Posts Tagged ‘crab claw sail’

Bamboozled by Bamboo’s Beauty

March 10, 2014

Oh, the subtle elegance of bamboo! Its slender culms, its lush, green foliage, its supersonic growth, its dry rustle in the slightest of winds, its ever-expanding rhizomes underground, its million practical uses, its formidable stiffness, its poetic representation in Japanese ink drawings, the simultaneous flowering of a all members of a species across the entire globe, well, I could go on and on and never even approach the essence of this simple grass, witch obviously has clear aspiration of wanting to become a tree.

As you must be aware, bamboo spars are an integral part of Aluna’s aeolian propulsion system. The slender pine saplings from the dense Humboldt County forests I originally tried proved to be not only heavy but much too bendy to give the crab claw sail an efficient shape. The stiffness of the bamboo culm is essential to make it all work, and its minute weight makes it practical to wield the bundled sail across Aluna’s heaving deck and raise it up the mast without breaking your back. The dimensions of our main sail are so big that not just any bamboo will do. Its vertical spar is a good thirty feet long and the lateral loads on its top third are substantial as the wind increases. To find a bamboo culm that is still at least four inches thick at thirty feet of height has proven to be a serious challenge. Only thanks to last year’s mishap while sailing close-hauled into stiff south easterlies with Aluna’s hulls a bit too fouled for comfort are we now closing in on achieving this goal.

You must remember the mainsail’s vertical spar breaking at the point where the halyard attaches and the following temporary repairs from last year’s post in mid-May. At the time our good friend and master ceramic artist Peter Yates had kindly donated two splendid specimens of phyllostachys latiflora culms. That species happens to be one of the best timber bamboos available on the face of the earth. After carefully cutting them down with minimal lesions to its naturally protective waxy coating, we had put them to dry slowly in the shady twilight under Tony’s porch, right up the hills of Opua and overlooking the almost always windy Kawakawa Inlet. A good half of a green bamboo culm’s weight is in the water it contains. But that water has to be extracted slowly. If the culm dries too quickly it will split between the nodes, which would immediately compromise its lateral stability.

So while we were basking in the tropical sun up in the Fiji isles, that excess water evaporated little by little out of Aluna’s new spars, and when I went up to see Tony and the long and skinny temporary protégés of his under the porch, I was pleasantly surprised to see the two culms dressed in a splendid yellow. I pulled the first one out from its shady winter nest. It was light! We easily carried it down the hill through the winding path in the bush underneath his house. Though turning corners with a ten meter long stick in dense underbrush isn’t exactly a piece of cake. We ended up down on the old railroad track, where in ancient times meat was ferried from the abattoir in Kawakawa to the Opua wharf. That track had also had its subtle transformation over the winter. Now covered with a layer of thick metal it had been converted into a bicycle path. For those of you unfamiliar with the quirks of Kiwispeak, metal here refers to grey split rock, which is used extensively as a road surfacing material. I had brought Ted’s bicycle there previously. All that was left to do now was to strap the long stick on its side and I could walk it the half-mile or so to the shop. I must have looked like a kind of present-day Don Quixote, stubbornly spearing invisible windmills while riding his tired old mare!

So here’s how you transform a simple bamboo culm into a high-tech sailing machine: The waxy top layer of the bamboo, as beautiful and naturally protective as it may be, has to go. Epoxy does not like it at all and will refuse stubbornly to adhere to it. Out comes the belt sander and with a good 80-grit belt and many swaying sinusoidal movements of my forearms that outer layer is completely removed and while doing that, the crested ribs at the nodes are also shaved off. Before the end of the afternoon a first coat of neat epoxy is painted on. With energetic brushstrokes I slap the sticky liquid onto the culm but all of a sudden I notice with horror that the couple hours of naked exposure to the burning New Zealand sun had been enough to initiate splitting in three or four places. There are fortunately only slender hairline cracks, but they are growing fast. I turn the culm over half way every ten minutes or so to distribute the heat, and hurry on with the epoxy coating. Soon enough the sun has moved overhead and down to the east. The long stick is now safe, resting in all its splendid length in the shade.

bamboo01 bamboo02There are many ways to skin a cat and many ways to glass a spar. The fiberglass socks I had used to glass the pine saplings are definitely my favorite. Once cut to length you bundle them over your forearm, slide it over the spar and then pull from both ends. The diagonal fibers now squeeze tightly around it for a perfect fit. But here in the New Zealand hinterland I had no access to such refined materials. A leftover roll of 6oz cloth left over from the building of Aluna still lives on in her bellies, so that’s what has to do. I cut the meter-wide cloth into four strips of a little less than a foot wide, with the idea to spiral wrap those around the spar with just a small overlap. For that to work without ending up wrapping that strip of epoxy soaked fiberglass cloth all around yourself in despair, the spar needs to rotate freely, so that you can apply the cloth always on the top. I screw a plate of scrap plywood to the bottom end of the culm and insert a strong screw into it at precisely the pivot point. This screw I then suspend in a notch on a stand, while the upper end of the culm is free to roll on a horizontal one on the other end. Yet another quickly fabricated stand serves as a helping hand to put down the roll of fabric while epoxy is applied.

bamboo05 bamboo07 bamboo06Good fortune is it that Tony had offered to come and help with the operation. It would have been a heck of a challenge to do this on my own! Once we have worked out the methodology of it all, it works beautifully, just like a charm. A soon as we have covered about a third of the 10 meters with cloth, and the epoxy starts to get tacky at the beginning, my very own cellophane trick needs comes into play. A roll of simple kitchen wrap is spiral wrapped tightly over the still wet glass cloth. This not only squeezes the epoxy down through the cloth into the underlying wood, but also shortcuts the laborious process of fairing and sanding. If done with sufficient dexterity it leaves an almost smooth surface behind once peeled off after the epoxy has hardened. On a flat surface the perfect tool to apply the fairing mix is a stiff squeegee or a trowel. I’ve experimented with many different things to be able to do the same thing on a rounded surface. This time I stumbled upon the ideal tool for the job. A simple length of round electrical cable of about a foot is held with both hands and pulled along the top half of the spar with the fairing mix spread on irregularly. Once again a certain amount of dexterity is needed, and practice creates the master. If you do it right one, round of fairing and sanding is all that is needed to make a good-looking finish. I was so enthused with my new invention that I used it also to apply the primer. I’m never after a glossy finish in anything I build, so I’m quite happy with how it has all turned out without having to sweat excessively and waste too much time for jus the looks. Two coats of white enamel paint should provide enough longevity to our new spars to justify the quite taxing workout!

bamboo03 bamboo04 bamboo08 bamboo12 bamboo11 bamboo10 bamboo09Once the spars are coated and painted I carry them on my shoulder down the same new bicycle track to the little beach under Tony’s house, where little Alunita is waiting to play the role of a tugboat. Both spars have a rope tied to one end and I slide them into the water. Before the little wavelets push them over to the rocky shore where their still tender enamel paint would be scraped and scratched, I paddle out with the canoe and the two long white sticks in tow. I’m unsure of what literary figure I might resemble now, but soon they pulled up over the hullsides and come officially aboard their new home on the decks of Aluna.

Business unfortunately calls out again for another stint down south to Auckland soon. Beatriz will take a course there to become a certified Pilates instructor, transitioning from the wild performer she used to be, to a diligent reformer of human bodies. I therefore do not have time to assemble the new mainsail before leaving. I’ll have to report back to you on how it all ended up. But there is just enough time to tackle another little project that has been sitting on the list for what seems to be approaching eternity. It all comes out of nowhere and is finished in a fleeting moment.


Plugging Away

May 12, 2013

Bamboo continues to be the hinge of Aluna’s propulsion system. It stretches the sailcloth out into the wind and is supposed to hold them there in a certain shape. This implies quite a bit of strength and stiffness, which bamboo is exceptionally good at. It is so stiff for its weight and diameter that only the most modern synthetic materials can come close to matching its properties. You might remember that this summers fierce Southeasterlies managed to bring those properties to its knees and break my mainsail spar not only once but twice. This meant that Aluna was deprived of her fair weather sail and had me looking for a replacement spar.

As happens so often here in well-mannered Northland friends come to your aid from all directions at once. Even before heading down to Auckland almost two months ago Peter donated two of his marvelously straight bamboo culms, which were cut green and have since then been drying slowly over at his magic little kingdom across the river. It will take a total of at least six months of pampering to get them to the point where they will have dried slow enough to avoid any splitting. In order for them to be encapsulated in epoxy, reinforced with fiberglass and painted to protect them from the sun they need to be thoroughly dry. And this will definitely not happen before we have to head out into the big blue again to escape the fast approaching winter. For our upcoming trip to Vanuatu by the end of this month we need a quicker solution!

Enters Ted, who caters to most any need a cruiser can have with his ingenious engineering genius here in Opua, coming up with solutions where others stand for hour scratching their heads and wiggling their toes. Those solutions go from the outrageously brilliant to the simply unusual and end up most always being very straightforward and practical. My usual reaction to his suggestions is a perplex ‘why haven’t I thought of that!’, so when he suggested using aluminum tubing for a quick replacement spar the little ethnic pride that was given to me at birth cringed and squeaked violently, but I had to listen. Instant engineering computations in his amazing brain had come to the conclusion that the resulting spar, made up of two 5 meter sections joined by a sleeve of a slightly larger tube would come out to be lighter by a couple kilos than my bamboo spar. It would be dead easy to assemble. Everything could be done most probably in a single day. But it came at a cost. For most people three to four hundred dollars is a miniscule amount of money, which can be spent without any second thoughts. It is amazing how cheap aluminum has become. But in our limited cruising economy it would rip a good chunk of the little fat our cruising kitty has been able to accumulate over the last year and a half out of existence and leave a gashing hole in our financial portfolio. So it all ended up where many a brilliant idea expires: in the dungeon of economic unfeasibility.

The spar had broken neatly at the point where the halyard attaches it to the tip of the main mast. When bamboo breaks it does not shatter like wood. Its resilient longitudinal fibers remain intact but separate from each other at the moment of failure. That separation typically ends at the nodes to either side of the break. This meant that the pieces of bamboo left over from the accident were more or less intact and if I could device a way to join them back together I might end up with a spar that could be stronger than the original, just like a bone that has fractured and the body repairs it with extra tissue around the breakage point.

Whenever the slowly degrading weather allows for it that’s descending heavily down on us on our slippery slide towards the austral winter, you can find me at Ted’s shop tucked into the hillside behind Ashby’s Boat Yard, which has recently been incorporated into Northland Holdings, the secretive but opulent state owned entity that is managing and diligently milking the lucrative Opua Marina. Engulfed in a cloud of fine sawdust I’m fabricating wooden plugs that will slide into the bamboo culms for the entire length of the internodes adjacent to the ones that broke. It’s a tricky process. The bamboo has been brought forth by Mother Nature’s creative evolutionary magic, which means there are no perfect circles and no straight lines. Touch, feel and go it is then, shaving off the wooden material little by little until there is just enough left of it for the plugs to easily slide into the openings, without them wiggling around in there too much. Epoxy filled with glue mix will take up any empty space and make for a perfect bond between the two different plant materials. And of course on the outside a couple layers of reinforcing fiberglass will provide for the ultimate strength of this makeshift repair. A bridle will further help to distribute the considerable load and bending moment that acts on the halyard attachment when the wind increases and generates more and more pressure on the sail.

It will be as always with man’s technical things. A good leap of faith is needed to venture with these marginally constructed machines out into the chaotic world of the wavy oceans, which can brutally tear to shreds any and all human inventions if it happens to find it pleasing to do so. At the very least we will not only have saved our cruising kitty from prematurely collapsing into a very private but intimate replay of the Great Depression, but also be able to sweetly sleep with the clean conscious of having complied with the ecological mandate of reusing elements and resources whenever and as much as possible, instead of contributing to the menacing existence of an aluminum smelter maybe somewhere on the black back of Iceland and become part of a collective responsibility for the accelerated melting of three glaciers under the bright orange midnight sun in the elevated latitudes of the North Atlantic.