Having spent all my life around wood and woodworking machinery I can remember 45 years ago my father complaining about the current price of timber and bemoaning the fact that it used to be so much cheaper. Well nothing has changed, if I look at the price now compared to 5 years ago, when I bought for my previous build, the price seems to have risen and the quality gone down. Many times I have stood in front of the timber section of the local DIY supermarket desperately trying to find a strait piece of timber amongst all the banana shaped pieces. Certainly the lumber you use for a boat should be free from defects and stable, this will usually mean that you will pay a premium price and you will probably need to go to a wood yard not the local DIY superstores, which in the UK tend to only sell poor quality pine.
Even with the assurance of standards we all get caught out now and again, so if the wood you buy turns out to be expensive firewood don’t whatever you do use it on the boat you intend to spend the next three years building. For the skin of my build I decided to use BS1088 Gaboon ply at a cost of £68 per sheet for 1/2”. Rather expensive but having tried the alternative and had it fall apart as I was cutting it makes it difficult to trust just the BS1088 standards mark without some pedigree behind it. Those sheets cost £25 each, I was told it was Asian but when the invoice came it said Chinese so I guess it was my own fault as I should have known better (I did get a full refund on the two sheets and got to keep them for pattern making for the trailer). The two photographs show the quality or should I say lack of it.
This is the expensive point in your build where you begin to have doubts and ask: have I got the right plans? - have I got the right tools? - am I sure of my abilities and the time it will take? It takes a lot of confidence to start shelling out serious amounts of cash on very expensive lumber and plywood. I try to work on the principle that 100 miles offshore in a gale is not the time to be considering “should I have bought marine ply to BS1088 standard instead of the exterior shuttering ply I am now standing on”. That’s all very well I hear you say but I don’t intend to be out in those conditions! Well neither do I, but if I buy good quality materials at least I can be sure of the boat, if not the weather.
You can save on the cost of timber if you are willing to do the sizing and smoothing work yourself, I wouldn’t recommend this be done with hand tools on a larger size boat as it will add extra time to your build. For a ready supplied kit boat, or timber cut and planed to size, there is a substantial premium in the time taken to prepare the wood and hence the cost. Buying rough sawn planks and ripping them to size and smoothing them yourself will usually save about half the cost of prepared timber (UK prices). Having spent most of my tool budget on a new table saw, I found that I could not afford the planer/thicknesser to go with it, and so am reduced to doing the job by hand. I can assure you it is very hard work removing the inevitable twists and smoothing bandsaw blade marks from white oak.
Having got the preliminaries out of the way, lets look at what timber is and some specifics. You probably know all about this, if so skip this paragraph. I just included it to make sure we are all at the same level of understanding. What is it? Well it is a plant material made from a mixture of compounds, mainly lignin and cellulose which combine to give a very stiff substance, don’t bother looking at the chemistry of it, its awfully complicated and won’t help you build a boat. The tree trunk has three distinct areas; heartwood in the centre; sapwood round the heartwood; and bark on the outside. In boatbuilding we don’t use the bark (except for a Canadian birch bark canoe) and apart from decorative effects or use as a garden mulch, the bark is not of much use elsewhere. The sapwood is the live part of the tree that transports water and nutrients (sap as the name suggests), again not much use in boat building as it tends to be less stable and softer than the heartwood due to its higher liquid content. Yep you guessed it, its the heartwood that we need to build a boat, this is old, dead, sapwood that has hardened due to the tree depositing its waste products here, it is also these waste products containing toxins that inhibit rot and deter insects sometimes for a considerable length of time and sometimes not so long, depending on the type of tree. The beauty of this natural system of growth is the fact that it consists of long tubes of tiny diameter tightly packed together, which can have great strength along the grain and can hold fixings very well. Don’t put screws or nails into end grain if you can help it as they don’t tend to hold well and can easily split the wood, but fixings and joints may be a good topic for another time.
The best wood to use will usually be specified by the boat designer, don’t slavishly adhere to this requirement as it could be that was his local timber or what he had to hand, but for you to purchase it may be prohibitively expensive. Any timber of equivalent strength that has been successfully used for a number of years on boats in your local area will usually be fine.
For my build I am using white oak. The plans specify this or Honduras mahogany (like I could afford mahogany, but the plans were drawn at a time when this was a viable alternative). I guess world resources are being used up fast, even the renewable ones. It will take a substantial time for young Honduras Mahogany trees to grow, with the speed we are using up the mature ones and the competition for land use from an increasing population this leaves us with a shortfall. I recall my neighbour telling me of watching good quality hardwood being used for concrete shuttering in the far-east because they don’t have coniferous trees.
I could have used English Oak, but although it is considered more rot resistant it is also twice the price and difficult to get defect free in long lengths. European Oak would also be an alternative, but again length, defects and price come into play, although it is cheaper than English Oak. My wood yard (Nick’s Timber of Gloucester) suggested that the best deal would be to buy 6 – 9 inch planks of American white Oak to saw down myself, so that is the route I took for the boat framing. I rather like the lighter colour so I will probably use that for interior finishing also, it is easier to stain a light coloured wood than bleach a dark one. Below is a picture of progress to date.
What wood to use can be a difficult question to answer, different timbers have different characteristics, all will perform badly if used in the wrong place, some split more easily, others rot quicker and some will creep or not hold the screws properly. You would think that the durability classes would be of some use in deciding what wood to use, but not necessarily for boat building, as some of the less durable woods are used to good effect. The table below specifies the durability of untreated wood when in contact with the ground, as sailors we usually strive to avoid the ‘contact with the ground’ bit.
Marine borer class
More than 25
Less than 5
As you can see the marine borer class matches the fungi classification, but how much use is this to us when we will be encapsulating the wood in epoxy resin, paint and preservatives in an effort to keep out detrimental processes such as fungi, insects, marine borers and last but not least UV. There are many other factors to making a good boat such as, quality of the design, are the structural components sized right and of the right materials. Does the design encourage rain water to stand, this will rot a boat more than seawater. Are the joints and the glue sound and well made. Is the finish of suitable materials and regularly maintained.
I find the best guide is to see what other people use and take a consensus approach. As a caveat, I don’t know what is used in the tropics or southern hemisphere so I guess this article will be of most practical use for Europe and North America. Now let’s look at some specific woods and see where and how we can use them in a boat.
Teak 630-720 kg/cu.m
In much demand for boatbuilding teak is a very versatile wood due to its durability, beautiful colour and good grain, it also has very little movement and so is ideal for doors and hatches. Nowadays, if you can afford it, it is used for decking, seats and decorative trim. It has a tendency to blunt tools due to high quantities of silica. Personally I would tend to avoid its use due to cost.
Mahogany (True) 545 kg/cu.m
Used to be used a lot for planking but recent research has shown that it suffers from nail-sickness hence it is now used more for interior finishing. It is easy to work and has a fine grain and lustre, hence its popularity, which sadly has resulted in its rarity and cost. Again another timber I would tend to avoid for cost reasons.
Sapele 640 kg/cu.m
A good cheaper alternative to Mahogany, it has more interlocking grain and is heavier, mainly used in furniture and flooring. It has good working qualities and will hold screw well. It is good for polishing and finishing but will darken with age so care must be taken not to make the finish too dark.
White Oak 590-930 kg/cu.m
A good wood for structural components, but not without its difficulties. While it is strong, strait grained, hard it has a small amount of movement when seasoned, the high acid content can make it difficult to glue and it will react with and rot any iron it is in contact with. It holds screws and nails well but will need pilot holes, if bronze screws are used I find the pilot holes will need to be exactly drilled in order to avoid sheering the screws. Green oak is particularly good for steam bending and the steaming will remove some of the tannic acid making it easier to fix. Green oak is notorious for splitting as it dries, but this is not usually a problem for smaller pieces used in dinghy ribs.
Iroko 655 kg/cu.m
Generally used as a cheaper alternative to Teak, it is a stable naturally decay resistant timber which weathers to a pleasant silver grey in about a year if not coated. It is a pale yellow when first cut and darkens to brown with age, it looks very similar to teak but does not have quite the same stability, it has good gluing and screwing capabilities. Dust may cause an allergic reaction and the wet wood may cause contact dermatitis. I have also seen some research stating the dust may be carcinogenic, but then again probably a lot of things are if only we knew.
Douglas Fir 530 kg/cu.m
Like Iroko another good timber with many uses. I have never seen it in the UK in sheet form, but I believe that DF plywood is very popular in North America where it is more plentiful. A good timber for structural work which glues well and holds screws well. The only downsides are that it can tend to delaminate along the grain, which is very distinctive and not particularly attractive. It does not steam bend well and like Iroko the dust can cause allergies. I intend to use it on my build for the deadwood, mast and other smaller structural components.
Okoume (Gaboon) 350-450 kg/cu.m
I have only used this timber as a plywood, where I find it very easy to work and glue. It has a tendency to be soft and easy to bruise but will provide a hard skin with a coat of fibreglass and a few of epoxy. It is a light weight wood and should compensate for the heavy oak framework on my current build.
Meranti 580-770 kg/cu.m
Though it is used extensively in marine plywood in the UK it is a wood I have tended to avoid using due to the weight, it is also brittle and has a tendency to split making it a bit difficult to work. If I had to choose between Meranti or Douglas Fir Plywood I would probably choose the Douglas Fir.
Western Red Cedar 380 kg/cu.m
Just about the most popular wood for light weight canoes, it is ideal for strip building and used as a core in larger boats fibreglassed either side. It glues well and is soft to work, so soft that it requires a hard protective finishing skin e.g. fibreglass. It does not steam bend well but for its common applications is usually no thicker than ½”, and so is easily bent. It can cause breathing difficulties and like oak react with iron. It is very durable, to the extent that it is used for shingles.
Sitka Spruce 450 kg/cu.m
In much demand for spars due to the fact that it grows tall and strait and has a very good strength to weight ratio. It is not a wood I have ever used but I will try to get some for my dinghy spars. Apparently it has good screwing, gluing and steam bending properties.
Other e.g. Cherry, Maple, Elm, Utile
Many other timbers are used in boatbuilding for interior trim. It depends on what is to hand and what you like the look of.
While this list above is woods I have used, or seen used in boats around me, it is by no means exhaustive. There are many other minor woods which suit specific uses or are difficult to obtain like Pitch Pine, unless you live in or near to the area where they grow the cost and difficulty in trying to obtain them are rarely worth the bother, when an acceptable substitute is available.
To categorise the woods by use:
Frames and structure; Oak, Iroko, Douglas Fir
Steam bent frames; Green oak
Decking; Iroko, Sapele, (Teak I would rule out on cost)
Rubbing Strakes; Iroko, Oak
Ply sheathing; Gaboon, Douglas Fir, Meranti
Interior trim; Teak; Sapele; Oak, whatever is available at a reasonable price
Wood strip construction; Cedar
Spars; Sitka Spruce, Douglas Fir
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