To Paint or Not to Paint

Last week the builder of one of my boats asked me about painting the interior of his boat, what should he paint and what shouldnt he paint? I had not really thought of it before, that there are different thoughts about what to paint and why. Before I answer, I will tell you of my experiences on a wide range of boats, those built by me and those built by others.

On all of the big boats that I have built (they were all for my own use), people who visited the boats or sailed with us often commented about how fresh they were down below compared with their own boats or others on which they had sailed. I had observed this as well. There was never any diesel smell, never any dank, damp odour and never any need for air fresheners on my own boats. In contrast, many of the other boats were oppressive as soon as I went below, with some rather bad smells.

Most of these boats had been owner-built or owner-completed and they all had large areas of plywood that were unpainted, left as raw timber, under berths, in the bilges etc. My own boats had no exposed timber, not inside lockers, under cabin soles, inside the lazarette, under berths, not anywhere.

So, how does this make such a difference? A boat lives in a wet environment and most are closed up the majority of the time. When the sun is shining, the inside of a boat is much warmer than outside and that warm air soaks up moisture from any water that is in the bilge or elsewhere. Humidity builds up and creates an ideal atmosphere for mould to grow. Mould spores are in the air all around us and waiting to proliferate.

When the air cools in the evening the moisture is wrung out of the air again. It settles as condensation on hull, deck and joinery surfaces throughout the boat. It doesnt care whether they are exposed surfaces that you see whenever you are on the boat or hidden ones that you seldom see. The humidity is everywhere in the boat when it is hot, so condensation settles everywhere when it cools.

The unpainted wood surfaces absorb some of this moisture and hold onto it. It becomes that ideal environment for the mould spores to settle and grow. Once it starts, if left unchecked, the mould will spread throughout the boat and can also be the start of rot problems.

Mould inside the boat can be difficult to kill off. It needs to be killed everywhere and the surfaces must be thoroughly dried then sealed with epoxy or paint so that the cycle doesnt start again. It would have been so much easier to have just painted everywhere when the boat was being built. Sure, painting everything will have added a few weeks to the build time but it will have been worth the extra effort to save the hassles of the future.

The same principle applies to preventing diesel smells. Every big boat has a diesel or oil spill or two in its life.That liquid will soak into any raw timber that it contacts. Once into the surface it is impossible to remove and it will result in diesel or oil smells inside the boat for the rest of its life. If those surfaces had been painted then the problem would never have arisen.

So, what coatings should you use? All surfaces of the hull and deck skins, as well as all associated timber framing (stringers, backbone, beams, sheer clamps etc) must be protected by three coats of epoxy. This should include the perimeter of bulkheads against hull and deck but you may prefer to coat all bulkhead surfaces as well. The epoxy needs to be protected from the attack of UV (even below decks) so I recommend painting over the epoxy with a prime coat, followed by undercoat and finishing coat of paint.

Elsewhere, coat with primer, undercoat and finish coat. That means every timber surface, whether you will see it again or not. If it is a sealed compartment, e.g. inside a swim platform, dont leave it unpainted either. These sealed compartments must be coated inside with three coats of epoxy but you dont need to paint them.

Aside from mould, smell and rot prevention, there are other reasons to paint everywhere. 

• Painted surfaces are very easy to clean. You can throw a bucket of water in the bilge or a locker, swill it around and then pump it out, no harm done. Or you can wipe it down with a damp cloth or sponge rinsed in a bucket, very easy.
• Light-coloured paint reflects light, unlike raw timber that absorbs it. The painted compartments are bright and make it easier to find things that have gone astray. A fully painted lazarette is not a dungeon that swallows up tools and other things that will not be seen again until you build up the courage to dive into that dark place in search of lost treasures. That also applies to cabins in the ends of the boat, which are much more bright and habitable if painted in light colours. Clear-finished okoume plywood becomes quite dark, has uninteresting grain patterns and is not as attractive as you might imagine, not by a long way.

This problem is not limited to owner-built plywood boats either. I have seen this regularly when poking around inside boats displayed on boat shows in London, Annapolis and other places. Many production builders dont bother to protect the timber surfaces inside lockers, lazarettes, berths or the bilge. It costs them labour and materials to do so and it costs the owner down the line to sort it out or live with the results.

So, dont bother to argue with yourself over which surfaces to paint and which to leave raw, just get down to it and paint them all. You can thank yourself later when you reap the benefits.

Allied to this is the need for good ventilation. Strategically positioned ventilators will help to keep the air fresh inside your boat, removing excess moisture and making it a much more pleasant environment for people instead of mould.

Dudley Dix
Dudley Dix Yacht Design
http://dixdesign.com/

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Paint Day

Today the paint job is finally finished.  Well, there is still the roof to do with sand to make a grippy surface and some other sandy grippy bits, but the pray work is done.  I just hope the problem with the paint doesnt re-appear.

So here it is in pictures.

Masking yesterday magnolia

Slap some on here

Like this

And some here

And here

A few hours later all unmasked and shiny

A good couple of days work making a huge difference.  More photos when I can get on the bow deck without damaging it.

The paint has been piled on nice and thick.  Jerry said he had never put so much paint on anything.  The magnolia has nearly 3 litres and the blue including the rear already done has used 8 litres.  All that needs to be done now is a good mopping.  This will be done in due course.

I have deliberately used standard colours as they will be easy to source in the future from vertualy anywhere in any form and in any base material.

The magnolia is from the BS 4800 standard  BS 08 B 15 

The steel blue is form the RAL standard RAL 5011

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An Interesting Observation About Paint

For those of us who are obsessed with small boats it is almost impossible to avoid becoming aware of the complexities of painting. Unfortunately, I have the sort of personality which over-complicates everything, and the subject of painting and varnishing was a vicious trap just waiting for me to come blundering along.

It was all a lot easier when I didnt know what I was doing. As a child, and as a young man, all I had to worry about was opening the can, stirring until the lumps disappeared, tipping in a little turps until the brush stopped dragging and everything was sweet. I assumed that bristles came out of brushes, so therefore I didnt try to pull them out of the applied paint, and I didnt get angry or stressed.

I also assumed that paint stuck to everything, so I didnt get stressed about chemical bonding windows, sanding of shiny surfaces to get tooth, and matching primers, undercoats, and topcoats. In addition, nobody told me that I would be struck down by lightning if I painted directly from the can rather than decanting into a separate pot. Oh, life was much more simple in those days.

Unfortunately, experience, common-sense, an inquiring mind, and a genetic predisposition to over-complicate everything has thown me headlong into the paint and varnish trap. Trust me whan I say that I have a true love/hate relationship with paint, and to a lesser extent, varnish.

?

A nice job of painting and varnishing. The Phil Bolger-designed Harbinger we built back in 2003/2004. She was built strip-diagonal, with an inner layer of 7mm Western Red Cedar strip, followed by two diagonal layers of 3mm Hoop Pine.

I think Ill write a few more articles about the various paint systems that I think are appropriate to small craft which live on trailers, but at the moment I want to bust a specific myth.

Two days ago, my wife, dog Brandy, and I went away on a 24 hour holiday. Hitching on our little caravan and having loaded my old sailing-canoe on the roof-racks, we set off for a nearby lake and spent 24 hours reading, sailing, paddling, and walking. We tend to regard visits to nearby destinations as not being "proper" trips, but the fact is it makes sense to maximise the stay time and minimise the travelling time. In this case we had no option - nearby destination, or no trip.

Not bad for a holiday destination less than 15 miles from our house!

 The boat on the car is an Iain Oughterd-designed MacGregor Sailing Canoe which I built in 1991. She has been on a number of interesting and long journeys, but in recent years she has sat around gathering dust due to my workload.

Because of the simplicity of this short trip, I just spent my time fiddling around, and I took the opportunity to wash the canoe and remove many years of built-up storage dust and mildew.

Scrubbing the old boat in pleasant surroundings

The outside of the hull and the gunwales were showing significant deterioration in the paint film. This boat had originally been painted with a single-pack, oil-based enamel, but the outside of the hull and the gunwales had suffered physical damage during a period of heavy use. As a result of this damage, a few years ago I decided to sand back and repair the hull and gunwale surfaces, and after very careful surface preparation, paint them with an exceptionally high-quality single-pack oil-based polyurethane-modified enamel from a very well-known international paint company based in Europe. The inside of the canoe was OK, so I left the original paint in place.

I was very pleased with the high standard of the new paint job, but when loading the canoe for an outing less than a year after completing the re-painting, I was horrified to note the appearance of some very fine cracks in the paint film, presumably caused by checking of the plywood veneers beneath. The planking of the boat is 5mm Hoop Pine Marine Plywood made to AS/NZ2272, which is one of the most stringent plywood standards in the world, so I knew that there was no problem with the quality of the plywood. As the surface preparation was good and the paint was one of the best available, I just shrugged my shoulders and decided that single-pack oil-based enamels are not suitable over Hoop Pine and (from what I have heard from American and Canadian writers) Douglas Fir plywoods. The fine surface checking of these plywoods has no effect on them structurally, but it obviously cracks through oil-based enamel paint - something I have encountered many times before, I have to say.

Back to cleaning the sailing canoe. After finishing the outer surfaces of the hull and gunwale, and noting how badly the paint cracking had progressed, I rolled her over to continue cleaning on the inside.

Contemplating the interior of the sailing-canoe.

 

Suddenly, like a bolt out of the blue, I realised that my old sailing-canoe was being a teacher, but that I, as a student, was somewhat slow. As I scrubbed away at the inside of the hull using my big sponge and a couple of gallons of lake water, the cleaned paint showed not a single crack. The surface showed some signs of wear due to abrasion in places, but was essentially in perfect condition after twenty-one years of intermittent use. At the time I built the boat I didnt have enough spare money for a fancy marine paint, so I said nothing to anybody and went ahead using plain old oil-based house paint (Dulux Super Enamel from memory) over pink primer and oil-based house undercoat.

Difficult to see here, but the outside is in poor condition but the interior is nearly perfect

The point of this overly-long story is that books, magazines, internet forums, and group conversations frequently contain debates about the difference between "marine" paint and "house" paint. I hasten to add, that by "house" paint I am refering to oil-based single-pack house paint which I guess is based on an alkyd resin. 100% acrylic water-based house paints are another thing again, but arent what Im talking about here.

Some people say that the only difference between "marine" and "house" paint is the printing on the can. I disagree, as most of the marine single-packs that we have available to us in Australia are polyurethane-modified enamels, and they do have a very hard and shiny surface. Regardless of the chemistry, the arguements have continued for as long as I can remember with the conspiracy theorists saying all the paint is the same. By the same token, there are many people who throw their hands up in horror at the thought of using "house" paint on a boat, despite the fact that some towering authorities have said it is OK - the late John Gardner being one of them - surely a weighty recommendation.

Sailing after the wash. The sail is not as per the plans, being a sprit-boomed leg-o-mutton from a Bolger Nymph set on a yard and boom as a boomed lateen - I just cant stop rig experimentation. The mast is the one for the proper rig, which explains why it looks to be too long in this photo.

Ive been up, down and around the painting tree many times, but for twenty-one years an experiment had been conducting itself in my own back shed. My Macgregor sailing-canoe has delivered a verdict to me which says that house paint is fine to use on a small sailing, rowing, or paddling boat made from wood. In fact, in this application it had performed better than the marine paint. Now dont get me wrong - the marine paints are extremely good as long as they are used in an appropriate fashion. In fact my favourite single-pack polyurethane enamel is Norglass Weatherfast which is a marine paint, and my favourite non-polyurethane-modified paint is Hempel Multicoat which is also very much a specialist marine paint (which is self-priming and self-undercoating as well!)

A pleasant evening sail

Ive got plenty more to say about paint, including a discussion about the use of 100% acrylic water-based house paint (known as "latex paint" in the U.S. which is interesting because there is NO LATEX in water-based acrylic paint ). Im also about to start a series of experimental applications of WR-LPU (water-reducible linear polyurethane), which I first used back in the year 2000. From my past experience, this stuff is tricky to apply properly, but if done well over the correctly prepared surface, it is exceptionally tough, UV-resistant, and durable.

In the meantime, if you feel like using a house paint such as Dulux Super Enamel for example, go ahead without thinking you are committing a nautical sin. As long as you follow the instructions and carry out the correct surface preparation, you will get a good result.

Back to the 24-hour holiday - it was wonderful, providing benefits which will last much longer than the trip away.

The view from my bed in the van...........

.......and from my camp-chair at night.

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Doing A Doughnut In My Boat

You may recall I decided to make a Shilling rudder.

This short video shows what it can do.

Enjoy. Sorry about the reflection

It works as you can see and Im glad I went to the extra effort.

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