One of the great increasing mysteries of today’s modern boatbuilding is the amount of hi-tech gobble-de-gook that the average home boat builder is expected to wade through when the time comes to paint the boat after the horrendous amount of sanding, fairing and hard work is (mostly) over and the fruits of your labour now require a shiny deep lustre that the painting now promises to bring. This part, to my mind at least, is one of the best parts of boatbuilding, the finish! (Well, at least the start of the finish!)
Painting a boat used to be a reasonably simple task. All one needed was a fine dry day, one of Dad’s paintbrushes, some turps, a roll of masking tape, a bit of pink primer left over from the decorating and a half gallon of shiny blue enamel paint from the local hardware store…they were the days!
Not so today, my friends! The unsuspecting boat builder who toddles off to the local chandlery or superstore best be prepared for the very worst- not only will he (or she) face a huge financial onslaught on their wallet but a mind boggling array of hi-tech whiz wow balderdash that the (generally) uninformed shop assistant will proceed to throw in their general direction in the faint hope that you will give in under the stress and buy several litres of the latest polurethanicalslitheryaminomolecular goop that’s just come in. For example, you’ll be faced with trade names like ‘Interlux Interthane coating’. I mean, come on, it sounds like a new space invaders game! This is bloody paint! There are many others but I’m sure you get the gist of what I’m saying.
Another example of the kind of thing that drives me nuts is that you can expect to buy several litres of a iso-cyanate two pack marine polyurethane paint only to be cheerfully told its illegal to spray it unless you have a proper licenced premises to do so, drone drone!! I suppose they have to make up new names to go with the new paint company policies of charging up to $150 a litre for some of these new fangled paints! What the hell have they discovered that’s so expensive to put in this stuff? I was under the impression that paint was a few litres of linseed oil, turps, some drying agents and a few ounces of pigments for colour…can I really be so out of touch?
BACK TO BASICS
So, why do we paint wooden boats? Or any other boat for that matter? The first part of that question is easy. Boats look much smarter and better if they shine and gleam a bit… it’s only human nature after all. The second part to that question is: We want to protect it. Ok, from what? Well, wood rots if you don’t paint it, right? – wrong! Wood left to its own devices does not rot. Wood only rots as a result of its environment. There are multiple cases of how, plain untreated wood can last for centuries as long as it is in the correct environment. There are basically only a few elements that start wood rotting. Biological attack from spores, fungi, temperature, high humidity or total absorption, physical attack from marine borers and crustaceans that allow ingress to all the other elements aforementioned.
Don’t let’s forget that polluted waters can degrade timber to the point where it will rot….we’ll add chemical attack to that list too. So, in view of all these very compelling reasons we protect our boat by painting it to coat it fully against these assaults.
PREPARATION OF TIMBER
The actual preparation of timber can cover a range of differing requirements. If your boat is a new build you won’t have to go through many of the preparatory stages that an older boat may have to go through. With some forms of boatbuilding where a boat has been built by a different method such as strip planking or cold moulding, we paint the boat as if it were a fibreglass boat, due to the fact that either layers of fibreglass cover the timber or that the timber has been coated with epoxy that does not allow conventional paints to adhere to it properly. However, if we wish to protect bare timber then we use a different tack. Timber in its bare natural state has millions of thin hollow tubes running through it, constructed of cellulose in its natural form. We have to seal these tubes to prevent the ingress of water into them. Therefore we seal and coat the timber first of all.
The first thing we do is to clean and remove any loose and flaking or damaged paint plus any dirt that remains on the hull – sounds easy if you say it quick but it must be done! If necessary (and most times it is) degrease the hull using a proprietary paint degreaser after removing all dust preferably with a vacuum cleaner. Don’t forget it won’t be absolutely necessary to get all the hull back to bare wood just dry, clean, grease and dust free.
FILLING AND IMPERFECTIONS
Obviously, not many timber craft are perfect on the outside. There are many blemishes, cracks, imperfections and splits both large and small to deal with by filling them and sanding them flush before priming the boat. It’s a bit of a chore but time spent here will reward you with a boat that will certainly look better plus have a longer life. Some folks fill these holes and imperfections in timber with epoxy filler but it is not a good idea. Sometime later, for example, when the boat has to undergo a repair, it will be the very devil of a job to remove the epoxy from a fastening hole. It’s best to use some kind of proper timber filler that dries hard and fast but is never that hard that it can’t be removed later on. For example, painter’s glazing compound is a fairly hard setting soft paste that can be quickly applied then sanded and painted satisfactorily. Carvel boats usually have their seams filled fair with a special seam compound AFTER the boat has been primed. Once the boat has been filled and faired smooth and all dust removed we are ready to put some actual paint on. Remember, the difference between a professional paint job and an amateur is the PREPARATION!
There are two schools of thought about treating bare timber with wood preservatives. I’ve heard stories that primers and paints don’t adhere to many of them. In my case, I have never personally had that happen to me, so I am generally in favour of using them. Nevertheless, I am convinced that in many cases where the paint refuses to stick to timber is because the wood has not properly dried out after application. There is a definite percentage of humidity level that every timber has (and most of them differ slightly) where paint of any description simply won’t stick. It can be up to fifteen per cent in some timbers. Above all, ensure that your timber is dry enough to allow any paint or filler to adhere to it. Remember too that salt deposits on timber will readily contain water and keep it damp…. if your boat was in salty water wash it off in fresh before commencing painting. When and only when, your timber preservative is dry the next stage is:
The first coat of primer to go onto your hull is metallic grey primer. It is a good primer to use because it is made up of millions of microscopic flat metal (aluminium) plates that lie on top of each other giving water a very hard time to pass though it…Pink primer for example, has circular molecules of substances therefore allowing water to ingress a lot quicker…fact! Grey primers also contain certain oils and most have anti-mould agents contained within (biocides to you and I) We put two coats of grey primer above the waterline and three, no less, below it.