hello world – 3, part 5a

Giang hàm thu ảnh nhạn sơ phi…

inished most jobs needed on the hull part, next come the deck part, which has even more things to do. First is the cockpit’s coaming. With Hello World – 2, it was intended to be a river kayak, so I made the cockpit very spacious to allow a comfortable seat. A sea kayak has a much tighter cockpit, to prevent water pouring in, with the coaming to fit a spray skirt, the thigh braces, the cheek plates… It’s less comfortable, but it just has to be like that, a “keyhole cockpit”.

I cut 5 rings of plywood, then join together to make the coaming. The upper 2 layers will be the coaming lip, and the next 3 layers as the coaming riser. Here, I choose an approach which differs from the plan’s suggestion (using a thin wall of plywood placed vertically as the coaming riser seems too fragile to me). I used the Dremel tool to bevel the edges, so that glassing would be easier later, but also the bevelled edges create more space to fill the putty in when joining the coaming to deck.

The plywood pieces are so delicate until they’re joined together into a rigid ring. I recall when first ordered the 5 mm plywood sheets for HW – 1 & 2, they’re actually measured at 5.3 mm. This time, I ordered 4 mm sheets, but they turned out to be 3.75 mm indeed when I checked with a thickness gauge. Once again, no standard can be assured or trusted here in Vietnam, and lots of cares, compensations and adjustments have to be made, if you want your quality under control 🙁 .

The coaming is then glued to the deck, with putty filled at the seam line. The edges are bevelled so well that glassing is easy and smooth. I apply the same kind of epoxy mixed with color pigment, wait for it to cure, then slightly sand it, then apply another fill coat. The cockpit coaming now is ready for painting. There’s quite some epoxy messing around, even though I’ve used duct tape to mask, cause I still can’t find a good type of duct tape that won’t let epoxy & paint leaking through yet.

hello world – 3, part 4c

Nhân sinh tại thế bất xứng ý,
Minh triêu tản phát lộng biên châu!

ecided to try a new technique when glassing the hull’s external side. I add some color pigment into the epoxy used for glassing (and later, also to the transparent paint when painting the bottom). The pigment I used has a dark brown with a bit of reddish wooden shade. If this technique works, then the lower part of the boat will have a very deep brown and reddish, semi – opaque, lacquer like finish. And if the technique fails, I’ll paint the bottom in black.

My idea is to contrast the hull with the deck: deck will have a brighter light yellow wooden color, and hence the whole boat would have a wooden outlook, especially the upper part. But it’s too early to say at the moment, I don’t have too many choices on the painting products (e.g: wood stain) available for wood working here in Saigon. Like the internal side, I glass the seams with 6 cm – width bands of bias – cut fiberglass, before glassing the whole bottom, all with epoxy mixed with the pigment.

The result is not totally satisfactory, but quite acceptable, the dark puce (a little bit too dark), lacquer – like shade is pleasing, at least to my eyes. Wooden working boats in Vietnam until today are usually oiled (not painted) in this color, it creates an “endurance feeling”. I applied one layer of epoxy fill – coat, then sanded the hull thoroughly with 80 grit sand paper and my random orbital sander, then applied another thin layer of epoxy fill – coat, lightly sanded again at 120 grit.

Next would come two layers of transparent paint mixed with that same color pigment. I’d lost all my confidence with most painting products I could find here, my previous experiments with painting in HW – 1 & 2 were not satisfying at all. That’s why I came up with the decision to use color pigment in epoxy, then use a kind of good top coat called: 2K gloss, it’s transparent, when mix with a dark pigment, it can offer a good protection to the epoxy layers underneath!

hello world – 3, part 4b

Giang thiên nhất sắc vô tiêm trần,
Hạo hạo không trung cô nguyệt luân…

ontinue to work on the skeg… but something I want to tell, not directly related to boat building though. A few days ago, I had a dream, a strange thing cause I often have good sleep and rarely have dream: a private house, a reading cabinet with lots of books, I found a small notebook hand – written in French, black ink, and annotated in Chinese, blue ink. I was skimming through the first few pages, which have drawings on boat construction, then I woke up.

Can’t remember much of the dream, except for a boat silhouette on the first page, a big phrase as notebook title: Jiang Long, and smaller Chinese annotated text underneath: (Vietnamese phonetic transcription: Giáng Long), obviously it’s the boat name which means: a descending dragon. Well, strange enough, at least I’ve never thought of such a ‘flowery’ boat name. What a pity that the dream was just a hint and didn’t tell me more on boat construction though! 🙂

Let quit all night dreams and day dreaming 🙂 , and let get back to work now! The Dremel Multi tool comes with a ton of accessories, including a router base with some miniature router bits, small enough to operate well within the 10 mm gap of the skeg box. I use a small round bit to bevel the edge of the skeg box before glassing (glass doesn’t like sharp edges though). Then I carefully apply a layer of glass over the edge. The skeg box job is properly executed and looks really great!

Some more miscellaneous tasks before moving to the next step: sanding the hull and deck’s external sides, adding two more thwarts at the bow (to better match the hull’s curve with that of the deck, for later, it’s gonna be easier to join the two parts). Thwarts at the bow would also help supporting the mast base, but for now, I have not yet come up with a good idea on how to implement the mast base yet. Just leave it there to a later phase, and go back to the thinking box!

hello world – 3, part 4a

Biển vắng sông êm gợn nước bằng,
Lung linh trăng tỏ sóng triều dâng…

ext comes in the skeg, a critical element of any serious kayak (you can go without a rudder, but better have a skeg for troublesome water and weather). The region I go paddling is extremely muddy, mud frequently gets into the skeg box and jams it, so I need a design that is as convenient for maintenance and repair as possible. After lots of thinking, I come up with the idea of an L – shaped skeg placed in a through hull, through deck well, controlled by a line and bungee cord.

This way, cleaning up and maintenance could be done with ease. I also make an extra skeg blade, carried with the boat, so that if the main skeg brokes, it can be replaced in the field with minimum tools. This is a lesson learnt from Hello World – 2, where the skeg, though functional, it’s often jammed and can’t be controlled while you’re already on the water. This is very important since you would be going virtually nowhere with lots of weathercrocking and without a working skeg.

I use my MultiMaster oscillating tool to cut the slot for installing the skeg box, which does the job nicely and cleanly (the tool is my only “Made – in – Germany” one, hence expensive, the others are all made in Malaysia, China). The box will be clamped between two small thwarts bridging the port and starboard inwales. Then I putty – fill the inner joints, then apply one layer of glass over them. The harder part would be glassing the outer bottom joint, which has to be done very precisely and carefully!

I made the skeg blade extra large, approximately 16 x 38 cm, the previous one of Hello World – 2 (14 x 32 cm) didn’t seem to be large enough, the boat still “shakes” a bit in turbulent water. More over, my plan is to equip HW – 3 with some kind of sail at one point in the future, so hoping that a larger skeg would provide more lateral force to counter balance the pulling force of the wind, in a relative sense, similar to a sailboat’s centerboard, but placed much furthur aft.

hello world – 3, part 3c

Đám mây trắng bềnh bồng trôi mãi,
Rặng phong xanh trên bãi gợi sầu.
Thuyền ai lờ lững đêm thâu?
Nhớ ai trăng rọi mái lầu tương tư!

efore installing the inwales, I expose the hull and deck into the afternoon tropical sunlight for a few days, for the epoxy to completely hardened. Noticed that for the currently used epoxy, it takes time (several days) for the “amine blush”, a wax like substance, to appear on the surface of the cured epoxy, like drops of dew. I need to wash & brush them with hot water & soap thoroughly, then giving it a slight sanding, then I would be able to install the inwales.

I cut thin wood stripes, 3 m long, 1 cm thick, and join them to the 5.5 m length of the inwales. The inwales just serve to join the hull and deck together, and as a frame to install the deck rigging hardwares later, so they don’t have to be too thick and strong. Next is to bevel the inwales, I used my table saw to make a 45° cut, then split cutting the two ends into halves, for it to easier to bend into the bow & aft curves. Later, I would use the angle grinder to bevel it more precisely.

Next, fitting the two forward and aft permanent bulkheads would stabilize the hull into it final shapes. The plan places the two bulkheads about 1.45 m apart, but my legs are not that long, I decided to reduce the cockpit size to 1.25 m, that is also counted the space reserved for a small bilge pump. It happens that the 3rd temporary bulkhead is approximately at that position, so I just use the temporary bulkhead as the permanent forward bulkhead, plus a newly – cut aft one.

The bulkheads fit well with some minor whetting on the edges, I decided to glass them on one side (the cockpit side) to prevent water leaking through. Having noticed that the curve profiles of the hull and deck (along the gunwales) slightly differ with each other, I’m gonna install some temporary spacing thwarts into the hull, to make it better match with the deck. Those are just temporary and would be removed once the two halves are joined together.

hello world – 3, part 3b

Trên nước sông xanh, thuyền tôi buông giữa đêm thanh,
Theo gió mong manh, thuyền trôi trên sóng đa tình…

Tiếng hát trên sông – Thái Thanh

oticed that the hull’s plywood scarf joints happen to be closed to the seat and (sail) mast base position, I decided to reinforce those places with a narrow (20 cm) stripe of glass. Also noticed that a small paint roller helps distributing the epoxy more even and quicker compared to a brush, though it does absorb (and hence waste) a considerable amount of epoxy. Saigon this season is so hot, all glassing need to be done at night, precisely and quickly.

Next is glassing the hull’s seams, and internal glassing for all the hull and deck (I don’t glass the deck’s seams, feeling that one layer of glass is enough). I use epoxy with the B5 hardener for the seams, it’s slow curing and somewhat elastic nature is more suitable for all glueing, joining, better bonding to some tropical hard wood (compared to the TETA). And I use TETA for the overall glassing, its hardness helps creating a rigid external shell, and it is also cheaper to be used in greater quantity.

I can’t find fiberglass tape suitable for boat work of any kind here, so decided to use bias – cut fiberglass (cut along the diagonal line) instead. At this point, I tried to bend the side bilges a bit, it’s really really tough, with the internal glassing only (the external is not yet on). Feeling pleased with my epoxy and glassing work, and by my estimation, I’ve put about 1.8 ~ 1.9 kg of epoxy on (for both the deck and hull), I’m now counting the epoxy to help reducing the final boat weight.

Next is installing the gunwales (the inwales), just learnt that these are British English, for American English, it’s called the ‘sheer clamp’. The plan suggests joining the hull and deck using fiberglass tape, but since I have no such, and since I have less confident in that method, I resort to the known technique of using the inwales instead. This gonna be a bit tricky, since the inwales need to be bevelled differently along their length, the good side is that there would be little difficulty in bending them.

hello world – 3, part 3a

Chiều nay trên bến muôn phương,
Có thuyền viễn xứ, nhổ neo lên đường.

Thuyền viễn xứ – Thái Thanh

he 511 putty comes in 2 parts: the resin and hardener, both premixed with a certain kind of thickening agent (filler), one has a dark gray and one has a yellowish color. Just stir them until you have a consistent light gray, highly viscous mixture. Since the hull and deck are tied to the framing boxes, I can easily slant the boxes to get the putty cured into the exact position, resulting into very clean seam lines. No need to use duct tapes to mask the lines though.

Fill the seams, wait for the putty to cure, cut the wires, then fill the remaining, repeat that for both the hull and deck parts. My precautious nature steps in as always, I made the seam lines of the hull much bolder and thicker, while the deck has very thin lines only. It’s easy, but it would take a few days to finish all these glueing tasks. After this, I would dry fit the two halves, to see if they match each other well, and to produce an initial impression of the final product also!

I recall glueing the seams of Hello World – 1, my first build. I used a small masonry trowel to apply the putty, about 1/2″ (!!!) thick, and epoxy is all messing around. Now it’s much tidier and cleaner, and I don’t even need a pair of gloves and just work with my bare hands. Well, lots of little know – hows, skills and experiences that you could never learn if you don’t just really do it. About this time last year, I was so doubtful if I could even finish myself a boat, now it’s (almost) the third! 🙂

A bit off topic here, but the thinking has been in my mind for a long time. About educational methodology, they’ve been arguing all the time, about knowledges, information, attitudes, practices, etc… But for me, it works a different way: if you want someone to build a boat, show him / her the immense beauty of the sea. Similarly, you don’t have to learn all those maths and algorithms to become a good coder, seek the inspiration in something else, e.g: the art of hand writing calligraphy! 🙂

hello world – 3, part 2c

Cô phàm viễn ảnh bích không tận…

he game of paper cutting and glueing again! 🙂 The efforts of building all those framing box and temporary spacing bulkheads now come into fruition, seeing the bilges fit perfectly, not any noticeable gaps between them. All temporary bulkheads fits well to the hull and gives you an assured feeling that the boat is taking a good shape. It’s a real pleasure to see things properly executed and the building quality is under your control.

I use smaller wires and drill smaller holes into the bilges’ edges, as the 4 mm ply need less fastening force compared to the 5 mm one. The ugly thing about the “Stitch and Glue” method is that there’re so many small holes to be drilled into the hull, about 250 for this Hello World – 3, and later, you would need to check and re – fill each of the holes before glassing, a tedious task indeed. The bevelled edges leave a good space for putty to go into, making very clean seam lines.

Contrary to my initial thought, the sharp edges stand together pretty well, they need some adjustments, some dots of Cyano Acrylate glue here and there, and some little wires fastening too. But overall, both the deck and hull part shapes are very satisfactory to me. My boat building workshop has been becoming too overcrowded and cramped with three boats, and many kinds of machineries, to get some good shots showing off the boat shapes. Oh, those gorgeous curves and shapes!

I proceed slowly as I would have little free time this week: check the geometries, fasten the wires, then glue the seams. I use a good local epoxy putty called: 511. The 511 came into my favor since it has long curing time, don’t have to worry about epoxy burning in pot anymore (it’s a real problem in hot tropical climate). It also has a constant viscosity giving you a consistent, predictable working behaviors (unlike the fillet I manually mixed with wood flour, which differ from time to time).

hello world – 3, part 2b

…Hoài thượng đối thu san.

he S & G Night Heron plan calls for beveling the bilges’ edges, and I follow it exactly, the bevels will help forming the boat shape more precisely, and also help to strengthen the putty joints. At first, I intended to use my routers to do the edges’ beveling, but switch to the frequently – used angle grinder instead. With the angle grinder, it’s harder to do the job, but it allows you to adjust the angle along the bilges, it’s steeper toward the boat’s aft and bow.

Next, I would add several layers of ‘penetrating epoxy’ onto the joined planks. This is my own experience in dealing with plywood, epoxy, and glassing. ‘Penetrating epoxy’ is nothing more than epoxy (with slow hardener, the B5) thinned with a solvent, I use xylene, which works best for me, mixed in 4/6 ((resin + hardener) / solvent) ratio. The plywood I could find here in Saigon is usually not of very high quality, I can see it absorb lots of thinned epoxy cause the veneer is so porous.

Using a slow hardener plus a solvent (applied in 3, 4 layers) causes the epoxy to cure slowly, usually within 12 ~ 18 hours. This prolonged time allows the plywood to absorb a significant amount of epoxy, and hence strenghthen the veneer. I estimate that the ‘penetrating epoxy’ adds up about 1 ~ 1.2 kg to the boat’s final weight, but that also helps glassing in the next steps to be more clean and strong, no more ‘white spots, white areas’ in fiberglass cause the wood is already well – saturated.

‘As usual’, I have the unpleasant feeling working with these long, narrow stripes of plywood. At this stage, they are very fragile and delicate, easy to break at any moment. But all would gradually build up strength once stitched together into a structure, have the seams filled with putty, and especially after being reinforced with fiberglass and epoxy. Nevertheless, it’s a very good feeling at this step to see the boat takes its initial shape, I work first on the hull, then proceed to the deck part.

hello world – 3, part 2a

Trường hận thử thân phi ngã hữu,
Hà thời vong khước doanh doanh?
Dạ lai phong tĩnh hộc văn bình.
Tiểu chu tòng thử thệ,
Giang hải ký phù sinh!

nitially, I’d planned to use dovetail joint (or finger joint) to combine the plywood pieces together, but after cutting them, the 4 mm ply is quite thin and fragile to work on, so decided to use scarf joints instead. I used this Bosch laminate trimmer to remove 2 mm of ply on the surfaces, apply the TiteBond 2 glue, then clamp them together overnight. The Bosch fixed base router is an excellent tool, easy to adjust the bit’s depth, small enough to be handled comfortably.

I’ve finished the scarf joints with almost no mistake. Next I would slightly sand the joints, bevel the edges, then apply a few layers of thinned epoxy (epoxy mixed with xylene solvent, that is what they call ‘penetrating epoxy’, more about this in the next post). A layer of fiberglass with un – thinned epoxy over the joints would make the scarf joints strong enough. Some notes about epoxy below, and I hope the information would be useful for anyone having to work with the resin in Vietnam.

There’re several kinds of epoxy resin, the ‘component A’, but for most tasks, the vendors will sell you the correct, most – frequently – used one, just say ‘epoxy resin’ and they will understand. For the ‘component B’, or the hardener, there’re at least 3 types that I know, named (after the local nomenclature): TETA, B5 and T31 (guess they’re the abbreviations of some chemical formulas). The TETA can be called the fast hardener, would cure within a few dozen minutes (in tropical weather).

TETA can be mixed by any ratio from 1/1 to 10/1 by weight (I usually mix in the 2/1 ~ 5/1 range), it produces a very hard but brittle output. The B5 can be called the slow hardener, it takes hours to cure, and need to be mixed at the exact 2/1 ratio. B5 produces a hard, but flexible result, with very little bubbles (but it’s more expensive than the TETA), also it has to be stored in the dark to remain its chemical behaviors. Both has a light ammonia odor. For the T31, I haven’t tried to say anything about it.