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.

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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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Expensive but somewhat interesting

A little needful reading, on tragedy being good for profits, and in the "it doesnt have to be the way it is" department...

So, Jimmy bought a new boat.

Not exactly the same old same...


Listening to some Toadies

So it goes...

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Spiling Lapstrake Planks Interesting Shapes

You often hear designers describing the "lay" of planks. What does this mean? Well, depending on the form of a boats hull, and the way in which the planking has been lined-off (another subject in itself), the shape of the individual planks when they are being marked out on the bench can be quite remarkable.

Here is an extreme example - the photo sequence shows the development of the sheer strake (top plank) of one of the Bolger Hope designs which we built. The boat is quite wide for her length, and she has extreme flare in the forward sections. Phil Bolger told me that the lapstrake planking might be a bit difficult up there, and he was correct (as always).
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Here you can see the temporary battens I used when carrying out the lining-off process. After establishing what I thought was a fair run of planking, tick marks were transferred to the molds and the battens were removed.

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Here you can see my son, Dave, marking the shape of the sheer strake onto the plywood planking material. He is tracing around the spiling batten which we had fabricated to lift the plank shape from the boat

This photo shows just how severe the shape of the plank appears when laid out on the flat. But after being bent around the complex shape of the hull, everything looks normal. In the photo, the end closest to the camera is the bow end of the plank.

With the planking complete, you can see that the strange and twisted shape of the plank pattern resulted in a nice, fair plank line on the finished hull.

This picture shows another extreme. These are the topside plank patterns for an Eve 16 - a boat which has very little twist and concavity in here sections. You can see that the plank patterns are all very similar, with subtle shaping. 

This is the planked hull of the Eve 16 - the bottom was laid up with glued-strip planking

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More Interesting Work from the Workshop circa 2004

Around 2004 we were building at least six boats at one time in the old workshop - with only three-and-a-half people on the job. It was a hectic time, and looking back on it, we did some creative stuff. At one point a customer decided that his outboard-powered boat (a Phil Bolger Hope which we were building with a lapstrake hull and a small cuddy cabin) would be better as a diesel in-board, even though she was nearly finished in the outboard configuration.. I quickly designed an inovative skeg arrangement, and we carried out substantial structural modifications to accept the Yanmar 1GM10 deisel.

The nature of the retro-fitted keel/skeg was such that I thought it needed extra support against side loads and so I made a pattern for a cast bronze propeller shaft strut which had an inverted "V" on the upper side of the bearing. Not an original thought, but my first attempt at pattern making, which had been made necessary by the extreme urgency of the situation. The foundryman was a marine specialist (Marine Castings and Manufacturing - still in business) and was (to my surprise) happy with the pattern. Not only did he cast the prop strut, but he cast and machined the propeller, and the water-injected dripless-seal. Everything worked!

Propeller and strut, loose fitted without the proper pads etc - but still looking good

12" x 10" propeller from memory.

Custom-made dripless-seal

Boat on launching night - secret launching before the official one to come the next day!

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Me, looking very relieved after the owner had gone home from the secret launching. Now I could get back to business on the details (and have a quiet beer, I think)

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Launching Day (Official) for the in-board boat

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The outboard boat awaiting the owners arrival for the final inspection.

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