serene – 2, part 12

ot entirely related to this Serene – 2 building, but I would want re – organize my woodworking workshop a bit. My working place is quite small in floor area, so everything need to be stored neatly and tidily. Having quit some ideas, but would carry them out only one at a time, since I still have limited free time in the present. First is a shelf to store my plywood and MDF sheets (lots of them), and many other things.

The plywood and MDF sheets need special treatments, they could deform in shape or absorb moisture if stored inappropriately for a long time. The shelf would have two sides, the sloping side is for storing the sheets, and the other side is reserved for other things. The whole thing would be put on 6 small wheels so that it can be pulled and repositioned around the workshop, or moved just for cleaning the floor.

1st image: making the shelf base, 2nd image: the 3 supporting walls (to withstand the MDF and ply sheets’ weight, which could be very heavy). 3rd image: the shelf taking shape, 4th image: the completed and marine – blue painted product, ply and MDF sheets stored on one side (facing the wall). I need lots of shelf spaces to store various miscellaneous assets, which is growing to a unmanageable number 😢.

Sometime, I’ve forgotten that I’ve purchased something just because there’s a huge pile of them around. The workshop looks very tidy now, having more spaces to store various things. It’s very important to keep thing tidy, uncluttered, as you wouldn’t want to waste time finding an item when needed. It’s now time to move on to the main parts of the project, I’ve been lingering around on other issues for long enough.

đèo ngang

Chưa đi chưa biết Đèo Ngang
Đi rồi mới biết Đèo Ngang… đang nghèo (!?)

hớ lại 1 chuyện khó quên gần đèo Ngang, Quảng Bình, gần Tết 2015. Chiều hôm đó, phi quá đây thì… xe xịt lốp sau, mưa xối xả, lạnh cắt da, đói và trời đã gần 6h chiều. Thấy cái khách sạn đầu tiên, quyết định nghỉ vì khó lòng đi tiếp. Sau một hồi đứng cho ráo nước, nhìn quanh thì thấy một cảnh tượng kinh ngạc, cái khách sạn sang trọng không từ nào tả xiết. Gỗ quý ốp từ sàn, tường tới trần, từ khắp sảnh trước ra nhà sau, cầu thang, bàn ghế, thậm chí cả sàn phòng tắm cũng lát gỗ. Không chỗ nào là không có gỗ, gỗ tốt khắp mọi nơi, chạm trổ tinh xảo, cầu kỳ, sang trọng đến choáng ngợp!

Bèn hỏi ngay lễ tân giá cả trước khi đặt phòng, thì được biết cái giá 150 ngàn/đêm. Lúc này thì thực sự đã kinh ngạc lắm rồi, không biết mình đang lạc vào cái “động” nào đây. Nhưng cũng ra vẻ tự nhiên xách đồ lên phòng, tắm rửa sạch sẽ rồi xuống ăn tối. Đồ ăn ngon, nêm nếm đậm đà kiểu Huế, 1 đĩa cá kho, 1 tô canh chua, 1 đĩa rau xào, cơm… tổng cộng 35 ngàn! Đến lúc này thì ngạc nhiên đến tập thứ ‘n’ chứ không ít! Nhưng tính không thích hỏi, số sướng cứ việc hưởng, nhìn chị chủ khách sạn chỉ thấy điệu cười tinh tế, nhè nhẹ, chu đáo, phong thái con nhà quý tộc chứ không phải buôn bán tầm thường.

Sáng hôm sau thanh toán tiền rồi rời đi, mình cũng không hỏi, không nói gì, mà chị chủ cũng chỉ điệu cười nhẹ nhẹ ấy! Bản lai diện mục các bạn thử đoán xem sao nhé! 🙂

mộng thuỷ tinh

âu lâu cũng post nhạc “đương đại” 1 chút, một bài cũng bình thường chỉ để thi thoảng hát nhóp nhép chơi: Mộng đẹp như thuỷ tinh rơi, Người xa, tình xa khuất chân đồi… Thuỷ tinh rơi thì sao, thuỷ tinh rơi sẽ vỡ… Cái logic hiển nhiên ấy khá phổ biến trong các ngôn ngữ khác (Anh, Pháp, Hoa…) nhưng lại không phổ biến với ngôn ngữ, với tâm hồn Việt, người Việt chỉ hiểu / chỉ muốn cái gì rõ ràng, trực tiếp… chứ không phải phiếm chỉ như thế. Cái ca từ này có lẽ được dịch từ ngoại ngữ, kiểu: shattered like a falling glass…😀

serene – 2, part 11

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, part 10

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! 😀

algorithms

ột phần quan trọng của 4 năm ĐH nằm trong cuốn này. Sách ngoại văn bìa cứng (hard cover), giấy tốt, đồng giá 50K/cuốn. Những năm 199x, FAHASA nhập sách ngoại về, bán chẳng ai mua, canh me đi qua lúc nó sale off, xúc luôn 1 lúc 20 cuốn, từ Algorithms, Data structure, Database… Algebra cho đến Mathematical Analysis, etc… Cũng là lý do tại sao thuật ngữ Toán, Tin… ko hề biết tiếng Việt. Cũng chưa thấy cuốn sách Tin học nào hay và bổ ích như cuốn này.

Nói cho đúng là cái cách hành văn khoa học tiếng Anh của nó ám ảnh mình, ít khi thấy được một cách hành văn hay, súc tích, dể hiểu đến như thế, cộng thêm minh hoạ cực kỳ xinh đẹp. Nếu nói mức độ hiểu 1 vấn đề nó thể hiện qua cái khả năng diễn đạt, trình bày lại để cho người khác cũng hiểu vấn đề đó thì tác giả cuốn này đúng là siêu đẳng !!! Về sau phát hiện ra, cả thư viện ĐH KHTN có đúng 1 cuốn này, mình có riêng 1 cuốn! Không có thói quen đọc nhiều sách, theo mình, cả ĐH chỉ cần đọc chừng 3, 4 cuốn, và cả cuộc đời chắc không cần đến 20 cuốn. Đọc nhiều quá phí hoài… tuổi xanh đi!

Dự định sau này mình sẽ đóng 1 cái kệ sách cao đến sát trần nhà, lý do là bỏ bớt những cuốn không đọc lên trên cao để không phải đụng đến chúng :D Sách thực sự hay ít như sao buổi sớm, mà sách lôm côm nhiều như… lá rụng mùa thu! Sau bác nào đó thấy sách ngon, mượn ko trả, tiếc đứt ruột! 😥

serene – 2, part 9

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, part 8

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.