Introduction: How to Make a Home Depot Surfboard


In a previous Instructable I showed you how to make a EPS (expanded polystyrene) surfbaord from start to finish. In this Instructable I continue my journey on surfboard building and will show you how to make a XPS (extruded polystyrene) surfboard from scratch.

I am going to make most of this surfboard with materials you can get at the local building supplies store, except for maybe a few exceptions like the leash plug and epoxy. Also I will try to focus this build to the beginner surfboard builder and not leave out important small details that might otherwise be overlooked by someone who has built a few boards.

You can buy a pre-made surfboard blank but shipping foam blanks or finding them depending on where you are in the world can be difficult and expensive. So an alternative is to make your own surfboard blank* from scratch. A thing to note is EPS and XPS are both foams that will melt if polyester resin (aka fiberglass resin) is used to laminate the board. So epoxy resin must be used to build these types of boards.

The traditional type of surfboards were made with a polyurethane surfboard blank and polyester resin. Some hardcore surfers or traditionalists like the feel or flex of a "poly" surfboard and how it rides. An epoxy surfboard doesn't flex as much and rides slightly different so that is something to keep in mind if that is a concern for you. I personally like the epoxy boards because they don't ding nearly as easy and can be made lighter than a "poly" surfboard. However epoxy boards are more expensive because the raw material is more expensive and there is slightly more labor involved when building one.

I have included instructional videos for each written section.

*a surfboard blank is a piece of foam with a wooden stringer that is in the rough shape of a surfboard that can be then shaped to into a final surfboard.

Also here is a complete playlist of videos building this surfboard:

Step 1: Materials and Tools

These are the materials needed to make the surfboard, I will try not to leave anything out, I also included some affiliate links to them on Amazon:

  • XPS (extruded polystyrene) or EPS (expanded polystyrene)
  • Polyurethane glue
  • Clear epoxy resin (I am using Resin Research)
  • Additive F (epoxy additive)
  • Fiberglass cloth in 6oz weight (6oz per square foot and you can buy this at boat shops or auto shops locally)
  • Waterbased paint
  • Automotive polishing compound

These are the tools I used but not exclusively the only ones that can be used, be creative and find or make your own, I also included some affiliate links to them on Amazon:

  • Surfboard stands or some other work surface (find plans online or look at pics to make one, they are very simple to make, Greenlight Surf Supply has a good set)
  • Ratchet Straps
  • Various Clamps
  • Automotive polisher/sander or Palm Sander
  • Digital Scale
  • Surfoam planer - must have tool
  • Hotwire Foam cutter (optional)
  • Rockwell Oscillating Multi-Tool (Love this tool)
  • Dremel Rotary Tool
  • Compact router
  • Cutout tool
  • Spokeshave
  • Various Grits of Sandpaper (20 to 2000)
  • Masking Tape
  • Some weights (this is to hold the surfboard in place when working on it)
  • Inexpensive paint brushes
  • Mixing containers such as ice cream or yogurt containers
  • Disposable gloves
  • Organic vapor respirator
  • Squeegees (autobody to spread Bondo ones work fine)
  • Rags

Note: I want to mention is a word about safety, when working with fiberglass and epoxy. These are materials that while are generally safe, a few precautions should be taken. When sanding, it's best to keep dust out of the lungs especially fiberglass dust, so keep a respirator on when sanding. When working with epoxy it best to always wear gloves as it can be a skin sensitizer, avoid contact with the skin until it has cured. While rare it can be an irritant and cause rashes in some people and at worst cause allergic reactions.

Step 2: Nomenclature

Here is a list of words with the associated meaning used in this Instructable:

  • Glassing - Applying a layer of fiberglass to the surfboard with epoxy resin
  • Laminating - same as "glassing"
  • Hot Coat - A cost of epoxy resin applied after glassing/laminating
  • Gloss Coat - A coat of epoxy resin applied after the hot coat
  • Delaminate - Fiberglass that separates from surfboard/foam
  • Lap - An overlap of fiberglass cloth

Step 3: Foam Type to Use

There are two types of foam that can be used to make a surfboard from scratch, EPS and XPS. While they have many similarities there are some differences.

EPS - Expanded Polystyrene

Pros: White in color, available at most building supplies and can sometimes be found in large blocks, does not delaminate easily

Cons: Can tear little beads out when shaping, must be vented, absorbs water if surfboard is damaged (open cell foam)

XPS - Extruded Polystyrene

Pros: Doesn't absorb water (closed cell foam), available at most building supplies, shapes and sands easily, does not need venting

Cons: Has a tendency to delaminate, blue or pink in color, found in sheets

I will be making this surfboard from XPS, mainly because the board does not need to be vented but both foams can make an excellent surfboard. I bought my foam from Home Depot and it's the pink construction foam with the Pink Panther.

Step 4: Gluing the Foam Sheets

The XPS foam comes in different thicknesses, I bought one 2" 4' x 8' thick sheet and cut it half to glue together. This will give me a 4" thick blank.

To glue the two pieces together, I used polyurethane glue. Some water was spritz on the foam and the glue was spread all over one sheet. The reason for the water is polyurethane glue cures or is activated with water.

Take the second piece of foam and place it on top of the first with the glue and using some long pieces of wood clamp down the two sides of the foam with clamps.

Next to clamp the middle of the blank use two pieces of wood and place them on the top and bottom of the blank. Using ratchet straps tighten them down against the two pieces of wood. This will provide a lot of pressure to keep the blank clamped while the glue is setting. Let sit over night.

The next day remove the clamps, what was a sheet of foam is now a block.

Step 5: Making a Stringer

A stringer is a piece of wood in the middle of a surfboard, it provides strength and flex to a surfboard. But with epoxy surfboards it's entirely optional but I like having a stringer. To make a stringer there are a few options, trace out an existing board, find a pattern online, draw one in a vector drawing program or my favorite method is to use the Clark Foam catalog.

Before Clark Foam went out of business they had the lions share of the market for surfboard blanks and their catalog was very comprehensive. For each surfboard blank it has a profile for a stringer, I like using these profiles and transposing the numbers to a piece of 3/16" plywood and creating a duplicate stringer.

The type of plywood you use is not all that important, you don't want one too heavy so I like to stick with thinner ones. Flooring plywood is a nice thickness.

Take the numbers from the stringer template and mark them on the plywood, the measurements are in 1' increments. So from the tail measure in 1 foot and then up 2" and make a mark, that will be the bottom of the stringer. Then for the top of the stringer add on to the 2" mark the number on top of it and make a mark. Do this will all the measurements.

Once all the measurements have been marked, use a flexible dowel and connect the lines with a pencil. Have a look at the stringer and make sure it visually looks correct. If it doesn't look right chances are something is off.

Cut the stringer out using a bandsaw or jigsaw, and finish using a spoke shave and sanding block. When sanding down the stringer make sure to use long even strokes, this will keep it looking smooth and even.

It helps to make an extra stringer for reference incase you make another board using the same stringer. If you plan on hotwiring the blank, make an extra 2 stringers. These will be used as guides.

Step 6: Installing the Stringer

Cutting the Foam Block in Half

Next in order to glue the stringer in the blank, the foam needs to split in half. To do this I like using a hotwire as it's quick and easy. There are plans online to make a hotwire cutting or check out my video where I explain how to make one. Or if you don't have a hot wire you can use a hand saw and saw against the wooden template.

Using two pieces of straight wood, clamp them on either side of the foam block at the half way point. Run the hotwire against the two pieces of wood that will serve as the guide. Clean up any high and low spots with a sanding block.

Gluing in the Stringer

I like trace out where the stringer will be glued into the center of the foam on the outer sides of the foam blocks. This step is done so the trace can be used as a reference for hotwiring later. If you are not hotwiring you could skip this step but it does help profiling the blank flat later as you know roughly where to top removing foam.

To glue the stringer in the foam, polyurethane glue was used again, spread it out on the foam and make sure to spritz with water, lay the wooden stringer on the foam and use weights to hold the stringer down. You may need to check on it as sometimes it will slide because the glue hasn't set. Let the glue cure for 24 hours.

Next is to glue the other foam block in place. Again spread glue and spritz with water but this time do it to the wooden stringer. Place the other foam block over the stringer. We need to apply pressure to keep the foam against the stringer. I found the best and most successful way is to place wood on both sides of the foam and use ratchet straps to clamp the whole thing together. This works really well and ensure a gap free glue joint between the stringer and foam.

Step 7: Hotwiring the Blank

Next is to remove the bulk of the foam so the surfboard blank is ready for shaping. I like using a hotwire as it's clean and fast. I have made many surfboards by sanding or grinding away at the bulk foam, it works fine but just takes time.

In the previous step the stringer template was traced on the outside, tape and clamp the extra stringers to both sides of the foam but the placement should be 1/8" higher than the outline. The reason for the extra high placement is in case there was some variance in the measurements, we won't cut into the foam to much and ruin the blank. These will serve as a guide for the hotwire.

Using a bow hotwire like before to cut the foam in half. Run the hotwire against the two stringer guides.

Repeat this on the bottom.

After this step we are left with a surfboard blank that is ready for shaping.

Step 8: Surfboard Templates

Now it is time to decide on a surfboard shape. There are a few different ways to make a surfboard template:

  • Find some free plans online
  • Create one or trace a picture of a surfboard in a vector drawing program
  • Trace an existing surfboard
  • Design your own on the fly

I have a surfboard shape I want to replicate so I will trace out an existing surfboard. The first thing I did was roughly trace out the surfboard on one side of the blank. Then I removed the foam with a saw and surfoam planer or sandpaper until I was happy with the shape. Using some paper I traced out the 1/2 of the surfboard that was just shaped and cut out the paper so I could transpose the shape to the other side of the blank. This ensure a perfectly symmetrical shape.

Remove the foam from the traced out template. When you are remove the foam, make sure you are using long even strokes, don't work away at the foam at any one spot for too long, as the surfboard will turn out "wavy" and bumpy. Use your eye, if it doesn't look even or straight your eye will tell you. It's better to have a surfboard with nice clean lines than one that followed the template perfectly. Chances are is the template was slightly off.

Step 9: Clean Up the Surfboard Blank

After the template has been cut out and the shape of the surfboard looks good, it's time to remove and clean up the deck and bottom of the blank. This is done by using a surfoam, level and sanding blocks.

A quick note about tools for shaping the foam, your best friend will be a Surfoam plane, you can buy special sanding blocks or tools (like the G-Rasp) but the Surfoam is the tool I always come back too. It is inexpensive and removes foam quickly. Other sanding tools that can be used is make one from good quality sand paper and some left over foam.

The last item that I recommend to make is a long sanding block from a piece of wood gluing some super rough sandpaper to it, I like using 20 grit sand paper that is used for flooring sanders. You want this sanding block to be the width of the surfboard. This allows the whole width of the surfboard to be sanded at once, this makes for leveling and evening out the blank very easy.

Other tools that can be used are power sanders or a power planer, I don't recommend these as they are very aggressive at removing foam and until you get a feel for working on the surfboard it's better to go slower.

So now that we know what tools to use, the blank can be leveled and the rest of the foam can be removed that was left over from the hotwiring. We want to level the blank down to the stringer, I like to plane down the middle of the blank first and then using the long block to work down the outer parts of the foam. Do this to the top and bottom of the blank. At this point the blank is looking more like a rough surfboard.

Step 10: Shaping the Board

Thickness and Cleaning Things Up

If you are happy with the thickness of the surfboard then you don't need to do anything else with the thickness. But if you want to thin out the board in places then you will need to use a small planer or spoke-shave to plane down the stringer and then remove the foam. Look at the nose and tail and see if you are happy with the rocker shape if you are not, then reshape it to your liking. I am not going to go into detail for this as this is more of a personal preference.

Make sure the edges of the blank where the rail will go are perpendicular to the rest of the surfboard. You want it to be 90 degrees to the deck and bottom. The squarer things are the better results you will have when shaping the rails and rest of the surfboard.

Shaping Rails

The trickiest part of shaping a surfboard is the rails. I like to mark measurements on the board to do this. I have enough experience that I mostly eye it now and mark it. But Greenlight Surf Supply has a really useful "rail band" marking guide, do a Google search for it (and I'm not sponsored by them).

So what I do is mark the center of the board and measure in from the nose and tail 1 foot and mark. There are a few marks that need to be made that will be guides for shaping the rails. At the middle mark I measure in 4" and 2" on the deck and mark, repeat on the other side.

At the nose I measure in x" and x" on the deck and mark, repeat on the other side. At the rail I measure in x" and x" on the deck and mark. Next it is time to connect the lines together. Using a flexible 1/4" dowel, I weight one end down on the middle of the board and bend to connect the nose at the inner most marks. Then trace the dowel with a marker, don't worry if it isn't perfect, we are just using this as a guide, as long as it doesn't look too odd. You want nice sweeping curves. Repeat and connect the rest of the lines.

On the side of the board the middle was marked at 1 5/8", the nose at x" and tail at x" from the bottom up. Again the lines were joined using the dowel and marker.

The "tuck" (bottom edge of the board) was marked at 3/8" at the nose, middle and tail mark but stopping 20" from the tail. The reason for not marking the length of the surfboard is at the tail you want a hard edge so water can release from the rail of the board. Again connect and mark with a dowel and marker.

What you should have now is a roughly lines marked on the board that will be the basis for where to remove the foam. The first chunk of foam to remove is the outer most lines on the deck. Using a surfoam or sanding block remove the foam until the lines on the deck and side of the board.

After removing the foam, draw a line directly in the middle of the area with the removed foam. This line will be the bottom guide for the next section of foam to remove. Next remove the foam on the deck where the second line and the new line that was just drawn. When removing the foam, make sure to use long even passes, don't scrub at any one spot as you will end up with a uneven and bumpy surfboard.

Do the same for the bottom lines that were drawn for the "tuck". The remaining foam is now looking like a rough surfboard.

Blending the Curves and Rails

After shaping the rails, it's time to smooth the surfboard out. All the hard raised corners need to be smoothed out, using a sanding block or surfoam, run up and down the full length of the surfboard and knock down the edges. Start forming the edges into a curve. Blending the corners into each other. I count the number or passes I do on each side so I can repeat on the opposite side. Look up and down the surfboard and make sure it looks good to your eye, if something looks off, fix it before moving on to the next step. If something looks off chances are the board won't ride correctly. Remember the lines that were drawn earlier are only guides, it's best to use your eye and make sure there are no oddly looking curves or wavy rails.

Fixing up the Glue Joint

Since the surfboard is made from sheets of foam glued together it is possible that the glue joints got damaged or torn from shaping. I like using a drywall compound or hole filler to fix up small patches. You don't want to use too much as this can add weight to the board. If there are big holes it might be best to take some foam and glue it in place.

Preparing the Surface for Laminating

Since XPS foam is closed cell foam, it doesn't like having glue stuck to it, which presents a minor challenge when fiberglassing. It is best to leave the surfboard very rough so there is lots of surface area for the epoxy to grab a hold when fiberglassing. Leave the surfboard with a rough 40-60 grit finish, small tears and gouges can help with adhesion.

Step 11: Laminating the Surfboard Bottom

Here comes the part of surfboard building that took me a while to figure out. Mainly because I had no clue how boards were built I kinda just winged it. It wasn't until youtube came along and I found videos of pros making surfboard that I finally figured it out.

The fiberglass and epoxy is what gives the surfboard it's strength. Fiberglass is rated by weight, a 6oz weight means that for every square foot of cloth it weights 6ozs. The glassing schedule (the weight of fiberglass used) is dependent on if you are making a shortboard, longboard or anything in between. Performance shortboards are usually glassed light, typically 4oz cloth, longboard are glassed heavier. I like using a 6oz cloth on the bottom and a 6oz + 4oz cloth on the deck for most of my boards. The reason for the extra layer on the deck is the deck takes the most abuse from your feet. It should also be noted that epoxy resin makes for a very strong board, so one can go with the same glassing schedule as a polyester surfboard but have a stronger surfboard when made from epoxy.

You need enough fiberglass so it is wide enough to cover the width of the board and it needs to be long enough to cover the surfboard 3 times with out any breaks. I find it best to just buy a roll of fiberglass, it's cheaper in the long run. So for this surfboard I will glass it 6oz on the bottom and 6oz + 4oz on the deck.

Also it should be noted that typically art work is painted on the foam before glassing or logos can be placed under the fiberglass. But since the color of the foam is pink and you can see the seams from gluing the sheets together, I am opting to skip any artwork at this stage and paint it later.

Cut-lap vs Free-Lap

So to fiberglass the surfboard it has to be done in stages, first step is to determine if you want to do a cut-lap or a free-lap. The "lap" is where the fiberglass overlaps each other when you fiberglass a board as the bottom and the deck are glassed separately. The difference between the two laps are:

Cut-Lap: The fiberglass is laminated to the surfboard but the excess fiberglass is "cut" and removed from the board. This leaves a nice clean looking line and must be done if you are tinting a surfboard.

Free-Lap: The fiberglass is laminated to the surfboard but the excess is not removed and sanded flush to the surfboard. This is typically done for surfboards that don't have any tints and are completely clear.

Technically the free-lap is easier to do because no real prep is required. However I find sanding the rough excess glass on the board to be troublesome and a pain. My preference is to do a cut-lap exclusively. But you can do whatever suits you. So I will show you how to do the cut-lap, if you are doing a free-lap just skip those steps and follow the rest.


Epoxy will be the "glue" that is used to coat the fiberglass, it comes in two parts, a resin and harder. There are specially formulated epoxies for making surfboards that have UV protection to keep it from yellowing, I like using Resin Research, I find it the most clear. The best way to measure epoxy is by weighing it with a digital scale. The epoxy will have instructions on amounts, follow them. I use a kitchen scale that I picked up for under 10 bucks. For the mixing containers, I usually use ice-cream or yogurt containers, so start saving them! Also there is a chemical called "Additive F", this stuff really makes epoxy surfboard building easier. It helps with cloth wetting, the epoxy flows better and when applying the hotcoat and glosscoat it prevents fish eyes. The reason why epoxy is used with XPS and EPS foam is regular fiberglass polyester resin will melt the foam.

Tinting and Pigments

If you want to tint your board now would be the time to do it but since the foam is pink, I'm not doing this for this surfboard, you will have to research more on this on your own. But the general idea is tints and pigments are added to the epoxy resin and then laminated into the fiberglass cloth. Then a clear coat of epoxy resin is coated over the tinted fiberglass. A whole other Instructable can be written just on this subject.

Laminate the Bottom of the Surfboard

Since I will be using the cut-lap method we need to start on the deck of the surfboard. Using some quality masking tape we mask the all the way around the deck of the surfboard about 1-2 inches from the edge of the surfboard. I like using a piece of wood or foam in the shape of an "L" with a pencil inserted and trace a line around the board, this ensures an even line all the way around. The tape serves to keep the fiberglass off the foam so it can be removed. Flip the surfboard over so the bottom faces upward.

The bottom of the surfboard is typically laminated first then the deck. The first step is to cut the fiberglass out. You need to buy the fiberglass so you have enough length to cover the bottom of the board in one go. Roll the fiberglass out on the bottom of the board and let it hang. Using a sharp pair of scissors cut all the way around the fiberglass so it just overlaps the tape where we laid down on the deck. Next make relieve cuts around the tail and the nose, see the pics or video on how to do this as it's hard to describe. Be sure toe wear a mask or respirator when cutting fiberglass, as each cut will put little particles of glass into the air.

Measure and mix up the epoxy, for my length of board I'm using about 700ml or 23ozs total mixed resin. The amount of resin used is really depends on a few variables: size of the board, weight of the fiberglass, how much the foam absorbs (XPS doesn't absorb resin like ESP does). Also you must laminate in temperatures above 15C (59F), if not the epoxy will take longer to set and it will not flow as easy. So mix up your epoxy and don't forget to add the Additive F.

Make sure to wear gloves and a respirator even tho epoxy is low VOC it still gives off some vapors, especially the Additive F. Pour out 3/4 of the epoxy resin on the fiberglass that is covering the bottom of the board. Using an autobody squeegee move in a slow motion up and down the board and spread out the epoxy evenly. Give it some time to soak in the cloth. Wet all of the fiberglass including the overhanging glass and pour out more of the resin as needed. Once the fiberglass is adequately whetted, take the squeegee and squeegee out the excess resin, you want the cloth to be soaked but you don't want epoxy pooling or too much of it. As you the excess resin is being squeezed out collect it in the container. When you run the squeegee over the fiberglass in a quick motion you want it to make a quick "zip" sound.

Next it is time to tuck the rails, using the squeegee, wipe off an excess on it and then run the squeegee over the bottom then around the rail and follow it to the deck of the surfboard. Do this starting from the middle of the board and work to the tail and then the nose. Make sure there are no bubbles or creases. Wipe the squeegee clean as needed. An easy way to wipe the squeegee clean is to use excess scraps of fiberglass, cut this ahead of time.

To tuck the relieve cuts at the nose and tail follow the same technique as for the rails, you will be overlapping fiberglass cloth on top of each other. This will be sanded down at a future step.

Depending on the temperature the epoxy will cure at slow or quick rate. Check on the board every few hours and when the epoxy has set to a point where it is tack free but not quite full hardness, it's time to remove the tape on the deck. Use a razor blade and cut the fiberglass where edge of the tape meets the foam towards the bottom of the board. Peel the tape and fiberglass off, it might need to be done in sections. You should be left with a very clean line all the way around the board.

Step 12: Laminating the Surfboard Deck

Once the bottom of the surfboard has cured, it's time to laminate the deck. The deck is laminated in the exact same fashion but with a few minor differences. The deck will require an extra layer of fiberglass, I like using 6 oz deck patch with a 4 oz cloth on top that wraps the rails. The reason for using the 4 oz on top is it has a smaller and lighter weave and the epoxy will smooth out better but the 6 oz cloth could be on top as well, it's not a big deal.

In the previous step we removed the cut lap material, we need to to either sand down the cut fiberglass line around the deck of the surfboard or using a piece of wood push down on the edge so it indents in to the foam. The smoother this line is to the deck the better results for laminating the deck. Running your hand over line should not catch at any point.

I am repeating a cut lap on the bottom so, repeat the tape method as mentioned in the previous step, trace out an outline and tape it.

Take the first piece of fiberglass (I'm using 6 oz cloth) and roll it out over the deck of the board. Cut out an outline so the deck patch covers the deck but does not over hang onto the rail. Ideally it would meet around where the cut lap stopped. Next roll out the next layer of fiberglass and repeat with the same method of cutting as the previous step for laminating the bottom so that it covers the tape on the bottom.

Mix up the epoxy and since there is an extra layer of fiberglass, the deck will require more epoxy resin.

Repeat the same techniques for laminating the deck as the bottom.

Let it set cut and remove the tape.

The cut lap on the bottom needs to be sanded flush and feathered into the bottom of the board. I like using a oscillating sanding tool to do it as it lets me work on small sections and vacuum to keep the dust down. A palm sander works great and so does hand sanding with a block. The reason I like to vacuum while sanding is the dust from sanding fiberglass can really make you itch, so I like to keep the dust to a minimum. Also pro-tip: when washing your hands after sanding fiberglass make sure to wash in cold water; as hot water will open up the pores of your skin causing the fiberglass particles to get deep into your skin and make you itch even more!

At this point the surfboard is laminated, from this point onward, avoid touching the surfboard with bare hands. The oil from your hands can cause issues in later steps.

Step 13: Glassing on Fins

There are a few different ways to install fins, the first way is to use fin boxes and the second way is to fiberglass fins directly on the surfboard. I am opting to glass them on to the surfboard. In my previous surfboard Instructable I installed Future Fins boxes. Fin boxes are easier and you can switch out the fins if you want to try different fins or add and remove fins depending on how you like to surf. However fin boxes sometimes need special tooling (router) and templates to install. Also FCS fins use a plug system where all you need is a jig and a hole drill and they can be installed, although they have a newer fin system that snaps in place, regardless it's still a fin box.. There are other systems out there but these two are the ones I am familiar with besides the traditional longboard fin boxes.

So to glass on fins, first we need fins. I am going to just trace off of an existing set of Future Fins and use them as my template to make my own wooden fins. You can go as fancy as you like when making wooden fins, gluing different exotic woods and then shaping them into a fin.

The setup with be tri-fin system in a thruster set up. I like having the tri-fin as it pivots more off the tail but it really depends on what you like.
The fins were cut out of the wood and the two side fins were shaped so one side was rounded and foiled/profiled and the other side was flat. The middle fin was shaped with both sides rounded and foiled. My suggestion is to look at an existing set of fins and see what works and copy. Another option is to just buy a set of ready to glass on fins. My tool of choice for foiling the fins is a angle grinder with a flap disc.

Now ideally the fins should be pre-fiberglassed with the edges reinforced with some fiberglass rope/strands. I skip this step as it adds extra work for minimal value in my opinion. I just like to glass the wooden fins directly on the board and reinforce with fiberglass when they are glassed onto the board.

Once your have your fins shaped, next it is time to layout the where the fins should be setup. My suggestion is to copy an existing board but my layout will be a typical thruster layout.

So the fin placement is very important and I won't go into detail about this, what I will show is how to actually glassing the fins onto the surfboard. A few things that need to be decided is the toe and cant of the side fins. The toe is the angle of the fin that turns inward from the front of the fin toward the stringer, generally speaking the more toe the more drag but better turning and responsiveness. The fin cant is the angle the fin is tilted outward towards the rails of the surfboard, generally the more cant the more responsive the board will be. There are online templates you can find to help with laying out the fins. I'm no expert in this so I defer you to doing your own research.

Once the fins are shaped or purchased and the layout is decided, it's time to glass them on.

The steps are:

  • Use hotglue to stick the fins in place and adjust the toe and cant as required. This trick really makes glassing the fins on simpler.
  • Cut out patches of fiberglass cloth slightly larger than the size of the fins.
  • Mix up some epoxy and wet the fiberglass using a small disposable brush (wear gloves).
  • Place the fiberglass patches on one side of the fin, then wet another piece of fiberglass and place it on the opposite side of the fin.
  • Squeeze out the excess resin and make sure there is some fiberglass cloth that is adhered to the bottom of the surfboard.
  • The fiberglass on each side should meet at fin edge. Squeeze out any excess air bubbles.
  • Repeat on the other fins and let cure until hardened.
  • Using a sharp utility knife or razor blade trim off the excess fiberglass around the fin, make sure to leave about 1/8" all the way around the edge of the fin. This can also be done once the epoxy is set tack free so it's easier to cut.
  • Sand the edges of the fin so it's cleaned up.
  • Blend in the fiberglass that is on the bottom of the deck so it's flush with the lamination fiberglass.

Step 14: Hotcoating the Surfboard

At this point the surfboard is glassed but it needs additional epoxy resin to fill in all the voids and bumps of the fiberglass. This step is called hotcoating and is just simply a coat of epoxy brushed on the board.

Before we hotcoat, a tape dam needs to be put in place. Start with the surfboard bottom facing upward. Using some high quality masking tape, (I like using 3M, don't cheap out on your masking tape) tape around the middle of surfboard rail. Let the tape over hang so any epoxy that will drip off will not end up on the other parts of the surfboard. Near the tail where the hard edge is, apply tape to create a dam so the epoxy will not flow over the hard rail.

Mix up some epoxy, (use 2/3 to 1/2 the amount that was used for laminating), make sure to add some Additive F to help with preventing fish eyes and makes the epoxy flow better. Also again super important to hotcoat when it is above 15C. Anything below that temp the epoxy will not flow well.

Once you have your epoxy mixed, dump the epoxy on the surfboard, don't let it sit in the container too long or else it will start heating up and hardening quicker than you want because it is undergoing a chemical reaction. Use a 3" soft bristle paint brush, coat the bottom of the surfboard, make sure to cover every last bit of surfboard. Drag the paint brush in long strokes across the board then the length of the board. Brush the rails to clean up any thick spots.

If you find you are getting fish eyes, it could be because of contaminates on the board or not enough epoxy is being used.

Let the epoxy set up until it is just starting to harden, (2-3 hours, depending on temperature) remove the tape. Removing the tape before the epoxy full hardens makes it much easier. Let harden for 24 hours.

To hotcoat the deck of the surfboard is exactly the same, run a line of tape around the middle of the surfboard but this time let it overlap the epoxy by 1mm. Repeat the steps for hotcoating just like for the surfboard bottom.

If you did glass on fins, flip the board on edge and hotcoat them one side at a time. It is possible to hot coat them when coating the bottom of the surfboard but I like to do them separately so i make sure to get a thick coat on them.

Step 15: Sanding the Hotcoat

So at this point a decision needs to be made. The surfboard can be sanded and then considered finished or it can be sanded and then paint and art work can be applied and a clearcoat can be sprayed on the surfboard or a gloss coat of epoxy can be applied. Also if paint was applied to the foam you could stop here as you might be happy with the way the board looks. Since I had to glue two sheets of foam together and can see the glue line, I am opting to paint the hotcoat to hide that, not to mention the foam is pink in color.

Reasons for stopping after sanding the hotcoat is if you are concerned with performance and want a light surfboard.

I am sanding the hotcoat, painting the surfboard then gloss coating it. I prefer a surfboard to last longer than go for all our performance.

To sand the surfboard there are a few methods, you can hand sand it, palm sand it or power sand it with a polisher outfitted with a disc. Hand sanding is slow but totally possible and typically the rails are hand sanded anyways. Palm sanding is the method I recommend for a beginner board builder as it is much more forgiving and most people will have a palm sander or at least they are very inexpensive. Power sanding with a automotive polisher is the way the pros do it and if you are not careful you can sand a hole in the board in a hurry. I will use a combination power sanding with a polisher and palm sanding and hand sanding for the rails.

Also sanding with a polisher will require special pads that have different hardness. so chances are the average person will not have these anyways. So I will only refer to sanding with the palm sander from here forward. If you are interested in seeing how to power sand watch the video.

If your hotcoat is fairly smooth then you can start off with a finer grit (120-140 grit), if the hotcoat isn't smooth to start with use a rougher grit and remove any ridges or bumps. Move around on the board and don't stay in one spot too long or you risk sanding through and exposing the weave of the fiberglass. If you do then you will have to fix it later by coating it with epoxy and feathering in the edges.

Hand sand the rails and make sure to use long even strokes so you don't sand in once spot and create an uneven surface.

Sand all the larger surfaces of the bottom and deck, until smooth, take it to a 220 grit if you plan on painting the board. If not then keep sanding going through the various grits (120, 140, 180, 220, 320, 400), each finer grit will take out the sanding marks from the previous grits. Once you get past the 220 grit, it is best to wet sand by hand with a sanding block or else the dust will really clog the sand paper. A 400 grit makes for a nice satin finish.

If you plan on gloss coating the surfboard leave it at 120-140 grit.

Step 16: Leash Plug

Depending on the type of leash plug, there are different methods for install them. Some are installed during the lamination step and then sanded open, some are installed after the hotcoat or glosscoat.

I am using a plug one that is installed after the hotcoat.

Drill a hole that fits the leash plug, if it is being installed where the stringer is, it might need to be routered out as the plywood stringer can be difficult to remove. Mix up a small quantity of epoxy and fill the hole 1/4 of the way full and insert the leash plug, add more epoxy if required. Some people suggest to use some fiberglass cloth between the plug and foam or add some chopped fiberglass into the epoxy for added strength.

Also at the same time I am installing an FCS plug that can be used to mount a GoPro camera.

Once set, sand the overlapping epoxy and feather into the rest of the board. If you are doing a gloss coat you can wait on this step.

Step 17: Paint and Artwork - Optional

This step is optional as technically the surfboard is ready for the water. This step is really up to the builder on how they want the artwork or color but the only really important rule is use only water based paints, as oil based ones will leave a residue that can cause adhesion problems with the gloss coat. I like to even wash the board with dish detergent after painting to remove any oils that could be part of water based paints.

There are paint pens that can be used to draw on the board, I like using the water based craft paints that are available at the Dollarstores, Walmart or Micheals. I have even used latex house paint mixed to a color I wanted. Just as a precaution make sure to test the paint on a surface and make sure that it's waterproof when dry. Some paints will absorb water even after it dries and will peel off.

There are printer papers that can be laminated underneath the fiberglass or under the hotcoat/glosscoat that will turn clear, only showing what has been printed on the paper.

Technically artwork should be done before laminating but because the glue seam is visible in the foam I opted to do this after the hotcoat. There is more than one way to build a surfboard!

Step 18: Gloss Coat and Polishing

The gloss coat is an additional coat of epoxy resin applied after the hot coat or in my case after the artwork and paint to protect it. A gloss coat is exactly as it sounds it's like a clear coat on a car. Apply the clear coat just like the hot coat: tape the rail, apply gloss coat to one side, let set, tape the rail then gloss coat the other side.

Also automotive clear coat can be sprayed on for a gloss coat and is much easier than applying epoxy. I have done this in the past but my preference is to just to use an additional layer of epoxy. The reasoning is spraying automotive clear coats is very toxic and takes a booth to spray properly. You can drop it off and see if an auto repair shop will spray the board for you when they paint a car.

The gloss coat will never be completely smooth since it is brushed on, so the final step to really make the surfboard pop visually is to sand and polish.

Depending on how smooth the gloss coat is, start with a 220 grit paper if there are a lot of bumps or waves in the finish. I recommend power sanding the flats of the board if they are rough but I generally hand sand the whole board. Typically I wet sand the board as it keeps the dust down and paper from clogging up. The professional use a powersander/polisher to do the whole board but play it safe and do it by hand.

Once all the ridges are sanded out, switch to a finer grit to polish out the marks from the previous grits, I like switching directions between grits so I can see if I sanded out the marks. Keep repeating this until the board is smooth.

If you have a hard time finding the super fine grits of sandpaper, check the automotive stores.

The grits I like to use are:

  • 220 - remove rough marks and bumps
  • 280 or 320 - wet sand
  • 400 - wet sand
  • 600 - wet sand
  • 800 - wet sand
  • 1000 - wet sand
  • 1200 or 1500 - wet sand
  • 2000 - wet sand

Once the board is wet sanded to the higher grits, it will still have a dull look to it. The final step is to hit the with some polishing compound, I like using Meguiar's Ultimate Polish. The use of the power polisher with a buffing pad will really save some elbow grease for this step. The surfboard should really start to pop at this step. Stand back and look it over and re-sand any spots you missed and polish as needed.

Step 19: Final Pics

The surfboard is almost ready for the water at this point! It's best to wait at least 7 days, up to a few weeks depending on the temperature to give lots of time for the epoxy to fully cure. While the epoxy may seem very hard, it can still be damaged much more easily if it's not cured.

Hope you enjoyed this Instructable and consider subscribing to my here and on youTube, I make various different projects.

Time to go surfing!