Introduction: How to Make a Chambered Wooden Surfboard
So I have been making surfboards as a hobby for several years with over 10 boards shaped. They were all foam, either XPS or EPS foam, (Check out my other Instructables). I was up for a challenge and I wanted to try my hand at making a wooden surfboard. There are two main types of wooden surfboards: hollow wooden surfboard and chambered wooden surfboard. Another option was to fake it and cover a foam core with wooden veneer.
After some contemplation and research I decided to make a wooden chambered surfboard. My reasoning is I wanted to make it completely from scratch and with no computer aided design. A hollow wooden board is more complicated to make as you need to design it on a computer first, cut out a frame and then skin it with wood. A wooden chambered surfboard can be completely made with no reliance on computers.
This build took place over the course of several months and I think the final result is outstanding for lumber purchased at Home Depot (more on this later).
So lets dive into this, even if you don't want to build a wooden surfboard, this process is very interesting so enjoy! Grab a coffee and some cookies as this is going to take a while.
Also I am entering this Instructable in the wood contest so if you like this, please vote for me.
Note: I will be including videos for some of the steps and eventually all of the steps but it will take me several more months of editing before I get around to finishing all the videos but pictures and a complete write up is included. This was a lengthy endeavour to document.
Step 1: Surfboard Design and Template
So what type of surfboard to make, I have a quiver of surfboards but what I was lacking is a nice small wave board. I went with a "groveler" type surfboard, a board suited to smaller waves but still can be used in larger conditions. I looked at a number of boards and then designed my own. I asked "Blending Curves" to make me a custom template based on my criteria. They will make you a custom surfboard template but also their website has tons of ready to print surfboard outlines. In the past I have designed surfboards based on pictures, existing surfboards I ride and like or just free handed one directly on the surfboard blank.
The dimensions was going to be 6' X 22 1/2 wide and 3" thick at the center. The board will be nice and thick to provide a nice amount of float but the rails will be thinned out so they can dig in to let the board hold when the conditions are bigger. Some considerations I had to take into account is I surf in cold water so I have to factor in a heavy wetsuit as well. When designing a surfboard board it's a bunch of compromises. When you change one part of the board it can positively or negatively or neutrally affect the surfboard performance. Finding the balance of what you want is dependent on the individual. My design will be different from another surfer, so keep those points in mind when designing your surfboard.
Surfboard design could be discussed ad naseum but key to remember is to keep the lines of the surfboard smooth and even. If the board looks odd or has weird lines then it probably has something off with it. An example is I once shaped a board that had really thick nose, tail and rails, what ended up happening for that surfboard is the board was very "corky". It makes it hard to catch a waves since you can't "fall" into the wave. You end up floating on top of the wave but never riding down into the wave, it sounds odd to describe but trust me, it was terrible at catching waves, I thought it would be a wave catching machine because I shaped it nice and thick. So lesson learned: it's ok to experiment but doing extreme things can not have the intended results.
Step 2: Materials and Tools
I'll try to list out all the materials I used but I may have left some things out. Also I purchase all my surf supplies from:
Awesome place to deal with and that is my affiliate link with them, tell them I sent you.
- 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 oz Fiberglass cloth
- Wood Screws
- Waterproof wood glue or polyurethane glue
- Super glue
- Surfboard leash plug
- Surfboard vent plug
- Fin boxes
- Automotive clear coat polish
The following are the tools I used but certainly these are not the only tools that can be used to make a wooden surfboard.
- Belt Sander
- Hand Power Planer
- Random Orbital Sander
- Router with bushing kit
- Sanding Pads
- Sanding block
- 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 3: 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 what I like to do is design one from the Clark foam catalogue. Clark Foam has been out of business for years now but you can still find the catalogue if you do a Google search for it. I find a template that I like in the catalogue and then I transpose the measurements of the rocker profile to a piece of thin plywood. I make my stringers usually from 3/16" - 1/4" plywood, but any thin wood will work. I connect the points using a dowel so I have a rough shape.
The stringer is then cut out and shaped to roughly to the profile I want, sometimes I will make two stringers at the same time so I can have an extra one. This can be done easily by using some double side carpet tape to hold two pieces of wood together. Write on the stringer what dimensions it is and what it will be used for, I have a collection of them so later on when I want to make another board that is similar or I can just trace out one.
Check out the video:
Step 4: Lumber / Wood
From all the research I did the best wood to use is Paulownia wood for a chambered wooden surfboard. However it's not indigenous to my area so I am using the most readily available lumber to me: SPF, Spruce, Pine and Fir. SPF is sold at all home building suppliers and is used for construction. It's relatively inexpensive, easy to obtain and very strong for it's weight and dent resistant, the disadvantages is the wood is denser than Paulownia so it's heavy even when dried.
I purchased 2x6 SPF construction lumber and let it season (i.e. dry out) for a several weeks. When sorting through the wood at the building supply I picked from bundles that were 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 I clamped all the pieces in one large block so as it dried it would all "warp" in the same rate.
After the drying period, I noticed that the wood was still very straight, so either I got lucky or my method paid off, regardless this saves a lot of aggravation later. Ideally running each piece of lumber thought a thickness planer would remove any cupping or minor warping (next time).
Also I included three stringers that were made from red cedar fence boards. I noticed that cedar is not as dense as the SPF, making a board completely from cedar would be nice too but expensive.
Step 5: Making a Wooden Blank
Ok so lets get to making the blank, the first step is to trace out the stringer template on each piece of lumber. I tried to keep the order of the lumber the same so if there was any warping the pieces of wood would fit together similarly (hopefully). When tracing out the template I made sure to look for parts of the lumber that had the least amount of knots and inclusions. When tracing out the template the ends of the stringer (nose and tail) were extended to the ends of the lumber and also the mid point was marked. The reason for this is it makes lining up the templated lumber easier and ensures everything will be square.
After tracing, using a jigsaw each piece of lumber was cut to shape. A bit of a gap was left between the blade and line so there would 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. See the pictures or video as it becomes clear once viewed instead of reading about it.
Next is to screw the templated lumber together to create a rough blank. This requires some thought and planning as I made a mistake and ended up with a few screws protruding out one of the boards, not a big deal since the lumber I am using has a lot of knots and different variations in color but if you were using more homogeneous or expensive wood I could see it would be a bit disappointing.
The pieces of templated lumber were lined up and clamped together temporarily so the paper surfboard template could be traced out onto the block of lumber. I lined up the mid-point line and the lines at the nose and tail ends of the lumber. Before tracing out the template there were a few high bumps so I used a hand power planer to level those areas.
I started by screwing from the middle stringer outward on one side and then the other side. Then the two pieces at 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 out stringer (in the middle part is best). If the screws are too close to the bottom or top, you run the risk of shaping into it especially when shaping near the rails. Pay attention near where the traced out template is, keep at least 1" away from those areas with the tip of the screw. I needed a few different lengths of screws to do accomplish this.
Once the two halves have been screwed together, I used used a few dabs or lines of glue to hold the two halves together. Do not use too much glue or you run the risk of not being able to take it apart later, this is only a temporary glue joint. Clamping was 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. I started by using my power planer and flattening the bottom of the blank. You want to get the bottom as flat as possible, remove the wood so the left and right sides of the stringer template match up. I should mention that it is important to level your stands so when you are shaping you can use a level to check that the deck of the board is level. When levelling the deck of the blank make sure check for evenness with a level.
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.
This is what a rough foam blank would be like if you purchased one, except this one weights 10 times more!
Step 6: Shaping the Rail Bands and Foiling a Surfboard
So here comes the fun part and where the surfboard really starts taking shape. For this this part I will explain my method of shaping the surfboard but some people freestyle and shape as they go. If this is your first surfboard I recommend drawing out some lines as guides like I do.
Starting with how you want 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 then you can design your own.
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 are determined by the type of rail you want to shape. I highly recommend heading over to www.greenlightsurfsupply.com (affiliate link) and grabbing their PDFs for examples on how to mark the rails.
For my board I am marking the top of the board at the middle at 2" and 4" from the edge of the blank. For 1 foot from the nose I marked it at 1 1/5" and 3" from the edge of the blank. For 1 foot from the tail I marked it at 1 3/4" and 3 1/8" from the edge of the blank. Then the marks are connected using a wooden dowel as a guide, I like using a dowel because it's nice and flexible.
On the bottom edge of the board and side the "tuck" of the board was marked for this I marked 1/4" on both but leaving the last 18" of the board with a hard edge.
Now we removed the first railband which is the material between the 1st rail mark and side mark. I used the hand power planer and then sanded it flat.
Once the first band of material is removed, then I marked the mid point between the second rail mark and connect the marks with a line using the dowel as before. Then this second railband, was removed using the power planer and belt sander.
Lastly the 1/4" tuck on the bottom edge of the board was removed 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. We want to blend them all together. Using a belt sander and long even passes the hard edges were brought down. I used a 60 grit belts to really remove material quickly. Try to count how many passes you do on one side and repeat on the other side. Also now is the time to thin out the blank if it's too thick. Just roughly shape the board until it's 90% to the shape you want. After chambering the board and putting it back together we need to do final shaping so leave a little extra material so that can be done later.
I'm keeping the bottom of the surfboard flat, mostly because I like a flatter bottom surfboard for speed, but now is the time to shape in a concave or any other type of bottom you want.
Step 7: Fin System
I am installing fin boxes for the fin system on this board, I went with Futures Fins and a 5 fin set up for maximum flexibility. The fins will be installed later but I needed to make sure to mark out where the fin boxes will go so I know where to leave some wood when chambering so the fin boxes can be routered in later. Marking the location of the boxes can be done with just a ruler and measuring tape but I use a tool called a Versa square (Greenlightsurfsupply sells them) that can speed up the process.
To mark out the fin boxes I used a template guide from Greenlightsurfsupply (affiliate link and you might need to create an account to access the info). There are many different variation on fin placement but I installed the tail fin 3.5" up from the tail. The side bites were installed at 7" from the rail (rear of the fin), 1 1/4" in from the rail with a fin toe in of 1/8". The full side fins were place at 12" (rear of the fin), 1 1/4" in from the rail with a toe in of 3/16".
The fin boxes were marked before chambering, they will need to be remarked after sanding.
Step 8: Chambering and Glueing the Surfboard
Ok now we have to take the surfboard apart so we can chamber it. What chambering is cutting out large holes in the center of the board in a staggered fashion to remove weight but still maintaining structural integrity.
A consideration is to try and keep the walls as thin as possible without sacrificing structural integrity, specifically for heel dents on the deck which is where the board will take most of the punishment. Since I will be fiberglassing the board after it's shaped I'm not as worried about the board thickness being too thin. Since I am using SPF wood, it's pretty strong as is.
First thing is to put a long board 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, I used a combination square set to 1/4" for the wall thickness, this gives lots of thickness and allow some variance when doing the final sanding. Marking the outside of the piece of the surfboard, I made the chambers about 12" each, with the ones near the nose and tail of the board being closer together. I had no hard and fast rules but I did make sure to stagger each piece of the board so when the board is glued back together it's one contiguous hollow chamber. Also I made sure to leave wood in the areas where the fin boxes were installed.
For the type of glue I used water resistant wood glue, since I will be glassing the board I'm not entirely concerned with it being 100% waterproof glue. What I like is I can glue multiple pieces together in the same day.
I glued each piece one by one and used a board between the clamp and surfboard, once the surfboard was too wide for my clamps I switched to using ratchet straps. Ratchet straps make awesome clamps for items that are either too large for clamps or are awkward shapes.
For the outer most edges of the board, I used a router to remove as much material as possible. Then used a rasp to grind away as much material in the corners of the pieces.
Step 9: Final Shaping After Chambering and Glueing
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. I used the belt sander to sand away all the glue and levelled out the bottom of the board (if you shaped in a different bottom then adjust accordingly). I had about 1/4" to play with so I tried to removed as much material with out sacrificing the strength of the board to keep it light.
For the top of the board I rounded off the rails and the dome of the deck. Once it was close to the final shape I switched to a random orbital sander and went over the whole board with 80 grit. Shaping all the rounded contours like the nose of the board, I switched to hand sanding with a block. Then to smooth out all the rails I hand sanded using piece of sand paper folded over. Usually when shaping foam surfboards you can "screen" the rails but in this case I just had to make the best of it using sand paper by hand.
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 I suggest to make your own filler using fine saw dust and super glue. Super glue and the saw dust will mix to make a nice match to knots of the surfboard. Also the filler will age with the rest of the board and darken over time just like real wood. You'll fine that light looking filler will stand out way more than dark filler. Once the holes and voids are filled sand and blend into the rest of the board.
Step 10: Installing the Fin Boxes
Since I am installing Futures Fin boxes, these fin boxes need to installed before the glassing of the surfboard. There is a template kit that is used to installed these types of fin boxes but it's super expensive. I used to just trace out the top and bottom of the fin box, router it by hand by adjusting the depth of the router bit. For this build I made my own wooden templates and used a bushing kit in my router, the process is very similar to making inlays in wood working. That way it was repeatable and consistent.
Since the board was sanded after the initial marking of the fin boxes we need to remark the location of the fin boxes.
Using a wooden template, router with bushing guide and a 1/4" single flute router bit, the first part of the fin box was routered. I find it easier to do multiple passes increasing in depth with each pass. I made a depth guide from wood as well to see what the idea depth for the fin box would be. For the larger flange of the fin box was routered out with a second template.
You want the top of the fin box to just sit slightly above the surface of the surfboard, this is so it can be sanded open after glassing and hotcoating at a later step.
Once I was happy with the placement and depth I mixed up some epoxy and set the fin boxes in with the fins installed, if the fin boxes didn't stay seated I taped them down, let the epoxy set then remove the fins.
The last thing to do is take some masking tape cover over the opens of the fin boxes and screw holes, fiberglass will be applied over the finboxes, they will be sanded back open later.
Step 11: Fiberglassing the Bottom
Glassing, fiberglassing, laminating, all three of these terms mean the same thing: applying a layer of fiberglass and epoxy resin to the surfboard. Since this is a wooden board, I could probably get away with just applying a sealer, varnish or epoxy directly on the wood and go surf it. I opted to fiberglass the board as it adds an incredible amount of strength and durability. The glassing takes place in two steps, first the bottom is fiberglass and then the board is flipped and the deck is glassed.
The fiberglass weight I will be using is 6 oz fiberglass cloth, that means for every square foot of fiberglass it weights 6 ozs. I probably could go as low as 4 oz cloth since this is a wooden board and inherently has strength unlike a foam surfboard.
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 layed 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, my preferred method is to do a cut lap for all my surfboards. Finally the cutlap is sanded to feather into the rest of the board.
Glassing the Surfboard Bottom
I started by applying tape to the rail of the surfboard where I wanted my 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 I 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. I laid down some thick plastic sheet to the floor, this is to catch any epoxy during the glassing and hotcoating.
Next is to mix up the resin, the resin I use is epoxy resin, specifically Resin Research, an epoxy that is very clear unlike a lot of boat building resins. This entire process could be done with polyester resin as well but I like using epoxy because it is low VOC and is stronger than polyester resin. When working with epoxy you can either measure it by volume for weight it. My preferred method is weighting it as I think it is a much more accurate method and you don't need graduated measuring containers.
- Get a cheap digital kitchen scale and save yogurt or similar containers.
- Read the epoxy manufacturers directions, it will give you direction on the mixing ratios.
- Use only good quality masking tape.
- Only work with epoxy resin when the temp is above 15C 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 you will need 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, I found 80 grams of total mixed resin per linear foot of surfboard is a good starting point for a single layer of 6 oz 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. Work around 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. You want 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 12: 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, we are going to do a cut lap, apply tape just under where the previous cutlap 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 cutlap and feather it into the previous layer of fiberglass, I can't stress enough how important it is to do a good job here, make sure there are no big bumps. Check the board over and sand down any odd bumps of epoxy or fiberglass.
Step 13: Hotcoating the Deck and Bottom
The hotcoat is a layer of epoxy that will be apply 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 at least 15C 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 you are hotcoating in the same area as you 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 allow for a nice clean hotcoat 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 I added some additive F to the epoxy, this is an agent that helps reduce fish eyes and makes the hot coat better, trust me this stuff works.
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 your way 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, sometimes the more you mess with it the more you can screw up the hotcoat.
After a few hours come back and check the board, when the epoxy is tack free, the masking tape was pulled. Let the surfboard sit and harden.
Once the deck hotcoat is hardened, flip the surfboard and then apply a layer of masking tape just below where the previous tape line was, maybe 1 mm 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 hotcoat, mix and apply epoxy just like the deck hotcoat. Pull the tape once the epoxy has become tack free. Let harden.
Step 14: Installing the Leash Plug and Vent Plug
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 delaminations or bubbles appearing on the board.
The vent plug that I am using is actually dual purpose, there is a built in Gore-Tex membrane that will automatically vent the surfboard and also the plug can be unscrewed so you can vent the surfboard manually.
I made sure to think ahead when chambering the board to route a path to the rear of the board so the entire board could be vented with one plug.
To install the vent plug a hole was drilled 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. I used some epoxy putty to seat the vent into the surfboard first. Then I can fill in the rest of the empty space for the vent with liquid epoxy.
The surfboard needs a leash plug so a leash can be attached and I installed this the same time as the vent plug when working with the liquid epoxy.
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. I'm going to install the leash plug after glassing. Where the leash plug was going to be installed I did 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 15: 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 you awesome results if you take your time. To sand a surfboard, you 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 you are going to make surfboards regularly I'd recommend getting one. I am going to use one just to speed up the process of sanding so I can flatten bottom and the high spots of the board, then I am going to switch over to a random orbital sander.
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 I'd recommend switching over to a rougher grit of sand paper. Once the surfaces seem flat and even, switch to 150 grit and subsequent finer grits all the way up to 220 grit. When sanding do 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.
Don't sand the rails with power sanders, hand sand those if you are not use to building surfboards because you can burn right through the hotcoat in a hurry if you stay 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, this is where we left extra epoxy earlier. 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 16: Glosscoat
I did a second hotcoat, also called a glosscoat, this gives an extra layer of epoxy to do the final sanding and polishing.
Alternatively I was going to use some spar vanish to coat the surfboard but I opted to do a second hotcoat because, varnish takes way too long to harden to a point where it won't scratch easily. (I did some testing)
The glosscoat is completely exactly the same as the hotcoat, 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 I installed the vent and leash plug, I taped 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 afterwards.
Step 17: Final Sanding
Once the glosscoat has set up and hardened, the board should be looking super shiny and level, you'll 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.
Even tho the surfboard looks super shiny and smooth, it's not a professional looking job until we hit it 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 sand paper 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 you might sand into the fiberglass weave. Use a spray bottle with water to wet down the areas to be sanded it helps remove the sanded material and keeps the fine sand paper 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 I hand sand using a 3M 1/3 sheet sander used for automotive body work, 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 you are sanding but don't soak the board, you 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 sand paper doesn't seem to be cutting as quickly change it, you can tell you need to change it when the water doesn't seem as cloudy since there are less cut material suspended in the water.
If you 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, you may need to cut them with a razor blade to open them up. Also I used 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 18: Polishing and Finished Board
By the time the surfboard is sanded to 1200 grit, the board should start getting some of it's shine back, if you like you can sand it with 1500, 2000 grits but found 1200 was good enough because the polishing compound I have will remove scratches 1200 grit and up. I'm using Norton Liquid Ice polishing compound that is used for polishing automotive clear coat but any good quality compound will work.
So 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 repeat 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! I can't believe how well it came out for my first wooden surfboard, this was such a fun project to build. This build totally exceeded my expectations!
Install the fins and time to go surfing!
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