(or how to build a small dinghy using cheap ply and expensive epoxy)

A couple of years ago I decided to build a rigid tender for use when my ‘ocean going’ West Wight Potter was on a mooring. Like many people I have a particular liking for boats which look good as well as sail, so I tried to make the resulting dinghy as ‘boat like’ as possible. I offer the following article to those readers who might be interested in how to build something similar that looks fairly traditional but which is strong and simple to construct.

Using modem materials, particularly epoxy resin, it's as easy to make a boat that looks and sails well, as it is to make a floating packing case. The dinghy covered in this article was designed to be built without specialist tools - the only woodworking tools you really need are a plane, a jig saw and a few G cramps - although some others can make life a bit easier. It is glued and finished in SP epoxy, which makes the use of cheaper ply and softwood possible.

The cost will of course vary depending how much your ply cost and upon how it is fitted out as the stainless steel pintles and gudgeons for the rudder will probably cost as much as the two or three sheets of ply needed to make the dinghy. Alternatives are fairly easily made if you can't scrounge any. Although it must be stressed that the use the boat is to be put to needs to be considered. Mild steel bits and pieces may be OK on a boat which lives in a garage for most of the year, but would be useless on one exposed to the elements on a long term basis. A visit to the hardware/DIY shop can provide eyebolts etc. which will cost you very little. Also it is worth collecting odd pieces of hardwood, which are often discarded in the building industry, but which can save you pounds - the mast support came from a window frame offcut - and as a real traditional touch, I bought the jute fibre rope from B & Q, that well known northern chandler.

The point is not just to make do with any old junk, this leads to the floating packing case type of DIY, but to understand what the item needs to do; this includes the boat itself. It is amazing what bits of improvisation can be seen on old boats. If you don't like this boat, perhaps this piece will help you work out possibilities for your own creations.

Now while I like making things, I also like to get them finished, hence I have always designed things so that it is as simple as possible to get the desired result. This dinghy was designed, a very grand sounding term for the way I work, to carry three or four people as a tender and to sail with a couple of twelve year olds on board. I really wanted a clinker stem dinghy, I do not like pram dinghies. The problem was how to accommodate the practical with the aesthetics.

The result of my deliberations was to use 6mm ply strakes formed over a single mould, built on a base of chipboard, although 4mm would produce a lighter boat. The rigidity comes from the box sections created by the buoyancy boxes. The bottom of the boat is really a large panel rather than being built up of strakes, again made of 6mm ply and carries a fair amount of buoyancy forward. The strakes were made in matched pairs, the approximate shape being worked out using a scale half-model made from a cornflakes box and masking tape. Being lapstrake it is easy to plane the strakes where they are a little ‘off’ once they are fixed together.

The stem, mould and transom are set up on the bench/building board in the correct position, linked by the 2 x I spine. The bottom panels are added and then the strakes. The use of an inner stem means that accuracy in cutting the angles on the end of the strakes is not crucial, as they can overlap the inner stem and be cut off level when the resin has set. The outer bit of the stem can then be added. Masochists can of course use a one piece stem and carefully cut a neat housing for the equally neatly cut strakes. The buoyancy compartments give the boat much of its rigidity and it is very strong. The whole lot was bonded, strengthened and saturated with SP epoxy which accounted for half the cost of building the boat. As this makes the boat so much more durable I would recommend it. What is more, a paste made from resin and micro-balloons which is a special powder for the resin, can be used as a fillet between the ply, reinforcing and filling any holes in one go.

On the subject of knees much has been written, and I while I am sure much enjoyment can be gained from sorting out the right bit of bent wood for a hand carved knee, on this boat they are ply and are really gusset plates. Our local builders’ yard is a bit limited on grown timbers, but all ply and pine for the mast came from builders yards, making sure of course that the ply was W.B.P. grade.

While building this way is sound, it is not an exact science - which really is in the tradition of working-boat building - therefore I leave working out the shapes of such things as the buoyancy boxes until the hull is formed. It is then possible to cut an accurate card template to the actual shape of the boat, rather than try to predict through a two dimensional plan. Of course it is worth taking a pattern in hardboard of the final shape if you plan to make more than one.

The Rig

I used a simple lugsail permanently attached to the boom and yard raised by a single halyard. On a boat this size it could be hooked in place on the mast. The mast, boom and yard are never taken apart, the mast is just plugged in, the sheet attached and the rig is ready. My boat has a cotton sail which is home made, mainly because I had some free cotton sheeting of a suitable weight, however for longer life synthetic sailcloth would be better - and more expensive. The mast is made from pine carefully selected for lack of knots and warps, but BEWARE, when buying from builders merchants as opposed to proper wood yards there is a great variety in wood of the same dimensions - what you want is often called `reds' for the reason that it is much redder than much of the softwood in yards and is much stronger. I have two masts for the dinghy, one fits in the boat and one is longer so the boom is higher. The latter is made from wood I chose in haste and is far less rigid than the original. The mast was shaped by using a mortice gauge to mark the length into three sections on each face, the corners then being planed off to make an octagonal section, the corners were then planed off again and the mast rounded with glass paper and a file.

However you don't need a mortice gauge, a simpler version can be made by using bits of wood and pencils. (see fig) The thing about boat building on a budget is to be flexible - if you can't quite get the shape of the rudder you originally drew out of the bit of ply you have, then make one that fits the wood.

Everything can be made to fit inside the boat for storage and transport, and the boat is just about light enough for one twelve year old and myself to put on the roof-rack. Built of 4mm ply I could probably do it alone. I had originally intended to use a leeboard hooked over the side instead of a dagger board and case. This as it turned out would have made it easier to beach, as when using the boat alone one has to sit in the middle and it can be a little awkward lifting the dagger board! With the addition of buoyancy boxes along the side and the use of an extra mould, the boat could be stretch to eleven or twelve feet with little trouble, or perhaps made double ended, that's up to you. I might get round to it after I finish my Backyard (Almost Traditional) Gaff Cutter.