serene – 3, part 10

ull and deck parts are basically stitched and glued, those two halves of a peanut shell. But that’s only a basic milestone, lots of jobs required still to make this shell functional. I continue to build the hatches and cockpit coaming, and various other accessories. 3rd image: the cockpit coaming glued in, stained with epoxy filled with black color pigment, later on, some layers of transparent PU paint would make the finish. While the cockpit is easy, it’s a bit more complicated for the hatches.

Both two hatches is of the same shape and size, for the sake of easy constructing (the hatches and their silicone gaskets). The forward hatch is built recessively into the deck, not only to keep a flushed, flat deck, but also simply because the hatch size is a few centimeters larger than the deck’s top, it needs to sink down to fit. It’s a bit tricky to build the recess, so I decide to get along with a rectangular approach (it’s much easier to build, though a circular one would certainly looks much better).

The aft hatch raises about 1 inch from the deck, not too high to interfere with reentry climb – in actions. I would try a new idea for hatch locking, something that’s easy to operate and tight enough (offer some pressure down) to secure the hatches in places and help with waterproofness. Hatches and hatch locks have been causing my headache for long, but it seems, the best solution is indeed simple, I wonder why my common – sense has not come up with it in the first place.

russian names

ừ Vladimir đến Vladimir, 100 năm (1917 – 2017) Vladimir đầu là Vladimir Ilyich, Vladimir sau là Vladimir Vladimirovich! 😅 Cách đặt tên của người Nga có chỗ khác biệt với phương Tây, ngoài họ (như Ulyanov) và tên (như Vladimir), tên đầy đủ của người Nga còn chèn thêm tên của bố – patronymic ở giữa, như trường hợp của Lenin là: Vladimir Ilyich Ulyanov.

Ở đây, ám chỉ là ông Vladimir, con của ông Ilya, họ nhà Ulyanov, còn của Putin là: Vladimir Vladimirovich Putin (vì bố ông ấy cũng tên là Vladimir). Cách đặt tên như thế có ưu điểm là khó có 2 người trùng tên nhau, nhưng thường chỉ dùng tên đầy đủ trong trường hợp trang trọng (hoặc nghiêm trọng). Thêm một chỉ dấu của một nền văn hoá cực kỳ… phụ hệ!

serene – 3, part 9

hat’s the stitch part (of “stitch and glue”), or more precisely, most of it (since there’re still the bow and stern pieces to be put in, but that would be discussed later on), next come the gluing. First the seam lines are “primed” with epoxy (applied with a small brush), then filled with fillet (the tried – and – true 2 – parts epoxy putty 511 that I’ve been using extensively). The “gluing” part is a very time – consuming job, you have to meticulously fill the putty, which slowly flow down under its own weight.

So I have to apply the putty in 2 turns, first fill in just a small bit of them, wait for it to cure, then fill over the first layer another time. This is to ensure that the putty could form curved seam lines that would be easier to glassed later on. You can also mix small batches of putty, wait for about 30 minutes for it to cure partially, then apply it on the seams, the higher viscosity of the slightly – cured putty enables it to better keep its shape. In all, it’s a very time – consuming (and dirty) job!

Next come in the bow and stern pieces. These small triangular plywood pieces need to be bended into curved shapes (see the 4th images below). I simply put them into boiled water for them to soften a bit, then slowly and carefully bend them with a pincer. The bow and stern parts are then temporarily fixed in place with hot glue and duct tape, then permanently glued with epoxy and fillet (putty). Now, the whole hull is rigidly glued in its internal side, similar job is applied to the deck part.

serene – 3, part 8

took great care in aligning a bilge’s parts, to make sure the final piece would come exactly to it designed shape, and to make sure the port and starboard bilges are identical, or else, the boat would have a twisted hull. All joints is slightly sanded, and applied a layer of glass on the internal side. Next come the job of putting everything together using a combination of fastening wires, super glue and duct tape. Having experiences from previous boat, I used very little steel wires this time.

It’s so good to see the bilges fit naturally into their position, with minimum pressing, adjusting efforts. The tendency to take shape easily proves that you’ve all done right in the previous steps: measuring, drawing, cutting and jointing the biges. This is for the first time, you would have an initial impression, of how the boat would finally look like. The computer 3D renderings are too small to have a precise assessment, and of course, it’s always much more lively with a tangible object! 😀

Looking at these two halves: hull and deck, having a senses of every details, it’s easier to arrange and schedule the next tasks. There’re so many jobs ahead: make and install the (recessed) hatches, hatches’ locks, install the cockpit coaming, rudder pedals and control lines, compass, the bilge pump, etc… and of course the whole complex electric & electronic system. Things should be better done this time, with the lessons learnt (tediously and expensively) from previous boat projects.

serene – 3, part 7

n parallel to cutting, jointing the bilges and forming up the hull and deck parts, I’m also making the cockpit coaming and hatches. They both use the same techniques of bending thin strips of plywood (2 layers of them) around a MDF frame to form the lips’ shape. Now that I have some much better – quality plywood sheets, which is not too easy to crack while bending into extreme curves, this enables me to construct the cockpit coaming and hatches in a much easier and convenient way.

Both 2 hatches would be of the same shape and size, a “rectangular” with 2 circular ends (or could be called: a rounded rectangular). The hatches’ lips and the coaming lips are built up from 2 layers of 4 mm plywood strips, glued together. The flexibility of the ply serves well to the building, the lips take up shape easily, and stay in that shape steadily. In all, they’re all simple really constructions. Special thing about the hatches this time is that they would have elastic silicone gaskets inside.

Recently, I’ve learnt about silicone molding, using 2 – parts silicone mixed together just like epoxy. So I would mold the gaskets specially to accommodate the hatches, and would describe that in another following post. Hatches’ waterproofness has long been a serious issue to me, hopefully, I could resolve it completely this time. An handy (last resort) trick could also be useful: cover a layer of (very thin) PE plastic over before closing the hatch, that would make it absolutely water – tight.

CMT10

ài trăm năm trước, Marx đã vẽ ra một cơn “ác mộng” về cuộc sống dưới chế độ TBCN, nơi mọi thứ sản xuất ra là để mua bán, đổi chác. Năng lực sáng tạo của con người bị biến thành một thứ hàng hoá. Sản phẩm và người làm ra sản phẩm rút cuộc cũng đều là một thứ hàng hoá, và cuộc sống hàng ngày bị biến thành một vòng xoáy bất tận.

Vòng xoáy của những zombie – xác sống, vật chất trở nên nửa – sống, còn con người trở nên nửa – chết! Thị trường chứng khoán vận hành như một thế lực độc lập, tự nó quyết định nhà máy nào sẽ mở/đóng cửa, người nào sẽ đi làm/nghỉ ngơi. Tiền thì sống, người thì chết, sắt thép mềm như da, còn da mặt cứng hơn sắt thép! Một vài suy nghĩ của ông ấy vẫn còn tính thời sự!

serene – 3, part 6

ext is jointing the plywood pieces: 8 joints for the hull, and just 1 for the deck, to form the bilges that would build up into the boat shape. For the 2 pairs of hull’s bilges, I flip one pair by 180 degree when drawing on the boards, so that to distribute the joints at different places across the boat length, and not to concentrate too much joints into one proximity. That old boatbuilding carpenter’s trick is not completely necessary with modern building techniques, but it’s nice to do so anyway.

The tried – and – true technique of straight finger joint is used as always. The straight joints are easy to cut, and most importantly much easier to be aligned following a straight line for all the jointing parts, so that to make sure all the bilges would be jointed into the correct shapes. All the joints are treated carefully, first is applying a layer of thinned epoxy (using xylene as a solvent, for the substance to penetrate deeply into the plywood), then gluing with epoxy, then a layer of glass on the internal side.

I beveled the edges of the deck parts a bit (at 45 degrees), so that they would fit tightly and nicely together forming straight seam lines. But that’s not applied to the hull, where the cursive seam lines don’t like very thin edges. Experiences from my previous boats showed that, it’s best just to use the squared edges, the thin edges doesn’t stay on each other very well, and would deform, distort the seam lines! You would later just apply thickened epoxy on both sides (in and out) of the seams!

serene – 3, part 5

he progress is really slow lately, several weeks passed, but little get done 😢! Things started moving anyhow, I “quickly” transfer the “offset tables” onto the plywood boards, draw all the bilges, bulkheads, and other parts. The greatest thing of all is that now I’ve purchased very good sheets of plywood, not truly marine – grade (there’s no such in Vietnam), but high – grade water – resistance ones. I could feel it when do the sawing, the boards are quit tough, not fragile as with my previous ply!

There would be an immediate consequence with the new plywood, I would just use less epoxy to pre – fill the boards, and since the boards is stiffer, the glassing would be done on the outside only, that would significantly save the boat weight, I hope. All drawing is completed quickly, I finished in just less than one day, next come the steps of cutting and jointing the bilges. Everything has been done many times before already, so I didn’t have to think or consider things much, just repeat it!

4th image: the cockpit coaming frame cut from a piece of 18 mm MDF. This cockpit is drawn using the mathematic formula mentioned in my last post. It came very closed to the shape of Serene – 2‘s cockpit, but slightly smaller on each sides by about 5 mm, so my existing spray skirt should fit tightly with this new coaming (on Serene – 2, it’s too tight). The coaming would be constructed from 2 layers of 4 mm plywood, and I would later omit out the (a bit tricky) glass reinforcement on this part!

how to draw a kayak cockpit mathematically?

ver the years of designing and building wooden kayak, often a recurring question comes to my mind: how can we precisely construct a kayak cockpit shape in a mathematical way. Today, I spent 30 minutes to figure out the problem, it turned out to be quite easy indeed. But first of all, there are so many different shapes for cockpits, and everyone may have his / her own preference on how it should look like. Here I try to plot a shape that is most suited to my eyes, and closed to what’s usually called “an ocean cockpit” found on Greenland kayaks.

I went to the Wolfram Alpha website (wolframalpha.com) and entered an ellipse function. Apparently a cockpit shape is not elliptic, but rather an asymmetric “egg shape”. I tweaked around the equation for a while, changing its components, and the shape came out, closely resembles that of my Serene – 2. I’d also tried to construct other types of “egg shapes”, for example, an 3 – ellipse that has 3 foci, something that could be drawn with closed thread of rope running around 3 nails pinned on a wooden board (similar to drawing an 2 – ellipse with 2 foci).

But it’s hard to determine the dimensions of that 3 – ellipse, and the positions of its 3 foci. Finally, I found out the formula that is best suited for me, something that could be determined numerically to ease out the actual drawing. The formula finally: x2 + 3.5y2 + 1.5xy2 = 1. Upon close inspection, the “egg shape” turned out to be very satisfactory. One might try changing just the “weight” parameters (e.g: 3.5, 1.5…) and retaining degrees of the polynomial’s terms, to experiment with different other shapes, to figure out what is best according to one’s need.

Next come the question of how to draw this shape onto the wooden board that would actually construct the cockpit coaming? A bit of thinking has the problem solved too. The Wolfram Alpha website provides us with numerical formulas. The general steps are like this:

1. Draw a bounding box in the dimensions you want, mine is: 39×72 (cm), the dimension that your spray skirt would fit into (and the spray skirt vendor usually supply you with this information before – hand). The x value would have the value range of [-1, 1].

2. Draw a dense grid of x & y inside that bounding box, for each value of x from -1 to 1, calculate the y value with the formulas given above. Giving very fine incremental values of x, say every 1 or 2 cm, it would be possible to construct a good looking “egg shape” then.

Of course, I want to find out a way to draw the “egg shape” more precisely and more conveniently, e.g: print the plotting actual size on paper, but found it a bit cumbersome as I have no printer of that size! Anyone finding out a good way, please kindly let me know! 😀

the final count down

i cũng biết bài hát xưa như trái đất này, nhưng mấy người biết nó nói về cái gì!? “The final count down” – lệnh đếm ngược: 9, 8, 7… 3, 2, 1… Preliminary stage, Intermediate, Main, Lift – off… đọc lời bài hát sẽ rõ, ngồi trên hàng trăm tấn thuốc nổ, trong một tích tắc là đi vào lịch sử (hoặc trở về với cát bụi) 😅

We’re leaving together, but still it’s farewell. And maybe we’ll come back to earth, who can tell? I guess there is no one to blame. We’re leaving ground. Will things ever be the same again? It’s the final countdown! We’re heading for Venus and still we stand tall. Cause maybe they’ve seen us and welcome us all, yeah. With so many light years to go and things to be found. I’m sure that we’ll all miss her so. It’s the final countdown!