serene – 3, part 2

lso, the deck height right after the cockpit is reduced, so that climbing in the kayak would be easier. The hull’s upper bilges now have much more flare, especially at the 2 ends, to help improving secondary stability, that also has Cp (prismatic coefficient) increased to about 0.52 ~ 0.53, a value usually seen on a faster cruising kayak, unlike the quite – low value of 0.5 on my previous Serene – 2. Transverse metacentric height – Kmt increased to 26 ~ 27 cm, which indicates satisfactory initial stability.

Thus, Serene – 3 is designed with a shift to (primary and secondary) stability concerns. Directional stability (reflected by the Cb – block coefficient value of 0.39) is ensured with an improved rudder system. The beam is slightly widen to 46 cm, and LOA stays at 17 feet. The 5.2m length is an important factor, cause it could entirely fit into a 4 meter truck, which could be easily hired to transport the boat if needed, otherwise at 18 feet, I would need a larger truck, which could be hard to find.

The hull features a deeper V – bottom, something similar to that of the Illorsuit. In all three Serene – 1, 2, 3 designs, I’ve always tried to combine deep V – hull with a narrow beam, something until now I’ve only partially succeeded. Various other improves would be incorporated into this boat. I would build different hatches with big silicone gaskets, to completely solve the water leaking problem (hopefully). Also, there would be 3 hatches along the kayak, to better utilized the storage volume inside.

serene – 3, part 1

t’s time to move on to a new kayak design 😀. Lessons learnt from my last failed trip signifies the necessity for a boat design that is geared toward a wide range of self – rescue actions such as: balanced brace, roll and wet – entry. Thanks to the very dynamic world – wide sea – kayak community, which constantly invents and improves various techniques, I’ve updated myself to some newer self – rescue techniques which I consider to be critically important for long cruising trips.

My previous boat, Serene – 2 has some obvious shortcomings though: initial stability is still slightly problematic, especially for reentry; the electricity system, though working very well, is hard to repair or upgrade, this is due to my inexperience with electrical wiring. I would incorporate into this kayak design various small improves here and there: the storage compartments and hatches would be rearranged to better utilize the boat’s volume, a new rudder system with better responsiveness, etc…

For the last 2 months, most of my free times is directed toward working with FreeShip, the very helpful boat – designing software. Some design parameters: LOA: 5.2m (17′), Beam: 46 cm, Displacement: 120 kg, Cp (prismatic coefficient): 5.3, S (wetted surface): 1.95, Cb (block coefficient): 0.39, Cw (waterplane coefficient): 0.7… The most important change compared to Serene – 2 is a significant increase in rocker, the boat is now much curvy, having the mid section deeper seated in water.

concrete boat

hi chiếc ghe gỗ đã quá nát, người ta làm 1 lớp lưới thép như thế này (cuộn dây thép gai loại dùng làm hàng rào gác ở bên trái), sau đó tráng lên 1 lớp xi măng mác cao dày chừng 1 ~ 3 cm, như thế có đc 1 chiếc thuyền bê tông, phần gỗ đóng vai trò như cốp pha. Kết quả là 1 cái ống bi bê tông di động siêu bền, siêu nặng. Dân gian họ không hiểu nhiều về kỹ thuật, kỹ càng và chi tiết, nhưng họ mày mò được cái gì đúng, cái gì tốt cho họ…

composite boat

ù không thích đa số các mẫu thuyền trong vịnh Bắc Bộ, nhưng phải thừa nhận 1 điều: người ngư dân miền Bắc chịu khó, nhanh nhậy và biết việc hơn hẳn những vùng khác. Như trong hình, cái vỏ composite dày khoảng 6, 7 ly, được đúc hàng loạt ở một nơi khác, ngư dân mua về, tự làm thêm phần mộc (boong, cabin…), phần cơ khí (máy, chân vịt, tời…) để tạo thành chiếc ghe như ý.

Thử hỏi vài câu, kiểu như: “nếu cái vỏ này thủng thì vá làm sao”… là biết ngay người ngư dân rành rẽ cách làm việc với sợi thuỷ tinh và keo (polyester resin?), không như đa số ngư dân miền Trung & miền Nam (không kể thợ đóng tàu chuyên nghiệp) vẫn còn trung thành với gỗ, chưa biết nhiều về composite, hoặc có biết, nhưng làm chưa được đúng…


gạc nhiên nhất trong ngày, lần đầu tiên thấy ghe biển chạy máy mà có cái xiếm – centerboard (thanh gỗ màu đỏ) như ghe buồm!!! Đã nói chuyện với 1 bác ngư dân và xác nhận đó chính là cái xiếm, đâm xuống đằng mũi ở vị trí ngay sát mớn nước. Và không phải chỉ có một chiếc, thuyền đi biển vùng này đồng loạt đóng như thế. Có thể vì cấu trúc thuyền đáy tròn, thân ngắn và rộng nên cần xiếm để cho bớt lắc và đi thẳng hơn. Hình chụp đâu đó giữa thị trấn Quất Lâm và vườn quốc gia Xuân Thuỷ – Nam Định…

serene – 2, part 42

ade some more longer paddlings (20 ~ 25 km) to get to really know her, my newly – built Serene – 2 kayak. It’s not until now that I could get myself familiarized with the boat’s primary stability, which could be really “frightening” to most novice paddlers. In reality, Serene – 2 is “more stable” compared to Serene – 1, but with a much higher free board, the secondary stability comes a bit later, to assure that everything is alright!

Actually, I’m a bit concerned about the boat’s primary stability, cause it has lots of V – bottom the under side. I would need to trail the kayak in its full capacity, to really make sure that the boat reaches its expected stability when fully – loaded with gears for a multiple – days paddling trip. The “fearful, uneasy feeling” caused by the low primary stability should not be taken for granted at all, even when I know that it’s safe.

Cause you would virtually going nowhere when all the time, you’re just worrying about it, worrying that something (a potential capsize) would happen. I’m pretty sure that the boat would be fine at its designed displacement, but only trialling would tell precisely. Looking back at all my boat building, boat playing times, lots of fearful moments, lots of self – doubting, self – disappointments, self – blaming, etc…

But that’s the nature of boating things, of “adventures” on the water. It requires lots of practicing and improving, to make sure that everything is right, that everything just works. My paddling performance is really really bad lately, with very little training ever since my last 9 days paddling trip in June. Obviously, something need to be improved here, and that would be among my resolutions in the coming new year! 😀

serene – 2, part 41

ade several longer paddlings (15 ~ 20 km) to see how the kayak would perform. As with all my previous boats, it takes some little time for me to adapt myself to a new boat, in particular, the primary stability. Each kayak differs by a little, after a few dozens of kilometers, I would feel more comfortable and confident with the boat’s motions. Only after that, the speed measures could be evaluated more accurately.

The Garmin GPS data shows that I could sustain about 7 kmph with my new kayak. That’s pretty much very good, though only slightly better compared to Serene – 1 (it was about 6.5+ kmph). The 7 kmph value is very closed to the average speed that other famous sea kayakers would usually make. The improvement at this point is very critical, since I can hardly make any more gain without sacrifices to the boat stability.

The weather this season is quite ideal for paddling, the temperature is dropping to around 20 ~ 25 degree (Celsius). The Northern wind is blowing, but much a lesser amplitude compared to this time last year. But too bad, I’m quite busy with my works and can’t spend much time on water, my paddling performance is not truly at its peak, so it’s still early to say more about the new kayak’s performance characteristics.

Anyway, I’m feeling very pleased with my new kayak, and I think that with more training, I could bring her to a much better performance level. Some more works required still on the kayak though, in essence, I would have to rework the USB – charging circuit, the current one is over – powered by the 3 powerful Lithium cells and wouldn’t work very well. Christmas and New Year season is coming, happy season to everyone! 😀

serene – 2, part 40

ontinue trialling and adjusting various boat equipments. The 2.2 Amph SLA battery works, but not to my expectation, first, it’s too heavy, second, its capacity is quite small, and third, the battery doesn’t hold its electricity for too long, about 2 days without charging and the battery would exhaust… After consulting with some other paddlers, I’ve decided to replace it with 3 Lithium cells, the results are just… superb!

I now have about 10 Amph in the very small 3 Li-ion cells, almost 5 times more the capacity, and 5 times less the weight, yet 5 times the price 😀, advancements in battery technologies is just amazing! According to one of my friend, an “expert” in electric and electronic devices, the Li-ion would usually last longer, and compared to the SLA, with zero maintenance cost. After replacing the battery, I fitted the last electrical components.

The AA charger and the USB charger, they’re positioned inside another waterproof box, connected to the battery box with electrical wires inside a plastic tube. The installation is pretty easy, the two devices are connected via two switches, simply put your iPhone (or your VHF radio, or your AA batteries) into the box, turn on the switch, close the box, and let the Li-ion cells, plus the solar panel do their job!

Also, I’ve removed the plastic seat, replace it with just a back – rest instead. The back – rest is built from plywood, bent into a curved shape, covered on 1 side with a rubber sheet (to make your back resting more comfortable), and fitted into the cockpit aft, it could be rotated slightly to suit my various sitting positions. These are last updates for the boat in this 2016 year, now it’s time to just enjoy the water!

serene – 2, part 39

ade several short paddlings (10, 12 km) to trial my newly – built Serene – 2 kayak. The overall feeling is very pleasing, the boat is much easier to control compared to my previous one Serene – 1, and it’s faster, taking up momentum in just a few light strokes! But the velocity measures would be postponed until I could finish all equippings, all adjustments, and begin longer paddling to know precisely.

Yesterday, I had a capsize in my kayak, reason is that the seat raises the center of gravity (CG) by approximately 5 cm, just a very short distance but severely affect the boat stability. This is something I’d already knew in the designing phase, but still try to do the silly thing of installing the inappropriate seat. The solution is quite simple: remove the seat, just sit barely on the bottom, and build just a back – rest instead.

Apart from that, everything works well enough: the bilge pump, the rudder and rudder pedals, other electrical devices, etc… The shorter hull reacts more sensitively to load balancing, the kayak needs to be trimmed a little bit further aft to reach its most stable point. I’m especially happy with the rudder, to give a decisive conclusion on the Rudder vs. Skeg debate: the Skeg is simply left too far behind to argue! 😀

Only long paddling would tell, if there’re some significant improves in “economical speed”, the important point of a kayak designed for cruising: the minimum effort required to propel the boat on large distance and in prolonged period of time. It takes some more efforts and times to really complete harnessing my Andalusian horse and make it ready for sea paddling trips in this Northern monsoon wind season!

serene – 2, part 38

any miscellaneous jobs required still to finish equipping my new kayak for upcoming paddling trips. First is adjusting the seat’s back rest, it’s a bit too high that strapping on the spray skirt could be a bit difficult. I simple cut down its back, then rivet the cut – out part onto the rest part. The hatches’ gaskets are cut from a thin (5 mm) rubber sheet (1st & 2nd images), should do their job of keeping the water out.

I made a new cart for transporting the boat on land, it’s just a smaller and lighter version of the previous one. I reused the pair of wheel, couldn’t reduce the wheels’ size since they have to be big enough so that the cart wouldn’t sink in when pulled on sand and mud. The result is quite satisfactory, big enough to easily transport the kayak, and small enough to not affect the boat stability when carried on the aft deck.

The list of small jobs to really finish the boat seems to be never ending, there’s always something I could do to improve, here and there, e.g: a mesh bag would be installed inside the cockpit, under the deck, to store various things I could need during a paddling trip, e.g: a small knife, a tiny light torch, a small monocular (to be equipped), reserved batteries for camera and GoPro, lighter, my tobacco box, etc…

It’s an interesting experience equipping a kayak for long paddling trips: everything need to be ready and accessible around your cockpit: food and drink, the back up paddle, the paddle float, radio and camera, everything… 😀 Fortunately, my newly purchased PFD has two pockets on the front side where I could hold some crucial things with me: the VHF radio, the Garmin and the Cannon waterproof small camera!