serene – 3, part 25

lmost ready for the water, but the tide is unfavorable for the weekend (its heights are at night), and the Tembin cyclone is crossing the East sea, threatening the area. So I take the time to complete a couple more things. Attaching the electric box through cable gland is quite straight forward, everything works out right, in essence the bilge pump and reed switch. I added one master switch to the electric circuit, in order to turn everything off and not to drain the 18650 batteries to exhaustion.

One critically important issue with the 18650 batteries is that, never used them to exhaustion, when the voltage drops below 1 ~ 1.5 V or so, the battery just becomes dead, you simple could just throw them away, a costly lesson the last time I hadn’t paddled for some weeks, and let the batteries run until dead 😢. Next, I “refurbish” one of my old paddles to match the new boat style, turning it to black, and make it a bit stronger (and slightly heavier) with an extra layer of fiberglass.

The paddle was specially built from rattan and balsa wood, and is light enough already at 0.8 kg. I would try to use this paddle first, before deciding if it’s necessary to make an extra new one, weight and durability are two major concerns. Third image: a “smoke test” to verify if the bilge pump and the solar panel all properly works. Now wait out for a few more days before going to water, just some 10 ~ 12 km of paddling, to see how the kayak behaves, how everything would feel out there.

serene – 3, part 24

askets fabrication: the critical thing in a hatch’s waterproofness is its gasket, and I realized that the best material for gasket is silicone: flexible, durable and offer a very good fit. And for a custom size and shape hatch, somehow I’ll need to make the gaskets too. It turned out to be pretty much easy, using the 2 – parts silicone available here on local market. You mix up component A to component B (catalyst, around 1 ~ 4 % by weight) and pour it into a mold, wait for about 2 hours, and it’s done.

1st image: the mold (cut from plywood) is filled with silicone, I use the “Silicone” (red bottle) spray as a mold release, it’s “strange” that silicone is used as a release agent also for silicone. 2nd image: the product, the O – ring released from the mold. 3rd image: the gaskets inside the hatch lids. The gaskets are 15 mm wide, 5 mm thick, and are pressed down to the hatch rings with those belt locks. I hope I would end up with excellent waterproofness, but let wait until “sea trial” to know better.

I reuse the bilge pump from my previous boat, it still sees very little use, the installation is quite straight forward using some cable ties fastening the bilge pump into its mount. The flexible water pipe leads to a hose right on the right side behind the cockpit, the hose is protected by a screw – in cap, to prevent water from leaking back into the boat when waves wash over the low aft deck. The bilge pump really offers lots of convenience and confidence when you are out there, in the roughness.

serene – 3, part 23

irst image: the aft deck hatch, secured by 3 belt locks. These locks are usually found on your backpacks, and while they are a bit cumbersome to install, they offer quite some holding power and downward pressure, which is essential for the silicone gaskets inside the hatches’ lids to properly work (would mention about those gaskets in the next post). Similar locking for the forward hatch (2nd image). There’re 3 locks per hatch, so if one failed, the other two could still full – fill their duty.

Next, I installed the rudder pedals and control lines. 3rd image: the rudder in retracted position, 4th image: the rudder in its working position. Thank to the lessons learnt with my previous boat, I redesigned, rearranged every details so that the rudder actions now is very light, smooth, and balanced: kick the pedals lightly and the rudder would follow, release a pedal and the rudder would come back to its neutral position. All control lines tension could easily be adjusted from within the cockpit.

I lubricated with silicone grease all the moving parts of the rudder system, the pivoting points, the lines and pedals, and everything became much smoother. I’m very happy with the overall working of the rudder, though this is still in – dock testing, let see how they would behave while on water. Can’t wait for water trial yet, as there’re still much things to be completed, the bilge pump, the electric box, the hatches’ gaskets, the seat, cart, and a new pair of paddles, etc… still many jobs ahead.

serene – 3, part 22

ne more lesson learnt: we can thin the epoxy when glassing too, sometimes the epoxy has such high viscosity (e.g epoxy from the bottom of the container) that it’s a bit hard to wet out the fiberglass, so I added some xylene solvent (less than 1/4 by weight), so that the glassing could go on easier, and the curing time is also prolonged, an important factor in hot tropical weather. Don’t worry about not having enough epoxy inside the fiber, cause we would usually have another fill coat anyhow.

Hull glassed, 1st image: trim the glass with a small scalpel and peel off the excess. Next, I put the fill coat on until no woven fabric is clearly visible, then slightly sanded the whole bottom. Then I sticked the white vinyl decals for the boat’s eyes and information (3rd and 4th images). Next, I painted the deck with 2 layers of transparent PU paint, and the hull with 3 layers. I ran out of PU thinner (butyl acetate) on the way, so I used acetone instead, it’s also a good solvent for thinning PU paint.

After 2 layers of paint on the hull, I slightly sanded it one more time, before applying the final coat. Well, I’m not particularly good at finishing, and like all my boats, all finish is just “barely – good – enough”, not a “very – fancy” look anyhow. But it’s important to have an even, smooth and thick – enough coating to protect the epoxy from UV and other abuses, the “2K” PU paint I used forms up a very hard protection really. In total, I used roughly about 1.2 kg of paint for the whole boat.

serene – 3, part 21

eck is stained with brownish wooden color, a color pigment is mixed with thinned epoxy and brushed over its surface. Epoxy is thinned for two purposes: first, to lower its viscosity so that the mixture flows easier and make a more even surface, second is for the epoxy to be absorbed into the deck, since there’s no glassing for deck, better to add some water resistance capability to the exposed plywood. This has always been my method of treating plywood if there’s no glassing.

Next is to glass the bottom, this gonna be a quite heavy kayak (estimated to be approximately around 25 kg) since I’d decided to glass both the internal and external side of the hull, while the deck only receives some glass reinforcement on the internal side. I run duct tapes along the deck (third image) to mask the margin for glassing, two layers of duct tapes to prevent the blackened epoxy to spill over the deck. One very annoying thing with every duct tapes I used is that no matter how I try…

Epoxy still leaks a bit under the duct tapes, and the border line between hull and deck would become blurry. I used a trick to overcome this problem, after sticking the tapes, I brush a very thin layer of transparent PU over them, cured paint would prevent epoxy from leaking through while still enable pilling off the tapes. Fourth image: glassing the bottom, epoxy is mixed with a deep black color pigment, almost jet – black. Later, several layers of transparent PU would make the final finish.

serene – 3, part 20

eck and hull jointed, for almost the entire length, almost no additional glueing is needed, almost a perfect fit, no light seen through 😀. Only around the cockpit, the widest part of the boat, needs some fillet to fill some small gaps. However, as a precaution, I applied some little additional fillet at places along the gunwales to make sure the joint is really secured. Now trimming the deck to match the hull, cut the slot on top of the rudder box, round the seam lines to facilitate glassing later.

Next, the whole hull and deck receive some sanding to smoothen out their surfaces, erase all the pencil and sketch pen marks. Those sketch pens offer very good indications, though they’re a bit hard to be erased off the plywood. Sanding is just a slow and dirty job, and it’s very itchy. The ugliest part of S & G boat building is sanding on fiberglass, it produces dust, which is essentially just tiny particles of silica sand, and those are extremely itchy, I have to take a bath 2, 3 times after the work.

Over the time, I devised a trick to cope with this: rub your exposed body parts with some mineral oil (e.g Johnson’s baby) before doing the sanding job, then taking a bath after would remove those hateful dust easier. This time, I do the sanding job more carefully, one at 100 grit and another at 120 grit before applying the wood staining. This time, I decided to go with a less vibrant color scheme, light brownish for the deck and black for the hull, unlike previous boats with bright yellowish tone.

serene – 3, part 19

ots of “unnamed” jobs need to be done: slightly modify the rudder (shorten its rotating arms, slightly shorten then rudder blade by 1 cm, add the carabiners for simpler rudder line attachment…), prepare the bilge pump mount, double check to make sure if all electrical wiring works (things made easy with a multimeter: voltage, current, resistence) etc… Then I carefully check the bevel along the gunwales, to make sure the hull and deck would match, adjusting their slopes with an angle grinder.

Then, let joint the two halves of the peanut shell 😀, it’s always a really good feeling when your boat initially is turned into its final shape! I ran out of the very handy and useful 511 putty, and lazy going out to buy a new batch, I fall back to working with wood flour fillet, though wood flour is not as good as the very fine grain powder of 511. Priming the joint with epoxy and some fillet, press the two halves together with weights, duct tapes, clamps, fastening belts… anything that’s convenient.

The deck has not come to its final shape yet since it’s cut oversized in order to have some fault tolerance. Next is the job of trimming the deck to the desired shape, then reinforce the hull – deck joint with some fillet at places, there’re still some small gaps between them that need to be filled. If done properly, it should make air tight (and water tight) compartments inside the hull. Later a layer of hull glassing would overlap about an inch onto the deck, to help securing the joint further.

serene – 3, part 18

fter lots of considerations, I made up my mind to implement the electrics – electronics system of this Serene – 3 kayak as simple as possible. There would be no built – in compass and nav lights. Only a set of six 18650 Li-ion battery cells charged from the solar panel, and a reed switch to activate the bilge pump. That would reduce the electrics wiring hassle to minimum, simplify the installation quite a lot. Of course, the compass still needs lighting to be used at night, and the nav light too.

Looking back on the electric, electronics part of Serene – 2, I’ve seen that I’d over – engineered quite a lot, things should be simpler. The compass and nav lights would now be a single hand – held torch, powered by rechargeable AA batteries, I would detail this “solution” in later posts. And the electrics components should be decoupled to facilitate repairing, upgrading. All the wiring runs inside plastic tubes (as additional protection) and can be pulled out of the hull for repair when needed.

So basically, the system composes mainly of Li-ion cells that would have 2 duties: power the bilge pump & the charger that would replenish some AA batteries. The AA batteries would be then used to power the Garmin and the light torch. Also in the waterproof electric box is the USB charger, which could be used for a variety of electronic devices. And I believe most if not all chargers could be modified to use either the 5V (USB) or the 12V (Li-ion) source, would try to check (prove) it later on.

serene – 3, part 17

ext came the rudder box, an interesting idea that I’ve come up with lately. First, when not in use, the rudder would be retracted completely inside the rudder box (and so inside the hull), it would be safer, tidier when transporting, moving the boat around. Second, and more importantly, the rudder box allows mounting the rudder in a lower position, which enables a smaller rudder blade. From the design phase, when drawing a hull with lots of overall rocker (the keel line has quite some curvature)…

I saw that bottom of the stern would barely touch water when the kayak is at full load, hence, it’s good to mount the rudder lower down, about 10 cm lower compare to my previous boat. So I would just reuse my previous rudder with more steering effect. Lessons learnt from Serene – 2 showed me that I need a more responsive rudder, so everything, from the rudder post to the control pedals must be redesigned, shorter “rotating arms” for the rudder, and smaller “moving distances” for the pedals.

For this Serene – 3, I would make the seat position fixed, so the rudder pedals must be adjustable, back and forth about 12 ~ 15 cm. Of course there would be only one paddler for this boat, that’s me, but an adjustable rudder pedals is desirable anyhow, though it’s not very frequently needed. I choose a pedal layout that would let me stretch and relax my legs and feet. Not a surfing boat, rudder is for some slight course adjustment only, I don’t have to rest my feet on the pedals most of the time.

serene – 3, part 16

ull is rigid like a walnut shell now 😀, I took it out for a slight sanding on the external side before applying extra layers of glass at bow and stern, the two ends that would withstand quite some abuse when landing on unfavorable shores. Then I install the rudder post, a piece of wood that protrudes the flat stern about 7 cm, glued, screwed, filled with putty and then finally two layers of glass. Lots of extra reinforcement for this rudder post, a lamination of 3 different layers of wood.

I carefully choose different types of wood, with different wood grains to make up this simple rudder post. The grains that run in different directions would ensure that this wooden block would be more resilient to forces from various “angles of attack”. Then I install the rudder control tubes, plastic tubes 10 mm in external diameter (6 mm internally), quite large indeed. The large tubes is, for later, I could easily try various types of rudder control cable, to see which works best.

The tubes run just below, and along the gunwales, through the bulkhead, fixed in place using epoxy putty and small strips of plywood. A lesson learnt from my previous boat: fix the tube positions, don’t let them run loose, slightly different port and starboard tubes would result into different tensions on the control lines, or an awkward rudder pedaling control effect. The tubes exit the hull through small slots cut very near to the stern, protected outside by small blocks of wood.