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fit and vent a fuel tank

John de Frayssinet (editor of Yachting Life)

In this age of plastics, it is gratifying to see such an abundant use of wood on many modern craft. While the price of glass fibre resin continues to rise, the cost of prime hardwood rises more so.

The cost of building a boat using teak or oak frames has become virtually prohibitive. And yet, only a small proportion of hardwood types have ever been used by the industry. Many species of hardwood still remain un-felled and their properties unknown. The reason for this is simple enough. The boatbuilder has for a long time had available to him a large choice of timber, all with well known characteristics. These timbers have stood the test of time, and it would be foolhardy for the builder or new owner to experiment with some new type of wood when building a yacht which is expected to remain sound for many years.

The construction of a wooden boat encompasses many timber requirements. The hull planking must be easily bent, and be resistant to water and borers, Frames must have much greater rigidity and mechanical strength. Exterior trims must be able to be finished attractively but be resistant to water, while interior woodwork must be capable of working to a fine finish.

The greatest problem these days is to find any wood at all that has been well seasoned. Very few boatyards carry large stocks of hardwood, air dried for many years, and even fewer are prepared to sell any quantity to outside buyers. Unseasoned timber is quite useless for boatbuilding. While seasoning takes place, wood undergoes contraction, as the moisture content is gradually reduced. If this contraction continues once the wood is in place on the boat, warping and opening of joints is inevitable. A lot of timber is now kiln dried and the moisture content driven down to an acceptable level. However, the quality of this wood is without a doubt reduced, and movement occurs much more readily in different moisture conditions. It is not always easy for the amateur to distinguish well seasoned timber, and often he must take the word of his supplier as gospel.

For many years, I fondly imagined Mahogany and Teak trees proudly growing in some South American or African forest In fact, many of the timber names used by the trade only describe a type of wood. As supplies become limited, different species can be marketed under familiar names, provided they closely resemble the original specification. However, in recent years the disparity has enlarged.

Most mortals these days are only interested in buying timber for trims. Rightly or wrongly we still think that a boat only becomes boaty when there is a reasonable amount of nice timber embellishing the otherwise clinical glass fibre. As the cubic footage involved is usually small it is still possible to use choice timber. The use of marine plies has reduced our requirements even further.

When a large area of timber is required, plywood, correctly used is preferable to solid wood as it does not suffer from any discernable expansion and contraction Also, its use in bulkheads is advisable as a laminated timber has a much higher strength to weight ratio.

The greatest expense in boat-building is labour, so if at all possible, it is well worth spending a little extra money on the right choice of wood and save a lot of trouble later on.

TEAK

Without any doubt teak is the prime timber for most aspects of boat construction. The high resin content makes the wood feel like a lump of lard, It is almost totally resistant to seawater and a yacht built in this material will outlive all of us. The resin content does make it difficult to varnish and glue together. Exterior bright work has a tendency to be sloughed off unless early varnish coats are very well thinned and the wood degreased. Conventional waterproof glues are unreliable, sometimes even after degreasing with carbon-tetrachloride. A resorcinol glue should be always used. However, these are dark brown or red in colour and often begin to show through joints after a year or so.


teak interior of a Nicholson 45 refitted by the author ('Jealousy' ex Yeoman 18)

Teak is without doubt best for all exterior woodwork. Unless you are keen on playing around with varnish it is quite unnecessary to seal it. Left to weather in salt water, the wood gradually becomes white in colour. Items such as rubbing strakes and toe rails are certainly best left in bare teak, as constant abrasion will ruin the varnish anyway.

Under no circumstance should exterior teak ever be oiled. This produces an excellent medium for fungal growth, which while it will not attack the wood will leave it a foul black colour in damp climates.

For all our latest super non- slip paints, a teak deck, for those who can afford it, still gives by far the best service and looks absolutely wonderful. When constant abrasion is expected on unsealed teak, it is important to buy rift­sawn timber, otherwise the softer grain will be worn away.

Many yachts are also finished inside with teak. The colour is attractive, but generally, with solid timber, there is little attractive grain.

I prefer working with teak to any other wood. It is straight grained and very rarely plays nasty tricks on you like splitting. Being quite soft it is easy to work but as a tendency to blunt power tools. The dust is laden with resin and does not therefore fly around and get up your nose.

IROKO

This is now used as a substitute for both oak and teak. Its colour is similar to teak but the grain is much more prominent and difficult to finish to a smooth surface. It is almost as hard as oak and approaches the rigidity of that wood. Many yachts these days are framed and planked with Iroko. While good service can be expected, it is necessary to keep the wood well painted. Iroko is not an easy timber to work, being very hard and brittle but with a lot of care excellent results can be achieved.

MAHOGANY

This is easily distinguishable by its rich red colour and attractive grain. Again this is a wood that must be very well protected. Many yachts are planked with mahogany but generally speaking, they will have a shorter life unless really well cared for. I know of nothing more attractive than a varnished mahogany carvel hull, but so much work is involved in maintaining it. If water is allowed to enter under the sealer a very nasty black stain occurs which is very difficult to remove.

Some types of mahogany now being sold are very much harder. In some cases it is almost impossible to put a screw into it, so care must be taken in its selection. The attractive grain makes working difficult. Planing a cross-grained plank can be soul destroying.

 


the glory of traditional mahogany (saloon of 'Lelantina')

 

AFROMOSIA

This is very similar to mahogany but has a straighter grain and is slightly less red in colour. The dust from sanding can be extremely unpleasant and is actually dangerous.

CEDAR


interior of 'She Too' under refit

A soft wood but one which is extremely resistant to seawater. Some racing boats have been built in this timber as it is extremely light and fairly strong. However, under normal circumstances I would not recommend its use except where little abrasion can be expected, as it is very soft. When varnished the appearance is very similar to teak. The photo is of a 1/2 ton yacht finished in cedar still under construction.

As with most softwoods of good quality, cedar is easy to work and is very straight grained.

 

PINE

This must always be well protected but can be a suitable timber for planking, although I personally would never use it. One or two boat yards have used pine as an interior timber to great effect. It makes a very nice change to the more conventional darker woods. If knot-free timber can be obtained it is quite easy to work.

BRAZILIAN TEAK

This is one of the more recent timbers gaining preference in boatbuilding. It carries many of the properties of teak but does not contain such a high resin content. It is lighter but stronger and very much harder and is reputed to be highly resistant to rot and marine borers.

OBECHI

This wood is more commonly known to modellers but can be used effectively as a laminated timber for deck beams. It has a very high strength to weight ratio but is prone to rot.

ASH

This is a very strong timber which will allow a high degree of flexibility and was used in early aircraft as structure. However, upon exposure to water it becomes ‘sleepy’ and loses much of its strength. It is, however, ideal for sail battens and is a lovely straight grained timber to work.

DEAL

While this is the most readily available timber and is used widely by the building and joining industry I can think of few more unsuitable woods to put in any boat. Much of it is totally unseasoned and even better examples are poor in strength and durability. Perhaps one could use it for hidden battens but I would have to be very short of money to contemplate it.

If totally encapsulated in GRP it can be used for floor bearers

BALSA WOOD

Believe it or not this is in fact a hardwood and some parts of the tree have a high strength to weight ratio and are quite resistant to rot. The most common use for this timber is as end grain sheets to produce a glass fibre sandwich. When used in this way it produces a very rigid structure that is low in weight.

PLY

Many other types of timber can be used mostly for decorative purposes below decks. At one time, Swan yachts made extensive use of Koto wood, giving a very attractive light finish. Should you decide to try a less conventional timber, by all means do, after you have taken advice from an experienced shipwright.

Plywood is now used extensively and again care must be taken that it is marked as marine ply. It is possible to use exterior grades but I would doubt that this is wise in the long run. Teak faced ply is now a crazy price. Many manufacturers use such a thin veneer that I am very reluctant to use it. Unlike solid teak, it is inadvisable to use teak face ply outside without varnishing, as much of the protective resin is removed during manufacture.

Marine ply is found in craft large and small and can be the basis of complete construction.