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HB20 Hull Assembly Method

HB20 Hull Assembly Method
(excerpt from building notes)

Step 1: Layout the panels first. See the nesting drawing: we use full size plywood sheets or almost, no cuts except for the part in the middle.

Cut the longitudinal butt blocks. Epoxy glue

DO NOT install the transversal butt block. This will be done later.

The centerline butt block will fit between the stringers and is used as keel reinforcement. Do not change our building method, do not scarf. We need the butt block for strength.

Cut plywood for the bow panels, sides, stringers and floor frames. See the nesting drawing for the best plywood layout. Note that many dimensions are taken from a centerline marked CL.

Step 2: Frame side panels and stringers all around with 2x2 cleats epoxy glued to the plywood parts.

(Side panel butt block not shown, starboard side panel not shown for clarity)

Step 3: Layout bottom panels.
Step 4: Install longitudinal parts: sides and stringers on bottom (dry)

Note that the bottom panels are loose. We will join them with butt blocks later but you may want to use some temporary blocks to keep them from moving.

Step 5: Cut and install bulkheads B and E (up to sheer line). Cut notches for stringers in these bulkheads: their location and depth is listed on the plans, it corresponds to the spacing between stringers. Install floor frames between longitudinals. Frame floor frames and bulkheads (as required).

Step 6: Epoxy glue longitudinal and transversal framing to bottom panels including side panels.

Step 7: Install bottom butt blocks between framing. Install the two bow bottom panels and build FG seams at bow bottom panels.

(Butt blocks are used on the flat part of the bottom, fiberglass seams at the bow. Specifications are given on the plans)

Step 8: Install transoms, build FG seams all around, inside, above sole level.

Step 9: Install sole panels in cockpits and inside, epoxy glued on framing, FG seams all around perimeter on upper side.

The HB20 has more bulkheads and different stringers. The drawing only shows the assembly method. In the HB20, the forward part of the stringers is higher and will become the side of the bunks.

Step 10: Build inside accommodations structure. Install rubrails.

(For clarity, not all bulkheads and frames are shown in this picture.)

Step 11: At this point, the hull is rigid and strong. Roll hull over. Fiberglass bottom as specified

Step 12: Install strakes, epoxy glued. Roll over.

Step 13: Finish inside, install roof etc.

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