At Christmas I started experimenting with building an unglassed wooden board. It is an idea I have had for a while and I finally had time to get it all together. Part of it was being able to build a board at home in the garage with few tools and less time and effort than other methods I have tried.
I started with an EPS core which is flexible and waterproof to a point , then polyurethane glue which is flexible and 100% waterproof. Paulownia timber which as you know is flexible and waterproof in salt water. Most people have used epoxy resin to glue wood to foam , but I wanted to try bagging the wood to the foam with the polyurethane glue as it is so much easier to use and way less mess. Also when it dries it is a close match colour wise to the timber. If things need to move or flex then all the components are pretty compatible.I started with a 5ft 4″ mini simmons design as I have built many of these and then the project wouldn’t need to be a big production. I used AKU shaper and took the normal foam board file as the base to work from and set about turning it into the core of the board. I took 4mm off for the deck timber thickness and 3mm off the bottom. Then squared the rails off by 23mm. This was to allow for a 3mm parabolic stringer in the initial stages of the build and then 20mm of rail lamination buildout. I use a Core Fusion EPS blank which is a very hard foam compared to most other EPS out there. The machine cut leaves the surface of the blank burnished and somewhat sealed from the heat of the cut as well as slight corrugations from the cutting blade. So I left it as it was pretty much as it comes out pretty clean.
First up I laminated the 3mm strip right round the perimeter of the board which seals the edge and creates a parabolic stringer to hold the rocker as the blank has no stringer.This is held in place with masking tape while the polyurethane glue goes off. At 3mm thick it flows round the outline pretty easily. If need be you could hit it with the steam iron and a moist tea towel which heats and steams it up to bend way easier.When it all sets off you just trim the timber to the foil of the board.
Next I cut the deck and bottom skins to about 5mm oversize all round .The deck is 4mm thick and the bottom 3mm thick. I use a squeegee to spread the polyurethane glue very thin on the EPS blank as it foams up as it takes in moisture from the air. I use a spray bottle and mist a little water onto the Paulownia skins to assist with the reaction. You see the glue go from a honey colour to a more creamy colour as it reacts and foams. You need to give it time to do this for it to do its job.
A couple of pieces of masking tape to hold the skins in position on the blank and then slide it into the bag. Seal the bag and turn on the pump for 2 hours to let the glue cure. It is all pretty simple. The glue foams and expands and the bagging process is compressing the whole lot so I imagine the glue is being forced into any pores of the EPS and certainly sealing it very well.
The vacuum pump does a great job as it is gentle even pressure on all surfaces at once. It can pull 90% of one atmosphere which is 90% of 14lb or there abouts so I believe. Vacuum bagging sounds hi tech to most people but using it this way it is simple, neat and tidy with no mess. If the timber skins are thick and the rocker in the board is significant then the bagging can flatten it out. You can cut some foam blocks to suit the desired rocker. Once you have the board in the bag and before you turn the pump on place the foam blocks outside the bag under the nose and tail in the right place to hold the rocker. Add a weight or maybe a tiedown strap over the middle or lowest point of the rocker in the board and pull it down to the table. Then as the air is sucked from the bag you can control the rocker integrity you designed into your board. You could also laminate a thicker parabolic stringer around the board first up to beef up the rocker retention.
Once you turn off the air and slide the board out you will be amazed at how neat and tidy everything is and how far you have move the construction process forward in such a short time compared with other methods. Also how light the board is. It is strong and light already before you even add the laminated rails.
So all you have to do is trim off the 5mm or there abouts of extra deck and bottom skin. Don’t have too much overhang when you bag it as it will be pulled down and be levered over the parabolic stringer as the weight comes on and may split. So just be neat and even all round.
Now all you have to do is laminate the rails the 20mm build out. That may be 4 x 5mm strips or 5 x 4mm strips. It depends on the grade and grain in the timber and the curves you are trying to pull round. Paulownia will soften greatly with steam as I mentioned. The more you trim the timber to the shape of the railband the easier and cleaner the job will be. Lengths with nice straight grain and no knots with bend evenly and make for a better result. I use the polyurethane glue and mist of water on all the glue ups as well and find I can pull most curves with masking tape to the board.
It is a matter of one at a time and with the glue going off in a couple of hours you can do a couple a day. For this reason it is easier to do a couple of boards at a time and alternate from one to the other. This way for hardly any more effort or time you can end up with 2 boards at once.When you have all the laminates done it is just a matter of a sharp small hand plane to first take the rail bands down to foil of the board. I find this the best way to then approach shaping the rails. So you end up with the rail band tapering out from the deck and bottom with a square edge to the outline.
It is a matter of planning the end result and checking your profiles in AKU , maybe even cut some templates to spot check by. With only a 20mm rail build out it isn’t that bigger job really. Take your time and have a sharp plane. Rub some candle wax on the bottom of your plane and it will slide real easy. Just finish it with some different grades of sand paper.By having the deck and bottom skins supplied thicknessed and drum sanded you should not have to sand them at any point. It all means you end up with a cleaner, better looking, more accurate board. It saves heaps of work as well. You just need to blend the rail to the deck quietly as you bring the rail bands down with the plane.
All you need to do is tape the spot where you route the fin boxes in and use epoxy resin because you have an EPS core. Sand over them to tidy it up and smooth things out.
There you have it, light, strong and ready to go. All you need to do is decide what finish you would like. I have often thought about lanolin ( the natural grease from sheep’s wool ). It is waterproof and if you have ever been in a sheering shed you will now how good it is at preserving wood and when buffed it polishes up nicely. So as part of my experimenting I coated this board I made at Christmas with Lanotec’s general purpose product. I brushed it on and let it dry in the sun and recoated it a couple of times. It only has 4 and 3mm of timber to soak into. It is dry to touch when it has soaked in. What was a surprise and bonus was when it hits salt water it is as sticky as and you don’t need wax at all. This board has been surfed extensively since Christmas and only been recoated twice since. Everyone has been amazed at the feel and grip level. I was not my intention but this may be the greenest way I know of building and surfing a board ? The Lanotec guys had not heard of this before and the Fix Tech guys who make the polyurethane glue I use had not had anyone use there glue for vacuum bagging before either. I have since built 4 more boards this way and they are very different to ride. I think the combination of no glass and so no hard surface allows the board to soak up vibrations and chatter and the EPS and captured atmosphere that it has gives it glide and a nice feel to the wave.