by Eric Coleman

Introduction

Many of us have sketched or made an outline drawing of the boat we would like to own. Even if only a dream, it is a pleasant way of spending a winter’s evening. To develop such a rough drawing to a finished design, to build up the flesh on the bare bones until every detail has been worked out, is a project of absorbing interest, creative and rewarding even if we lack the facilities (or courage) to build, for, like a picture, it is complete in itself. It is, however, important that such an exercise should be more than just building castles in the air, otherwise much of the point is lost. My purpose is to outline all the various steps in the design and give guidelines so that if the boat were built she would behave in a satisfactory manner.

Bearing in mind that the article is intended for those with limited experience, I have confined the treatment to family dinghies and pocket cruisers developed from them. The latter type, when amateur built, has never been developed to any extent in the UK so there is ample scope for the designer. Their great advantage over the scaled down yacht is versatility, dinghy performance and handling plus stability and accommodation.

Knowledge of design is still useful when building a boat from plans, for they can be modified to meet one’s particular requirements.

Abilities Required

The idea of designing and building one’s own boat seems, at first sight, to be an effective method of throwing money away with the maximum amount of effort. Suppose, after months or years of work and vast expense, the thing turns out to be a ghastly failure? Surely the design at least should be executed by a qualified professional; someone with practical experience in designing, building and handling boats, who has academic attainments to manage the scientific and mathematical aspects? As for construction, it is well known that many people build boats but bearing in mind that we are expected to twist large sheets of plywood into vicious curves, clamp them down and drive home dozens of screws in the ten minutes or so before the glue hardens, it is obvious that something more than ‘handyman’ skill is required. In fact, most of the construction seems to involve curves — far more difficult to build than a piece of furniture where everything is straight and square.

These sentiments are commonplace and I too once held them. They effectively prevented me from designing and building boats for many years, to my lasting regret. The most I achieved was an outline drawing of a dinghy for cruising, based on three seasons sailing experience. I gave this to a builder of traditional boats (they do not need detailed plans) to indicate my requirements. He followed my suggestions very closely, somewhat to my alarm, but the resultant dinghy served me well for eighteen years. I realise now that the number of people who have the abilities to design a boat is far larger than most of us would believe. The trouble is that we lack the confidence to tackle the problems so never find out that their solutions are within our grasp.

I think that we should take another look at that first paragraph. To expect that a designer of small boats should be a naval architect is using a sledgehammer to crack a nut. Schoolboy mathematics is more than adequate for yacht design, even those ten times the size we shall be considering. Scantlings and rigging strengths are based more on empirical information than calculation. Few yacht designers possess academic qualifications of professional standard, even the majority of those who try to impress us with letters after their names. Practical design experience is, of course, very useful but not essential provided the knowledge thus gained is available in print. A complete novice can expect to bake a satisfactory cake at the first attempt by following the directions in a cookery book. Any handicap from lack of design experience will be more than outweighed by the advantages of designing a boat to our own requirements. Admittedly she may not quite achieve our ideals in practice but that is not an uncommon experience, even in the case of leading designers. However, if the design is executed with due regard to common sense guidelines and use is made of available information, the result will be a practical boat.

The minimum standard of skill required for boat construction is far less than that assumed by writers of building instructions. They write for the experienced amateur woodworker, which makes for a simple approach — ‘just pop the boat together’. If, however, we tackle the problems of construction, we will find that there are alternative approaches to the use of skill, such as the use of slow setting glues which avoid the need for speed in assembly. Here is what Adrian Neison had to say in his book Practical Boat Building for Amateurs published in 1890 when construction was immensely more complex than it is today. ‘The reason, perhaps, why amateurs do not more often try their skill on boat building is because there are technical difficulties which seem to throw a barrier in the way of all who do not care, or have not the time, to spend a thorough study of the subject. Such an idea is a mistake, for boat building is well worth the amateur’s attention; for it is really a simple craft, not requiring nearly so much skill and technical knowledge as good joiner’s work’.

The reference to joiner’s work brings us back to furniture. Admittedly a chest-of-drawers is straight and square but precision is required because there are many moving parts which have to fit accurately together. A drawer will only slide smoothly if it has the minimum of play. On a boat, close fitting moving parts are avoided because of the warping and swelling of timber which occurs in the damp conditions. Modern gap-filling glues eliminate the need for accurate workmanship and most of the joints are of the simple butt type. The curved surfaces of a boat seem rather daunting at first sight but only because this type of construction is unfamiliar. It is basically a matter of covering a framework of curved timbers with plywood. Getting the required twist in the panels is a matter of technique rather than brute force.

What then, are the abilities required? When drawing the lines, it is an asset to have an eye for a smooth flowing curve. Many of them will have a tight bend at the forward end and straighten out as they run aft. The eye should detect that the transition is progressive, without flats or humps and that each line harmonises with adjacent ones, in other words, that the lines are ‘fair’. There are good reasons for a ship being a ‘she’. Patience to achieve a high standard of accuracy in the lines drawing will minimise the work involved and make the early stages of construction straightforward. When these drawings are complete some calculations will be made concerning displacement. They involve simple arithmetic only. Layout and construction drawings involve less art and accuracy but a good deal of head scratching as, for instance, when we try to fit large accommodation, a large cockpit and plenty of stowage space into a pocket cruiser. The ability to visualise a drawing in three dimensions is an asset. Much of this work is highly absorbing but attending to the small details can be less so. However, a painstaking approach to small problems can pay dividends later on when building the boat because, in the design stage, a re-hash only means changing a few lines. It is not necessary to be a trained draughtsman for this work but the drawings have to be clear enough to be understood some months (or years) later. If the design is to be published a few drawing conventions will have to be learnt but the standard does not need to be high.

Obviously you must be able to handle tools in order to build a boat but perseverance is a substitute for skill which is the ability to work fast, accurately. If you cannot saw along a line, then saw near to it and plane or chisel down to it. You get there in the end but it takes time and patience. In the hands of the expert, the saw seems to follow the line of its own accord and very little trimming is required. But remember that your expertise is constantly improving with practice. Ingenuity is a great asset. It saves much time without the use of skill. I am often asked how long it will take to build a boat but one builder may take a month to build a dinghy while another could take a year, even if they both worked the same number of hours per week. Much depends on the energy of the builder. Some people work in a cloud of flying chips and sawdust. I like to get my pipe going, then I pick up a plane and make a vague pass at a piece of wood, then my pipe goes out… I think it would be only fair to say that boats take longer to build than one’s estimated time but the complete awe-inspiring creation is simply the addition of a large number of straightforward tasks.

Groundwork

The design of a simple dinghy or pocket cruiser does not require a vast knowledge of boats but it is only common sense to learn something about them before putting pencil to paper. Before commencing any study, the mind must be opened to receive information. I know I am stating the obvious but some mental discipline is needed to prevent preconceived ideas from influencing one’s judgement. For instance some may think that difficulty of design increases with size but those who have designed and built a small dinghy for use as a yacht’s tender will know otherwise. The time to form definite ideas is after all relevant data has been studied. If we want a dinghy which is light for trailing, we should not skip over the fact that the lighter the boat the less the stability. Problems of this sort can be overcome but they first have to be recognised and that is done by thinking around the subject instead of concentrating on the main aim; by comparing our design with others so that the weak points stand out.

I suggest that books used be supplemented by a loose-leaf file containing assorted data on any subject which may be useful. The widest and cheapest source of information is the library. Many books and magazines give lines and plans of boats which we can add to our file by using the library photostat printing service. A visit to a boat show will pay handsome dividends. Quite apart from rushing around the stands feverishly gathering up leaflets, many of which will give layout and sail plans, there will be the opportunity of studying boats in the solid. Surreptitious use of a tape measure will give useful information on mast sections and centreboard, rudder blade and thwart thicknesses etc. Such activities are admittedly of little help to manufacturers who have gone to considerable expense to exhibit their boats. On the other hand, we may find a boat near enough to our ideal and decide to buy rather than build.

It is often useful, during winter months and early spring, to visit the upper reaches of creeks and rivers where the smaller boats are laid up. Many of them will be amateur built and the effects of age and weathering can be examined. Owners who are fitting out are always willing to talk about the advantages of their boats and the disadvantages of all the other boats in sight, so much practical information can be picked up. Carelessly parked cars, unruly children and dogs running loose are not welcome.

To get an idea of the sections and thicknesses of wood to use in the construction and how to arrange parts lists etc., it is worthwhile to buy a set of plans of a boat designed for the amateur to build from scratch, in the same general category as the one we intend to design. They can probably be sold when we have finished with them. We will, of course, require a set if our intention is only to modify the design. If we intend to publish our design, it should be all our own work, not a modification of someone else’s design. It does not matter if there is a superficial resemblance; it is difficult to avoid that anyway. The object of studying other designs is to obtain general guidelines on hull shape, rig, construction practice etc.

Finally, we will require catalogues of fittings and timber lists. Some timber merchants sell fastenings, glues etc. and they all advertise in magazines.

Before leaving our information file, I would give an example of its use. Suppose we wish to design a family day boat with good freeboard to keep the crew dry. The problem is — ‘What is good freeboard?’ If we make a stab at the answer, we may be wildly out. Boats designed by inexperienced amateurs on this principle are often found on the quiet upper reaches of rivers and creeks. They would not survive at sea. So we measure the freeboard of all the dayboats in our collection and choose one at or near the top of the range. The point of this exercise is that our decision is based on practical boats. We are standing on the shoulders of experienced designers.

How much practical sailing experience do we need before designing a boat? I think that a reasonable guide would be enough experience to feel that a specialised or ‘custom built’ boat would come much nearer to our requirements than a stock design which has to please everyone but delights no one. It is sometimes said that personalised designs are difficult to sell. In the case of knock-about dinghies and pocket cruisers, however, attractive features can be incorporated which are not found on mass-production designs.