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(Updated 10/15/07) Special NoteThese building instructions are intended for people who:.
You may use these instructions to build your own kayak for non-commercial purposes. Rough Cutting the PanelsCut from 3 sheets of 8 foot by 4 foot marine grade 4 mm Okoume plywood:
Joining the Rough PanelsUse butt or scarf joints to join the rough panels. There is enough extra length in the rough panels for either type of joint.
Lofting the panelsThe lofting numbers for the panels are easy to understand. From a starting point on a panel, the numbers tell you how far to go to the right, and then from there, how far to go up or down for each point. For example, one of the lines for lofting the side panels reads, "At 3 feet to the right the chine is up 25/32 inches and the sheer is up 7 1/4 inches." Important! The panels for the Mini Benny are measured stern to bow. Be sure mark the stern and bow on the panels to prevent installing them backwards. Make sure the lines are fair, meaning the curves are smooth and without bulges or hollows. Being off by as little as 1/32 of an inch can cause a noticeably unfair line. If a lofting point seems a bit off, don't be afraid to ignore it to make the line fair.
Side PanelsMeasure stern to bow with the chine on the bottom and the sheer on top.
Bottom PanelMeasure stern to bow.
Deck PanelMeasure stern to bow, beginning on the stern panel and centered exactly 3 feet and 11 1/2 inches behind where the center panels meet the stern panel.
Paddler/Cockpit LocationIn the proper paddling position (sitting straight up or slightly forward), the paddler’s lower back must be exactly 4 feet and 3 1/2 inches forward of the stern. Any variation in the location of the paddler will alter the intended performance of the kayak. Generally, it is best to have 4 inches between the paddler's lower back and the back of the cockpit. As a result, the back of my cockpit is 3 feet and 11 1/2 inches forward of the stern, which is also where the center deck panels meet the stern deck panel. Cutting and planing the panelsUse a jigsaw to cut just outside the lines, and then use a plane to go down to the line. Check the lines on panels for fairness. If they are not fair, don’t be afraid to use the plane a little to make them fair.
Assembling the HullWith the inside of the side panels facing each other, wire the bow and stern stems. Place the bottom panel on top of the side panels. Line up the bow of the bottom panel with the inside bow of the side panels. It is easy to mix up the bow and stern ends of the bottom panel, so check where you marked the bow and stern to make sure the bottom panel is not installed backwards. Starting from the bow, drill holes through the chine of the bottom and side panels and wire it, alternating the sides of the hull to keep the wiring even as you go along.
Stations are not used to help shape the hull. Instead, the deck is temporarily taped to the hull. Note that it is necessary to have the deck temporarily attached to the hull to help shape the hull into the proper form. Skipping this step or using sheer clamps will result in the hull not being shaped properly, especially in the rocker. Due to the deep bends in the side panels, sheer clamps will not work with this design.
Now comes the most critical part of plywood kayak construction. It is extremely important to sight down the seams to make sure that the lines are fair. Now is the best time for any adjustments to correct the lines. If the lines are not fair, check to see that the panel edges are even against each other. If necessary, loosen some wires, push and pull the panels until the edges are even, and then retighten the wires. Also, make sure that the kayak is not twisted. Sight along the bow and stern stems to make sure they are both vertical. Check for any twist along the bottom panel. You may need to twist the hull to get it straight. With the hull upside down, use a syringe to apply a small amount unthickened epoxy to the seams of the hull. After the epoxy has hardened, remove the deck and carefully pull out the wires, which are not necessary now that the seams are epoxied. With the wires removed, it is easier to sight along the seams to check again that the lines are fair or straight. If a line is bothering you, use a razor knife to cut through the epoxy in the seam and rework it. This is your last chance to make any changes. Once you are satisfied with the lines, tape the deck back in place and fill the outside seams of the hull with thickened epoxy. Next, remove the deck, and fillet and fiberglass the inside of the hull. As soon as the epoxy is no longer tacky, temporarily replace the deck and leave it on for a day or more to help shape the hull. The outside of the hull can be fiberglassed before or after the deck is permanently attached. Assembling the DeckFrom scrap plywood, make a template for a cockpit that is the size and shape as desired. The template is used for the marking the inside line of the cockpit on the deck, and later the cockpit coaming spacer and lip.
Use the cockpit template to draw the inside line for the cockpit on the deck. When positioning the cockpit on the deck, it is important to keep in mind that in the proper paddling position (sitting straight up or slightly forward), the paddler’s lower back must be exactly 4 feet and 3 1/2 inches forward of the stern tip on the deck. Any variation in the location of the paddler will change the intended performance of the kayak. Generally, it is best to have 4 inches between the paddler's lower back and the back of the cockpit. As a result, the back of my cockpit is 3 feet and 11 1/2 inches forward of the stern tip, which is also where the center deck panels meet the stern deck panel. Cut just inside the cockpit line on the deck to allow for trimming down to the cockpit coaming when it is attached later. You may also want to leave thigh braces when cutting the cockpit on the deck. The deck area on the center panels in front of the cockpit is peaked. This peak is formed by pulling up the center of the 2 center panels at the front of the cockpit and filling the gap formed in the peaked deck with a strip of 4 mm plywood that is trimmed to fit.
The assembly of the deck peak can be done on a flat surface or on the hull. If the assembly is done on the floor, place pieces of scrap wood under parts of the deck to roughly follow the curve of the sheer in the hull. For a depth of 10 inches at the front of the cockpit, a 2 3/4 inch long piece of wood is used to raise the center of the center panels at the front of the cockpit. Place weights on the deck as needed to prevent distortion of the deck. Trim a piece of plywood to fit in the gap caused by the peak in the deck. Epoxy this trimmed piece in the deck. Once the epoxy has hardened, reinforce the topside of the peak with fiberglass tape. Then turn the deck upside down and reinforce the underside of the peak with fiberglass tape. Now is also the time for reinforcing the underside of the deck with fiberglass as desired. Before doing so, use scraps wood to allow the sheer of the deck to curve approximately as it would on the hull. Attaching the Deck to the HullPlace the deck on the hull, and make sure that the deck is centered on the hull. Beginning at the bow and alternating sides, drill holes through the hull and deck as close to the sheer as possible and wire the deck to the hull. Using thickened epoxy, fill the outside of the sheer seams to glue the deck to the hull. Pull out the wires after the epoxy has hardened but is not fully cured. Use more thickened epoxy to fill the voids where the wires where removed. Then file and sand the sheer smooth and fair with the hull and deck. Fillet the inside sheer seams and reinforce them with 2 inch fiberglass tape. To make applying the tape easier, cut the hatch holes so you can reach through them. The tape doesn't need to be applied all the way to the ends. As far as you can reach is good enough. Roll up the length of tape you need, and soak it is a plastic cup of epoxy to wet it out. Remove the excess epoxy by drawing the tape between two fingers. Roll up the tape again and then unroll along the inside seam. Fiberglass the deck and sheer. Using sheer clamps to attach the deck to the hull doesn't work for this design, because they prevent the top of the side panels from being flexible enough to match the outline shape of the deck. The CockpitThe coaming spacer is cut from ¾ inch, 5 layer, hardwood plywood, and the coaming lip is cut from the 4 mm plywood. Use your cockpit template to draw the inside lines for the spacer and lip. The spacer should be about ¾ inches wide, and the lip should be about 1 ¾ inches wide. Cut the spacer and lip so that they are one piece each, with a thin cut down the front center of each to allow for the peaked deck. Epoxy the spacer to the deck, using clamps to hold it down until the epoxy has cured. Then epoxy the lip to the spacer, using clamps to hold the lip down until the epoxy has cured.
Fill the gap at the front of the spacer and lip with a trimmed to fit piece of ¾ inch hardwood plywood and several trimmed layers of 4 mm plywood, which allow for rounding off the top of the lip at the front of the coaming.
Reinforce the coaming with fiberglass as desired. The Point Bennett Sea Kayak This page © Copyright 2007, Duane Strosaker. All rights reserved. |
