Posts Tagged ‘fibreglassing’

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.