On our way south towards Cadiz, the bag normally containing the No3 genoa had ripped. Once in Weymouth, where it had enjoyed an artisanal manual repair, but then again later when out at sea. The end of its life had come, and it was time for a replacement.
There were two immediate options open to achieve the goal of getting a replacement on board: make or buy. To explain why I thought I'd attempt making a new bag I need to make a small detour, going back some years when I was in Norway, spending a full year understanding, modeling and writing a computer simulation of the four strokes comprising the diesel combustion cycle. It was a complex task and indeed it took a good part of the year to produce an OK-ish result: the virtual engine ran quite well with the computer steadfastly making the calculations, one crankshaft degree at a time.
Real engines are not concerned with this kind of one-degree-at-a-time complexity, they just get on with it. The largest marine diesels running at around 60 rpm complete a (2-stroke) cycle every second. Struana has a 4 cylinder 4 stroke diesel on board with a top speed of 3600 rpm. So opening the throttle fully (and assuming a clean prop) means every cylinder completes 30 cycles of the intake-compression-combustion-exhaust cycle, per second. Going one step further, the diesel in a typical car may reach double Struana's engine speed, so 120 revolutions of the crankshaft or 60 diesel cycles per second. Incredible technology, I still have difficulty imagining what actually goes on inside an engine, at such incredible speeds...
I think that the same story can be told about a sewing machine. To push a thread through cloth and then to perform some magic wrapping it around a second thread I can understand in very slow motion, but to perform that 20 to 30 times per second? That required further investigation, so why not stitch together a new bag for the No3?
I decided to reverse engineer the existing bag to see how it was put together originally, and to ensure the various panels, etc, had the right shapes. The new bag would subsequently be an improved version of the existing, retired one with the following enhancements:
Colour. No poison yellow or camping blue as per the old one, proper dark blue (navy?) and white. Same as Struana.
Identification. A large 3 or maybe even two large 3's to make sure it would be possible to differentiate one sail from the other (Genoa 1, 3 or 4) just in case I replace the other bags too. Irritating to have to figure out which sail is which when they are stacked on the cabin floor.
Nothing more irritating though than trying to fold an empty bag in the cramped cabin, trying to find the half way mark (these bags are long...) and then beginning to fold realising you were nowhere near the halfway mark.
So in the below the result. Quite happy though I fear the cloth might be a little too light, it may rip quite easily. We'll see back out at sea in due course...
Disassembling the tired, old bag:
Reusing just the centre strip (a mesh allowing water out of the bag, expensive stuff, did not find any), here we go with the foundations for the new bag
White & blue, supposedly to match Struana's hull:
Bright orange stripes, placed every quarter, to also accommodate the straps securing the bag and genoa within once in use (the very reliable heavy-duty Singer sits in the background, ready to pounce with more stitches per second than Emelie and I managed in 30 minutes repairing the old bag in Weymouth):
Finished!
