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Stitching up the hull

The bulkheads are all in place, leveled, straightened etc. now the first bottom panels can go on the boat. After the two bottom panels are stitched together they need to be lifted onto the bulkheads. One way is to bore a hole 3" in from the keel line and at the middle of the panels and lift them up over the bulkheads and then spread them open as they are lowered in place. Another way is to bore the hole on the opposite side of the panels, through only one of the panels. Run a rope overhead and tie it off on the panel. With the panels laying on the ground beside the strongback and with the keel stitching away from the strongback, lift the top panel and as they spread pull them over the bulkheads and in place.

Fiberglass Epoxy plywood Construction

The bottom panels will not lay perfectly over the bulkheads, but as the rest of the panels are stitched on they will slowly pull themselves into place. The next set of bottom panels, I will refer to them as the upper bottom panels, can be installed. In the larger boats it is difficult to stitch the first few feet so I cut small blocks of plywood and use construction screws to hold the upper bottom panels and lower bottom panels together. If the screws are overtightened there is a tendency for the joints to straighten to much so backing off on the screws a bit will sometimes help the panels relax into place. Stitching the panels takes several people, one is needed to drill holes from the inside and feed the wires through, another to tighten the wires and two or three to hold and manipulate the panel as it is stitched aft.

There are times when the stitch line will run over a longitudinal, The blocks and screws can be used in these places as well. There will be pictures where you will see this was done. I also like to use construction screws at the bow joint instead of wire stitches. It the screws are installed toward the edges, a fillet and glass can be applied to the inside joint and after it has cured the screws should come right out.

Fiberglass Epoxy plywood Construction

Chine logs need to be installed before the lower side panels can go on. Shorter pieces can be scarfed together to get the desired length. To scarf, the pieces need to be stacked and cut just like the plywood was for the hull panels. Two layers will be epoxied together so the scarf joints don't need to be real long, 8" on 3/4" stock will work fine. When gluing the pieces it is important to make sure the scarf joints are as straight as possible. A screw at the joint and one and one three feet on each side of the joint will hold things in place until a clamp can be used.

Plywood epoxy fiberglass construction

When notching the bulkheads out for the chine log I like to notch big so I have room to work. The logs can always be wedged later, but it is a pain to remove material with it in place.

Stitching Plywood Hull Panels

The image below is of the sheer clamps being glued up, but it was the same principle for the chine logs as well. The notches in the bulkheads get taped so the chine logs and sheer clamps don't stick to the plywood. The pieces should be dryfit and marked so they can go right in place once the epoxy is applied. Wet out both mating surfaces with slightly thickened epoxy and starting from the bow screw both pieces to the first bulkhead (3" construction screws) and screw both pieces of the clamp/log every 12" as you work aft. The aft ends (port and starboard) are wired together to put a slight curve between the last two bulkheads, otherwise that section will be flat of the clamp/logs will be to flat. Wire or block both ends at the proper height so they maintain the fair curve.

Plywood Stitch And Glue Construction

After the epoxy has cured the chine logs can be sanded and shaped and reinstalled for the final fit. They do not need to be glued in, just screwed at each bulkhead. They should be wedged out so they can be trimmed to the proper angles. If a straight edge is set at the inside corner of the bottom panel and also set on the chine log you can see what angle the chine log need to be trimmed to. The other half of the chine log can be trimmed when the sheer clamp is installed. The sheer clamp does not need to be trimmed like the chine log if it is wedged in place at the proper plane, again a straight edge run form the chine log to the sheer clamp will show you what needs to be adjusted.

Plywood Stitch and Glue Construction

After the chine log has been trimmed the lower side panel can be stitched on. The bow was fastened just like the upper bottom panels, with screws and blocks, and then stitched the rest of the way.

Plywood Stitch and Glue Construction

After all the stitching is completed it is a good idea to go throughout the entire boat and make sure all the stitched joints are even. It works best to tap the panels from the inside. The side panels can be wedged out from the chine log so thickened epoxy can be brushed on the two mating surfaces. Use temporary construction screws to hold the panel in place, just enough to so the surface touch and don't overtighten. Bring together the bow joint just like the previous panels were at the bow. After the epoxy has cured the fasteners along the chine log can be pulled, slightly countersunk, and stainless fasteners can be installed permanently.

Plywood Stitch And Glue Construction

The sheer clamps can be laminated and fit just like the chine logs were and the upper side panels get screwed to both the chine log and sheer clamp the same way as the last panels were

When stitching/screwing the hull panels together there a contact points on the bulkheads that you want to use and other you do not want to panels to touch. The first bottom panels contact the bulkhead on each side. The next bottom panels only contact the bulkhead on the outboard edge. The inboard edge uses the stitch joint as the contact point. The problem you can run into by trying to get all the panels lay against all the facets on the bulkheads is a lumpy line. Always treat the outboard edge of a panel as the contact point for the next panel and don't worry how it lands on the bulkhead. It may be hard top grasp the concept, but as you get into it it should make sense. It is very easy to wedge later on than to to try and trim a bulkhead with panels laid over it. I treat the bulkheads as a rough guide and use battens all over the outside to check for fairness. If I find I need to wedge panels away from the bulkhead to get the hull fair I will. That and the transom fit all comes on the next page.

Plywood stitch and glue construction



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