Category: Lower Extremity

How to Make a Chambered Wooden Surfboard

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How to Make a Chambered Wooden Surfboard is a do it yourself product designed for those individuals with cardiovascular and upper extremity disabilities to create.

Technical Specifications: 

Step One: Surfboard Design and Template.

  • Decide what type of surfboard to make. (This example is a chambered surfboard design.)
  • This design is 6 feet length X 22 1/2 width and 3 inches thick at the center.

Step Two: Gather materials.

  • SPF wood, which in North America is regular construction lumber.
  • Cedar fence boards.
  • Epoxy resin - one with UV blockers and completely clear, Resin Research is the best IMO.
  • 6-ounce Fiberglass cloth.
  • Wood Screws.
  • Waterproof wood glue or polyurethane glue.
  • Super glue.
  • Surfboard leash plug.
  • Surfboard vent plug.
  • Fin boxes.
  • Automotive clear coat polish.


  • Jigsaw.
  • Belt Sander.
  • Hand Power Planer.
  • Random Orbital Sander.
  • Router with bushing kit.
  • Polisher/Sander.
  • Sanding Pads.
  • Sandpaper.
  • Sanding block.
  • Drill.
  • Various drill bits.
  •  Wood Rasp or power file or rotary tool.
  •  Digital Scale.
  •  Mixing containers for epoxy.
  •  Surfboard stands.
  •  Wool and foam buffing pads for polisher.

Step Three: Making a Surfboard Stringer.

  • The stringer will determine the rocker of the surfboard. The rocker is the bottom curvature of the surfboard from the nose to the tail that will determine how the water flows under the board, ideally, it is shaped so it fits the curve of the wave face. This isn't a guide on how to design a surfboard, more of a technical how to.
  • There are a few different ways to design a stringer, one way is to trace out an existing board, create one in CAD, vector drawing software or similar design program or design one from the Clark foam catalog. Clark Foam has been out of business for years now but users can still find the catalogue if they do a Google search.
  • Transpose the measurements of the rocker profile to a piece of thin plywood. Make stringers usually from 3/16 - ¼-inch plywood, but any thin wood will work.
  • Connect the points using a dowel so the user has a rough shape.

Step Four: Lumber / Wood.

  • Use 2 x 6 SPF construction lumber and let it season (i.e. dry out) for several weeks. When sorting through the wood at the building supply store, pick from bundles stacked tightly, this makes finding straight and true pieces easier.
  • Usually, construction lumber is in varying degrees of dryness and the issue is as moisture leaves the wood, depending on how the wood is cut and the number of knots, the wood will warp, twist, cup or crown in varying degrees. To help mitigate this clamp all the pieces in one large block so as it dried it would all "warp" in the same rate.
  • Ideally, running each piece of lumber through a thickness planer would remove any cupping or minor warping (for future notice).
  • Also, include three stringers made from red cedar fence boards.
  • Note: Cedar is not as dense as the SPF, so making a board completely from cedar would be nice too but expensive.

Step Five: Making a Wooden Blank.

  • The first step is to trace out the stringer template on each piece of lumber. Try to keep the order of the lumber the same so if there is any warping the pieces of wood will still fit together similarly. When tracing out the template make sure to look for parts of the lumber that have the least number of knots and inclusions. When tracing out the template the ends of the stringer (nose and tail) are extended to the ends of the lumber and also the mid-point is marked. The reason for this is it makes lining up the templated lumber easier and ensures everything will be square.
  • After tracing, cut the lumber to shape using the jigsaw. A bit of a gap may be left between the blade and line so there can be extra wood to make up for any variations between each template. Square up the ends of the boards and then using a combination square extend the stringer template lines across the end grain of the lumber.
  • Next is to screw the templated lumber together to create a rough blank. This requires some thought and planning.
  • The pieces of templated lumber are then lined up and clamped together temporarily so the paper surfboard template can be traced out onto the block of lumber. Line up the mid-point line and the lines at the nose and tail ends of the lumber.
  • Start by screwing from the middle stringer outward on one side and then the other side. Then the two pieces can be glued together at the stringer with a tiny bit of wood glue. The reason for this is so the screw heads will be hidden and it avoids any large holes if were just to screw the lumber together starting from one side to the other. The screw heads have to show at either the left most or right most piece of lumber.
  • When screwing the boards together try to keep the screws between the top and bottom of the traced stringer (in the middle part is best). If the screws are too close to the bottom or top, the user can run the risk of shaping into it especially when shaping near the rails. Pay attention near where the traced template is, keep at least 1 inch away from those areas with the tip of the screw.
  • Once the two halves have been screwed together, use a few dabs or lines of glue to hold the two halves together. Do not use too much glue or the user can run the risk of not being able to take it apart later, this is only a temporary glue joint. Clamping is accomplished by using a few bar clamps and some ratchet straps. Ratchet straps are a very cost-effective way to clamp large objects.
  • Once the glue sets, it's time to start shaping. Start by using a power planer and flattening the bottom of the blank. The user wants to get the bottom as flat as possible, remove the wood so the left and right sides of the stringer template match up.
  • Note: It is important to level the stands so when the user is shaping.
  • When removing material around the deck of the nose, it is necessary to turn the hand power planer so it runs crosswise against the pieces of lumber. Once the blank is flattened and squared, re-trace the template onto the blank. Then using a jigsaw with a long blade cut out around the template. Clean up the edges of the blank with the power planer.

Step Six: Shaping the Rail Bands and Foiling a Surfboard.

  • Note: It is recommended to draw lines as a guide.
  • Starting with how the user wants the surfboard to perform will dictate the type of rail. Rail design is a very in depth and would take an Instructable equally as long if not longer than this one to cover. But the basics are easy to follow and customizable.
  • First make perpendicular lines on the surfboard at 1 foot from the nose, 1 foot from the tail and at the middle. The basics of designing the rails is to then mark 2 lines on the deck of the blank and two lines on the side of the board. The placement of the lines is determined by the type of rail the user wants to shape.
  • For this board, marks are made at the middle and top at 2 inches and 4 inches from the edge of the blank. For 1 foot from the nose, a mark is made at 1 1/5 inches and 3 inches from the edge of the blank. For 1 foot from the tail, I marked it at 1 ¾ inch and 3 1/8 inches from the edge of the blank. Then the marks are connected using a wooden dowel as a guide because it's nice and flexible.
  • On the bottom edge of the board and side, the "tuck" of the board was marked for this at ¼ inches on both but leaving the last 18 inches of the board with a hard edge.
  • Now for the making of this board, remove the first railband which is the material between the 1st rail mark and side mark. Use the hand power planer and then sand it flat.
  • Once the first band of material is removed, then mark the mid-point between the second rail mark and connect the marks with a line using the dowel as before. Then this second railband, remove using the power planer and belt sander.
  • Lastly, the ¼ inch tuck on the bottom edge of the board, remove with a random orbital sander.
  • Now it's time to foil the blank to round off all the hard edges from the previous railbands that were removed. Blend them all together. Using a belt sander and long even passes the hard edges are brought down.

Step Seven: Fin System.

  • The fin boxes are marked before chambering, they will need to be remarked after sanding.
  • Step Eight: Chambering and Gluing the Surfboard.
  • First thing is to put a longboard underneath the middle stringer of the surfboard and supporting the rocker with shims, then clamp it down on a work surface. Tighten down the clamps and cut along the stringer glue line. Eventually, the board will break apart, start taking the screws out to take the board apart. Chamber each piece of the surfboard one by one, this will minimize warping issues.
  • To chamber, use a combination square set to a ¼ inch for the wall thickness, this gives it enough thickness and allows some variance when doing the final sanding. Marking the outside of the piece of the surfboard, make the chambers about 12 inches each, with the ones near the nose and tail of the board being closer together.
  • Note: Water resistant glue works best.
  • For the outer most edges of the board, use a router to remove as much material as possible. Then use a rasp to grind away as much material in the corners of the pieces.

Step Nine: Final Shaping After Chambering and Gluing.

  • Once the surfboard is glued back together, it will weight significantly lighter. Now it's time to remove all the excess glue and do the final shaping of the surfboard. Use the belt sander to sand away all the glue and level out the bottom of the board.
  • For the top of the board, round off the rails and the dome of the deck. Once it is close to the final shape switch to a random orbital sander and go over the whole board with 80 grit. Shaping all the rounded contours like the nose of the board, switch to hand sanding with a block. Then to smooth out all the rails, hand sand using a piece of sandpaper folded over.
  • Note: If the surfboard has any holes or voids that need filling, now is the time to do it. It's tempting to use store bought wood filler, but make adjustments to the user’s preference.

 Step Ten: Installing the Fin Boxes.

  • Note: Since the board was sanded after the initial marking of the fin boxes, the user needs to remark the location of the fin boxes.
  • Using a wooden template, the router with bushing guide and a ¼ inch single flute router bit, the first part of the fin box is reuttered. Once happy with the placement and depth mix up some epoxy and set the fin boxes in with the fins installed, if the fin boxes don't stay seated tape them down, let the epoxy set, then remove the fins.
  • The last thing to do is take some masking tape cover over the openings of the fin boxes and screw holes, fiberglass will be applied over the finboxes later.

 Step Eleven: Fiberglassing the Bottom.

  • Notes:
  • Glassing, fiberglassing, laminating, all three of these terms mean the same thing.
  • The fiberglass weight used to make this product is 6-ounce fiberglass cloth, that means for every square foot of fiberglass it weighs 6 ounces.
  • Since the surfboard will be glassed in two stages (bottom and deck) there will be an overlap where the fiberglass meets. There are two ways in dealing with this overlap, with a free lap or cut lap. A free lap is where the fiberglass is left free and is laminated directly to the board and once set is sanded to feather it into the board. A cut is lap is where a layer of masking tape is laid down on the board and the fiberglass is laminated over the tape. Once the epoxy is set, using a sharp razor or hobby knife, the fiberglass over the tape line is cut and then the tape is pulled off and with it the fiberglass as well. This leaves a nice clean line that is easy to sand.

Step Twelve: Glassing the Surfboard Bottom.

  • Apply tape to the rail of the surfboard where the user wants to cut lap, then rolling out the fiberglass cloth onto the bottom of the surfboard, then cutting around the board leaving the fiberglass so it overlaps the tape but not so much that it hits the deck of the surfboard. Then make relief cuts around the tail and the nose of the surfboard so there will be no creases when laminating. Keep the excess fiberglass scraps and cut them into pieces, these can be used to clean up excess epoxy later. Lay down some thick plastic sheet to the floor, this is to catch any epoxy during the glassing and hot coating.
  • Next is to mix up the resin, the resin. When working with epoxy you can either measure it by volume for weight it.
  • Tips:
  • Get a cheap digital kitchen scale and save yogurt or similar containers.
  • Read the epoxy manufacturer’s directions, it will give direction on the mixing ratios.
  • Use only good quality masking tape.
  • Only work with epoxy resin when the temp is above 15 degrees Celcius and the surfboard is at that temperature too. Or else the resin will be too viscous and hard to spread.
  • To determine how much total mixed epoxy resin needed for glassing depends on how big the board is, the shape of the board, the type of fiberglass and layers of fiberglass. As a general guideline, 80 grams of total mixed resin per linear foot of surfboard is a good starting point for a single layer of 6-ounce fiberglass cloth.
  • Grab a pair of disposable gloves, put on a respirator (epoxy hardener does have some VOCs) and set aside a plastic spreader. Using a digital scale and weight out the epoxy resin, then add the proper amount of hardener. Using a flat mixing stick, mix the epoxy well, scraping the sides and bottom, but do not whip the mixture as that will add air bubbles into the epoxy.
  • Once the epoxy is mixed, pour the entire contents onto the board in a long stream along the length of the stringer. Using the plastic spreader move the epoxy around giving it time to soak into the fiberglass. Spread the epoxy all over the board but avoid the rails until the main part of the board is covered and transparent. Then move resin out to the rails and let it soak in, using your other hand hold the fiberglass and use the spreader to saturate the fiberglass. Go back to the main body of the board and start "scraping" out some of the resin, not so much that it leaves the fiberglass dry but no so much that the resin pools, you want to be able to slightly see the weave of the fiberglass.
  • After the rails of the fiberglass has time to soak in, it's time to wrap the rails starting from the middle of the board, take the plastic scraper and fold over the fiberglass onto the masking tape. If any strands of fiberglass become loose and fray from the edge, cut off the excess with a pair of scissors. Using fiberglass scraps wipe off the plastic spreader to get rid of any excess epoxy. Workaround the main sections of the board then fold over the nose and tail relief cuts at the end. Look over the board to make sure that there are no loose areas of fiberglass, let it harden for a few hours.
  • Come back after a few hours, depending on the temperature will affect how quickly the epoxy sets up. The user wants the epoxy to be set up so that it is tack free, then cut the fiberglass around where the tape line is, then pull the tape and fiberglass off. Let the epoxy harden then sand the cut lap so it feathers into the surfboard, including the nose and tail relief cuts. The better the feather the better the glassing job will turn out. Also, from now on only touch the surfboard with gloved hands, this is to avoid oils from your hand from contaminating the surface.

Step Thirteen: Fiberglassing the Surfboard Deck.

  • With gloved hands, flip the surfboard over and wipe down the areas that were sanded with some denatured alcohol or acetone. Very similar to glassing the bottom, the user is going to do a cut lap, apply tape just under where the previous cut-lap was done. Sometimes deck patches are added but not necessary for a wooden surfboard.
  • Layout the fiberglass, trim to the tapeline, add relief cuts at the nose and tail. Mix up the epoxy and apply the epoxy just like for the bottom and let set until tack free, trim then let harden.
  • Then sand the cut-lap and feather it into the previous layer of fiberglass.

Step Fourteen: Hot coating the Deck and Bottom.

  • The hot-coat is a layer of epoxy that will be applied over the fiberglass lamination, it fills up the visible weave of the fiberglass and seals up the surfboard. To get a good hot-coat it is important to apply the epoxy at a minimum of 15 degrees Celsius and ideally at room temperature. Do it in an area with no drafts and ideally a dust free area if possible. Vacuum up as much as dust as possible if the user is hot-coating in the same area as they sand, including the surfboard.
  • Start by wiping down the sanded areas of the surfboard with denatured alcohol and acetone. Then apply a piece of masking tape at the mid-point of the rail, this allows for a nice clean hot-coat line, reduces drips and saves effort when sanding. At the tail of the board, leave the hard edge un-taped.
  • Get a chip brush ready by smashing the bristles into a piece of masking tape to pull out any loose bristles.
  • Mix up some epoxy same as the glassing step but reduce the amount by 1/3 as a rough guideline. Also, add some additive F to the epoxy, this is an agent that helps reduce fish eyes and makes the hot coat better.
  • Pour out the epoxy onto the surfboard and using the chip brush plow the epoxy around on the board, making sure to cover all areas of the board evenly including the rails. Then using long even passes go up and down the surfboard, then using cross strokes go across the board working down from the nose to the tail. Then wipe around the rails with the brush and fill in any missed areas. Look the board over to see if any spots were missed, it should be nice and even. The whole process should only take a few minutes, once done, leave it alone.
  • After a few hours come back and check the board, when the epoxy is tack free, the masking tape is pulled. Let the surfboard sit and harden.
  • Once the deck hot-coat is hardened, flip the surfboard and then apply a layer of masking tape just below where the previous tape line was, maybe 1 millimeter below the other line, so a bit of epoxy is showing. At the tail of the board create a tape dam so some epoxy can collect at the edge of the tail, this will be used later for sanding a nice sharp edge.
  • For the bottom hot-coat, mix and apply epoxy just like the deck hot-coat. Pull the tape once the epoxy has become tack free. Let harden.

Step Fifteen: Installing the Leash Plug and Vent Plug.

  • Vent Plug:
    • Note: It is very important to vent this surfboard because the chambers are filled with air when the temperature changes the air expands and contracts. If the surfboard is not vented then there is no place for the air to go and can end up damaging the surfboard, either with delamination or bubbles appearing on the board.
    • To install the vent plug a hole with a drill and the wood removed because there is a void in the hole that connects to the chambers, roughly sand the vent plug and wipe down with acetone. Use some epoxy putty to seat the vent into the surfboard first. Then fill in the rest of the empty space for the vent with liquid epoxy.
  • Leash Plug:
    • Note: The surfboard needs a leash plug so a leash can be attached and installed. There are a few different types of leash plugs: installed while glassing the surfboard, ones that include an automatic vent and ones installed after glassing. For this example, the user installs the leash plug after glassing. Where the leash plug is going to be installed do not chamber that area of the board.
    • To install the leash plug is simple, drill and router a hole for the leash plug, rough up the leash plug with some sandpaper and wipe down with some acetone, mix up some epoxy (add a thickening agent like Cab-o-sil or some baking soda) and fill the hole with some epoxy, set the leash plug into the hole. Let harden.

Step Sixteen: Sanding the Surfboard.

  • Once the epoxy for the leash and vent plugs have set it's time to sand the board. This step will be dusty and messy but will give the user awesome results if they take their time. To sand a surfboard, they can use a polisher fitted with a sanding pad made specifically for sanding surfboards. This method is quick and provides awesome results but it throws a ton of dust around and if the user is going to make surfboards regularly it is a good idea. For this example, use one just to speed up the process of sanding and so to flatten the bottom and the high spots of the board, then switch over to a random orbital sander.
  • Note: A palm sander is also another option but it will just take longer but it does give excellent results.
  • Start by sanding the whole board with 120 grit sandpaper. Then start flattening out the board, if the finish is still too rough. Once the surfaces seem flat and even, switch to 150 grit and subsequent finer grits all the way up to 220 grit. When sanding does not stay in one spot, move all over the board, this will minimize the risk of sand throughs and keeps the surfaces even and flat.
  • Note: Don't sand the rails with power sanders, hand sand those if the user is not used to building surfboards because they can burn right through the hot-coat in a hurry if the user stays in one spot too long. Blend in the epoxy seam with the rest of the rail.
  • At the tail of the surfboard, sand the bottom and side rail so there is a nice sharp edge. Switch to a random orbital sander if required as it has more control.
  • If there are any places that have sand throughs and need to be touched up with epoxy now is the time to fix up those spots. Or if doing glosscoat then the sand throughs are not an issue as they will be covered up later.

Step Seventeen: Gloss coat.

  • Do a second hot-coat, also called a gloss coat, this gives an extra layer of epoxy to do the final sanding and polishing.
  • Alternatively, use some spar varnish to coat the surfboard but it wasn’t used in this example.
  • The gloss coat is completely exactly the same as the hot coat, just make sure to clean the board off with some denatured alcohol or acetone to remove any grease or oils or you may have problems with fisheyes.
  • Since the user installed vent and leash plug, tape over the holes and cut around to remove the excess tape. This keeps the epoxy out from filling in the holes. They will be opened back up afterward.

Step Eighteen: Final Sanding.

  • Once the gloss coat has set up and hardened, the board should be looking super shiny and level, the user wants to be left with a tape line at the rail and probably some small pieces of dust in the finish, it just happens but not to worry it can be fixed with the final sanding.
  • Note: Even though the surfboard looks super shiny and smooth, it's not a professional looking job until the job is done with some sandpaper. Sanding it will make the surfboard dull but don't worry we'll bring back the shine soon.
  • First using a sanding block and some 320 grit sandpaper sand the tape line until it's blended into the rest of the surfboard but be careful, the rail has the least amount of resin so go easy or the user might sand into the fiberglass weave. Use a spray bottle with water to wet down the areas to be sanded it helps to remove the sanded material and keeps the fine sandpaper from clogging.
  • Once the rail is sanded, sand the whole surfboard, except the rails with a medium sanding pad on the power sander with 320 grit or 400 grit. After that, hand sand using a 3M 1/3 sheet sander used for automotive bodywork, it takes 1/3 of a sheet of sandpaper cut lengthwise and is very comfortable to use. Wet the board with the spray bottle as the user is sanding but don't soak the board, just want the board wet enough so the epoxy resin dust doesn't clog up the sandpaper.
  • When the whole board is wet sanded, move along to the next finer grit 600, 800, 1000, 1200. Every grit from 400 upward is not really removing that much material, all each grit does is remove the scratches from the previous grit of sanding. This will take some time so keep at it and dry the board to see how things are progressing, also if the sandpaper doesn't seem to be cutting as quickly change it, user can tell they need to change it when the water doesn't seem as cloudy since there are less cut material suspended in the water.
  • If the user installed Futures Fin boxes, now is the time to sand them open, also if the fin boxes were set slightly too deep into the board, the user may need to cut them with a razor blade to open them up. For this example, use the razor to cut around the tape for the vent and leash plug to open them back up sand the edges to blend in.

Step Nineteen: Polishing and Finished Board.

  • By the time the surfboard is sanded to 1200 grit, the board should start getting some of its shine back.
  • The board will still have a matte look to it after sanding it, even up to the super finer grits. To bring back a nice high gloss requires the use of some polishing compound and a wool pad fitted to the power sander/polisher. Wet the wood pad with the spray bottle and pour a bit of compound onto the surfboard and polish at low RPMs. Compound the whole board several times.
  • Check the board to make sure it's not heating up and if it dries out, add some water. The wool pad provides the cutting action to remove the 1200 scratches. Clean off the board and check to see how it looks it should be nice and shiny, if it isn't repeated by adding some more compound or if there are deeper scratches go back and wet sand.
  • Once all the scratches are removed, I switch to a foam pad for the final polish, again using some polishing compound and water. At this stage, the surfboard should be super glossy and light should reflect off it beautifully.
  • The surfboard is done, install the fins and time to go.


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How to Make a Chambered Wooden Surfboard NOT DONE