Down with the old varnish!

Down with old varnish

The plan was simple: to give a new shine to our yacht's gelcoat Amel maramu, released in 1981, and to protect the fiberglass laminate underneath from the weather, you need to re-varnish the hull and deck.

And indeed, today, six months later, our "La Gitana" shines again in the sun, as after launching. But behind this brilliant appearance is a very laborious overhaul, during which it was necessary to get to the fiberglass itself, and which lasted for six months, although it was originally planned for two months.

In all cases, such extensive repairs will not be appropriate or necessary. However, for many solid fiberglass yachts built in the 7080s, this investment pays off. After all, yachts made of fiberglass, which do not require special care and do not contain harmful substances, and thirty, forty and even fifty years later, are far from having served their life. Anyone looking to enjoy their fiberglass yacht for longer should protect the aging gelcoat with new paint while still in good condition and of sufficient thickness. Otherwise, you will have to do a major overhaul, as happened to us (see Box 1).

The perfect foundation

Blistering, cracking, flaking, loss of shine or color: an improperly prepared base is the main cause of premature paint failure. Therefore, a high-quality surface preparation is the basis for a perfect, shiny and long-lasting varnish.

It starts with an analysis of the available surface. Provided appropriate pre-treatment, the gelcoat coat can be reopened without problems with most types of varnishes. The same cannot be said for old coatings. This can lead to chemical and mechanical incompatibility with the new paintwork material. For example, one-component varnishes cannot be overcoated with two-component varnishes, although if you do the opposite, no problems usually arise.

If it is not clear what type of varnish the yacht is covered with, or if a material compatibility test is negative, then the old varnish must be completely removed in any case.

In our situation, the gelcoat was brittle, cracked and did not adhere well to the fiberglass. Therefore, it had to be removed in order to reach the undisturbed surface. Only this can guarantee the maximum adhesion and therefore the durability of our new coating.

Grind, grind and grind again

Removing an old, incompatible or damaged surface is usually carried out by sanding, and when applying a new varnish it takes the lion's share of the work time. If you add the leveling of the putty areas to the sanding of the old surface, then it is not at all surprising if eighty percent of the working time of the entire varnishing process falls on sanding work. This is a huge amount of work, the volume of which we estimated at the beginning of our repairs completely wrong.

After all, while rough sanding of large, smooth hull surfaces is relatively fast, sanding hard-to-reach corners on the deck or in the cockpit can take days or weeks.

For this reason, and to ensure a continuous surface to be varnished, it is imperative to dismantle as many deck equipment as possible prior to starting repairs (see Box 2).

Due consideration should also be given to sanding equipment, the use of sandpaper and proper sanding technique. This can save you a lot of time and money (see box 3).

Naked truth

Week after week, millimeter by millimeter, we delved into the brittle gelcoat of our "La Gitana" eccentric sanders and by hand. It was clear early on in the project that in many places the gelcoat would have to be removed completely to provide a solid base for the new varnish.

In the course of the work, it was gradually realized that it would be advisable to remove the entire gelcoat. Thanks to this, we were able to reach the fiberglass below, which was still in good condition, and fix some of the damaged areas.

After five weeks of sanding every day, we saw the uncovered fiberglass housing of La Gitana. Fortunately, there were no nasty surprises. There was no damage to the fiberglass of the hull. It was only on deck, where for the past six years the tropical sun could leave its destructive traces without any hindrance, did we find some places where fiberglass had become brittle and brittle. Without a doubt, fiberglass is an extremely strong and durable material, and therefore we repaired damaged areas without much difficulty (see box 4).

Smoothness for shine

So, we got to the “bottom” of our renovation. We created a reliable base for the varnish everywhere and fixed the damaged spots. From that moment on, we no longer removed the old material, but began to prepare a solid base for the new varnish.

Before applying the first layer of varnish or primer, it was necessary to putty all the irregularities and shape the areas that were supposed to have a mirror shine in the future.

To do this, the gelcoat and fiberglass must be carefully checked for the presence of small craters, the so-called pores. They are sealed with a medium density filler to prevent future paint defects.

At this stage of the project, the desired design changes also had to be made. Therefore, we filled in the joints of the coating typical of the company's yachts. Amel and imitating a teak deck, so that later it would be easier to make an anti-slip surface without recesses. This stage is also best suited for cockpit upgrades or similar work.

By filling, filling the pores, sanding the hull and deck, among other things, it also creates the basis for a perfect finish with lacquer. Strenuous work using a light putty compound and a long sanding board prevents future undesirable “distorting” or waviness effects on the glossy surface. The more precisely this work is done, the better the varnishing result will be (see Box 5).

In order for the filler to adhere firmly to the fiberglass, a suitable adhesive primer must first be applied. We decided to treat the entire hull and deck with several coats of epoxy.

As a result, we not only got good adhesion between fiberglass and putty, but also protected the fiberglass with an effective vapor barrier, which replaced the previously removed gelcoat.

After two months of preparation "La Gitana" was ready to apply a new varnish, which we will talk about in the second part of our story.

Michaela and Volker Kisling since 2005 have been traveling around the world on a yacht Amel maramu... They spent six months in Fiji last year to overhaul their "La Gitana"... On your own website www.seezigeuner.de they talk daily about the most recent events from their life under sail.

1. New varnishing or overhaul?

Whether the planned new varnishing will turn into a major overhaul can be said already before the start of work by assessing the condition of the base, i.e. gelcoat or fiberglass.

After all, the quality of the varnish is always determined by the worst varnish coat. It is a waste of money and time to apply the material on an inadequately prepared surface, on an old coating or on top of a poor quality gelcoat. After a short time, the varnish will peel off again.

If the gelcoat has just faded but is generally in good condition, it is often sufficient to sand and then paint. The more fragile the gelcoat and the more small cracks there are, the more laborious it will be to apply a new varnish, since all the material must first be removed until a “healthy” surface is obtained.

In our case, it was necessary to remove the entire gelcoat, covered with cracks, down to the fiberglass - the planned new varnishing turned into a major overhaul.

2. Removing the deck equipment

The deck can be varnished without dismantling the deck equipment. However, there are a number of reasons why (supposedly) additional work is worth doing: first, you will get a visually more attractive result if you do not have to sand and varnish around masked fasteners, etc. In addition, you get a solid new surface that is not interrupted by many small details, which can affect the durability of the varnish.

Bow before removing most of the deck equipment. The expended efforts are compensated by the convenience of work and a better result

In addition, it is possible to detect and treat damaged gelcoat or rust underneath deck equipment. This also applies to these details themselves. Sometimes it is only through dismantling that defects such as rotten bolts or latent oxidation of aluminum can be detected.

On top of that, thanks to the dismantling, the stainless steel parts can be polished, which will add an extra shine to the yacht.

It is very important to remember exactly the location of the screws on the deck equipment. It is best to screw them back into place right away. Due to the different thickness of the fiberglass, for example, the Genoa shoulder screws can be of different lengths.

Since at the time of new varnishing the deck equipment, as a rule, has already been on the deck for several years, thanks to dismantling it is possible to “kill two birds with one stone”. After all, after such a time, they would still need to be putty again. The holes remaining after dismantling are best repaired with a polyurethane putty such as Sikaflex. Since it is flexible and easy to set, the holes can be easily found after the paint has been renewed. In no case should silicone be used for this purpose, since the varnishes do not adhere to it. Holes that will no longer be used are sealed with putty.

3. Correct grinding

The eccentric sander is the right choice. But they also require physical strength and skills.

Removal of old layers to obtain a reliable base for the varnish coating requires great patience and physical strength. The surface to be sanded must be free from seawater, grease, wax, silicone and other contaminants that prevent the adhesion of the varnish. Suitable solvents can be used if necessary. If this is not done, then during grinding, the dirt will penetrate into the base and later interfere with the adhesion of the varnish and the treated surface.

Grinding it is much easier to perform with eccentric sanders than by hand. However, using them requires some skill. They should lie flat on the surface to be sanded, they should not be placed on the edge, since in this case depressions are quickly formed, which then have to be putty again. For this reason, such machines are only partially applicable to very curved surfaces.

During grinding, the machine should be guided evenly, without excessive pressure; Motions should resemble large eights so that the substrate and sanding paper do not get too hot or stick together. The paper should be regularly cleaned of dust to prevent fast sticking.

Grinding is intended not only to remove old layers, but also due to the appearance of grooves in the base to be treated, it helps to increase the surface and, consequently, improve the adhesion of paint layers. Therefore, grit 40 is used first for removing old coatings and for pre-sanding. When the old base has been removed or the old paint has become dull, the grit should be gradually reduced.

80 percent of the working time during the repair is spent on grinding. In the cockpit alone, with its many corners, you have to spend more than one hour

4: Repairing damaged fiberglass

In some places, the fiberglass was already damaged by ultraviolet radiation, water and plastic canisters on the deck.

After removing the gelcoat, some damaged fiberglass were visible on the deck. In our opinion, the cracks were caused by ultraviolet radiation, standing water and chemical reactions under the plastic canisters located in these places. In the future, we will try to avoid these negative impacts.

Even if, at first glance, the cracks make an unpleasant impression, the damaged places were repaired without much difficulty.

To do this, we first carefully removed the brittle laminate with an angle grinder. At the same time, it became clear that the formation of cracks was only superficial. After removing 2-3 mm of the old laminate, the “healthy” fiberglass was visible.

The transition from the damaged area to the surrounding normal laminate now needs to be slightly angled so that new overlapping glass mat can be applied. In this case, so much material is applied to the damaged area so that the new thickness is slightly larger than the original one. The excess material is then sanded to the height of the surrounding laminate.

Initially cleaned areas are filled and reinforced with several layers of glass mat

Damaged laminate is removed at a slight angle

5. The path to the ideal surface

Before puttying, the polyester fiberglass is sealed in several layers with epoxy resin and primed

In addition to the absence of damage to the base, the ideal surface for a new varnish coating must have, first of all, one more quality: it must be absolutely flat so that the effect of a "crooked mirror" does not occur.

This ideal surface is created with a special low density filler and long sanding boards.

The ideal filler with a fine structure for creating a suitable surface consists of so-called microspheres. These are microscopic hollow balls of glass or polypropylene that are added to epoxy to produce an unusually lightweight and easy-sanding filler. Despite their low density and light weight, these putties are very resistant to mechanical stress.

Microsphere putty, mixed with epoxy resin, applied with large trowels or flexible spatulas

With the help of large spatulas, this world-renowned filler is applied to all areas that are to receive a glossy finish in the future. In places that will then be processed under an anti-slip coating, it is not necessary to strive for a perfectly flat surface. The matte anti-slip base will later hide minor irregularities.

After the putty is applied and completely dry, it is sanded using the longest sanding boards. The longer the board, the smoother the shape will be, since the large contact area does not create shallow depressions or depressions.

Rock 'n' roll: with a long sanding board, shapes into an easy-to-sand putty

Often, after the first sanding pass, it becomes necessary to apply a second or even a third layer of putty in order to obtain the desired surface evenness and uniformity.

Text and photos: Dr. Volker Kisling

18.03.2012