Daniel Hobbs, is the Director and Manager of Classic Yacht Shipwrights S.L. based in Palma, Mallorca since 2003.

Since serving his apprenticeship with a reputable yacht builder and refit Company on the South coast of England, Daniel has been involved with numerous teak deck projects; he has gained a wealth of experience from replacing, repairing and fitting new teak decks.  He now feels it time that this knowledge be put to good use in creating a teak deck care guide, to enable owners captain and crew first hand information into not only what is involved in laying a deck, but more importantly how to best care for it once laid.  

Working at the sharp end, Daniel has seen first hand that many teak decks only ever achieve half their realistic life expectancy due to poor workmanship during construction and/or over zealous / enthusiastic crew, scrubbing the life out of them or attempting to maintain their original colour using chemicals.  Sadly, this process not only damages the deck, but also has a serious negative impact on the environment.

The following information contains tried and tested ideas, practiced over the last 8 years.…

Why teak and why so many black lines? (caulking)

Teak decks were originally an integral part of the boat’s construction.  Before the days of plywood, modern glues and adhesives or solid sub decks, the teak planks were laid in the way we see today, but on top of open deck beams.  Before the black caulking (which was pitch or tar back then) the planks were caulked using boat cotton or oakum. The planks were individually caulked. The caulking was introduced into the seams with caulking irons and the caulking would then be knocked hard into the seams.  This had the effect of making the whole deck very stiff and solid, thus adding to the overall solid, watertight construction of the boat. The black pitch or tar was then poured on top of the caulked seam to give an additional watertight seal. There are many planks in a deck and this is because to bend a larger board around the sheer without it breaking was just not possible.

These days, teak deck planks are normally laid onto a solid sub deck. They serve as being one of the best nonslip surfaces available (wet or dry).  This aspect, coupled with its natural aesthetic beauty visually, means that just about every yacht over 15 metres has a teak deck.

Are they worth it?

Can you imagine your yacht without a teak deck?  No probably not!  This probably doesn’t help when you decide to, or your Captain tells you that you need to replace it.  

Why are Teak decks so expensive?

Here is brief over view of the process:-

You take a teak tree that has been growing in a tropical rain forest for the last 40-50 years (the best wood comes from the older trees). The tree (along with various others) is felled and dragged to a lumberyard.

In the yard, the trunks are categorised into their apparent quality.  At this point, it comes down to the experience of the guys selecting.  There is no way of knowing whether the grain is tight, straight, knot free and will yield long lengths.

Next the trunk will be converted.  The best teak decking is gained by quarter sawing the trunk (this just happens to be the most wasteful way to convert the trunk).  Each cut turns more then 3mm of the trunk into dust.

Fig 1.  One way of getting quarter saw teak planks

The best teak plank is when the grain runs up and down over the thickness of the plank as in

Fig 2 Quarter sawn plank showing grain running up and down the plank this is the best teak for a deck.

Fig 2. The ideal grain for a teak deck

Once each trunk has been converted into planks, the teak then needs to be seasoned.  Air dry seasoning when stacked properly can take anywhere from 1 – 2 years, depending on location.  To use the teak with any of the modern adhesives, it needs to have a maximum moisture content of 12%.

These days, almost all of the teak decking used will be kiln dried.  The teak is stacked with sticks between each plank, and then placed in a large kiln building where the temperature and humidity is raised close to 80ºc and 100% humidity.  Over the next 48-72 hours, the humidity is slowly lowered down to the recommended 12% which in turn draws out the moisture within the wood.  This process alone uses massive amounts of heat and energy.

Once completed, the teak is then ready for the shipwrights to start laying the new deck on a very high quality deck.  No knots will be permitted, grain run out must be minimal (see figs 3 and 4)

Fig 3. Grain Run out              

Fig 4. Knots

The labour involved with laying a teak deck is huge.  Obviously, on book motor yachts where there are big areas of square straight laid decks, it is fairly straightforward.  But take a modern sailing yacht with winches, hatches, masts, sweep of the deck, long planks, margin boards, there is a lot to think about and everything needs to be symmetrical and pleasing to the eye.

Once the teak is laid with its 4-5mm seam, each and every seam needs to be cleaned out, all butts and snaips cut to size, ready to receive the primer and caulking.

Only after the caulking has had at least one week to cure, can the deck be sanded back to the finished product. This is to allow the caulking to cure completely, during the curing process of the modern caulking products a small amount of shrinkage occurs. If insufficient time is given for the curing and is sanded earlier, the caulking continues to cure and this shows up as a slight concave on the surface of the new deck. This also puts extra stress on the bond between the wood and the caulking.

Deck care

Everyone loves a freshly sanded deck!  They look great, but the reality is that within 6 – 8 weeks (less time with plenty of salt water and sun), the teak patinas down to the grey/white colour we are used to.

A well laid teak deck should last at least 20 years minimum.  It all comes down to the way it is looked after.  The quickest way to ruin your deck is to pressure wash it.  Second on the list is hard bristle brushes and scrubbing.  Third is acid deck washing which is normally done with a hard bristle brush.  If done regularly, you will be lucky to see 3 – 4 years life out of the deck.

The reason being, teak is a natural product and has grain.  In the spring and summer seasons (or wet season), the tree grows faster, the cells in the wood are full of water, moving up to supply the rest of the tree with the nutrients required to photosynthesis

Later in the winter season (Dry season) the tree’s growth slows down and this is when the hard grain is produced.

Back on board your boat, you or your crew are busy scrubbing the deck to bring it back nice and clean, seeing all the dirty brown water wash over the side is quite satisfying.  Later when the deck is dry you see the results of your work.  It looks great, yes, but what you have actually done is scrubbed away a layer of the soft fast growing wood in the teak.  The dirty water was full of wood pulp, not dirt.

Many people use acid to clean their decks.  This just exacerbates the problem.  Acid washing the deck not only makes the soft pulp of the teak wear off faster, it also breaks down the UV inhibitors of the caulking.  The caulking starts to break down under sunlight, leaving sticky black marks on hands, feet and clothes.  Another problem with acid washing, aside from the environmental impact is it also affects the bond between the teak and the caulking.  When this bond fails, water can travel down to the sub deck.  If this happens, and the sub deck is steel or aluminium, you can start to get corrosion problems.  This in turn can lead, potentially, to removal of the teak, as this is the only way to rectify the problem.  This is why it is so important that the sub deck and the teak are bonded together well, without voids.  Sometimes an aluminium or steel deck is first covered with a marine plywood sub deck to which the teak is bonded.

An aluminium or steel deck is difficult to lay perfectly flat, due to the heat when welding so it is not unusual to have a plywood sub deck laid first which can be faired smooth and then the teak is laid on top.  It is very important that when the plywood or the teak is laid, that there are no voids.  If there are voids, the water will find them and that is when the corrosion starts.  

Laying a teak deck is no mean task and the decision to replace one should not be taken lightly.  When the decision has been made to undertake this work, each stage, from the first laying of the sub deck to the last teak plank, the last run of caulking, each stage needs to be overseen with a keen eye on the quality.  After all, it is not just the money, it is the environmental impact, when you consider that it takes approximately 10 – 12 teak tree trunks to lay a deck on a 40M yacht.

Deck Care

If you want your deck looking like it’s always just been freshly sanded, then you should seriously consider one of the products available, which seal the wood.  This process needs to be done regularly but it does save a lot of wear from the constant scrubbing.

Teak deck care is simple.  Never use a pressure washer, hard brushes or Acid washes.  Just a light brush across the grain with a soft soapy brush or a soft scotch pad is sufficient to remove any dirt just as you would on your paintwork.  

Fresh water is the enemy of teak. If you find that during the winter for example, you notice mould or mildew growing, making the teak look dirty, after a wash down (and whilst the deck is still wet) sprinkle salt all over the teak and lightly brush it in.  Leave in the sun for a few days or even a week and then wash it off.  You will be surprised how clean and white the deck then looks.

If you notice persistent wet areas on deck after a wash down, don’t just ignore it, they are a sign of problems.  Normally it’s along the seam that a damp area will persist, but upon closer inspection it could be that the rubber bond to the teak has failed and the water is entering and sitting in the split.  This water will eventually work its way down to the sub deck. If you have various wet spots like I’ve described, get them repaired soon. Or at least get a professional to have a look. Perhaps you need a re-caulk? It’s better replacing the caulking then waiting a year or two and then having to replace the whole deck, especially if the sub deck is aluminium or steel.

Every two years I would recommend giving the deck a light sand with a fine grade paper this works far better than giving the deck a hard scrub.  You maintain the caulking at the same level as the teak, the deck is left smooth, there for the mooring lines or sheets don’t pick up and rip out any splinters. An over scrubbed deck is uncomfortable to walk on as the caulking remains proud and is very grainy.

This article is intended to be informative to owners and useful to captains and crew alike. The introduction and the section explaining how the wood is processed ready for decking, then the laying of the teak is very brief, there are many ways and techniques employed by the shipwrights and boat builders around the world and all have there merits, my intention in this article is to explain that teak decking is a very costly (financially and environmental) luxury, there fore should be done to a very high standard to get the maximum life out of them.

Should you wish to add information to this article so that ultimately teak decks (and teak trees) get better care, please feel free to contact me with your thoughts and ideas so that they can be passed on to the yachting industry in general. My email address is daniel@cys-sl.eu

By Daniel J Hobbs

Classic Yacht shipwrights S.L.