how to dry laminate or how to remove interlaminate damage
  • Boat owner does not have the time or tools to do the job right
  • Boat owner is unfamiliar with any of the repair materials needed
  • A large hole was punched deep into the hull
  • Torn fiberglass fibers or coring is visible
  • Fiberglass laminate is damaged
  • Repairs must be made in a difficult spot to reach
  • Too difficult to match new gelcoat color to old gelcoat
  • Hull is fatigued in an older boat (time to see your boat dealer or broker)
  • Unable to tell the extent of the damage from the cracks in the gelcoat
  • Boaters falsely assume a small stress crack is cosmetic when in fact it’s letting water seep in to wreak havoc inside the hull or deck

A marine supply store can sell you a package of fiberglass cloth, but then what? Do you know the right resin to choose, which may or may not be the resin originally used during boat construction? Or you may decide to open up an area, meaning you want to remove just the damaged gelcoat and fiberglass. Do you know how to remove “just enough” with a grinder? It’s easy to grind too deep and turn a small job into a big one.

The problem with DIY fiberglass and gelcoat repair jobs is that the end result is often visually unsatisfactory, the job is bigger than thought or the repair turns into a bigger problem due to mistakes made. It’s like so many DIY home repair jobs!

A Note on Fiberglass Maintenance

Maintaining fiberglass is important to prolonging its condition and life. Following are some fiberglass maintenance suggestions that wise boaters follow:

  • Regularly wax the exposed fiberglass above the waterline
  • Keep the fiberglass deck and components clean if the boat sits in water and wash the whole boat regularly if pulled out of the water
  • Don’t put off fiberglass repairs, whether they are DIY or done by marine technicians
  • Don’t ignore cosmetic fiberglass damage because it could be hiding a bigger problem
  • Keep the engine or outboard motor running smoothly to minimize boat vibrations
  • Faithfully use your marine electronics, like depth finder, to avoid unnecessary impacts
  • Periodically clean or have cleaned the hull section that is underwater of algae growth, oil, slime, barnacles and anything else that decides to attach itself to the fiberglass
  • Maintain the bilge pump to ensure water doesn’t sit in the bilge for an extended period of time

With good maintenance, a fiberglass boat can last decades. You’re likely to upgrade into a bigger, better, more high-tech boat before the fiberglass becomes irreparable. Maintenance is the boater’s first line of defense against major fiberglass repair.

Find Marine Fiberglass Repair Near You:

If you do not live in one of the locations above, click here to search for a marine fiberglass repair specialist near you.