Bryan's First Stand Up Paddleboard
Decided to build a SUP for my summer project. A 12'6 Kaholo Stand Up Paddleboard from Chesapeake Light Craft.
Just a brief summary of the SUP to be built. It is to be constructed of fiberglass over marine ply.
The designer intended the carry load to be 87kg max for the 12'6 model.
The sheer clamp timber is to be light hardwood such as cedar.
Sourced out my marine ply. Got myself
1x 4mm Meranti marine ply for the bulkheads
3x 3mm Gabone BS 1088 marine ply for deck, sides and hull.
First time driving a 4m trailer when I needed to bring these back. That was the only nerve wrecking event for me.
Laid out the plans to study. It has all the components in actual size. It also came with a building instruction book. Found it to be rather vague in its instruction. Little did I know, it is more of a guideline. Technical skill need to be honed and discover as the construction goes.
Part of the plan provided. Gives me an idea of what's what and where's where.
The idea is to trace and transfer all the shapes and lines of components unto the marine ply.
Borrowed a sewing wheel to transfer the line. Sounded easy and straight forward at first... Turns out, the line was not quite fair...
I then opted to use the docking method. Had nails every few inches on the line to achieve a better fairing when it comes to using the fairing batten.
The deck stringer
line had been successfully transferred unto the marine ply with the aid of a half dowel timber conveniently available in the garage. It does the job... I just have to improvise with what I have.
The bulkheads were made from 4mm Meranti ply with lightening holes in them. To achieve that, i scribed the line on each one of the bulkhead before i holed them out using my Triton 1400w MOF001 plunge router. As expected, took me awhile to route them all.
Next time: I will be making a master pattern jig with 9mm ply for the bulkheads. That way, subsequent SUP project can be built more efficient, and safely.
The three pictures above represent the making of deck stringers (three required).The deck stringers are to be made of 4mm ply. I lofted only ONCE before
combining the other two together for planing purpose. To keep them from
moving or shifting, i dag nails into them to affix position. This way, I can
minimize the lofting work. Shave/plane to line (pics below).
Kunz flat head spokeshave used for this task. See the line? there is only ONE line.
Deck stringers? Mission accomplished.
Before any cutting was done, restudied the plan again. Carry out nesting of the various components to maximise the available resources. At this stage, i needed to prepare the sides (required scarphing), the bottom (required scarphing), and the deck (required scarphing)!
Ply 1 and 2 - Gabone 3mm- First- segregate the different resources to prevent confusion down the line. The 'narrower' strip on the left of the saw will later needed to be cut in half (horizontally) prior to scarphing.
Used my trusted japanese saw because i could not utilise the jigsaw due to poor set up availability (Don't even have a proper work bench... seriously). Improvise! Other reasons include, the thickness of blade is only half a mm, i can cut straighter and cleaner with the japanese saw....
Ply 3 - Gabone 3mm - This last ply is used solely for the construction of the paddleboard deck. Precision is key here. As i did not have a long enough straight edge, i had to resort to using builder's stringline. Marked out a few spots along the string before joining them with my metal rule. AGAIN, emphasis on precision and accuracy. Could not stress this point enough due to the fact the variance for error is very small, only a few mm...
Once marked, this ply would then be cut on the line.
With that, all the plys had been utilised and cut for their intended purpose.
Transferal of lines to the cut ply for the different components. Dagging nails, remove plan, redag nails, fair a line using fairing batten.... Time consuming. Patience is a virtue to achieve good job.
How i initially set up my make shift work station for the scarphing process. Scarphing for the sides/railing of the paddleboard. When i started planing, i noted, the surface where the ply is sitting on is not flat, affecting the planing. I improvised.... again... See next pic or two
Used my granite slab i have lying around as base for the ply to sit on. If you are wondering, i acquired the slab for its flat surface property which i needed to hone and tune my handplanes.
The scarphing ratio used is 8:1.
Job was satisfactory, not perfect, but satisfactory.
Below are some pics for the cutting and scarphing of the deck panel. They are rather self explanatory.
A point of interest to note is the scraphing side. I know the end product would need to have one side good grain surface and the other the ugly side. What i did not want is half the top surface is the nice face and the other is ugly. To prevent such error, the scraphing needed to be done one on the good side and the other on the bad side. Same logic were apply to all my scraphing.
Below are pics governing the cutting of the forward bottom of the paddleboard.
Using my trusted japanese saw, i began sawing just outside the defined line using the crosscut teeth side of saw. I gave a few mm offcut which i intend to plane down to line. On hindsight, i could have half the offcut amount to lessen my work.
Why is there two panel cut together? To minimise work and to ensure the shape are symmetrical simply based on one cut.
Top two: Constantly shifting work piece to allow sawing of the plys comfortable without risking accident. Always think safe and use common sense. My japanese saw is pretty cool....
Left: Nearly there with the forward bottom component. All i need to do now is to plane to line.
Some detailed picture of the forward end of the forward bottom.
Once i hand plane to line, i then have symmetrical port and starboard pieces that will form the forward bottom of the paddleboard.
Time to cut out the sheer clamp pieces.
Sheer clamp scantling = 12x18 mm
LOA of paddle board 12'6 = 3.81m
Dim of available timber =2400x200x25 mm
Timber = Kahikatea
Notes
- Scarphing of the sheer clamp necessary
- There cannot be any knots in the sheer clamp
Cut out timber strip using circular saw. The width of cut is 15mm. Improvised since I do not own a table saw. Took extra care to ensure timber strip is cut straight.
It took me close to 20 minutes to cut out one strip as i had to shift work piece every so often for safety reason. I needed four timber strips. Would have taken me 2 minutes using a table saw for all the pieces i needed. Just glad i did not have to rip cut using my japanese saw...
Let the scarphing begin.... Decided on the 8:1 ratio.
Decided to use the 206 hardener instead of 205. 206 is a slower hardener. I figured since there is only myself to rely on, i may need the extra time to work on the epoxy resin. Good thinking.
Setting the glue. It is not clear from the picture, but the gluing were done for the bottom and the deck, separated by plastic.
It was just clear epoxy resin, no added fixatroph. I first spread wholly the faying surface with the clear epoxy, letting it sink in. Added on another layer after 10 minutes just prior to joining the two scraph pieces.
Sad to admit, but the only option i had was to use weight, plenty of weight. I really did not have a solution to prevent sliding of the ply. I just hoped for the best.
More scarphing... The scraphing with granite slab sitting on is for the side of the paddleboard. Then there is the sheer clamp scarphing.
For scarphing the ply, i used only clear epoxy. As for the sheer clamp, i added fixatroph for the scarphing. Was not sure if this is ideal, but i made sure the mixture was just off watery.
First mistake that cost me without the benefit of learning experience. Gutted. Preventable. Took two pumps instead of one. Now, each time i make a pump of the resin, i visualise $5 of liquid dispensed.... Epoxy resin is not cheap stuff. The most expensive type of resin compared to polyester and vinyl-ester.
Once the scarphing is done, the glued had settled and hardened, it was time to transcribe lines to the ply.
Pictures below: Shape of paddleboard sides/railing had been cut to shape with some offcut. To plane to line, i found using the spokeshave was much easier and convenient.
Paddleboard sides readied. Satisfied with the fairing of it, given the availability of resources...
Pictures below: Time to cut out the deck using my japanese saw.
Deck panel cut and trimmed/planed to line. At least i can now see the project taking shape.
Dry fitting 100gm fibreglass cloth on the worse/uglier surface of the deck.
Laid out plastic under the work piece to catch any overflow of epoxy resin.
Wetted out fibreglass cloth with epoxy resin. Crucial to wet out every surface area. There cannot be any air bubble, white spot or grey spot.
I did however have puddle of resin here and there which were overseen. Used plastic spreader for the job. Perhaps, using a roller would yield a better result.... need experimenting.
The sheer clamp was roughly 15x25. The scantling specified is 12x18. The difference is what i had to plane off manually. I had to accommodate the work piece however i can to allow easier planing.
Lesson & discovery - when the timber pieces were scarphed, the surface grain were running the opposite direction. It was easy to handplane one half of the sheer clamp (by following the grain), before cutting against grain on the second half. Readjustment of setup required.
Would definitely pay attention to grain direction when scraphing next time.
Look at all the shaving....
Can't stress enough the importance of sharp handplane, and determination.
Dry fitting the sheer clamp to the railing. Could only do one side at a time as i did not have enough hand clamps.
The aft end of the sheer clamp need to be trimmed to line. Why? Because the tail block would be sitting inside. Allowed 6mm of gap.
Pictures above: Gluing the sheer clamps to the railings. The wider face of the sheer clamp is glued to the face of the railing. I set it up to have a bend in the middle because i thought it would make the railing mounting much easier later on. My experiment was inconclusive. The sheer clamp was only 12mm thick that it was flexible when mounting.
Had to spend two days doing just this. Why? One day to glue up one side of the railing. I could have gotten more clamps, but i really did not want to waste money especially if time was not a constraining factor. Another clever idea was to do it back to back utilizing the same number of clamps, since the railings are mirror image anyway. Trouble was, there is only myself working on the project. If i had an assistance, this would clearly be a viable and preferred option.
Stitch and glue method.
Used stainless steel wire instead of the copper wire recommended. Reason for this - stainless steel wire is easier to obtain (from hardware store) not to mention it is cheaper. The advantage of copper wire though is that it is soft and easier to work with.
Cut wire to four inch segments.
Stitching with wire through the pre-marked, pre-drilled wire hole. Needs to be done for every single bulkheads and more.
Notice the gap, it was left intentionally at this stage, The goal is to form the shape of the paddleboard. Tightening of the wires will come later once all bulkheads are in place.
I started first with the middle bulkhead, it being the widest. Big mistake. My reasoning staring from the middle working outwards was so that the railing will be bent and stretched smoothly.
Improvised with a strip beam of pinus radiata to keep the paddleboard on the same plane. Problem solving is the name of the game.
Another problem - the bulkhead, made out of 4mm ply is not holding its form. Especially true when i am trying to stitch wire into them. This i believe is caused but the sheer clamp spring back.
Used half dowel, cut to length, clamp to the top of the bulkhead (in line with the sheer clamp piece). The bulkhead now holds its intended position. Classic example of problem not illustrated by the vague building instruction.
A different angle.
After much twisting of wires, the paddleboard is finally taking a 3D shape. The wires had yet to be tightened. What i have here is the underside of the paddleboard, the stitching was done upside down.
Note: I should have done the stitching from the bow working aftward. Why? Notice how the nose of the paddleboard is not coming together easily. This could have been avoided if i had stitched it first.
Murphy's law - all that can go wrong, will go wrong - begins...
On the left, there is gaping hole down the centre line of the forward bottom.
On top, there is more gaping holes where the bottom meets the railings.
The general shape however is acceptable. I will be relying on the power of epoxy resin with fixatroph....
1) Could assume this "step chine" was done intentionally and it look cool, OR
2) Admit i mounted the bottom in error. Like the stitching of bulkheads, i started from the middle of the paddleboard. The forward end is short by 3 mm while the stern was protroding out by 3mm.
Should have started the stitching from the bow.... Biggest error....Damn Murphy...
Turning paddleboard upright. A proud moment in the construction of it....
Time to install the deck stringers. But first, i needed to cut out he stringer housing on each of the bulkheads.
It was difficult to cut out the slots given all the bulkheads are installed. But, i would NOT make any changes in the future. Why? Because cutting the slots may compromise the structure of the bulkhead. It was already flimsy to begin with, in my opinion...
Deck stringers : Checked!
Wires tightened. It was time to add glue to the joint. Took extra care not to bury the wire in epoxy.
Added some weight here and there to conuteract a slight twist in the whole structure. Worked out fine at this stage.
Once the epoxy dries, went around cutting and removing all the wires. The glue is strong enough to hold the paddleboard in shape.
Time to apply timber sealant to the interior of the paddleboard. Thought of using clear epoxy resin as interior sealant initially. Decided against that because the epoxy resin is much dearer and i was worried of the quantity of epoxy resin left.
Sealing the interior of the paddleboard, including the deck stringers.
Pictures above: after timber sealant dried. I noticed how the epoxy bonding looked pathetic. Decided to coam the edge. Made a filleting stick out of ply for the coaming job.In the future: 1) Would try the syringe methodto keep work tidy, 2) do the coaming before sealing the interior of the paddleboard
Building the nose block with kahikatea timber. Scribing required to get the nose block sits snugly once planed to line. In the future, i would pay particular attention to the grain of the timber block. It should run parallel (straight) or perpendicular (horizontal) (if that makes sense) to the paddleboard.
Dry fitted the nose block where its meant to be, planed to fit. Mixed a batch of glue, readied packaging tape and few clamps at hand.
The extra glue did not go to waste. Used the offcut from the sheer clamp to form the backing timber intended for a handle.
My original plan was to have handles on the sides of the deck (not the middle). However, when i dry fitted the cleats, they deformed the fairness of the sheer clamps. Some thoughts need to be put into this in the future.
Installed the deck stringers. To keep the deck stringers in place while the glue dry, added some weight on top. Works just fine.
Pictures below: Different angle of the deck stringers installation.
Handplaned the sheer clamp to achieve equilibrium level. Important to have level surface for the deck panel to sits on.
Port side
Starboard side
Bulkhead
Marked the underside of the deck when dry fitting the deck - the side that had been fiberglassed earlier on.
Spreading the glue for the deck installation. Took me close to 45 minutes to spread the glue. It harder than it looks.
Next time, i would get an assistant to help me with spreading the glue. Twice the human resources, half the time needed. Just ideal considering the set off period for the epoxy.
Below are some pictures governing the mounting of the deck.
All in all, i have just under 200kg of weight sitting on the paddleboard. There was a concern on my part that the weight may be straining the paddleboard so much so that it will break...
Glue dried, removed weights. Pleased with the result so far.
Pictures below: Removing the bulk excess of the overhang
Removed the rest of the overhang by planing using a block plane.
Setting up the work site for the fibreglassing process. Note the plastic underneath.
A different angle of set up. Port side view
Starboard view. Notice the white patch in the middle of the starboard railing; had to "fill in" as there was a collapse in the shape. Suspect either
1) the bulkhead there is slightly smaller (unlikely) (Why? lofted from the actual plan provided) OR
2) the scarphed sheer clamp joint is not bending as it should be. (Potential solution(s) in the future? scarph sheer timber without fixatroph, remove the properties of fixatroph)
Fibreglass cloth: 200gm / 6 oz
Overlaid fibreglass cloth to suit. Cloth need to sit and cover the railings on both sides. To cut; taped the cloth with masking tape, before cutting along the tape. Why? helps in preventing the strand of the fibreglass from becoming undone.
The cloth needs to overhang to encapsulate all surface of the railing.
From then, saturate the fibreglass cloth with clear epoxy resin as best as i can... Used a plastic spreader and a small brush for the edges or tricky parts.
Apparently, my best is not good enough... This picture is taken the morning after. Swear that I dabbed bucket load of epoxy to saturate and stick the cloth to the ply before I deemed the work is good enough.
To remedy this problem, sanded away the non-attached cloth away exposing the ply underneath. Proceed to "fill" the gap with new batch of epoxy resin.
Saturated fibreglass cloth. It just turn clear when wetted.
Another huge problem. There is pocket hole! Applied the same remedy as the bow error.
An interesting point - the bottom ply is actually overhanging over the railing ply. MEANING - the fairing is poor.... another kick to the gut.
A more holistic view of the fibreglassed hull.
Stern to forward view of the fibreglassed hull. There are "puddle" of epoxy resin clearly visible all over the place. Next time - would experiment with foam roller to determine the spread of the epoxy.
Excess cloth (overhanging cloth) were trimmed before turning the paddleboard over for the next phase - fibreglassing the deck
At this stage - I could implement cutout pattern unto the deck before fibreglassing over. Its all a matter of finishing - to varnish or paint. Decided to paint instead. A tinge of regret there....
More preparation ensued. Sand the edge with grit 80 sand paper. Actually, been sanding non-stop at every stage.
Orbital sander with grit 80. Personal experience; where the surface is flat, the orbital sander does a good job. Where the surface is curved or compounded, it is easier to sand by hand (not even using a sanding block).
Dry fitting the fibreglass cloth for the deck. Trimmed the cloth to overhang roughly 50mm over the edge of the deck.
Wetting of deck and tail block/stern complete.
Relocate work piece out of the garage. Some serious sanding is about to begin....
Took a lot of sanding by HAND to rid of bumps and uneven surface. Used grit 40 sand paper for this job.
Quick note - when hardened fibreglass is protruding out. DO NOT sand using power sander, in this case, an orbital sander, it will "chip" away and propel pieces of broken glass everywhere. By the way, it hurts when it hit uncovered skin. True story... thank goodness I had safety glass on.
Gave a second layer of gel coat in attempt to cover the weave of the fibreglass cloth.
An interesting phenomenon occured - there are pin sizes gelcoat blisters appearing various areas.
After much internet research - all I can conclude is that there are water trap inside. Left scratching my head because when all the fibreglassing work were done, the days had been bone dry...
Clearly this is an area that warants extensive research, not just understanding the cause, but also best practice for prevention (preferably as cheap as possible, me being a student and all...)
Transfered the fin dimension unto a piece of A4 paper, before making a master template out of offcut ply.
Fin template lofted...
Left fin cut out and sanded. The fin thickness is only 3mm. Will be fibreglassing both sides of the fin.
Marking out the position of the fins. Apparently its important to keep them parallel to the center line.
Fins glued to the bottom. Used a piece of timber block to hold the fins in place while the epoxy dries up. Did more sanding on the fins up to 220 grit sandpaper.
Added 50mm strips of fibreglass cloth on both sides of the foot of the fins. Saturate with clear gel coat.
Once dry, more sanding up to 220 grit sandpaper.
Yacht primer for the paddleboard. Honestly, i think it is an overkill. No clue on where to begin painting the paddleboard. Additional research only further confused this poor soul. Two systems, three systems, etc....
Time for experimentation
Two layers of yacht primer. Grey in color.
Aft to fore view. I'm thinking... varnish the deck later on....
Fore to aft view.
In need of testing the paddleboard to determine it is not a submarine.
The completed article. Learnt quite a bit as well in regards to finishing. Too many mistakes made to account. At the end of it, I came out wiser. The next paddleboard will be better with a wow factor.
On launch day. One of a kind paddle board. Very retro
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