Keeping up Appearances - Part Six

Of all the things that enhance a modern fibreglass cruiser, nothing approaches the beauty of a well-laid teak deck that provides a warm, timber contrast to the polished mouldings.

As these articles are about maintaining the appearance of your boat, I thought that this month we would look at teak decks and how they are laid. The decision to fit this option to your boat is generally made before the vessel is manufactured. However, after-market fitting is not only possible but is done quite often.

THE RIGHT SHIPWRIGHT
If you are contemplating this course of action, be careful when selecting a shipwright to do the job. Laying teak decks is not the most difficult job in the world; however, like most things, there are tricks to make the work go smoothly.

If the shipwright doing your job hasn't laid a deck before, then these tricks will have to be learned, and you will, in effect, be paying for "on the job training". The end result will probably contain mistakes the shipwright will never make again, because of lessons learnt on the job. This, however, is cold comfort to you, as your eye will be drawn to those errors like a magnet. So always ask to see an example of a shipwright's work beforehand.

Teak decks are expensive; their installation involves a lot of labour and frightening amounts of costly materials, so this is a time to take care. At the time of writing, an average deck will cost around $800 per square metre, plus GST. With these sort of numbers, you definitely don't want any stuff-ups.

The most important thing to consider about a deck is the quality of the timber used and the way in which it is sawn from the log in the first place. Quite a few timbers are suitable for decks - oregon and beech are often seen - but teak is by far the most common. Being a hardwood, it is very durable and as a rule of thumb outlasts a beech deck by a factor of two.

Quarter-sawn timber is the best, as the grain in the board runs parallel to the edge. This means the board won't have a tendency to "cup". Cupping of the boards only becomes apparent after the deck has been down for a while, so it's important that only the best timber is used. The moisture content of the wood shouldn't exceed 12%; in other words, the wood should be well-seasoned to prevent shrinkage after laying.

Also, take the thickness of the timber into account. Generally, timber merchants machine the boards to a thickness of 12mm, which is adequate for most decks. However, extra thickness greatly increases the life of the deck, as there is more of the board to wear away. The downside to this is that it's harder to curve the plank to the shape of the deck, and shaped planks are what make the job look so appealing.

The board can be any width, but the most common used today is between 42mm and 48mm, with a 5mm x 6mm rebate machined down one side. This rebate is filled with a polyurethane sealant at the end of the job - but more on that later.

SCREWS OR STAPLES?
The boards are usually screwed down with stainless-steel screws every 300mm or so. The screw is almost always countersunk into the timber to a depth of 8mm, using a spade bit. These type of wood drills leave an accurate hole and cut the timber very cleanly.

After the screw has been driven through the plank and into the deck below, the counter-bored hole is filled with a timber plug that is cut from a piece of scrap. These plugs are made with a small tool called a plug cutter and are available from most leading hardware stores.

A word to the wise here: if the spade bit you are using is metric, then the plug cutter will have to be the same size in metric - and these are not all that common. If you have a 3/8in plug cutter, make sure that you use a 3/8in spade bit, not the 10mm equivalent, as this will result in an over-sized hole in which the plug will rattle around. Before too long the plugs will start to pop from the plank, and that lovely teak deck will become a burden instead of the delight it was intended to be.

Another, less common, method of installing a teak deck is to use staples. In this system, a stainless or bronze staple is fired through the rebate to fasten the plank to the deck. Sealant then covers this staple, resulting in a deck without visible fastenings (plugs). If there is a lot of curve in the deck, this system is more difficult to apply, as the staple is seldom strong enough to hold the board against the tension of the timber. When this happens, it is best to use the screw and plug method.

Another clever arrangement that conceals fastenings is to staple through the middle of the plank, after first placing a thin piece of plywood over the board. This allows a stronger fixing of the timber, as it's fastened through its centre rather than its edge as in the previous method described. Remove the staples when the glue has cured; the tiny holes that are left are almost invisible to the eye.

Both staple systems offer savings in labour and material, and they are ideally suited to thin boards without much curve in them. The downside is that the whole deck relies primarily on the integrity of the glue, and if this ever lets go, then big, expensive repairs are the order of the day. Aren't you glad you bought a boat?

Any well-laid teak deck will need to be bedded into a thick film of epoxy glue, as well as fastened down with screws or staples or whatever. This is because timber used on a boat's deck is being asked to withstand extremely demanding climatic conditions. The sun, for instance, sometimes blazes down on the deck with such ferocity that it will become too hot to walk on.

Traditionally, teak is left to weather, which means that protective paints and sealers can't be used, and it is only due to the nobility of the timber that it manages to maintain its integrity. Because timber is generally laid on a fibreglass deck, and the expansion rates are different, it is imperative that no movement between the two takes place. Hence, bedding in epoxy makes sense, because no other glue bonds timber like epoxy. Unfortunately, no other glue costs as much, but here is not the time to skimp.

If the glue is skimped on - and it costs so much the temptation is there, believe me - the whole job could be ruined and delamination of the deck could result. If this happens, then often the only remedy is to remove the whole deck and start again. Which just doesn't bear thinking about.

Not everyone recommends epoxy glue as the bed, as there are some flexible urethane bedding materials available that have a lot to recommend them. But for my money, give me the epoxy every time.

Fibreglass boats don't always have fibreglass decks. Plywood decks and superstructure are more common than you might imagine, particularly if the boat is a one-off or was manufactured in Asia.

In either case, the preparation to lay the planks must be thorough and particular. In the case of fibreglass, the moulding is often a raised diamond pattern to provide a non-slip surface. This must be completely ground off using a small grinder. For making a mess, this job is hard to beat. An assistant with a vacuum cleaner will help a lot.

If the deck is plywood, carefully inspect it for any signs of damage or rot and repair it if necessary. Coating the plywood with dynel cloth and resin before laying the planks is a good idea. The most important thing is that if the deck is not in absolutely first-class condition, then laying planks over the top of it will be a waste of time and money.

ASSEMBLING THE JIGSAW PUZZLE
The shipwright laying out the job generally does everything possible to avoid inserting a split plank. The initial setting out allows quite a bit of latitude, as edge boards are generally used against cabin houses and at the outer edges of the deck. These boards can be any width the shipwright likes and are scribed and sawn to accommodate the curve of the vessel. By juggling the dimensions of these edge boards, it's usually possible to come up with an even and pleasing lay pattern.

It would be impossible to describe here all the permutations that can be achieved when laying down the planks - shipwrights have favourite methods, which often become their signature on the finished product.

Truly artistic decks are seldom seen on production boats for obvious reasons, not the least being cost. By far the finest workmanship I have encountered has always been commissioned by a wealthy owner who simply wanted the best and was prepared to pay for it.

After the planks have been glued and screwed down, plugs are inserted into the screw holes, again using epoxy glue to make sure they will not "pop" after time. True artists make sure the grain in the plug aligns with the grain in the plank; I guess it depends on just how fussy you are. When the glue has cured, the whole deck is sanded to achieve a smooth, even surface. This also brings all the plugs down to the same level as the plank.

Finally, the deck is cleaned in the most thorough manner possible, preferably with a high-powered industrial vacuum cleaner. If high-pressure air is used to remove debris from the grooves, make sure that an oil trap is fitted into the line as minute droplets of oil will seriously affect the quality of the next operation, which is the application of urethane sealant into the rebates of the boards.

I personally recommend the Sika range of products, as I have always had success when using them. Sika also produces a marvellous Application Guide, a 70-page colour book describing in detail the correct use of their marine-grade products. (It's imperative that you read and follow the manufacturer's instructions.)

Complete cleaning and priming of the rebates are essential to prevent the sealant from losing its adhesion over time, which leads to it releasing from the joint. After the application and tooling of the sealant, protect the deck and allow it to cure for around a week. At this point, all the excess sealant is removed using a sharp chisel or knife before being sanded with a belt sander or something similar.

Now is the time that the true beauty of the deck is revealed, and all the pain of the mess and noise of the past few weeks is forgotten. I have often thought that boats are among the most beautiful things that man has created, and certainly a well-laid teak deck will elicit admiring glances from just about anyone, whether they're interested in boating or not.

As always, there is a serpent in paradise, for teak decks must be maintained, possibly repaired, and sometimes simply removed - which is similar to filling in the swimming pool, I guess. All these exciting, time-consuming and expensive subjects will be considered when I next reach for my pen.