serene – 2, part 4b

irst image: assembling the rudder’s components, the rudder in its dropped down position, 2nd image: the rudder in its retracted position. Everything works smoothly as calculated, the blade could be pulled up and down by a pair of line running back to behind the cockpit (but that would be done later, when attaching the rudder to the kayak hull), with two circular ratchets glued on the two side of the rudder blade.

4th image: the rudder stained with colored – epoxy and then painted (with transparent PU – PolyUrethane). It looks so nice, the dark brown color with coarse wooden grains 🙂 . The rudder control system is another complex problem, but that I would address it later on on the following phases of this building project, as I’m still hesitating between the two styles of rudder steering mechanisms as described below.

One style is the T – bar of those Olympic kayak, and the other is the normal 2 – pedals usually found on touring boats. The Olympic style is simpler, but it’s quite counter – intuitive as you would have to use the left leg kicking the bar to the right, in order for the boat to turn right. The 2 – pedals system is more user – friendly, you simply kick with the right leg to turn right. I also may use kind of a cross between the two mechanisms.

This is the first time I use a rudder, so many consideration and calculation have to be made. First in designing the hull, the hull should work efficiently and independently without a rudder, that is, it should track straight in most circumstances. Only under extreme turbulences that the rudder should be deployed, to save yourself from the extreme fatigue of one side paddling, or to have more responsiveness to the moving water.

Serene – 2 photo albums
part 1




serene – 2, part 4a

keg, rudder or none!? It has always been an everlasting debate among the sea kayaker community. Some advocates using none, as getting the job done with your paddles alone would greatly improves your skills. While I partially agree to this argument, I also think that the argument only holds true on flat water only. When in turbulences, which could be extreme, you would need something to assist in tracking and steering the boat.

All my previous kayaks was using skegs. While a skeg wouldn’t help in steering, it would help a lot keeping the boat on a straight track when underway. Gradually, and especially in my last 9 – days trip, I realize that a rudder could potentially become a great benefit. You could pull it up to reduce drag (with a retractable rudder) and maneuver the boat with your paddle alone when it’s relatively calm, and deploy it down in turbulences.

Not only it helps turning your boat to compensate leeway, it’s also a way to have instant responsiveness, e.g: to deal with large chasing waves. So I decided to overcome my fear of complexity and build a rudder for my next Serene – 2 kayak. Yet, complexity is the reason most pro – skeg paddlers would give, to justify their favor for skeg. But serious sea – paddlers would agree, I think, that rudder outperforms skeg in most situations.

It’s not too complex (as it seems) to draft out the rudder’s parts on wood. 1st image: elements of the rudder, 2nd and 3rd images: gluing them together. 4th image: the rudder blade is (like they usually call) a high – aspect – ratio foil, 10 x 50 cm in dimensions. The 2 circular discs: ratchets for pulling the blade up and down. Now, I definitely think I could build a rudder that would work, both efficiently and reliably! 🙂

Serene – 2 photo albums
part 1




serene – 2, part 3c

he structure of the hatches is nothing fancy, three tight rings nested inside each other per hatch, two belongs to the lid, and the other would be attached to the base (deck). First image: the 9 rings forming 3 hatches, filled with some thinned epoxy (about 400 gram of epoxy) to harden the MDF. This is not a very good way to make hatches (weight wise), but it would be just as heavy (or lighter) compared to plastic ones.

I was thinking a lot about the hatch locking mechanism. But finally decided to just use cords and cleats to tie down the hatches. The metal locks are too complex and fragile, unendurable to salt water. Tying down the hatches is much simpler and secured, and is easy to repair when something breaks. Between the 2 rings of the lid is a thin layer (about 3 mm) of epoxy (the softer, elastic kind) filled in to function as a gasket.

At first, I intended to glass in and out of each of the hatches’ rings, but the 9 mm – thick MDF walls have absorbed enough epoxy, and have become really strong (maybe more than enough, they’re now a bit too heavy 🙁 ), so there’s no need for glassing. The good thing is that once everything is assembled together, they fit very tightly, the lids and the bases, and the dark brown color is stained nicely too!

3rd image: the complete products, lids opened, 4th image: the lids closed. Once I’ll finish building up the kayak’s deck, the hatches would simply be glued on. Only the front hatch needs some special treatments, as the front deck is curved in shape. Also, the compass would be mounted right on this front hatch lid, to save deck space, and to simplify the building process. But that would be another later phase of this project.

Serene – 2 photo albums
part 1




serene – 2, part 3b

ad a major setback with making the hatches with wooden strips, the strips didn’t make perfect circles as I’ve expected, although they bend quite well, they’re off by small amount (e.g: 0.5 ~ 1 mm) here and there, and that’s an unacceptable precision for hatches, just a small gap and water could leak in. I had to abandon the method of making hatches using wooden strips, and tried to find some alternative ways instead 🙁 .

Finally, I resorted to cutting the hatches’ rings (lips) using my routing table. The home – built machine is made quite a long time ago, but this is only the first time making some serious use of it. It’s quick to make a circular cutting jig, as shown in the 1st image: the MDF “disc” would rotate around a pivot point that could be adjusted by sliding the wooden bar. The jig proved to offer good cutting accuracy (sub millimeter).

That’s really good, as I want very tight fits between the hatches’ rings, 3rd image: 2 rings cut, there’re still lots of it to be made. Using solid MDF as hatches’ rings has a serious down side: you would need to fill the MDF with much epoxy for it to be hardened, and waterproof, thus increasing the overall weight. On the other side, MDF is easy to cut into perfect shapes! Decided to go this way anyhow as I have few material choices!

Last image: all the hatches’ rings is cut, 3 hatches, 3 lips per hatch, and 2 rings per lip (since they’re cut in 1.5 cm MDF, it requires 2 rings to form a 3 cm height lip), quite some work to be done, and too much of sawing dust too 🙁 ! And I’ve taken care on “quality assurance” to make sure that each ring is cut at its precise diameter. Though I don’t expect the hatches to be waterproof, it should be watertight as much as possible.

Serene – 2 photo albums
part 1




serene – 2, part 3a

‘ve been thinking about kayak hatches over and over again. Starting from the very early days with my plywood hatches (in Hello World – 2, 3) which are obviously not watertight, to the Beckson hatches on my Serene – 1 kayak. The Beckson is very good, watertight and even air tight, but sadly that’s only true in ideal conditions. In reality, in multiple days trip, when mud and sand has get into, it would leak by a small amount.

The Beckson is not ideal hatch for kayak in my idea (for other purposes, it may be ok). The reason is that the hatches are built flushed with the mounting surface, and some inner elements are even recessed… When the water washes over (as always happened to the very low freeboard of a sea kayak), and when the O – rings are not properly lubricated, or when there’re some mud, sand inside the joints, water would leak in.

That’s why I decided to build my own hatches for this Serene – 2 new kayak. The idea is really simple: the hatches are raised a few centimeters above the mounting surface, and even when the seals are not too tight, that would suffice to keep most of the water out. Examine many sea kayak hatch designs, I’ve found out that simple thing, that the hatches should be raised (not flushed or recessed) above the deck.

1st image: cutting thin (2.5 mm) wooden strips used to build the hatches. 2nd, 3nd images: the 3 MDF templates for hatch building: the rear, the front and the day hatch, sizes in diameter: 30, 25 and 20 cm respectively. 4th image: building the hatches’ coaming with thin wooden strips around the templates, each coaming consists of 2 layers of strips which bend easily around without cracks and without the need for steaming.

Serene – 2 photo albums
part 1




serene – 2, part 2c

inished with Serene – 2‘s first paddle, continue to the second one. This would be the pair of paddles, one Greenland style, and one Euro style, that I would use on the new kayak, intended to be slightly smaller in size, and much more lightweight compared to my previous ones. The Greenland paddle is not a typical Greenland one, it’s rather quite short with bigger blades, and the Euro paddle is not of typical Euro style neither 🙂 .

As it is quite small compared to most Euro style paddles. It’s quite hard to justify my design decisions, but all came from my paddling experiences, that I would need a slightly bigger Greenland paddle for all – round paddling, and a slightly smaller Euro paddle to provide more power in “adversary” conditions. The second one would be lightly & simply built also, with that same kind of rattan shaft, and thin plywood blades.

1st image: the finished Greenland paddle. 2nd image: dry fitting the Euro paddle’s blades and shaft. 3th image: bending the plywood blades, I want them to be just slightly curved around the longitudinal axis, it’s just nearly impossible to bend the plywood around multiple axes, to decided to stay with the simplest blade design. After gluing the blades and shaft together, the paddle would receive a layer of fiberglass all around.

4th image: glassing the second paddle, next to it is the finished Greenland paddle, the pair of paddles near completion, they all need to be “trialled” soon, to evaluate their performances, and to see how they would behave in real world. Final weights, the Greenland paddle: 0.82 kg, the Euro paddle: 0.9 kg, not up to the “standards” yet, but quite near, that’s fine anyhow, as they’re very light (compared to my previous paddles) 🙂 .

Serene – 2 photo albums
part 1




my possession

Kéo cưa, lừa xẻ,
Ông thợ nào khoẻ,
Thì ăn cơm vua.
Ông thợ nào thua,
Thì về bú tí.

leaning and tidying up the workshop in preparation for my next Serene – 2 build. Having a chance to look back at the past few years’ works. Apart from Hello World – 1, my first build, a small canoe which is no longer functional (it was turned into an in – house shelf), the 3 kayaks seen here are built in a 3 – years time span, one in each year. Still feel not having enough of them, still in the quest for my “perfect expeditional kayak”! 🙂

Hello World – 1 photo albums: part 1, part 2
Hello World – 2 photo albums: part 1, part 2
Hello World – 3 photo albums: part 1, part 2, part 3
Serene – 1 photo albums: part 1, part 2, part 3, part 4
Serene – 2 photo albums: part 1, part 2, part 3, part 4

serene – 2, part 2b

he first image: cutting two hardwood blocks to attach to the paddle’s 2 ends, 2nd image: scraping the paddle blades with a power planer and a spokeshave. 3rd image: the paddle takes its final shape, next it would be sanded, colored (stained with thinned epoxy), glassed then painted. The paddle would receive a layer of fiberglass all over the body, to waterproof the porous balsa wood, and to strengthen the whole structure.

This is only the first of two paddles I’d intended to build. A lightweight Greenland paddle would be my convenient, all – round thing to propel the boat with. But under some particular circumstances, e.g: very strong wind or current, I would need a more powerful tool, that’s why my next one would be a paddle of the usual Euro type, it would be also very lightly built, and has much smaller blades, around 50 x 14 cm in dimensions.

I’ve not yet to really realize which paddle type is better: Greenland or Euro, but thought that they all has their uses in different situations, and decided to build and use… both. Also, my paddles all has become smaller and shorter, their lengths now are around 1.85 ~ 1.9 m. My thought is that sea – kayakers nowadays are using paddles that are longer than needed (around 2.2 m), especially those going for long touring.

I made a terrible mistake, using the wrong duct tape to mask the paddle for coloring. A kind of 3M duct tape is so sticky that it’s extremely hard to be removed after having painted the paddle blades with colored – thinned – epoxy. I seriously scratch the surface while removing the duct tape (with a chisel) resulting in a very poor finish on one blade 🙁 . The paddle would be perfectly usable, but not as good – looking as I’d expected.

Serene – 2 photo albums
part 1




serene – 2, part 2a

till don’t have some free times to start my Serene – 2 kayak building yet, and all preparations (mainly materials purchasing) has not been completed. So I start slowly with building some other miscellaneous objects. First are the paddles. A typical WRC (Western Red Cedar) Greenland paddle weights around 0.7 ~ 0.8 kg. My two paddles, built with tropical hardwoods, though durable, weigh too much: 1.3 ~ 1.5 kg.

A lightweight paddle has very obvious advantages on long journeys, and I’ve been thinking about resolving this weighting issue. So I’ve decided to realize an idea which I’ve been having for a long while, in a tropical country like Vietnam, the best material you could use for a paddle is… rattan. Rattan is very lightweight, but it’s also very durable, flexible, and stiff, an ideal material to be used for building the paddle’s shaft.

In order to keep weight to minimum, in combination with the rattan stick, I use balsa wood for the blades. Construction is quite simple indeed, the rattan stick is splitted into two halves at the two ends, and two balsa wood blocks are inserted to form the blades’ shape (see the 3rd image). Balsa wood is quite hard to acquire in Vietnam, I’d made the wood block from 6 small 5 – mm – thick balsa sheets, laminated together.

Next is the job of careful – carving down the blades’ shapes. The 4th image: empty spaces at the two ends of the paddle, that would be the places for two hardwood blocks in order to better resist against cracks upon physical impact. The paddle would receive a layer of glass to further strengthen the structure and to protect it against water. Balsa is too porous and without protection, it would takes on water in the long term.

Serene – 2 photo albums
part 1




serene – 2, part 1c

pent a considerable amount of time on optimizing the hull and deck lines. Some little more rocker at the bow, and less (almost square) at the stern. The hull is now a bit finer (less full), hence reducing Cp (prismatic coefficient) further into the [0.48 ~ 0.5] range, quite low indeed. Primary stability is also reduced a bit, with Kmt (transverse metacentric height) at about 21 cm, but the boat is sufficiently stable already.

Cb (block coefficient) is now reduced to 0.33, stepping outside the normal range of [0.35 ~ 0.45]. That is, the boat wouldn’t be very efficient at lighter load, e.g: with the paddler alone. But that would be fine anyhow, since the hull is optimized toward its full displacement, beyond 115 kg. And as confirmed with experiences in my previous kayak Serene – 1, the boat would feel a bit heavier, but more comfortable at full load.

Some other design considerations still need to be done, but they won’t be reflected into the 3D modeling, for the sake of simplicity: the cockpit size and shape, the size and position of the hatches, the rudder and rudder control, etc… Serene – 2 will have a 3rd hatch, or usually called: the day hatch, which locates right behind the cockpit, to store food for lunch and other frequently – accessed things during a paddling day.

2nd image below: the stability curves for various loads: 85, 95, 105, 115 and 125 kg. The curves look exceptionally fine in my eyes, they won’t decrease until 50 degree of heeling angle, and the shapes of the curves closely resemble each other, showing a predictable behavior in hull’s stabilities. Almost done with the designing, I think, next is finding some free times to build the boat in the upcoming months.

Serene – 2 photo albums
part 1