We're located in the Port of Everett's craftsman district with an indoor heated repair facility and able to haul out up to 33 feet. We specialize in fiberglass boat repairs, custom-built fiberglass marine parts, complete fiberglass restorations and polyurethane, acrylic & alkyd topcoats. There's no repair to small or large for us to handle.

Need to get the bottom of your boat painted, just pull up to the dock and well take it from there. No more waiting to pull your boat into the slings, just tie up and walk away. We take pride in taking care of your vessel and guarantee it will leave as clean as it arrived. You'll have the peace of mind knowing that your boat is safe & secure in our inside facility.

A boat is made up of many different materials, some durable, some delicate.

Lakota Marine Services boat detailing delivers the highest standards of excellence in our boat detailing and yacht detailing maintenance program. We offer the finest marine services in the Everett to Seattle area. Bring your boat to us or we can provide mobile service to you at your home, dock or slip.

Whether we're bringing a yacht or boat back to life or continuing a regular boat maintenance program, we will conduct our work with the utmost attention to detail. With the harsh Washington elements constantly attacking your paint, gel coat, metal, leather, wood, vinyl and isinglass, regularly washing to remove salt with fresh water goes a long way towards preventing unnecessary deterioration. Furthermore, preventative protection will keep your boat glistening and pristine, while extending its life and prolonging depreciation.

Fiberglass & Gelcoat Repair

Lakota Marine Services is a one stop fiberglass boat repair facility located in Everett Washington with expert technicians who take pride in doing a good job. We specialize in custom-built fiberglass marine parts, complex fiberglass boat repairs & complete fiberglass restorations.

  • Gelcoat Repairs
  • Bottom painting
  • Experts in Polyurethane, Acrylic & Enamel Coatings
  • Fiberglass Extensions
  • Mold Construction for custom cabinets, deck boxes & more.
  • Minor & Major Structural or Cosmetic Fiberglass Modifications
  • Minor & Major Structural or Cosmetic Fiberglass Repairs
  • Blister repair
  • Custom Gelcoat Color Matching
  • Custom Fabrication


  • Boat Detailing
  • Buffing and Waxing
  • Bright Work and Varnish
  • Top Coating from Stripes to Complete Hull and Deck Paint Jobs
  • Monthly and Quarterly Detailing and Maintenance Service

Boat Wash and Boat Wax

Popular maintenance program after your boat detailing or yacht detailing is steps above your average boat wash and boat wax. We use a non abrasive boat wash which prevents stripping any of the boat wax coating protecting your gel coat. We also remove all rust stains and yellowing, scrub the non skid, clean and polish the fixtures and bright-work, clean and condition the vinyl, and clean and wax the isinglass. Lakota Marine only uses high quality Carnauba wax which is applied to the boat or yacht by hand to ensure proper coverage. This service is a little extra than a standard boat or yacht wash, however that extra goes a long way.

Boat Compounding

Boat Compounding is used for oxidized boats. Our high quality compounds can restore heavily sun faded yachts and boats. - If your boat is in need of some rejuvenation Lakota Marine Services is the right choice!

Metal Restoration

All metal work -- bow rail, cleats, T-Top stands -- our metal restoration service removes rust and tarnish from all metal types. Your metal will shine while being protected against future erosion.

Leather and Vinyl Cleaning

Upholstery cleaning, mildew removal and conditioning of all leather and vinyl. Once our vinyl & leather cleaner has brought your upholstery back like new, our conditioner will ensure they remain supple and protected against the elements.


Restoration, cleaning and conditioning of isinglass improves visibility and prevents cracking.


  • Custom Painting and Refinishing,
  • Gelcoat Management and Protection,
  • Pre-Sale Used Boat Preparation

If you're looking to keep your vessel standing tall, let us come aboard and you'll see the difference.

Topsides Painting

Painting the topsides and deck of your boat with a quality marine paint can make it shine like new, helping it do one of the most important jobs of a boat: make you smile! It's fun to look at a good looking, shiny boat while preparing for a day of fun on the water, and easier to clean at the end of the day. So how do you get from your chalky gelcoat or old paint to a yacht that appears new in the color of your choice? Paint it! Marine paints like Awlgrip, Imron, and Interlux Perfection, Toplac or Brightside, Pettit Easypoxy and others can all give you a durable, smooth finish that will last for years with proper care.

Primer and Paint Selection

The quality and durability of all the modern yacht paints is very good, giving years of color and shine and resisting scratching, staining, and fuel or chemical spills of many kinds. If you buy a low end yacht enamel and put it on a tired looking boat, it will look great! So why would anyone buy those expensive high end marine paints? What is so special about Awlgrip, anyway?

The fundamental answer is that the highest quality paints last longer, hold color better, resist abrasion and fading better, and are easier to clean and shine. The middle of the road paints do all those things pretty well, and the cheapest boat paints do a decent job, but won't hold up as well. If you look at the cost per year, they all cost similar amounts. How often do you want to repaint your boat?

Polyester Polyurethane Boat Paints

The longest lasting yacht paints are the two component polyester linear polyurethane (LPU) two stage paints such as Awlgrip, Sterling U-series, Interspray 900, Interlux Perfection and others. These paints form a hard, shiny exterior skin, like a clear coat, that makes them durable and easy to clean. They resist scratching and should generally be cleaned only with soap and water using a soft brush, and polished and shined only using the manufacturer's recommended products. Rubbing compound can remove the protective shell, as can high speed polishing with a machine. Just clean it, apply the protective manufacturer's recommended products twice a year, and it will last at least ten to fifteen years in the tropics, longer up north. Note that the solvents used in two pack polyurethane paints can destroy the one part paints, so one part paints must be removed before applying a two part paint.

If you are not sure what kind of paint is on your boat, you can test whether the two part paint you want to use can be safely applied over it by soaking a rag in reducing solvent and taping it to the hull in an inconspicuous place. If the paint gets soft within 24 hours, it is a one part polyurethane paint and must be completely removed before applying two part marine paint. If a two part polyurethane paint is scratched, repair will involve blending the hard surface of the existing paint with the repair coats, a job that will challenge even professional painters.

Acrylic Polyurethane Boat Paints

The one part acrylic polyurethane marine paints such as AwlCraft 2000, Interlux Toplac and Brightside, Pettit Easypoxy, Sterling 68A series and Interspray 800 are not as hard as the polyester based paints, so they can be scratched more easily by dinghies, pilings, fenders or anything else that may rub against a boat's topsides. Dark colors will not last as long in one part acrylic polyurethanes as in two part polyester polyurethanes, especially in tropical climates. Acrylic polyurethanes can be compounded and waxed by machine without the risk of damaging the tough skin of a polyester polyurethane, and repairs are easier to blend. One part paints can be applied over a previous coating of any polyurethane paint, and are somewhat more forgiving of imperfect application conditions or techniques. While one part polyurethane topsides and deck paints are not as durable as two part paints, many boaters get years of service from these paints with occasional polishing and protective wax.

Alkyd Enamel Boat Paints

The oil based alkyd enamel boat paints were great for topsides and decks before polyurethane paints became available, and some still use them for their ease of application, compatibility with wood hulls, and low price. You can get a good finish from an alkyd enamel paint, but a polyurethane will perform better for exterior applications, so alkyd enamels are used to paint interior spaces in boats.

Mixing and Testing

Manufacturers recommend certain amounts of reducer depending on the temperature, but the exact "right" amount may be a bit different from their recommended ratio. Factors other than the air temperature affect how the polyurethane paint cures, including sunlight, breeze, humidity, and the application style of the individual painter. To find out the mix that will work best on a given day, have a test subject available. A dinghy, a dock box, or a piece of plywood painted with primer and prepped like the boat can be an invaluable learning platform, and can wind up looking really sharp and matching your boat when you are done.

Roll and Tip Application

Enough has been written on roll and tip application to confuse any sane person who tries to digest it all, and there are videos on youtube showing different techniques. If you are apprehensive about learning the roll and tip method, first understand how polyurethane paint works and how you need to help it along. You can think of polyurethane paint as a bunch of bungees swimming around in some goo. They want to link to each other, and all of them want to stretch as the goo evaporates away, and if you get it right, you end up with an even layer of interlocked and tightly stretched bungees, creating the glossy shine and inherent durability. To achieve that result, you have to spread them around thin and even, but every time you touch them, you mess up the ongoing interlocking in that area. If you overload the roller, you have to roll a lot to get it thin and even, but if you underload it that can cause additional rolling as well.

Tipping is so called because you do it with just the tip of a clean brush, gently popping any bubbles and leveling out any roller stipple with as few light touches as possible. Keep two tipping brushes going, changing to a clean one that has been soaking in reducer frequently. It is important to get the right reducer mix so that the paint has enough "goo" between the "bungees" to lubricate the whole process of attaching to each other, but not so much as to allow whole areas of bungee mat to slide - that is what creates sags. If you have too little reducer, brush or roller marks will not level themselves out, but if you have too much the paint will sag before it cures and bonds together enough to hold shape. As mentioned, practice on a dinghy or something, and to make sure your application technique can produce a flawless, smooth surface, paint a sheet of glass. If you don't like the mix, it is easy to clean the glass off with thinner and try again.

Bottom Paint Questions and Answers


That depends on the type of antifouling that is used. The longevity of multi-season copolymers such as Micron Extra & Micron CSC is related to the amount of paint applied. These paints will retain the antifouling properties as long as the paint is on the hull. Hard antifouling paints work by leaching biocide out of the paint film and leaving the paint film behind. When this paint film is left out of the water it oxidizes and any biocide that is left in the coating will not leach out at the proper rate to control fouling.


Antifouling paints are not meant to be cosmetic or decorative coatings and while every effort is made to make them as aesthetically pleasing as possible. The copper compound within the antifouling is difficult to mask with color pigments.

All antifouling paints change when they are immersed. So don't be surprised when you have finished and the color is not what you had hoped from the color chart, The true color will establish itself after the boat has been launched. Copolymer and ablative type coatings tend to fade more than hard antifouling paints.

Along the waterline you will often the antifouling looks dirty or faded, and can even turn green. This is due to the reaction of the paint with oxygen forming green copper oxide. Also paints with a higher copper content will turn greener at the waterline than paints with a lower copper content. For these reasons you should try keep the paint as close to the true waterline as possible. Fading is more noticeable in of ablative coatings than in hard coatings.

What Is The Difference Between Hard & Soft Paints?

Antifouling type is dictated by the quality, combination, quantity and type of resin.

Copolymer and Ablative Antifoulings

These types of antifoulings are partially soluble which means that as water passes across the surface of the coating, the coating wears down much like a bar of soap would wear away The action of the water steadily reduces the thickness of the paint at a controlled rate, which results in always having fresh biocide at the surface of the paint throughout the season. For this reason these types of antifoulings have the capability to perform in the areas of highest fouling challenge.

Hard antifoulings leach the biocide out of the paint film and leave the paint film behind on the hull, which causes a build up of old, spent coatings, Because copolymer and ablative types of antifoulings wear away with use. There is no build-up of coatings that will eventually have to be removed from the surface. The minimal build up reduces the maintenance and preparation needed when it is time to apply more anti-fouling. In addition Copolymer types such as Micron Extra with Biolux and Micron CSC can be hauled and relaunched without repainting as the longevity these coatings are related to the thickness of the paint. Ablative types such as Fiberglass Bottomkote Act do not retain their antifouling ability for more than 30 days after being hauled out.

Hard Antifoulings

The technical term for these types of antifouling paints is "contact leaching". The paint dries to a porous film that is packed with Biocides, which leach out on contact with water to prevent fouling growth. This leaching is chemically design to release biocide throughout the season, but the amount will steadily decrease until there is not enough biocide coming out of the paint film to maintain fouling protection. Once the biocide is exhausted, the hard paint film remains on the boat. One of the main benefits of this type of antifouling is its resistance to abrasion and rubbing. This makes it ideal for fast powerboats, racing sailboats or boats where the owners have the bottoms cleaned regularly.

Most hard antifouling paints can be wet sanded and burnished prior launch to reduce drag and improve hull speed.

A disadvantage to hard antifouling paint is the buildup of residual paint film that occurs when the surface is not properly sanded prior to application of new coats of antifouling. When hard paints are hauled and stored for the winter season, the paint film, as well as the biocide oxidizes and this makes it more difficult to release more biocide out of the film. For this reason, they must be sanded and recoated with fresh antifoulinq before relaunching.

Teflon Antifoulings

Most people associate Teflon with nonstick household products or with the space program, but the properties that made it perfect for those applications also make it an ideal ingredient in antifouling paint. Teflon creates the lowest coefficient of drag in any coating available. The lower the friction, the less energy is required to move the boat through the water. For powerboats this means greater RPM's, increasing speed and fuel savings. For sailboats, greater speeds are achieved with less wind.

Soft Antifoulings

Soft or sloughing antifoulings provides dependable low cost protection for cruising boats or boats with displacement or non-planing hulls. These paints are easy to clean and remove at haul out which prevents paint build-up. These types of coatings must be launched within 48 hours of painting to retain maximum effect effectiveness.

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Is More Copper Better In Bottom Paints?

The level of copper is not the only determining factor of how an antifouling paint will perform.

The resin-binder system, the material that holds the paint together, is equally important. Not only does the resin-binder system hold the paint together, it is the mechanism that determines how fast the copper and other biocide will be released. The resin-binder system must be carefully tailored for the amount and type of copper and other biocides used to obtain maximum efficiency The amount of copper or other biocide may effect the life of an antifouling paint but the sophistication of the resin-binder system to hold and release copper or other biocide at the proper rate is far more important to the effectiveness of the antifouling. A copolymer or ablative antifouling will release biocide at nearly constant rate throughout its life. For this reason, highly efficient antifouling paints like Micron, are less dependent on large amounts of copper and other Biocides and deliver the best possible performance.

The presence of boosting biocides, such as Biolux, by keeping the bottom clear of slime will make the copper more effective.

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Why Should I Bother Painting My Boat?

Once fouling has established a hold on a boat hull it will rapidly spread or "colonize" the surface. Prevention is therefore better than the cure of having to remove the fouling by scraping.

There are a number of key reasons to keep your hull free from fouling:

Safety - Heavy fouling growth reduces responsiveness of the craft. The added weight of the fouling can make the boat sit lower in the water than intended. This can have obvious implications in heavy weather conditions.

Protection - Prolonged growth of certain types of fouling can damage the substrate of the hull. For example, the natural glues used to attach organisms to the hull can damage wood and fiberglass. Fouling can also clog water intakes and cause damage to the engines.

Speed and efficiency - Fouling causes drag. As drag is increased, fuel consumption increases and speed is reduced even to the point where a planing hull may not be able to get on plane. For racing boats, this can be the difference between winning and losing a race.

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Interlux's Biolux Anti Slime Additives?

What is Biolux

Biolux is a unique antifouling technology developed by Interlux incorporating organic boosting biocides into a special biocide release system. This blocks slime growth for a fouling free boat bottom.

How does it work?

Just like ordinary plants, Slime and Algae feed on sunlight. Formulations that use Biolux technology prevent algae and slime from being able to grow by acting like sunscreen to block this process.

Soon after the boat is launched it comes in contact with algae in the water. Once these materials attach and feed, they begin to secrete a gel like substance that attracts more algae until it begins to look like a carpet on the bottom of your boat. This increases drag, increases fuel consumption and makes the boat more difficult to handle, which can be a problem in heavy weather. If left on the surface, it restricts the copper being released to the surface to prevent shell fouling.

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Blisters & Laminate Hyrdolysis


Commonly called blisters, the raised bumps on the bottom of the boat are the visible symptom of a condition that is commonly known as hydrolysis of the laminate. It has become obvious that hydrolysis is the real problem and that blisters are an unsightly and destructive by-product of the hydrolysis of the polyester resin in the gelcoat and laminate. As you will see, not all bottoms with hydrolysis damage have blisters, but all bottoms with blisters have some degree of hydrolysis damage.

The cause of the problem was well established in the 1987 University of Rhode Island study by Thomas Rocket and Vincent Rose, The Causes of Boat Hull Blisters. In simple terms, what happens is this. Water penetrates the gelcoat both as water vapor and as liquid water. Water is particularly good at this due to the small size of the H2O molecule. The gelcoat is a rather poor barrier against water penetration when constantly immersed. The glass fibers assist by acting as capillary tunnels to transport the water molecules into the laminate. Once adjacent to the resin in the gelcoat and laminate, the water goes into chemical solution with what are known as "water soluble materials (WSMs)" in the resin in the gelcoat and laminate. These WSMs include phthalic acids, glycol, cobalt, mekp and styrene which have not gone to full cure in the hardening process. To varying degrees they are present in all cured polyester resins. Five percent is an excepted norm. In some rare cases the quality of the materials or their application may be inferior causing a higher than normal percentage of water soluble elements.

Though this all sounds rather like it is taking place on a "micro-chemical" scale, the affects of hydrolysis of the laminate are visibly apparent. It appears to be affecting most conventionally built polyester fiberglass bottoms that are continually immersed. It is our experience that a large percent of boats built with conventional polyester resin and gelcoat, show signs of hydrolysis deterioration of the outer laminates after 5 to 10 years of immersion. These signs include "sediment piles" where hydrolysis fluid is exiting the hull, increased moisture content in the outer laminates, reduced resin and glass fiber clarity, reduced resin hardness as well as the obvious and well documented blisters. A switch to using vinylester resin for all or a substantial part of the outer layers of the bottom seems to have been one of the most successful methods to date.

So what about these blisters you might ask. Well, blisters form when the flow of water into the laminate exceeds the flow of hydrolysis fluid back out. It is that simple, FLOW IN EXCEEDS FLOW OUT. To understand technically what happens, we have to understand osmosis and osmotic theory.

Osmosis: If there are two fluids separated by a semi-permeable membrane and one is more concentrated than the other, the more concentrated will draw the less concentrated solution through the membrane until the two are of equal concentrations. The force that does the "drawing" is called "osmotic force" and it can be substantial as we will see.

The acidic solution that is a by-product of hydrolysis collects in an available space in the resin, perhaps a small air bubble trapped in the original layup. This solution cannot pass back through the gelcoat (the semi-permeable membrane) as readily as the water came in because of its increased molecular size. The hydrolysis fluid is more concentrated than the water the boat floats in, so the hydrolysis fluid draws the water in through the semi-permeable membrane (gelcoat) in order to reach equilibrium. As fluid builds up, pressure builds up from the osmotic force and blisters start to form. With time they grow larger and slowly start delaminating the outer layers of laminate, that is, a blister. If enough blisters form, severe delamination can occur.

As time goes on, the blisters may break from the internal pressure and form a pinhole or a crack in the exterior surface. This rupture allows the blister fluid to rapidly leak out and sea water to flow into the laminate much faster. Now hydrolysis can continue more rapidly, working deeper into the laminate. New blisters form at a deeper level, eventually rupturing and the process continues.

Sometimes we find a gelcoat which is cracked, crazed or otherwise quite porous. If the gelcoat is sufficiently porous, small blisters may never occur because the blister forming fluid is not contained and can freely flow back out of the laminate and gelcoat. Sometimes in this instance, large blisters will form at deeper levels in the laminate after many years of immersion. Sometimes blisters do not form at all, but the damage to the laminate is taking place just the same. We often see small piles of sediment on surface of the bottom when the laminate is being hydrolyzed. This sediment is the laminate resin solids precipitating out of the fluid flowing out from the laminate through cracks or pinholes. Such sediment piles are evidence of a hydrolyzing laminate even when there are no blisters visible.

One great paradox is that the efforts of many of well intentioned boat builders to make their gelcoats less porous have actually results in more rapid blistering of the bottom. By "tightening" up the gelcoat to a considerable degree but not enough to fully stop water flow they have increased the difference between flow in and flow out. Hence, as little bit of water makes a lot of blisters. It is important to understand in this situation, that considerably less water has entered the laminate and so though blistered, the underlying laminate tends to be in better condition. Boats that blister in the first six years seldom have serious laminate damage.

One of the most asked questions are "Why did the old boats have fewer blister problems than the boats of the 80's. My old Pearson (or whatever) is 20 years old and never had a blister." What's been found is the older gelcoats are so porous that "flow out" equals "flow in". The gelcoat is not a semi-permeable membrane, rather is a fully permeable membrane. The result is severe hydrolysis but no blisters. Some modern boats have tighter gelscoats which the boat builders had hoped would stop blistering and hydrolysis. Though hydrolysis is greatly reduced, blistering occurs sooner and more dramatically.

People often ask if the whole bottom is affected or if the problem could be a "local" one. Blisters may seem more concentrated in certain areas; the hydrolysis of the bottom is very uniform at equal depths. Remember, blisters are a very small, local phenomenon which is a by-product of hydrolysis. Hundreds of cases of hydrolysis have been looked at over the years and one of the consistent observations has been the uniformity of the hydrolysis both over the immersed area and in depth. It is also noted that hydrolysis is very layer specific and the effects will vary from layer to layer of glass fabric and that the affect on a specific layers will be uniform throughout the layer and throughout the bottom. It should be obvious by now that the areas between the blisters are being affected by hydrolysis as well as at the blister site.

On rare occasion, say one time in a hundred, there is a local phenomenon. It is important to recognize this but testing for it is difficult and it may not be until the boat is stripped that the lack of uniformity is noted. This may be a good place to note there are often local blisters around keel joints, fittings, rudders, etc. where fairing compounds have been used. This is a completely different problem from laminate hydrolysis, is far less serious and is easily recognizable to the experienced.

Besides the normal reaction of water and a well constructed laminate, there are numerous potential pitfalls in the original hull construction process that may exaggerate the problem as well. Normal construction technique involves applying a gelcoat to a mold. Then, several layers of fiberglass matt are laid into the mold followed by alternate woven roving and matt layers. The layup work is often halted to permit the resin to cure up so that to successive layers can be applied without damaging the layers already in the mold. Working around lunch and quitting times can also be a factor. The interface between cured resin and new resin is a boundary layer which contains a higher concentration of water soluble elements. These boundary layers are often associated with blisters of the larger variety and delamination.

The fiberglass matt that is just below the gelcoat is also believed to be a contributing factor. The short, random, non-woven nature of the glass fibers orients many fiber ends against the gelcoat. These fibers act as capillaries for moisture into the laminate. The sizings used to hold fiberglass mat together in sheet form are also considered to be part of the problem. The incidence of blisters and hydrolysis in the woven fabric portions of the bottom laminates is considerably less than in matt fabrics or chopper gun applied matt.

Laminates with a relatively higher percentage of air bubbles in the laminate seem to be related to a higher incidence of hydrolysis. Both matt sheet goods and chopper gun applied matt fibers have an inherently higher percentage of air bubbles than occur in woven laminates. It is believed that air bubbles provide space for hydrolysis fluids to collect and concentrate.

Resin formulation, age, storage, catalyzation rate, and application as well as application temperature and moisture conditions all seem to play a part in the ultimate solubility of the finished resin. Most boat builders strive to produce a high quality product, but the number of variables and the fact that the polyester material is still soluble under the best of conditions make one wonder about its suitability for building boats. Boat builders are using a variety of new materials and barrier coats and it would appear with some degree of success.

So why are blisters and hydrolysis a problem? Well, the blisters themselves slow the boat and are unsightly. The blisters slowly delaminate the fiberglass laminate locally and if there are sufficient numbers of blisters, may direct affect the structural integrity of the laminates. Nothing seems to scare off a potential buyer faster than blisters though this is changing as the buying public becomes more familiar with the problem and the effectiveness of well done repairs. The affects of hydrolysis on the resin, however, are of more concern than blisters. The hydrolysis process softens, weakens and removes the resin from the laminate, thus reducing the rigidity of the laminate. As rigidity is reduced, the amount of flex experienced in portions of the bottom increases. With increased flexure comes increased risk of fatigue failure. Most yacht hulls have a safety factor of 2-4 to 1, leaving quite a bit of room for deterioration. These safety margins, however, vary widely and are constantly under pressure to be reduced in the name of performance. If a hull is of cored construction, structural damage can occur quite quickly. Large scale core saturation is largely irreparable at a reasonable cost. It should be noted that the presence of water alone in a glass laminate, even when no hydrolysis damage has been done, significantly decreases laminate's resistance to structural fatigue.

You might ask how long might it take for the deterioration to become a structural concern? This cannot be answered categorically. The truth is, to date; little research has been done to establish deterioration rates and quantitative strength losses over time. Complicating factors include the thickness of the hull structure, the intended use, the surrounding water temperature, the degree of water absorption, the degree of blistering and hydrolysis, the age of the laminate at the time of blister onset, the materials used in construction and the design of the vessel all have a bearing on the rate of deterioration and the effect of deterioration on the structure.

Preventative maintenance is simple in principal: KEEP THE WATER OUT OF THE POLYESTER LAMINATE!!!


There are several stages of inspection one can use to assess hydrolysis damage to the laminate resin.

The first is to have a look at the exterior:

  • Identify the size and frequency of blisters. Blister diameter is often associated with the depth of the blister and thus a rough gauge of the depth of the hydrolysis. Though it is risky to place too much emphasis on blister size, bigger blisters mean bigger problems.
  • Look for cracks, crazing and pin holes. These may be letting lots of water into the laminate and accelerating hydrolysis.
  • Look for sediment piles. These typically indicate active hydrolysis, even though there may be no blisters
  • Look for hull distortion. Distortion may be the result of lower laminate rigidity from hydrolyzation
  • Take moisture meter readings. It is hard to draw conclusions from high moisture readings on the surface, but low readings usually rule out the possibilities of ongoing problems.

One cannot, however gather sufficient information from the exterior to define the extent of the hydrolysis damage or to design a repair. For this, one has to look into the laminate interior.

The depth of laminate removal is a critical decision point in the repair process. As a general rule, the laminate will be of poor quality at least to the base of the deepest blisters. Usually, there is some hydrolyzed laminate below this level, but eventually, a solid, resin rich, laminate with little residual moisture is usually (but not always) reached. We often see the entire exterior matt outside of the first woven roving) is in poor condition.


There is a wide divergence amongst both repairers and owners as to the best way to repair blisters and hydrolysis. On the simplest level, one simply pops blisters and fills them. This completely ignores the problem of water continuing to get in to the laminate and cause more blisters and hydrolysis.

A popular but less than successful approach has been to remove the bottom paint and gelcoat and a slight amount of the outer laminate. Deeper blisters are ground out, the hull is "dried" out and a barrier coat is applied. In my experience, providing the barrier coat is 20-30 mils thick, this method will work for 2-5 years, maybe a little more if the boat is dry storage every winter. The barrier coat usually fails by blistering due to the high percentage of water soluble materials left behind by the "drying" process and the moisture that passes through even a good barrier over time. The repairer has not changed the nature of the resin the boat was built with. If the original polyester laminate absorbs sufficient moisture again, it will blister again and the resin will continue to hydrolyze.

This is probably a good time to talk about "drying out". This term is thrown around a lot in this field and it is important to understand what it really means. It implies that all the water that is in the laminate is removed and the laminate goes back to its like new condition. Nope, what happens is that IF you get MOST of the water out, which is the best you can hope for, what you have left is dehydrated hydrolysis fluid. The laminate resin has regained none of its strength, rigidity or density and it contains a high percentage of water soluble material. In my opinion, "drying out" the laminate is a misnomer. Though I would agree it is foolish to install a barrier coat over a "wet hull", drying out does not solve all the problems the term might imply. The other thing to keep in mind is that drying out takes a long time. The use of heated tents, heat blankets, etc. are an attempt to accelerate the drying process and to some degree do so at some added cost.

In my opinion, the most successful repair of blisters and hydrolysis on the simple concept that hydrolyzed laminates are not redeemable. The repair removes the hydrolyzed material, replaces the removed material using materials that will resist hydrolysis and keep water from getting in again by application of a barrier coat. This method side steps the "drying out" problem and deals directly with the deteriorated laminate

The relaminating with new material serves two important functions. It returns removed laminate to the boat and if laid up with a hydrolysis resistant resin like vinylester, it substantially increases the thickness of the portion of the bottom exterior that is very resistant to water damage. This represents a premium repair and is more costly, but for those who are looking for the utmost protection, there is little doubt the added material and thickness of barrier coat makes for a more durable barrier.

The best repair is made by removing all the hydrolyzed laminate and exposing the undamaged laminate as the start of the repair. The amount of repair laminate should be at least the same as that removed. The replacement laminate fabrics used will vary depending on the repair design, but in general, a high percentage of woven and uni-directional type fabrics are preferred to all matt layups because they are more resistant to water incursion and because they are stronger and more rigid than matt laminates.

There are practical limits to how much one can take off the bottom and successfully relaminate. The primary problem is structurally connecting the new laminate to the topsides. When the bottom laminate is damaged deeply and you wish to remove it, the only place to match the connection is at the waterline. Thick laminates require wide joint areas and the repair ends well up into the sides of the hull. Structurally, this is great but cosmetically a disaster. To deal with the cosmetics, it is necessary to fair in the repair and paint the sides. This is a very costly addition. The final decision of how much can be safely removed from the bottom is dependent overall laminate thickness, cost considerations and the details of dealing with the cosmetics.


Once the amount of laminate to be removed has been established, the removal process begins. In the distant past this was laboriously done by grinding and sandblasting. When more than a 1/8" of laminate had to be removed we used a tool called a "stripper"; a chisel welded to a pipe. The stripper was worked into the interface between two delaminating layers of laminate, wedging the top layer off. If all this sounds a little primitive, it sure felt like it when we were doing it.

We now use a tool that has become commonly known as a Peeler. It cuts the gelcoat and laminate off like an electric planer. It is a hand held tool that can take off measured thickness plus or minus .010". The hull after laminate removal is left quite smooth, requiring only moderate sanding. The cutting tool is a much cleaner operation in comparison with grinding and sandblasting, both for the boat and interior as well as for the environment. The advent of the modern "peeler" tool was the final piece in the repair puzzle and revolutionized the repair process.

The peeler crew carefully works to specifications established in the Profile, uniformly removing the deteriorated laminate. Following peeling, areas that could not be reached by the peeler are taken down by hand with grinders. .

We are often asked about removing thru-hulls prior to peeling and relaminating. Though fine in principal, the actual work is far more expensive than is justified by the results. Removal and reinstallation of thru-hulls runs $35-$50/ft plus materials (parts are often broken during disassembly). We have seen no evidence that not removing thru-hulls results in failure around thru-hulls and considering the high cost, removal seems a superfluous luxury.


Assuming the laminate removal has taken off all the hydrolyzed laminate, the hull is now ready for relaminating. In cases where it has not been practical to remove all the hydrolyzed laminate, that which has been left will need to dry out. This can vary considerably weeks, months, but assuming the worst of it has been removed, in practice, the drying time of the remainder is usually fairly short. The resin used in relaminating can be epoxy, polyester or vinylester resin. Isophalic polyester resin is cheaper and easier to work with. Epoxies, if done well, offer much higher resistance to moisture but are less compatible with the original hull resin and are very costly and hard to work. Vinylester resins offer a high degree of durability at a cost in between epoxies and polyesters and though harder than polyester to work, experience permits us to use vinylester for all our layup work these days.


Following removal of hydrolyzed material, drying and replacement of glass as necessary, a barrier coat is applied. Until 1988, epoxies were generally used for this because of their high physical strength and waterproof qualities. In practical use, however, epoxies were less than ideal. Their application is difficult, requiring exact measuring and mixing habits, warm temperatures and dry atmosphere to achieve claimed physical properties. In the field, it has been noted that epoxies are only marginally tolerant of polyester substrates and seem to reject acidic laminates over time. The results are often blistered barrier coats and reduced protection and durability.

Vinylester resins have increasingly become the standard barrier coat used for blister repair. Designed for high corrosion resistance and high physical strength, they combine the good water proof lab specs of epoxy with the ease of application of a polyester resin. The theoretical "waterproofness" for equal skin thickness is marginally less than epoxy but because of its flexibility and lower cost, vinylester resin can be applied in thicker skins, greatly increasing waterproofness. Thickness is an important factor in a barrier coat. Vinylester is much more compatible with the polyester than epoxies. The bonding strength of vinylester to the original polyester is better than either polyesters or epoxies.

As a barrier coat, we apply six rolled coats to arrive at a thickness of .030". This is two - three times the thickness of most epoxy systems. On top of the barrier coat, a vinylester sanding primer is applied and largely sanded off to smooth the bottom. By using the gelcoat and laminate removing tool initially and careful filling and sanding, the bottom fairness is quite good and meets most owners' requirements. If race quality finish is required, this is accomplished by many hours of hand fairing.

Once fair, two coats of antifouling complete the repair. The boat is cleaned and launched.


After the repair is made, several points should be kept in mind. The coating should be inspected annually for evidence of failure. Failure will usually be evidenced by blistering of the barrier. Barrier coats, because they are much less porous than gelcoat will blister with less moisture. Deterioration is a function of exposure to water by immersion. Dry storage reduces exposure.

Lakota Marine Services offers limited warranties on all bottom repairs. In our opinion, a repairer who does not warrant his repairs lacks experience and confidence in his work. Warranty terms will vary depending on the type of repair done and are defined at the time of contracting the repair. Most of our work carries a 5 year warranty. Note that we offer NO warranty on simple barrier coats without relaminating. In our opinion, their performance is not predictable enough to warrant.


We are occasionally asked about preventative use of barrier coats over an existing, unblistered gelcoat. Unless the boat has only been in the water for a few years, getting the bottom sufficiently dry without removing the gelcoat is a very slow process, often 12 to 18 months. The gelcoat, while not sufficiently waterproof to prevent blistering, is still dense enough to slow drying down to a snail's pace. Most boat owners are not willing to give up their boat for a year for a preventative measure. Considering the work will cost half of a blister repair, most owners opt to wait until the bottom blisters. Never the less, a properly applied barrier coat will greatly reduce hydrolyzation over the years. The cost of maintenance of this barrier coat will, however, be rather high.

In the case of a new boat, however, if the manufacturer has not applied a barrier or built the boat out of a non-blistering material such as vinylester resin, a barrier coat is highly recommended before the first immersion. It won't last forever, but it will forestall hydrolysis and blister formation. This is especially important if the boat builder does not have a definite, long term, written policy on blister repair warranty.


Simple barrier coats, that is simply removing the gelcoat and applying a barrier without relaminating can run $300/ per foot. For reasons listed above, however, we seldom perform this kind of repair these days. Relaminating is much preferred. The cost over relaminating is $400 to $500 per foot of boat length (LOA) depending on a variety of factors including the area of the underwater portion of the hull, whether the keel is glass or exposed metal, the quantity of laminate to be removed and replaced, etc.


Repair methods and costs have largely stabilized, with each yard having adapted the method that works best for them. Fifteen years ago, it was fashionable among many repairers to admit they knew little about the blister/hydrolysis problem and its repair. Price variations were substantial and written contracts were often avoided. Failures of expensive repairs were common and warranties were conspicuously absent. Written warranties are now the standard. As time goes on, new boat building techniques will outdate the need for these repairs.


Resin: A generic name for any plastic material that starts out as a liquid and becomes solid through a curing process. Epoxies, polyesters, and vinylesters are all resins.

Polyester: A form of resin based on a phallic acid and glycol commonly used in fiberglass construction. Most boats are built with resin based on orthophthalic resin.

Orthophthalic: A form of polyester resin commonly used in yacht construction. Unfortunately, it is also the most likely to blister and suffer from the hydrolysis process.

Isophthalic: A higher grade of polyester resin based on Isophthalic acid. Though it less soluble than orthophthalic resin, it hydrolyzes and blisters as well. It is more expensive and somewhat harder to work with compared to orthophthalic resin.

Laminate (verb): To build up a solid sheet of material by successive layers of fiberglass cloth and resin. (noun): The resulting final product of laminating fiberglass cloth and resin. The laminate is distinguished from the gelcoat or core material.

Hydrolysis: A chemical process of decomposition involving splitting of a bond and addition of the elements of water (Webster's). When used in reference to the polyester bottom blister problem, the bond being broken is the ester linking molecule between the phallic acid and the glycol in the polyester compound.

Hygroscopic: An adjective referring to a material which absorbs water readily. Talc for instance is extremely hygroscopic filler used in conventional polyester auto body putty and accounts for the rapid deterioration of this material when immersed.

Osmosis: Diffusion through a semi-permeable membrane separating a solvent and a solution that tends to equalize their concentration (Webster's). Osmosis is believed to be the process by which water is drawn into the laminate. The membrane is the gelcoat, the solvent is water and the solution is the acidic solution that forms when water and the "water soluble elements" in the polyester resin are combined. Osmosis is why the small concentration of acidic solution grows into a blister.

Vinylester: A modified epoxy resin in an ester linking system. High physical properties and outstanding corrosion resistance. To our knowledge, there has never been a blister in a boat built with vinylester resin.

Epoxy: A form of resin based on coal tar. Very high physical properties and corrosion resistance. The highest in water proof characteristics, but difficult and expensive to use and only marginally tolerant of polyester resins, especially polyester laminates that have been damaged by hydrolysis. Boats built entirely of epoxy resin do not blister but cost a small fortune.

Gelcoat: The solid, hard, pigmented polyester resin used on the vast majority of fiberglass boats as the protective outer coating on the bottom, sides and deck. Works well on the sides and deck, but is not waterproof enough on the bottom to prevent hydrolysis.

Barrier Coat: A protective outer coating applied to the bottom to reduce the ingress of water into the bottom laminate. Typically an epoxy or a vinylester resin, the barrier coat can be applied over an existing gelcoat as a preventative measure or as a replacement after removal of the damaged gelcoat and laminate.