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Introduction
(This page)
BACK TO FULL LIST OF PROJECTS
Introduction
(This page)
Here are techniques of GRP repair that you will find nowhere else! Yes you can paint damaged areas of the hull with new gelcoat and you can restore faded gelcoat with simple polishing techniques without re-course to Epoxy/Urethane paints (or other restoratives).
Maintenance free GRP is a bit of a myth! It's a fact of boating life that all plastic boats, however careful their owners, become scratched. Also, minor bumps and sunlight induced ageing cause localised cracking of the plastic. These blemishes gradually spoil the appearance and greatly devalue the boat.
These pages aim to show that GRP maintenance is not difficult and if the damage is dealt with promptly (say at the end of each season), it is easy to keep your boat looking immaculate! Sospiri was acquired at a knock-down price simply because there had been no such maintenance and, although structurally sound, the gelcoat (the coloured coating of the GRP), was in very poor condition. Using the techniques described here the boat has been transformed and the resale value increased accordingly.
The linked pages on the left menu bar show how Sospiri's GRP was restored and, in so doing, provide a detailed guide on GRP repair, renovation and maintenance. Whether you want to do a complete make over or just simply make good a scratch or repair some isolated crazing or cracking, these pages will guide you through it.
It was quite clear that there had been no maintenance to the GRP of Sospiri's hull and deck since her manufacture in about 1980. The Aquamarine hull was faded, dull, scratched and cracked in places. The Duck-Egg Blue decks were likewise faded almost to white and there was a lot of crazing in some areas. Crazing is fine cracking in the gelcoat usually caused by sunlight (UV radiation), making the gelcoat brittle. Flexing of the underlying laminate then causes the overlying inflexible gel coat to crack. So can the gelcoat of a boat in this condition be renovated and if so, what are the best methods?
The usual advice for faded and scratched gelcoat on a GRP hull is to paint it. It has to be said that paint is much more water resistant than gelcoat. However, to paint a hull properly the whole surface area (or each side at a time) has to be painted in one operation. There is also a considerable amount of preparation involving abrading the surface (to provide a key) and filling any residual scratches and indentations. After completing the surface preparation, a primer has to be applied followed by an undercoat and then the topcoat paint.
If the gelcoat is totally oxidised then painting is the only option as no amount of polishing will restore the original colour & finish. Paint can include brush or spray applied conventional Urethane or Epoxy-based systems. Alternatively a special gelcoat with a 'Patch Booster' additive to enable spray application can be used.
Unless done professionally, it is very hard to get a really good paint finish - especially if working outside. For me, an important factor was the desire to retain Sospiri's original Aquamarine and Duck-Egg Blue colour scheme which is such a distinctive feature of the early Luggers. It would have been very difficult to obtain paints to match these original colours.
In contrast, gelcoat restoration is a simpler (low tech) process using pigmented flowcoat also known as Topcoat (a special kind of gelcoat), as well as conventional gelcoat to touch up areas of damage (with no primer or undercoat required). Also, unlike painting, the repairs can be undertaken as a succession of small operations as and when time permits.
The down side of this method is that, unlike paint, the newly applied gelcoat has to be ground smooth and then faired in and polished to blende with the adjacent original gelcoat which can be quite a labour intensive process. Overall, my preferred option was not to paint but to try & restore the existing gelcoat. But could it be restored? Was the degradation superficial or was the whole gelcoat layer decayed beyond redemption?
The condition of the underlying gelcoat can easily be tested by very gently rubbing away some of the weathered surface. This is best done using 1200 grade wet-or-dry paper (used wet) on a sanding block. Some test 'rubs' on sections of Sospiri's hull revealed that the surface fading was surprisingly superficial and the original Aquamarine colour and shine could be restored very quickly. The Duck-Egg Blue of the decks was generally more oxidised and the problem was compounded by the fact that the gel coat was extremely thin in places.
It was beginning to look as if the gelcoat could be restored. However, additional suitably coloured gelcoat (the term gelcoat as used here includes conventional gelcoat & the flowcoat variety), would be needed to replace areas where the original gelcoat had been irrepairably damaged. So the last crucial question was how easy would it be to obtain gelcoat matching the original colours? Gelcoat is a translucent (typically greyish) slightly viscous liquid & pigments are added to give the required colour before it is used. Pigments such as white and the colours used in currently produced Drascombe/Honnor Marine boats are readily available, but the original Aquamarine and Duck-Egg Blue pigments are no longer made. Stewart Brown at Churchouse Boats can mix up and supply small quantities of suitably coloured gelcoat but this would have been prohibitively expensive for the amount of restoration that Sospiri required.
I found that the only way round this problem was to purchase some gelcoat pigment pastes (which are relatively cheap), and then carefully mix them until they matched those of Sospiri. Colour matching is not an easy task but, once achieved, keeping an exact record of the proportions of the component pigments used, makes it very easy to replicate the colour if required for future repairs. For more information on mixing pigment pastes see Colour Pigments on the left menu bar. All the other GRP materials I required were likewise readily available either purchased on-line or from my local chandler.