How To Build A Hollow Surfboard

Below is how I and hundreds of others have built hollow wooden surfboards…

This is a process I pioneered in 2001 and it has evolved to be simpler with each board I built or helped build… I have taught over thirty hollow board workshops around the world… Many times I didn't know the native language and they did not speak mine… That was never a problem… Every board but one turned out as good as if I made it myself… It's the process that works…

Over the years the “How To” that is posted below has been refined and you will see that the example boards below are not the same board through the whole process… Don't get hung up on that…

One thing I guarantee is that through this process you will be frustrated beyond belief and you will also have equally amazing epiphanies… Highs and lows are normal.. It still happens to the best of us… Persevere, take a break or push on…Don't quit…

One thing that is consistent with builders of hollow wood boards… Every one of them starts with one expectation over any others… The Board… Invariably, at the end of the process the best thing about building the board is the personal growth through the ups and down… You will likely feel that too…

All that said, let's get started…

Process

Building even the simplest hollow wood board takes significantly more time, skills, and patience than the most complex foam /fiberglass board …The time to build a hollow can take weeks or even months…

The tools needed to build a hollow are what a small cabinet shop usually has…Table saw, stationary planer, routers, belt sanders…etc… An understanding of wood’s properties and its tendencies to move are also important…Also, there is a need to be open to materials not specifically designed for surfboards…

The number of steps to make a hollow board are many…Foremost is the planning of how to create a blank from thin flat wood…It requires a vision, and a plan with flexibility to make the complex form take shape…It requires getting the right materials for the specific task … understanding the differences in selecting the right adhesives for specific tasks…It requires cutting the rough parts to precise pieces…A typical hollow board has over 300 pieces…It requires sensitivity with the tools, where one mistake can and will ruin weeks of work…It requires patience beyond belief…It requires a mastery of the process…With the ability to adapt to minor crisis’s and be open to new ideas and materials…

Tools

Tools that are essential for building a Hollow Surfboard…

Pencil...

Tape Measure...

The best Utility Knife you can buy, always with a very sharp blade...!!!...

Jig Saw, they're all about the same...

Small, hand held router with a "Flush Trim" router bit...

Block Plane or Surform...

Drill & drill bits...

Belt Sander - I like the 3" x 21" Bosch or Ryobi...

Orbital 1/4 Sheet Sander or plenty of elbow grease sanding...

Spring clamps - At least a dozen...

Harbor Freight has these on sale for cheap, all the time...

Fine Tooth Handsaw...

I only use Japanese "Pull Saws"...

A Table Saw

and maybe a Surfacing Planer.

If your lumber yard is any good, and you have any kind of working relationship with them, they will have both of those that they can use to cut and mill your wood strips that'll be your deck and bottom skins...

If the lumber yard can't do that, most Door or Cabinet Shops will have that stuff in back and can help you out...Again explain what you are doing and make them part of the process...It will save you from having to buy those two big tools, unless you really want them...They do come in handy for lots of other things around the house though...Just my opinion...

You will use a lot of masking tape, don’t buy really cheap tape, it just doesn't stretch...You don’t need that more expensive "Blue Tape"...Just get a high quality professional grade tape...

A roll of non-stretch “Filament Tape” is great on stubborn areas…

Have fun …!!!...

Sources of Supplies

Your local lumber yard is the best place to start...Go talk with the "special orders" person, let them know what you're doing...Bring a picture of what you're trying to do...Get them stoked to help you...I always show my local yards what I'm up to...They get a bit emotionally connected and see themselves as being part of the process...A good thing...Explain to them that there might be some products that you're looking for that they might not be familiar with, but they most likely can order...They probably don't even know some of the stuff exists...Be patient with them...It really pays off...

Lowe's / Home Depot has a lot of the bulk stuff you need...Adhesives, sanding belts and sheet sandpaper, hand tools, power tools, etc...Just don't expect the special order stuff to come through them, it's not their gig...

Online sources are aplenty…

Of course, the best resource for anything surfboard related is www.swaylocks.com …

A www.google.com search can be very productive also...

Materials List

Gluing Form:

One sheet of ¼” plywood…

About ¼ sheet of ¾” plywood or pine to be cut for blocking…

Some sheetrock nails or screws to keep it together…

Stringer and Cross Ribs:

About ¼ sheet of 1/8” luan plywood… LuanPlywood

Inner Rails:

Another ¼ sheet of 1/8” luan plywood…

If you’re building a board with a round nose or a round tail,

maybe get some 1/8” bending plywood, if the curves are tight…

Yellow Glue & Hot Glue

Deck / Skins:

1/8” Cedar / Basswood / Redwood / Whatever…

If you use Balsa get it ¼” thick…

Outer Rails:

One sheet of 1/8” bending plywood - NorthAmericanPly

48” x72” of 3/16” sheet cork… CorkStore

One gallon of Solvent Based Contact Cement - WeldwoodContactCement

Interior Carbon Fiber or Fiberglass - FiberglassSupply

One layer of either…4 oz. or 6 oz….Remember there’s 2 sides…

Exterior Fiberglass

I like 4 oz. S-cloth...E-cloth is fine also…Get 3x your boards length…

Epoxy Resin

1.5 gallons of Epoxy Resin – I only use ResinResearch

Fins …Fin Boxes…

You know what you want…

Templates

To start making a hollow board, you’ll need a couple of full size templates, a ½ board “planshape” template and a full size “rocker” template…

Creating a Planshape Template

The planshape template can be transferred from an existing board by simply tracing around a reference board with a pen or pencil onto your template material…I’ll use either a piece of 1/8” plywood, cardboard, or heavy paper for templates…Most of the time I use 1’8” plywood, since I’ll likely be using the templates again…They’re just more durable…When tracing, be sure to keep your pen or pencil straight up and down…

Creating a Rocker Template

(above) I have a reference board, bottom up on my work table…Along the stringer, I’ve laid down a strip of masking tape for writing down the measurements…I have a straight edge clamped in place with a couple of spring clamps…The straight edge is relatively flat to the center of the board…

Use a square to locate the nose and tail… Next make pen marks on the masking tape at 12” increments...I measure and mark from the nose to the center and from the tail to the center…I also mark the board center…These will represent where the cross ribs will be on the hollow board… Write on the tape the rib names (T-1 …N-2 , etc.)… N-1 would be the rib that is 12" from the nose…T-3 is the rib that is 36” from the tail…It helps to keep the parts separated… They will look similar so it’s important to keep things simple…

(above) I’m measuring the rocker along the reference board…The measurements are taken at the 12” increment marks…

(above) Write on the masking tape the rocker measurement on the tape, at each location…

(above) Be as accurate as possible…

(above) Go to your template material…Trace a straight line…Mark on the line your 12” from nose and tail rib locations…From the masking tape on the reference board, transfer the rocker numbers to your rocker template…Measuring and marking carefully…Next connect those dots with a flexible strip of 1/8” plywood…Smooth is important…Most of the time I use previous rocker curves to connect the dots…Take your time to get it the way it needs to be…At the bottom of the picture is the ½ planshape template with lines at the rib locations…

(above) Next, with calipers measure the thickness of the reference board at the 12” intervals…Write them down… Before you transfer those numbers to the rocker template, you’ll need to subtract the thickness of the wood top and bottom skins that the hollow board will have…Remember, right now you’re making an interior part…You’ve just measured an exterior surface…There’s a difference…. I usually figure the deck and bottoms to be each 3/16” thick…Combined that’s 3/8”…So if you subtract 3/8” from your reference board thickness measurements, you’ll have the measurement of the hollow board’s stringer…

(above) Now you can transfer those numbers to the rocker template… Mark the nose and tail with perpendicular marks to the straight template edge...Again you connect the dots… Smoothly…This is important...Looks good…???...If not take the time to smooth out the lines…

Now go back to the planshape template…You’ll need to adjust the width of the template to account for the built up “inner-rails” and finished rails of the hollow board…You’ll need to allow 1-1/2” for each of the finished rails, and ¼” for the inner-rail…So you’ll need to subtract 1-3/4” from the outside edge of the planshape template…Make the necessary compensation and your ready to do some cutting...

(above) Now that you're ready to cut out the templates, congratulate yourself for getting this far...Here I’m just cutting cardboard, but the 1/8” plywood cuts well with a SHARP utility knife…A jigsaw works well, too...I usually just use a knife...Hand strength helps here…Make the cuts on both the planshape and the rocker templates, then clean up the contours with a sanding block…

Your rocker template is now your Stringer...There's more to do with it later...

If you are not building a round nose or round tail board, transfer the Planshape template

onto a piece of ¼” plywood and mark the Stringer and Rib locations and cut out the plywood…

You can skip the next chapter on Gluing Forms, because you don’t need one…

Pattern Making

Sometimes I might want to make more than one board from a set of templates…Here’s how I do that…This method is similar to a CNC cutter in its ability to replicate parts over and over…At a fraction of the cost and it’s something I can do without outsourcing…

You’ll need a few things…Your paper templates, some 1/8” plywood for the underlying template, some 1/4” -3 ply plywood, wood glue, some ½” brads or pin-nails, a handsaw and a router with a ‘rub collar” guide and a ¼” straight cut router bit…

First, I’ll create the lines and curves that are the Stringer, Ribs and Outer Frame Rails on 1/8” plywood…You simply transfer a paper Template Kit to 1/8” plywood by tracing around the templates…Next I’ll cut away the parts, either with a knife or a saw…

(above) Once I have a part, in this case an Outside Frame Rail for an 11’6” Paddle Board (the dark brown hardboard piece), I’ll cut a few 8’ strips of ¼” 3ply plywood… The strips for this project are 5/8” wide…You can see I also have some wood glue, a hand saw, a nail gun with ½” pin nails…Underneath the hardboard template is a piece of ½” plywood or insulation foam…It’s sacrificial in that it will get routered into later…

(above) Here I’ve spread some glue on a strip of ¼” thick plywood…

(above) One minute later, I’ve pin-nailed the ‘flexible enough’ plywood strip to the hardboard template…Start in the center of the board and work to the ends…Be sure the plywood strip is flush with the edge of the template…You’ll be surprise by the flexibility of the plywood strips…

(above) The bottom strip is now glued and nailed…So far so easy…

(above) Since this is an Outer Frame Rail and I’m wanting to make more than one board and have the assembly easy, I’ve decided to have the Ribs have tabs that will go through the Rails…There are pictures below that will show that, but now I’m adding vertical plywood strips that are at the Rib / Rail contact points…Above, the pieces are all cut and a gob of glue is dropped…

(above) You with me so far…???...When I cut out the template I chiseled out holes that are where the Rib pegs will penetrate the Rails…If you do not want or need to build your board this way, skip down seven pictures in this section…

OK advanced builders, above you can see a couple of things…First is the router base…It has a ¼” bit in it and a Rub Collar guide bushing…Eventually all these 5/8” plywood strips will be guides for the Rub Collar to move against while the router bit cuts away the stuff we don’t want…The goal is to remove excess weight…The other thing you see is the piece of 1/4” plywood inserted into the Rail Template…It’s there temporarily to give me a clue to where to place the vertical Guide Strip…I eyeball a small gap between the Rail Notch and where the Rub Collar will ride…Once in the right place, I pin-nail the strip to the template…

(above) This Rub Collar needs 5/16” clearance…

(above) So I cut a strip of plywood a bit wider than 5/16’’…

(above) From that strip of the 5/16”+ wide ply, I cut a piece to mark the top of the Rail notch…No glue yet…

(above) The bottom piece of 5/16”+ is cut as well as the other vertical 5/8” wide piece…Glue is placed…

(above) Then pin-nailed…Not the 5/16” pieces, they’d split…Glue alone is fine…

(above) Above you can see the other vertical Router Guide Strips ready to glue and nail…I spaced these about 3” between each other…Enough vertical support for the purpose…

(above) Glue dropped and ready to nail…I like to do an entire series of actions…Cut all the strips…Spread all the glue…Nail all the pieces, instead of going one by one…Production…

(above) Elapsed time so far, about a half hour…Ready to router…

(above) Simply place the router between the guides and have the Rub Collar follow the guide strips around each opening…Set the depth about ½ way or maybe 1/3 of the way through for the first pass…Your router will appreciate not having to work overly hard…Make another pass or two at lower depths until you are through the template material and into the sacrificial plywood below…

(above) What it looks like after the first pass…

(above) And after the last pass…With a putty knife carefully separate the Templates from the sacrificial plywood…Sand down any pin-nails that stick through the templates…

(above) Alright, as you can see all the patterns are done…All of them were created the way I just described…

To use the Router Patterns to make the real board parts, I again get the sacrificial plywood and on top of it I lay the real plywood that will be the parts, then on top of that I place the Router Patterns…A few pin-nails through the patterns, the real plywood and into the sacrificial ply is next..Use the router and cut out the parts as you did above…

Interior Ribs

(above) You made the Stringer when you were doing the templates...Now, you’ll make the cross ribs…They are also 1/8" Lauan plywood…

Get the Gluing Form (or the ¼ “ plywood Planshape Template) and make a straight pencil line, on one side of the gluing form, it doesn't matter which side, from nose to tail ...Next get your stringer and transfer the cross rib locations to the gluing form... Make perpendicular pencil lines all the way to the rails at the cross rib marks...This is where the cross ribs will be...

(above) The cross ribs are cut from 3.5” strips of 1/8" Lauan plywood...Each rib is cut to width as indicated on the gluing form...Then cut to height as measured from the stringer... Each rib is different... Mark on each rib its location so as not to confuse it with a similar one...T-2 , N-3 , etc...

Where the ribs attach to the stringer, lay out on the stringer an area that would allow a rib to be inserted diagonally through the stringer’s webs then rolled vertically to lock it into place...Look at the picture of the parts at the bottom of this section...

(above) The webbing of the ribs is 1/2”... Cut away the rib’s excess plywood carefully with a sharp knife, or a jigsaw. This significantly reduces the weight if the framework. On the center of each rib cut notches that are the depth of the webbing of the stringer. In these pictures, the ribs aren't notched yet...

Sometimes, the stringer is reinforced with a layer of Fiberglass or Carbon Fiber/ Epoxy to significantly strengthen the stringer... I only laminate the stringer, the ribs only hold the rails apart until the deck / bottom is on, and provide some compression strength underfoot...

If you laminate the stringer, do it after you’re done with the webbing cutouts...Put masking tape on the other side of the stringer that you're laminating...It helps to keep the other side clean...I like to wet out the wood stringer with epoxy then lay on the cloth, then fill in with more epoxy on top of the cloth...After the epoxy has gelled pretty firm but not rock hard, it's easier to cut away the Fiberglass or CF from the cutouts and edges...When you're ready to do laminate the other side of the stringer, again use masking tape on the down side...

Outer Frame Rails

If you are not building a board with a round nose or tail, and you can get through this stage of design, you won’t need a gluing form...It works well on a fish type board, or a pulled in pintail gun, or a square tail retro-style single fin…Using this method will save you a lot of time, something like five days of evenings and weekends…

So pay close attention…

(above) Let's say you have your Planshape Template drawn out on paper...

Transfer that to a piece of thin plywood and cut it out...

Go ahead and mark the location of the Ribs on the plywood, perpendicular to the stringer...

(above) Next get a thin strip of 1/8" plywood a little bit taller than your Center Stringer and

press and bend it on edge against the curved plywood Planshape Template ...

(above) Make pencil marks where the nose and tail end, and the location of each of the Ribs….

(above) This piece will be your template for the Outer Frame Rail… So far so good…

(above) Next get a marking square and a pencil, and make perpendicular pencil mark on your thin strip of Plywood ( Outer Frame Rail Template) where the Ribs will be on those Rail locations...

(above) Get your existing Center Stringer and lay it on the Outer Frame Rail Template...

Starting at the middle rib location (IMPORTANT) and working in one direction at a time,

mark the bottom rocker of your Center Stringer to the Outer Frame Rail Template...

(above) You will have to slide your Center Stringer a bit to adjust for the increased curve of the Outer Frame Rail... It increases more at the nose and tail...Keep an eye on the Rib locations on the Center Stringer and the Rib locations on the Outer Frame Rail Template… You have to be a bit artful to get the lines right in those areas…

(above) It’s not hard, but keep it smooth…That’s it for the bottom…

Next, the deck line...

You will likely need to adjust the Outer Frame Rail Template to reflect the depth of

the Ribs at their contact point on the Outer Frame Rail Template...

You probably have a domed deck, tail vee, etc. that need to be compensated for...

(above) Get your Ribs and line up the bottom of the Rib with the

bottom of the Outer Frame Rail, make your marks on the top edge…

(above) Connect the dots using the Center Stringer as the tracing curve…

(above) Take your time and get those points / lines right...

That's it...Not so hard and it just saved you a ton of time…!!!...

(above) Cut out the Outer Frame Rail Template with a sharp knife…Use a new blade…

(above) A few passes with a sharp knife goes through the 1/*” plywood pretty easy…

No hurry, stay safe, smooth lines…

(above) After the Outer Frame Rail Template is cut out and the edges are sanded smooth,

drill two holes on either side of the rib location…

Through these holes will go a Zip-Tie to pull the Ribs and the Outer Frame Rails together…

It’s our clamping method…Super simple and strong…

Get some good quality 1/4" plywood and trace your Outer Frame Rail Templates onto it…

Make two…

Those will be your Outer Frame Rails...

Cut them out with a Jigsaw and sand the cut edges smooth and you’re done…

Go ahead and drill out the Zip-Tie holes now…

Frame Kit

(above) The Center Stringer, Cross Ribs and Outer Rails…

(above) The Cross Ribs are inserted through the Stringer…

(above) The Outer Rails are Zip-tied to the Cross Ribs…

(above) The frame parts are numbered specific to their location

and are notched to fit together easily…

(above) The Cross Ribs are inserted and rotated into the frame…

(above) Zip-ties are loosely connected through the Outer Rails and Cross Ribs…

(above) The Cross Ribs and Outer Rails are precisely positioned…

(above) The Zip-ties are finally drawn snug…

Start at the middle of the board and work towards the ends…

(above) At the nose and tail there is greater stress on the thin plywood that is the Outer Rails…They are susceptible to breaking without something to back up the accelerated curves…Attached to the Stringer and the last Cross Rib are curved pieces that ease the Outer Rail plywood into position…

(above) Here is the Tail Insert on a custom board…

At this point, the Frame Parts can be glued together…

I use Polyurethane type glue (Gorilla Glue) which expands and fills the joints nicely…

Run a bead of glue on both sides of all the joints…

After the glue dries and you remove the Zip-ties, the frame is now a single unit, but probably a bit un-straight…Not to worry, that is to be expected…But you do need to align the frame, before you attach the Bottom or Deck skin to it…

Here’s how to do that…

Get a piece of scrap 1/8” or ¼” plywood about 4” wide and as long as your board…Draw a straight line as wide as the stringer, lengthwise down the center of the plywood… Next lay that piece of thin plywood over the frame and mark where the cross ribs are…Fire up your hot glue gun and glue some 1” x 2” wood blocks on both sides of the stinger line, close but not tight, and away from the cross ribs…You just made a Stringer Alignment Jig …See below …

(above) The Stringer Alignment Jig is now Zip-Tied to the frame…Note the plywood blocking next to the stringer… (ignore the shaping rack cross brace)

(above) Here’s how it looks from the top…

(above) Simple but effective…

(above) The Outer Rails at this point are a bit flexible and need a bit of firming up…

The sticks on the frame are ¼” x 3/8” Balsa…If you hot glue them between the cross ribs, flush with the edges, the frame will stiffen up perfectly, with little weight gain…You do not need to add the strips at the nose and tail, but it doesn’t hurt either…

(above) One edge done, one side ready…

In addition to stiffening up the frame, the balsa strips add some surface contact area for when you glue on the deck or bottom…

It’s not a bad idea to add similar balsa strips to the deck side cross ribs…

Leave the Stringer Alignment Jig in place until you attach the deck or bottom…

The Deck / Bottom Skins

(above) A variety of woods can be used for the finished deck / bottom skins...Balsa, Basswood, Cedar, Douglas Fir are all light, strong enough and are comparable in density...The wood strips are planed to 1/8” thick and vary it width from ¼” to 2 ¼”... If its only Balsa, keep the wood ¼”…

A typical board might have 30 strips per side, depending on how intricate you want it to look…

If you don’t have access to a planer, or can’t get thin wood strips, an alternative to the “wood strip” method is to simply use a good looking piece of 1/8” plywood for the “skins”…If you do it that way, 1/8” plywood even when glassed on the outside, might need a few more cross ribs under where you stand… Maybe space those cross ribs at 8” on center…

(above) Arrange all the wood strips top-side up on a large table...With good quality masking tape…Start from the center of the board and use the tape to "tie" one strip to the next…Put tape pieces on perpendicularly from one strip to the next...About every foot...

Good quality tape has some stretch, use it to your advantage...It works great...You'll figure out how much tension to use in a short while...

(above) After the perpendicular tape strips are all on. Tape over all the wood seams lengthwise...The reason for this is you don't want epoxy draining through, and gluing your deck / bottom to your work table ...The subsequent clean-up / sanding is a hassle…I learned this the hard way...You'll easily go through a full roll of tape per side...Tape is cheap…

(above) When all the taping is done, flip the deck / bottom over, so that it's tape side down...You are now looking at the surface that you'll laminate with the Fiberglass and Epoxy resin…I usually just put one layer of Fiberglass on the inside of the bottom and one on the inside of the deck...

This board had a Fiberglass cloth on the inside, but in the past I’ve used Carbon Fiber cloth… It is much stronger…However, the increasingly limited availability leading to the extra cost of CF push the overall board cost up more than it’s worth…It’s one of those cost / benefit ratio things…Use it only if you really need a lot of extra strength…Most of the time you won’t…

(above) If I’m going for light and extra strong, I'll add a 2" strip where the stringer makes contact with the deck / bottom skin, and on the deck between where the cross ribs are, not where they contact the ribs…

After the fiberglass cloth / epoxy has set-up, flip it over and remove the masking tape…Timing is important, you want to pull the tape shortly after the resin sets and is hard, but still just a bit tacky before it gets fully hard…If the resin gets too hard, pulling the tape will be very difficult due to the bleed through of resin between the boards…Time it right it’s super easy, wait too long and you have hours of frustration in front of you…

Next, get the gluing form and trace that shape onto the skin…Cut away the excess skins…Be sure to oversize the cut by an inch in width and a couple inches in length…The reason for the increased length, is the gluing form width does not have the inner rails on it, and the length of the deck / bottom skins is longer as it curves to follow the rocker…Nothing is worse than cutting out the skin to find it won’t cover the frame…Don’t ask me how I know, just trust me that I do…!!!...

(above) To attach the deck / bottom skin to the frame, I use a heavy duty, polyurethane construction adhesive from a caulking gun or a Polyurethane glue like Gorrilla Glue…

Run a bead on top of the ribs, stringer and rails...

Carefully lay the deck / bottom skin on the frame, make sure the nose and tail are aligned with the stringer, then use spring clamps to hold the skin to the rails...

Let the adhesive set up firmly before removing the clamps, overnight is good...

Use a flush trim router bit to remove any deck / bottom skin overhanging the rails. Repeat the procedure on the other side of the board.

Fin Box

(above) Installing a Fin Box is more demanding of one’s skills than a “glass on” fin…If you are not 100% sure about your skills, and understanding of this process, go with a glass on…But, you’ve made it this far, and you know whether you’re ready for the task…Have fun…!!!...

If a fin box is used, it is installed after the bottom skin is attached to the frame, but before the deck is installed…

The fin box is installed to the inside of the board…

(above) Details of a fin box installation…

With the bottom of the board facing up, position the fin box where you want it…Make some light pencil marks on the bottom of the board where the fin box will be…Remove the fin box…Carefully measure the size of the slot in the fin box…Then mark on the bottom of the board exactly the length and width of that slot… It’s usually about 3/8” wide…Next get four small nails and push them through the bottom where the slot will be…

Flip the board over…With the inside of the board now facing you, you should see the nails…That is where you want your fin box…With a fine handsaw, cut away the stringer and tail rib enough to get the fin box to fit over the nails…Position the box carefully in straight alignment with the bottom of the board…

Mix up a small amount of epoxy and brush it to the contact points of the fin box and the inside base of the board…This will set up and hold the fin box in place while you reinforce the fin box with carbon fiber or fiberglass cloth and epoxy…

Cut some carbon fiber or fiberglass strips large enough to over-lap the fin box in all directions…Next, cut a couple of 1/8” plywood strips 1” tall and 10” long…These will be used to compact the epoxy and cloth as the epoxy sets…

(above) Mix up another small batch of epoxy, this time enough to saturate the cloth and fin box…Brush the epoxy over the fin box and onto the inside bottom of the board…Place the cloth in place and brush on some more epoxy…Get the 1/8” plywood strips and place them along the sides of the fin box…Use a couple of spring clamps to squeeze them tight to the sides of the fin box…Smooth out all the epoxy and cloth…Let it set up…

After the epoxy has set, flip the board over and with a very sharp knife, very carefully cut away the wood where the slot is… Take your time and make it clean…

Building out the Rails

The Outer Rails are built out from the Inner Rails to a thickness that allows for a shaped finished rail…

(above) This is a cross-section drawing of how I usually build out the rails… Multiple layers of cork/plywood are applied until the final rail thickness is about 1.5”…

In the drawing, you can see the top and bottom, a rib, router guide strip and the inner rails…You can also see how the rails are built out in a ‘stair-step' method to create a hollow rail…It saves a lot of weight…The drawback is, it takes longer…

For aesthetics, I like to alternate between cork and plywood layers…It creates an interesting contrast between light and dark... On the drawing, ‘C’ indicates cork, and ‘P’ represents bending plywood…

Cork also has as one of its physical properties, when glued to a more solid surface such as bending plywood, the ability to compress and expand…This allows for the cork to overcome minor inconsistencies of the lay-up of the rails…Something an all wood rail can’t…

(above) For my 10’4”, a 4'x8 sheet of 1/8” bending plywood and a 4'x8' sheet of 3/16" cork are needed.

All the cork and plywood layers are attached with industrial strength contact cement….When using this solvent based cement, a vapor respirator is a must, something more than just a dust mask…Good ventilation is necessary also…There are water based contact cements with low VOCs (bad stuff) but they take a lot longer to set up and cure…To me time is important, so I use the solvent based cement…

Even if I use the faster high VOC contact cement it still takes all day to build out the rails…This is the single longest step to the board building process…Get comfortable, you’re going to be here a while…

(above) Before I put any glue on anything, I like to protect the deck and bottom surfaces with a layer of protective paper…I hold my tapeline about 1/8” in from the edge…

When it’s time to start spreading glue, I like to have my bending plywood strips ripped to the width they need to be, starting about ½” to ¾” and to have the cork un-cut…I backside tape the plywood strips together, flip it over, then with a 4” paint roller cover the wood and cork with a generous layer of contact cement…Next I go to the board and roll on some glue to the inner rail…I let the glue dry to the touch, then put one more coat on everything…

(above) After the contact cement has dried to the touch, I cut a few strips of cork using a razor knife and a metal straight edge…With a strip of cork in hand, I carefully place it on the edge of the board, glue to glue, following the rocker…Once the glued faces make contact, that’s where they will be…No second chances unless you know some tricks, which I’m not going into here…Just make sure you have things aligned…

Cork is great for being able to bend great in one direction (along the planshape curve of the rail) and not bad for following the rocker…I use butt joints from strip to strip…

After the first cork strip is on I use a laminate roller to apply pressure to the cork / board connection…A smooth block of wood is an OK substitute for a roller…Just try to compress the two surfaces together…

Next you need to trim the excess cork (later on, plywood) from the plane of the deck / bottom…I use either a sharp knife or a flush trim router bit to get the rails the same as the top / bottom…

Now it’s glue time again, I put a coat of glue on the cork that I just put on the board…Often I’ll roll some more glue on the next strips to be put on the board…Again, wait till it’s dry to the touch, then put on a strip of bending plywood onto the cork layer that’s on the board…If you have ripped the plywood to ½” or ¾”, you can get it to conform to the rocker, if it’s not too extreme…Plywood isn’t as forgiving in it’s bend-ability in two directions…Sorry…

Continue the cork / plywood layering until the rails are the desired width…Have fun…

(above) If the board has a round nose, or a more curved rocker, here is how to layer that area…Get a wider piece of bending plywood and span the area with a single piece…Alignment is critical…

(above) One way to finish off the nose or tail is with a wedge of wood…Here, I’ve pre-glued the wood wedge, then marked it carefully on the board, both on the top and the bottom, then with the fine handsaw cut out the cork / ply rail…Some yellow glue and tape keep the wedge in place…

(above) After the glue has set, peel away the tape and cut away the excess wedge…

(above) Now you’re ready to shape…!!!...Congratulations the hardest parts are over…

Shaping the Rails

The shaping of the rails is done primarily with a belt sander with a 36-grit belt, followed with progressively finer grits, finishing with various hand sanding blocks...

(above) Before you start shaping the rails, put on the outer edge of the deck/bottom skins one or two layers of masking tape as a guard against sanding into the finished deck/bottom skins...

(above) Hold the sander parallel to the rail and move the sander horizontally in long smooth strokes.

(above) Don’t work on one rail too much. Keep both sides even…Stay smooth…

Keep these words to live by in mind, as you’re shaping the rails…”Don’t do more, than you can fix…”

Oh, the headphones…They are industrial level ear protection that I hot glued some earphone speakers into…It’s easy to get into the “zone’ with a set-up like this…!!!...Rock on baby, rock on…!!!...“

After the belt sanding I use a series of progressively finer sanding papers, with and without sanding block backing to get the rails like I want them…

Sand the deck and bottom with an orbital sander followed by hand sanding parallel with the grain of the wood. Finish up the machine sanding by blending the deck and bottom with the rails by hand…

It’s important to sand with the grain of the wood…You’ll be surprised how cross sanding scratches will show up…Don’t say you weren’t warned… Progress through the grits, finishing with 150 or 220 grit. Again, look carefully for cross grain scratches.

(above) Ready for glassing…You should be feeling pretty good about now…!!!...

Vent

A hollow surfboard is full of air…That’s obvious…What’s not so obvious is what air does within a sealed container, as is a hollow surfboard…Think of a balloon, as it heats up it expands, as it cools it contracts…Those movements are dictated by physics…Those same air movements within a sealed surfboard can physically do structural damage to the hollow board…To prevent that kind of damage, it’s important to vent the board when it’s not in the water…

(above) The part that goes into the board is a product called "Book Binding Screw Posts"...

These are for 8/32 screws... My local screw specialty store orders them for me...I only use brass, with an open back...

(above) These are the brass 8/32 screws (real size: the shaft is about 3/16” in diameter) that go into the binding post…

You can see they are drilled out... I did that with a handheld power drill, something I do not recommend anyone else trying…

If you look at the screw on the right, just below the rubber o-ring, you can see the drill hole that connects to the hole in the shaft…

I install one near the nose of the board after laminating the deck with fiberglass, the next phase of this process…

I drill a hole in the wood deck of the board and slip the binding post into the hole... I put a bit of epoxy under the flange to keep it from turning...Finally I put a patch of fiberglass over it… To keep the hole clear during fiberglassing put a small plug of surfboard wax in the binding post screw hole...

In action with this set-up, I only have to loosen the screw a bit until it self-vents…No need to fully remove the entire screw…Just unscrew it a few turns, enough to expose the hole and "Voila, It Breathes"...

The best part of this kind of vent is there are no more lost vent screws... Nice…!!!...

Fiberglassing

(above) Following sanding, the board is covered with. fiberglass cloth and epoxy resin…Due to the inconsistent results of polyester resin to bond with wood, epoxy resin should always be used….

(above) Ready for resin……………….

However, this is where “How To Build A Hollow Surfboard” ends its process description…

There is just too much to the fiberglassing part of the board to go into here…

But don’t despair, there is more… If you have more general board building questions, the best source for answers is www.swaylocks.com , and if you are really stuck, I’m here to answer yours…

That’s it, How To Build A Hollow Surfboard…

I hope you’ve had fun through the process and are a better person because of it…

Paul Jensen

Building A Hollow Surfboard - Start To Finish - Photos Only

How To Build A Hollow Surfboard

Process

Pattern Making