Mould for the main hull.
Draw the mould frames on second grade plywood and cut with a jig saw. Mark the centre line and base line on both sides. Construct building frame and set up on floor making sure the frame is rigid and level, the floor does not need to be level but the frame does. Stretch a wire between the ends of the frame for the centre line. Bolt the mould frames to the building frame.
Main Hull
MAIN HULL PANELS You will need 12 sheets of 6mm Gaboon or Pacific Maple plywood for the hull panels. Apply a soak coat of epoxy resin. When cured sand surface lightly (don't sand too far or the wood fibres will be exposed). Scarf the panels to the appropriate length. A SCAFFER attachment is available from ATL Composites Pty Ltd. Make a batten for drawing the panels by scarfing lengths of 20x6 silky oak or similar to make a batten about 7.0 metres long. Cut the panels using the dimensions that are supplied with the plans.
The hull can be stitched together using copper wire. Scrap wire about 1mm dia may be obtained from electric motor repair shops. Cut the wire into short pieces about 60-80mm long, Place the bottom panels (port & starboard) into the mould and "stitch" together with copper wire. Add the next panel on each side. Holes are made on each side of the panels and joined together with the wire. "Tack weld" the panels together by applying small amounts of filleting compound between every second or third wire. When the tacks have cured the wires are removed and the whole joint filleted with filleting compound and glass tape applied. Add an extra layer of glass tape on the keel. Add the rest of the panels to the mould and stitch with wire. Tack the panels remove the wire and fillet and tape. Add an extra layer of glass 500mm wide along the keel to add stiffness in this area.
Frames & Bulkheads
The frames and bulkheads are now marked out, cut and sealed with resin. The ring frames are made using an aluminium core with 9mm plywood faces bonded to it. Tack in the bulkheads and transom. Fillet and tape. It is difficult to tape inside the bow. A good solution to this problem is to laminate glass cloth in the nose leaving enough space to fill later. When the resin hardens a mixture of resin and aerosil can be poured in the gap. Do this in stages as the mixture generates considerable heat as it sets. Cut out and fit the bunk top. Attach the ring frame. Fit cockpit floor. Construct the port and starboard bunk/shelf in the cabin. Add mast step, partial bulkhead at the mast post.
Cabin top
Fillet deck stringers to frames. Cabin/cockpit sides may be fibreglassed and sanded before fitting to the hull. This is much easier and quicker to do flat on a bench or similar than when the panels and deck are fitted. "Stitch" the side panels and fillet and fibreglass tape to the frames and hull panels. Cut a piece of ply to roughly fit the foredeck extending back to frame 3 & temporarily staple in place. Cut ply for sloping section allowing for some wastage at the sides, temporarily staple in place. Make the top section of the cabin top and staple in place. "Stitch" together at the joints and along the edges to the hull and cabin sides. Fillet and fibreglass tape to the inside of the hull and cabin sides trim round off and fibreglass tape over the outside of the joint. Fillet to the deck beams/frames and stringers.
Cockpit
Cut seat risers and mark out and cut openings (save the cut outs to use as doors). Glue and fillet the risers into position. Attach cockpit seats.
Turning the hull
Place a beam under the forward part of the hull and another under the aft section. 100x100x2 metres long is ok. Support the beam each end and place carpet under the keel to protect it. Jack each beam slightly and support to lift the hull off the mould frames. Brace the hull so that it won’t tip from side to side. One at a time remove the mould frames from the building frame and finally slide out the building frame. With six friends lift the hull off the beams, have someone remove the beams and turn the hull onto its side. (it is wise to have old carpet or similar on the floor to protect the hull). Roll over and lift again and place the upside down hull onto stands under the beam stubs (stands may be premade from 2/150x15mm ply strips about 750mm long and bolted through the pivot holes.Glassing outside of the hull
True up all joints before rounding off. Fill and seal the joints. Measure and cut the fibreglass. Biaxial cloth may be laid either across or along the hull. If laid across the hull the fibreglass is easier to handle but there are more laps to fair (this is the recommended way). Either way the fibreglass must be lapped over the keel approximately 500mm to provide a double thickness over the panels adjacent to the keel. Trim the edge at the sheer line to lap 50mm with the deck and cabin fibreglass. Wrap the glass around the stem to provide a 75mm each side and add an extra layer to provide an additional thickness for 150mm each side. Carry these extra layers to just past the turn of the stem. Cover the transom with the same glass and lap 50mm. To help keep the glass cloth in place staple small ply wood pads (50x50) to the hull and remove them as the glass is wetted out. Add peel ply as work progresses. Use a hole saw to cut out cockpit drains, seal the edges with resin. Fill and fair the hull and seal with resin before painting with high build undercoat and top coats. Get the previous 6 friends back and turn the hull back over. Support in a cradle. Use window template to mark out window and cut out, seal the edges with resin. Cut polycarbonate or acrylic sheet to size allowing about 20mm overlap for sealing and fastening. Seal with Sikaflex and screw through pre-drilled holes. Use masking tape to mask off as Sikaflex has a habit of going where it is not required. Also wear disposable gloves. The protective paper must be removed where the window will seal against the cabin side.
Floats
Brief notes on building the floats and beams.
Mark out and cut the plywood for the float mould frames from the dimensions on the plans. Draw the base line and datum line on one side only and bolt to the building frame. Set up initially with the marked side facing aft. This will produce starboard half shells. Coat and seal 12 sheets of ply with resin and sand smooth. Scarf 3 sheets for each float half and stack together. Mark out and cut as was done for the main hull using the dimensions from the plans. Wire the panels together, tack with filleting compound, remove wires and fillet entire joint as was done on the main hull. Fibreglass the inside of the hull, the glass may be laid along the hull. Glue in the stringer, stem piece, deck and keel mating members. Cut out the bulkheads to the dimensions given on the plans, seal and sand smooth. Fillet and tape in the bulkheads. Construct the premade fillets to the port side of the bulkheads by stapling 80mm wide strips of tape covered ply to the edge (centred). Measure the angle to the hull skin and reproduce that as close as possible (use a bevel gauge). Make fillets and when cured remove ply, clean up and sand. The starboard half of the starboard float may now be removed from the mould. While storing be careful not to damage the premade fillets.
Reversing the mould.
Unbolt the mould frames and reverse, ie the marked side facing forward, check that all base lines are aligned, the frame is level and the datum lines are aligned. The stem mould also has to be reversed. Construct the port side of the port float as described for the stb side of the stb float. When complete, dry fit the starboard side and check that the deck and keel mating members have good contact, the premade fillets may need to be altered with sand paper. When satisfied with the fit remove and coat liberally the premade fillets, stem piece, deck and keel members with thickened resin. Refit the half shell and clamp together using ropes, web straps, ratchet tie downs or similar. Wire the stem if necessary. Glue on the transom, trim and round off edges. True up all joints, fill and round off. Fibreglass the outside lapping 50mm both sides over the deck & keel centrelines. Fill and fair with light weight filler and seal with resin. Cut openings for the beams using the marks previously made. You should now have 2 floats and are in big trouble if they are not OPPOSITE HAND.
Beam mould
The beam mould is constructed from 15mm plywood for the sides (webs) and 6mm for the top and bottom (flanges).
On a sheet of 15mm ply mark out and cut as dimensioned on the plans.
Be very accurate in marking out the pivot holes and drill 6mm dia pilot holes.
Cut out 2 identical webs, (stack 2 sheets of ply and clamp together).
Seal with resin, 2 or 3 coats and sand smooth on the inside faces.
Cut 6mm ply for the top and bottom flanges, seal with resin and sand smooth, glue and staple to the webs. Glue on the end piece. Radius the joint at the bottom flange and web and fillet all other joints, (use lightweight filler and sand smooth).
Lightly seal the inside by wiping resin over the ply and fillets. Be particular about the finish as any irregularities will be reproduced in the surface of the beam. Place masking tape over the pilot holes.
The mould must now be waxed with a mould release wax obtainable from Fibreglass suppliers.
Beams
Cut the required number (from the plans) of strips of unidirectional and double bias fibreglass and set aside in groups. Note: the less handling the better as unidirectional tends to fall apart if handled often. Best way to cut is with a Stanley knife & straight edge.
Place the mould upside down on a flat working surface covered with plastic.
Coat the inside surface of the mould with a heavy coat of resin and allow to set "tack free". Lay in one layer of double bias cloth and wet out making sure there no voids in the corners, lay in the second layer of double bias, use gloved fingers, brushes and compaction rollers (parsley chopper type) to compact the cloth and remove entrapped air.
Take one strip of uni for the top flange and wet out on a plastic covered flat surface. Lay a second and third layer wetting out and compacting each layer.
Pick up the 3 layers together and lay into the mould. (this is easiest with an assistant), position the glass accurately and compact. Repeat until all the layers have been placed. Make sure the uni is continued into the end plate, allow to extend past the bottom of the end plate, the waste will be cut away after cure.
Laminate the bottom flanges 3 layers at a time as was done for the top flange.
Wet out double bias 200x250mm and laminate in way of the pivot holes, continue 3 at a time until all layers have been placed, compact each layer and continue onto bottom flanges.
Let the resin "set up" but not cure and laminate the third layer of double bias over entire beam. The reason for letting the resin stiffen is that with so many layers of glass they can be easily disturbed. After cure DRILL THROUGH THE PILOT HOLES IN THE MOULD TO LOCATE THE PIVOT CENTRES BEFORE REMOVING THE BEAM FROM THE MOULD.
Leave the beam in the mould for at least 2 days before removing. Use thin hardwood wedges to break the bond to the flanges at the inboard end. Don't use screwdrivers or chisels as they will damage the mould. Trim the edges of the flanges and end of the end plate with a jig saw or diamond studded disc in an angle grinder. Wash the beam moulding with strong detergent to remove any wax and lightly sand the surface.
Make the external web stiffener for the inboard end and bond to the beam.
Fillet in the internal web stiffener to the outboard end of the beam.
Make 3 more identical beams. At the outboard end cut the bottom flanges back for forward or aft beams as shown on the drawing.
Carefully drill out the pivot holes with a hole saw (slow speed) and seal the edges with resin, check fit for pins, they must be a push fit.
Fitting beams to floats
Measure down and mark the location of the top of the beam between the double bulkheads.
Lay the float on it's side with the beam mounting hole facing up. Run a a string line from the stem to the centreline of the transom and level.
Dry fit the beam by drilling through the end plate and screwing (use a power driver with long shank screwdriver head) into the 12mm ply diaphragm.
clamp the inboard ends of the beams to a timber batten and check that the centre to centre dimension of the beams is the same as for the beam stubs on the main hull. Do yourself a favour and check a few more times.
Run a string line between the beams through the pivot holes and make sure it is level.
Clamp another batten lower down near the outboard end.Remove the screws through the end plates, lift the beams out and coat all mating surfaces liberally with thickened epoxy. Replace the beams into the recesses. Replace screws and check dimensions, level and squareness to the level string line. Do yourself another favour and check it all again before the resin "sets up".
Note: the end plates of the beams must be in contact with the 12mm ply diaphragm (achieved by screwing fairly tightly).
When the resin has fully cured remove the screws. Cut a small piece of 6mm plywood to fill the hole remaining in the float and glue / fillet to the inside of the beam and float. Glass over lapping onto the inside of the beam and float.
Fillet all around the float / beam joint and laminate unidirectional strips as per detail on the drawings to the top and bottom flanges. Finally cover the entire joint with double bias. Fill and fair with light weight filler, seal with resin.
Cabin
