This boat is a tender. Its prime job is to ferry people between the shore and something larger. It has secondary roles of providing for sailing for recreation. It must be possible to power it by oars, outboard, or sail. It must tow well between ports, but be compact enough to stow on deck on long passages.

It needs to be buoyant, with a high carrying capacity for its length. This makes it beamy. It needs to be stable, with a shallow draft so that people can get in and out without getting their feet too wet. This gives it a flat bottom and a hard bilge. It needs to tow well, and plane easily when towed empty so that it is not overwhelmed by its own bow wave. This gives it a buoyant bow, and reinforces the need for a flattish bottom. It needs a certain amount of built-in buoyancy so that if swamped, it does not sink. It needs to be directionally stable, so it has a skeg. It needs to be light, but strong because it will spend a fair amount of time bumping around on beaches and slipways.

It ought to carry at least three adults, preferably four in calm water (say 33 - 44 stone/210 - 280 Kg total weight), and yet be manageable by a large child. It needs enough sail area to make it interesting even in light airs, yet not so much that it becomes overpowering in gusts. It would be nice to be able to stow the spars within the boat. It ought to be inexpensive to build, preferably by an unskilled amateur working in his garage or somewhere similar, yet have enough shape to be interesting to look at. Essentially we are talking about a floating box, but a pretty one.

This boat is slightly under 8 feet (2.4 m) long and about 4 feet (1.2 m) wide. It has a flat bottom and a hard-chine bilge to minimise the draft, and make it easy to build. It has a broad stern to take the weight of an outboard and driver, and a slightly raked transom bow to save length. It will carry four adults at a pinch (one aft, two amidships, and one forward) or a few more children. It is stable and buoyant. It can carry enough sail to go well with a single adult or a couple of children, yet the spars are all short enough to stow within the hull.

The bottom is made from a single sheet of 8 mm thick plywood for strength, and the sides from 6 mm ply. If it was not going to have a hard life then you could reduce these both by 2 mm. Even so the boat should not weigh more than about 75 lb./35 Kg. The transoms, centre bulkhead, and forward and after decks are an integral part of the stiffening, and these major parts are also made of 8 mm plywood. The after deck takes most of the thrust of the outboard and transmits it to the sides; the forward deck and centre bulkhead sort out most of the sailing stresses. Incidentally, bow and stern transoms, and the bottom, fit inside the sides.

The sailing gear is shown as an option because not everyone will want to fit it to a tender. The daggerboard slot will undoubtedly add some drag when rowing, and when not sailing the case needs its cover on to stop water slopping up inside. The trouble with any boat of this size is getting the sail area large enough. This boat is designed to be sailed by a single adult or teenager or a couple of children sitting on the centre thwart. The sail is about 40 square feet (3.75 sq. m.). Anything larger and the spars would be too long to stow in the boat. Of course if you have several children who want to sail together then you can add a jib on a bowsprit and a mizzen or even a topsail and spinnaker so there is something for each to handle. The daggerboard is big enough to take about 55 sq. ft. to windward without being overpowered, which is more than enough for a hull of this length. If you sail it frequently in strong winds, you might like to increase the width of the gunwale aft so sitting out becomes more comfortable. An extra inch (25 mm) should be enough to stop it digging too hard into your thighs. Toe straps, if fitted, should be bolted down to the bottom through 8 mm thick plywood pads.

If you prefer to use power then a 2 hp outboard should be big enough for most circumstances. Certainly anything over 4 hp should be avoided, as it will just weigh the stern down to no benefit. If you are going to use an outboard regularly, then I recommend pinning a sacrificial pad of plywood on top of the transom paintwork to protect it.

Note: "Timber" may be soft or hardwood unless otherwise specified.

Bottom - 8 mm marine plywood - needs one sheet

Keelsons - 2 off, 3" × ¾" (75 × 20 mm) fin. hardwood (for preference) 8 ft (2.4 m) long

Bow and stern transoms - 8 mm marine plywood

Towing eye backing - 8 mm marine plywood about 4" (100 mm) square

Centre bulkhead - 8 mm marine plywood

Forward and after bulkheads - 8 mm marine plywood

Sides - 6 mm marine plywood

Thwart/deck stringers - 2 off 8 ft (2.4 m) of 1" (25 mm) square timber

Centre thwart - 48" × 8" × ¾" (1220 mm × 200 mm × 20 mm) fin. hardwood

Forward and after decks - 8 mm marine plywood, king plank - 6 mm marine plywood

Deck beams & supports - 1" (25 mm) square timber

Daggerboard case sides - 6 mm marine plywood

Dagger board case ends - 1" (25 mm) square timber planed down to ¾" (20 mm) finished thickness

Daggerboard case tops - 2 off, 18" × 2" × 1" (0.45m × 50 mm × 25 mm) timber

Mast box - 8 mm marine plywood

Stern transom doubler - 4 ft × 6" × 1" (1.2m × 150mm × 25 mm) hardwood (for preference)

Bow transom doubler - 2 ft × 3" × 1" (0.6m × 75 mm × 25 mm) timber

Inwales - 2 off 8 ft × 1" × 1" (2.4 m × 25 mm × 25mm) timber - should be free of knots

Rubbing strakes - 2 off 8 ft × 1" × 1" (2.4 m × 25 mm × 25mm) timber - should be free of knots

Bow bumper - 2 ft × 2" × 1" (0.6m × 50 mm × 25 mm) timber

Bilge keels - 2 off 8 ft × 1" × 1" (2.4 m × 25 mm × 25mm) timber - should be free of knots

Skegs - 2 off, cut from 20" × 3" × 1" (500 mm × 75 mm × 25 mm) hardwood

Epoxy resin, thickener and fillers. 22 ft (7 m) 4" (100 mm) wide glass tape

Mast - 8 ft (2.4 m) of 2" (50 mm) diameter softwood, or 50 mm o.d. aluminium tube with a wooden plug at the top to take the halyard sheave. (If you do not have access to a lathe to make the plug, a suitable one may be obtained from Bell Woodworking Ltd, Leicester - ask for a Mirror dinghy mast top).

Boom - 78" (1950 mm) of 1½" (30 m) fin. square softwood or 30 mm o.d. aluminium tube.

Boom jaws - cut from 8 mm marine plywood or plastic rowlock set into end of boom.

Yard - 96" (2440 mm) of 1½" (30 m) fin. square softwood or 30 mm o.d. aluminium tube.

Daggerboard - 40" × 12" (1000 mm × 300 mm) 12 mm marine plywood with 2" × 1" (50 mm × 25 mm) timber strip glued each side at the top as a handle

Daggerboard case cover - from scrap 3" × ¾" (75 mm × 16 mm fin) timber.

Rudder - made from 12 mm marine plywood

Tiller - 2 off 30" × 1" × 1" (750 mm × 25 mm × 25 mm) softwood.

Halyard, parrel line, boom downhaul - 5 mm dia pre-stretched polyester rope, 6 m required in total; Mainsheet - 8 mm dia polyester rope, 6 m minimum, 8 m maximum; Painter - 5 mm polypropylene (or similar floating rope) - 6 m recommended

Note: paragraphs marked with an asterisk apply only to the sailing version.

Cut out the bottom from a single sheet of 8mm plywood, cut the keelsons to length and taper the ends down to a flat edge (so they do not interfere with the fillet joint). Bend the bottom to its approximate curve, and glue and screw the keelsons in place. (The easiest way of doing this is to clamp the keelsons in place, turn the whole lot upside down across a 7 inch high support placed 3½ feet from the stern, and hold bow and stern down to the floor. Then screw the keelsons in place. Keep it all bent until the glue has set.)

Cut the sides, bow and stern transoms, and wire them all together and to the bottom. Fit a temporary strut across the centre of the boat to hold the sides apart. Glue and screw the thwart stringers along both sides,. Cut out the centre and bow and stern bulkheads, and force into place under the stringers. (You may need another temporary strut at the bow.) Check that everything is square, and then fillet the centre bulkhead into place along its aft edge. Glue the towing eye backing block inside the bow transom (if it is wanted), then run epoxy fillets along the chines, and bow and stern bottom joints.

Fillet the forward and after bulkheads (both sides), and also the joints between transoms and side (but only as high as the thwart stringer). Fix the frames at each end of the centre bulkhead. When the glue has set on those, the temporary strut may be removed. Fit the deck supports along the tops of the bulkheads, and on the bow and stern transoms. Plane down the supports and stringers so the decks will fit snugly. Cut the drain holes at the base of the bulkheads, and clean off any splinters so there is nothing to trap any water.

* Glue the daggerboard case together, and when the glue is dry, shape its base so that it fits snugly to the bottom just in front of the centre bulkhead. Mark out the end of the slot through the hull, and drill a 3/8 inch (10 mm) diameter hole just inside each. (See drawing). Do not cut out the slot at this stage. Glue, screw and fillet the daggerboard case to the centre bulkhead and the bottom. (The single screw through the bottom at the front of the case is there simply to hold it all together while the fillets dry.)

Cut fit, glue and fillet the after deck and centre thwart into place. *Note that the centre thwart will need a slot cut in its forward edge to allow the daggerboard to pass through. Fit and glue the transom doubler above the after deck and fillet the joints between it and the sides.

* Make up the mast box as per the drawing, shape the base to fit the angle between the forward bulkhead and the bottom, and glue and screw it into place. Run epoxy fillets around the outside of the box where it meets the bottom and bulkhead. The bottom of this box is subject to quite a bit of wear from the foot of the mast, and needs protecting. Make sure the boat is level, mix up about 30 ml of epoxy, stir in about 20 ml of silica thickener and quickly pour the lot into the bottom of the mast box. It will set to give a very hard surface which will take a lot of abrasion. Measure the internal depth of the box, and drill a drain hole through the bulkhead to that it comes just at the bottom.

Cut, fit, and join the two halves of the forward deck, adding the king plank on top, the beams underneath, and drilling a 2 inch diameter hole for the mast (if needed) so that it lines up with the centre of the mast box. Pin and glue the deck into place, running epoxy fillets along the joint to the sides and bow transom and also the rest of the joints between the bow transom and sides.

Cut and fit the bow doubler and the inwales, and plane down the bow doubler so that the transom knees will lie snugly on top. Cut the knees from left over bits of 6 mm plywood; glue and pin them into place.

Cut and fit the bilge keels and skegs screwing them through the bottom into the keelsons. Run epoxy fillets around the joint between the skegs and the bottom for extra strength. Add a half-round strip of metal along each to protect them. Cut and fit the rubbing strakes along both sides and the bow bumper. *Cut the daggerboard slot between the drilled holes, and open it out to produce a slot the width of the daggerboard case with oval ends.

Fit 4" (100 mm) diameter inspection hatches and drain plugs to the forward and after bulkheads, and, if required, bolt the towing eye to the outside of the bow transom. The bolt heads should be on the INSIDE and the outside ends of the bolts should be riveted over to ensure the nuts do not come off.

* The rudder and daggerboard are made from half a sheet of 12 mm plywood. The rudder is designed so that it lifts well clear of the water when it is raised. This is to help the boat to lie better on a mooring with the rudder shipped.

* The mast and spars can be planed from good quality softwood or made from aluminium tubing with wooden plugs top and bottom. The mast top needs a slot for the halyard sheave chiselled through, and the bottom needs a cleat for the halyard and an eye for the tack downhaul. The boom needs an eye at each end for the sail, one underneath for the mainsheet block, and a cleat for the tack downhaul. A kicking strap is not really necessary with this size of sail. The yard needs an eye each end for the sail, and an eye, as drawn, to locate a strop for the halyard. If your sail does not have reef points, then it ought not to need a parrel to hold the yard to the mast, but if fitted then the parrel line should run from the halyard eye to another eye on the yard set about 12 inches (300 mm) further forward.

* The mainsheet runs from a 10 mm dia hole drilled through the transom, up through a block on the boom, and back to another block mounted the other side of the transom.