người đi qua đời tôi

hích nghe chữ gió thứ hai trong bài này, không phải chỉ ngũ cung mới có sự luyến láy, non một chút, già một chút… So chất giọng với phần đông ca sĩ bây giờ, khác nào đem âm thanh đàn organ điện tử so với cây đại phong cầm (pipe organ, không phân biệt được âm thanh của organ và pipe organ thì xin mời ra quán nhậu hát nhạc boléro kẹo kéo!)

Người đi qua đời tôi - Thái Thanh 
Người đi qua đời tôi - Quỳnh Giao 

Thực ra tôi cũng thích nghe Thái Thanh hát nhạc Trịnh Công Sơn 😀, ví như: Tuổi đá buồn, Ca dao me… (nghe trong post trước về Thái Thanh của tôi). Lẽ đương nhiên, “thích” có vô vàn sắc thái, góc độ khác nhau, cũng có vô vàn ẩn ý, ngữ nghĩa khác nhau, ví như tôi cũng thích nghe boléro, ví dụ như bài này.

serene – 1, part 4

inalized my new kayak design, a considerable amount of work on optimizing the hull shape, adjusting it back and forth to find out the minimum drag numbers (based on the Kaper algorithm) while keeping stabilities and other parameters under control. Some numbers: LOA / LWL (length overall / waterline): 5.500 / 4.945 m, BOA / BWL (beam overall / waterline): 0.452 / 0.420 m. I reduced the boat width to exactly my hip plus 4 fingers (that is: 36 + 9 cm, my fingers are quite big, 9 cm for 4 fingers).

Designed draft: 0.11 m, Designed displacement: 95 kg, Cp (prismatic coefficient): 0.5475, Cb (block coefficient): 0.4064, LCB (longitudinal center of buoyancy): 0.5225, VCB (vertical center of buoyancy): 0.0690 m, LCF (longitudinal center of floatation): 0.5136, Cw (waterplane coefficient): 0.6445, S (wetted surface area): 1.699 m2, Aw (waterplane area): 1.329 m2, Am (midship section area): 0.034 m2, Cm (midship coefficient): 0.7466, KMt (vertical transverse metacenter): 0.196 m.

Predicted drags at 0.11 m draft (95 kg of displacement): 3 knot ~ 7.122 N, 4 knot ~ 12.622 N, 5 knot ~ 23.763 N. Predicted drags at 0.121 m draft (110 kg of displacement): 3 knot ~ 7.679 N, 4 knot ~ 13.611 N, 5 knot ~ 25.506 N. The hull is heavily optimized for speed in the [4 ~ 5] knot range with some sacrifices in stability and load capacity. Now that all “theoretical calculations” has completed, it would take a few months to build the physical boat to tell the real truths about the design! 😀

Serene – 1, part 1
Serene – 1, part 2
Serene – 1, part 3
Serene – 1, part 4

While 45 cm could be considered “extreme” for nowadays kayak (few available on the market has width at or below that value), it’s not really so with the traditional Greenland ones, some could be as narrow as 39 cm. Well for sure, it requires lots of skills to handle such a narrow boat.

The very important point here is the CG (Center of Gravity) used in calculating stability. The Sea Kayaker magazine uses a standard 25.4 cm as CG, as a reference point to compare different kayaks. I used the midpoint of VCB and KMt as CG, which is usually [12 ~ 14] cm for my cases.

serene – 1, part 3

ade some good progress in the process of modeling my new kayak… For a human – powered watercraft, water doesn’t like complex curves and shapes I think, so they need to be as simple as possible (it is not too simple to come to that simplicity though). The model is then decomposed by Free!Ship into several “developable” plates, at this point, professional builders could just output the plates to a large CNC machine, which would precisely cut the plywood accordingly.

I print those plates to paper to make a 1:15 paper model. Cut the plates with a pair of scissors, then stitch them together using transparent duct tape. Making a paper scaled model would help verifying about the “develop – ability” of the product, double check if there is any design mistake, and give a clear view on how we should compose the pieces into the final boat. For simplicity, I didn’t draw details such as the cockpit, skeg, lines or hatches, just the basic shape of the kayak.

The paper model is a bit ugly (my hands are not too skillful though), but the pieces come together perfectly, the shape just looks like a bamboo leaf! This gonna be a long, thin kayak with very little freeboard! Next would be finding some free time to materialize all these drawing onto the plywood sheets. I don’t have a printer that’s large enough to print the plates in their real sizes, so I would just redraw them using offset table exported from the CAD software, actually, I prefer this manual method!

Serene – 1, part 1
Serene – 1, part 2
Serene – 1, part 3
Serene – 1, part 4

Back to the number 70.39 Watt, a heavy labour (such as a bricklayer) produces about 75 Watt on average, and for only 8 hours. You know what it’s like to paddle 10, 12 hours on a minimum basic, or even more, like I was paddling for 16 hours from Vũng Tàu back to Sài Gòn in my last trip!

The book Kayaks Of Greenland by Harvey Golden is a great guide for home builders, it contains dozens of kayak models ready to be built, with all the necessary drawings! I used some models from the book as references and comparisons when designing this Serene – 1 kayak!

thời hoa đỏ

Anh mãi mê về một mầu mây xa,
Cánh buồm bay về một thời đã qua…

Thời hoa đỏ - Nguyễn Đình Bảng 

serene – 1, part 2

t tooks just a few hours to learn the new software and construct the basic 3D objects: hull & deck. The time – consuming tasks are adjusting the shapes and playing around with hydrostatics. Some basic measures: LOA / LWL (length overall / waterline): 5.50 / 4.44 m, BOA / BWL (beam overall / waterline): 0.483 / 0.451 m, Draft: 0.1 m, S (wetted surface area): 1.66 m2, Cp (prismatic coefficient): 0.5619, LCB (longitudinal center of buoyancy): 0.5150, LCF (longitudinal center of floatation): 0.5192.

Additional hydrostatics parameters, VCB (vertical center of buoyancy): 0.0590 m, Cb (block coefficient): 0.4684, Cm (midship coefficient): 0.8336, Cw (water plane coefficient): 0.6385, Displacement: 0.096 tonne… Well, I wouldn’t pretend that I fully understand those parameters above, cause they contain insights into a boat that can only be correctly interpreted by an experienced designer. However, I’m tweaking around to optimize the parameters toward a higher Cp, higher LWL, and lower S.

Drag (resistance) predicted by the KAPER algorithm looks fine till now, however, the displacement is sacrificed already, 96 kg, barely enough for me (65 kg) plus 30 kg of gears. This gonna be a demanding boat with low primary stability, not recommended for beginner. It takes some real world experiences to understand why low initial stability is indeed a good thing, and why a kayak which appears to be very stable on flat water could probably throw you up side down in bumpy conditions.

Serene – 1, part 1
Serene – 1, part 2
Serene – 1, part 3
Serene – 1, part 4

Some rough calculations on the energy required to propel a kayak. My target speed is 7 kmph, or 3.8 knots. From the numbers recorded by my Garmin over the years, in normal big rivers and sea conditions, speed is reduced by 1/3 compared to the ideal condition of flat water.

That is you have to struggle at 5 knots to assure that 3.8 knots. The Kaper algorithm tells you that, this Serene – 1 hull produces a resistance force of 27.35 Newton at 5 knots (or 2.57 meters per second). Making the multiply: 2.57 x 27.35, that’s the output required: 70.39 Watt!

serene – 1, part 1

n the progress of learning to design my new kayak… you know its name already. I’m using Free!Ship, a CAD software running on Win XP virtual machine (with VirtualBox) on my Macbook. I haven’t used any CAD software before, haven’t designed anything 3D, not to say about a watercraft. So why designing a kayak!? Well, first, just for the fun of doing something yourself from A to Z. Second, though I’m no naval designer in any sense, I believe I have some guts on how a good kayak should be!

Many kayaks are designed for 70 ~ 90 kg paddlers on average, I’m not that bold, and I need something slimmer, lighter, with the drawback of sacrificing some load capacity of course. I’m re – modeling my kayak after Björn Thomasson’s Black Pearl, using just some publicly – available pictures of the boat. And it’s not a copy, there’re some modifications: slightly narrower beam, slightly less rocker, and slightly deeper V – bottom. And I would stick still to my familiar stitch & glue construction method.

Why stitch & glue!? Strip build generally offers best boat shapes, but look at the Inuit people’s SOF (skin on frame) kayaks, those “hard chines” suit naturally to S&G, the method is simpler and takes less time (which I don’t really have much for now). It gonna be not an easy process: just for the hull, adjust the 60 control points back and forth, recalculate the stability and performance parameters, repeat again and again until you’re satisfied with the results. I hope I can finish the design in about a month or so.

Serene – 1, part 1
Serene – 1, part 2
Serene – 1, part 3
Serene – 1, part 4

Recently, I’d noticed that Japanese kayakers usually use kinds of slim, long kayak similar to the Black Pearl, that’s quite understandable cause the body – building of Japanese is Vietnamese alike, we’re not too bold. Use a slimmer, lighter boat, and pack your gears cleverly for longer trip!

It’s interesting to know that, in the old day, in building kayaks, the Inuit people has “recipes” to measure the size of the boat: length should be 3 times the height of the paddler, width should be the hip plus somewhere from 4 to 8 “finger”. Well, like shoes, boat is tailored to match the user.

300 ca khúc Thái Thanh

Giọt mưa trên lá, tiếng khóc chơi vơi,
Thế giới lạc loài, chưa thoát ra phận người…

hừng này tạm đủ như một lời giới thiệu ngắn gọn về giọng ca Thái Thanh, hơn 300 ca khúc của nhiều nhạc sĩ khác nhau: Phạm Duy, Phạm Đình Chương, Dương Thiệu Tước, Hoàng Trọng, Văn Phụng, Văn Cao, Lê Thương, Trịnh Công Sơn… Các ca khúc được xếp theo thứ tự ABC để tiện tìm kiếm. Những tựa in đậm là những ca khúc tôi thích và thường nghe. Chất lượng âm thanh không đồng nhất, tốt có, kém có, nguyên bản nhiều, remixed cũng lắm. Chất lượng âm nhạc… cũng thế!

Nhưng có hề gì, miễn là cảm được giọng ca Thái Thanh, hay nói như NS Phạm Duy: Thái Thanh chỉ cần cất giọng là người ta đã mê, bất kể bài nào. Đến giờ, không còn mấy ai cảm được cái kiểu luyến láy nhấn nhá như trước nữa… Một số người vẫn cất công kể lể nhạc xưa thế này, Thái Thanh thế kia, blablabla… Nhưng tôi không nghĩ là họ đã nghe đủ, và càng không tin là họ có hiểu một tí gì, vì dù có nghe cũng chắc gì đã hiểu!? Thực ra tôi không cần đến 3 giây để nhìn ra những điều như vậy!

Dù đó là những đĩa than đã mòn nhẵn với thời gian, hay những thước băng cối đã nhão đến mức khó nhận ra âm điệu gốc, từ những bản thu mộc âm thanh mono cách đây hơn nửa thế kỷ, hay những thu âm CD số hiện đại sau này, thì giọng hát Thái Thanh vẫn không thể lẫn vào đâu được. Nhiều chất giọng cũng cao như thậm chí là hơn Thái Thanh, nhưng những bội âm trong chất giọng của bà là điều mà không một ai bắt chước được, không một kỹ thuật hiện đại nào có thể tái tạo được!

my workshop – 2

Như dòng sông ra đại dương, qua bao ghềnh và đá cheo leo.
Đấu tranh này bền lòng em ơi, mới tới ngày nắng ấm…

Lời người ra đi - Trần Hoàn - Khí nhạc: Nguyễn Đình Nghĩa 

ake my little free time to do some updates for the workshop, it’s covered with layers of dust after months without any woodworking projects 😢. First is the wall – mounted kayak rack, a simple structure to stack – up my boats to better utilize the room’s space. Seen mounted on the rack are my HW – 2 & HW – 3 kayaks. The HW – 1 canoe has been in dis – use for a very long time already, so I decided to turn it into… a shelf!

Cut out the aft part, attach a MDF sheet to make a standing base, erect it upright et voilà, you have a shelf to store various miscellaneous things! 😀 I was a bit hesitating in “scarifying” a canoe in such a way, but I would stick with sea kayaks for some years to come, would be back to canoes at an uncertain time. Also, I’m in the initial stage of planning for my next build, something I would start by designing it, or at least learn to design it!

Lê Quý Đôn sailboat

n update to a previous post on Vietnam Navy training sailboat, construction and fitting are by now almost completed, delivery is estimated sometime next month in Cam Ranh port. The boat is named “Lê Quý Đôn”, after Vietnam 18th – century prolific scholar and polymath, can see it clearly at the boat’s bow, still not sure which number (HQ – xx) would be assigned to this Naval training vessel. To be honest, I’m feeling envy with those 30 Vietnamese sailors being trained onboard that watercraft!

hông tin thêm, tiếp theo 1 bài trước về con tàu buồm huấn luyện của Hải quân Việt Nam. Quá trình đóng và trang bị tàu đã gần như hoàn tất, sẽ chuyển giao cho phía Việt Nam vào khoảng tháng sau ở cảng Cam Ranh. Con tàu sẽ mang tên “Lê Quý Đôn”, đặt theo tên học giả uyên bác người Việt sống vào thế kỷ thứ 18th, tên đó đã được sơn rõ ràng ở mũi tàu, nhưng hiện chưa rõ là con tàu sẽ mang số hiệu (HQ – xx) nào. Thực lòng mà nói, tôi đang cảm thấy ghen tị với 30 thuỷ thủ người Việt đang được huấn luyện trên tàu!

One may wonder what’s the role of sailboat training in modern naval warfare, where ones sit in air – conditioned rooms, in front of LCD displays, with high – tech missiles at their fingers’ control? First, sailboat training help forging a sailor’s strength, moral and will, second, it equips the soldiers with skills: rowing, swimming, other survival skills… so that in the worst case that could happen to their ship, they know that they could still survive. That would bring more confidence for them to do the utmost into a naval battle.

Sẽ có người hỏi tại sao lại dùng tàu buồm, trong chiến tranh hiện đại, mọi người ngồi trong phòng máy lạnh, trước màn hình LCD, chỉ nhấn nút một cái là các tên lửa công nghệ cao được phóng đi. Để trả lời, đầu tiên huấn luyện thuyền buồm sẽ giúp rèn luyện thể lực, tinh thần, ý chí cho học viên. Thứ hai là trang bị cho họ các kỹ năng: bơi lội, chèo thuyền, và các kỹ năng sinh tồn khác… để nhỡ khi tình huống xấu nhất xảy ra với con tàu, thì các thuỷ thủ vẫn còn cơ hội sống sót. Chính những kỹ năng đó mang lại sự tự tin, giúp họ dám liều mình trong chiến trận.

the blue lagoon

he 80s again, another film that I’d seen when I was a young boy, and liked it very much: The Blue Lagoon. Broadcasted on Vietnamese (analog) TV under the title: Eo biển xanh, the film was a strange phenomena, in an extremely closed and strictly censored environment as Vietnam as of the 80s. It’s the 1980 adaptation from the book of the same name, there’re many other adaptations as well: 1923, 1949, 1991, 2012…

The Victorian era, two children shipwrecked alone on a tropical island. They thrive on the bounty of jungle and lagoon, the boy grows tall, the girl beautiful. When their love happens, it is as natural as the sea, and as powerful. Despite its extreme nudity, negative reviews, quite low rating etc… (which I only know by now), back then, I simply did (and still do) just love it! 😀 To know why, see the movie screenshots below!