In this issue we’ll begin to cover the refurbishment of your aging boat, or the ‘previously loved’ boat you bought. I’ll only be covering the refurbishment of a fibreglass vessel; wooden boats require many skills that I admittedly lack.
Working with fibreglass requires a certain level of expertise that will come with experience so once you know the basics, which I’ll explain, you just need to make the effort and prepare for a bit of a learning curve. The beauty of working with resins and fibreglass is that you can fix any mistakes, dings, cracks, holes or construction so that you’d never know they had been there.
What are resins and fibreglass?
Resins are basically the construction materials with the fibreglass being the strengthening material for the resin. What you actually see as a finished product is the resin, not the glass. Resins are produced for specific applications but in our case we will concentrate on using the product known as General Purpose Resin or GPR. For resins to set they require the addition of a catalyst, usually in a dose of one teaspoon (5 ml) catalyst to a cup of resin (250 ml), depending on weather conditions, warmth, etc. Remember, the more catalyst you add the faster the resin will set or ‘go off’, so as you become used to working with it you’ll work out how much to add on cool days as opposed to warm days or how quickly you want it to set. A fast-setting mix is known as a ‘hot mix’ because the chemical reaction heats up the resin, at times to such a degree that it cannot be held with bare hands and on occasion will even explode – not the ideal scenario so be careful.
The outside of your boat is coated with a resin based product called ‘Gelcoat’. Gelcoat is applied to a boat mould before the fibreglass layers are laid up; this gives the boat its colour. It can be quite difficult to repair without a fair bit of practice and a lot of patience, so try to look after the outside of your boat. For a resin-based paint job, like on the fibreglass on the inside of the boat, we use a product called ‘Flowcoat’ or ‘Topcoat’, this product also requires a catalyst mix the same as GPR, but it is much heavier in consistency and is available in different colours. It can be thinned with GPR to make it easier to apply with a roller or brush.
Take caution when looking to brighten up the outside of a fibreglass boat, only paint it as a last resort. The paint job gets scratched no matter how careful you are and you’ll end up with a myriad of scratch marks the colour of the primer used, usually grey or yellow. Revitalising the Gelcoat is hard work but well worth the effort; we’ll cover this aspect of refurbishment a little later.
Fibreglass cloth is available in various weaves with the most popular and easiest to work with being ‘chop-strand’ and ‘mat’. Chop-strand has multidirectional strength, meaning it can take pressure from any direction and retain its integrity. Matt, on the other hand, is bi-directional, meaning its greatest strengths are in the direction of its weave. These cloths are available by ‘weight’, with the heavier weight being the thicker cloth, for example a 600 g mat is thick and will absorb a lot of resin but will be very strong and quite robust. Remember, the more layers you apply the less the final product will flex or bend. I have found that the 450 gram chop-strand is the best all-round cloth for our application of carrying out a few changes and repairs.
Working with fibreglass and resins:
Before you start, cut sufficient cloth to the shapes and sizes you’ll need for the job and lay them out in order for easy access. Make sure they fit correctly before moving on. Place your tin of resin, the hardener and bottle of acetone on a level working surface, along with containers, measures and sticks needed for your mix. Make sure the mix container is acetone proof or you’ll end up holding a dripping lump of goo. Now put on your disposable gloves.
First, you need to mix just enough resin for the job at hand. When you start out you’ll not be all that familiar with quantities required so it’s better to keep the tin of resin and a bottle of hardener handy to make a quick mix if need be. You’ll want to apply all the resin in one go, while it is in liquid form, it helps everything bind together much better. Stop the application if your resin mix starts to go like jelly, this is the resin starting to set. From here on it’s best to throw the remains away or it’ll become lumpy and messy, rather mix a fresh batch to continue.