Okay, the Humpback waterwing was no instant success. The leverage didn't work, the hinging proved to be pointless, it was too wide, had too much buoyancy, in short, I reanimated an old bowhead wing to fin myself through the summer.
My thinking about the humpback wing dripped on. It simply had to be weighted down✹, but how and where?
I had gouged the handle before and poured in molten lead, but this space was largely lost by the narrowing down. Because I had bought a pricey bag of lead granules I toyed with the thought to scoop out furrows on all four opposite (front/rear+left/right) sides on exactly the same place from the middle and fill them with molten lead. That would mean a lot of ultra precise work, the filling of the right amount of lead, because of the rapid hardening, being the most infeasible.
The easiest way seemed to fasten the weight in the middle, but it should not be in the way of my hands. I thought of several shapes in which I could bend, melt or inlay the lead, but first I had to know how much lead I needed so the wing would just keep floating.
With hindsight, a brain wave seems invoked by logic. I still had a kilo piece of diving lead and a spare weight belt. The lead I buckled as tight as possible on the handle, wound the rest of the belt around it and fastened this with a hairpin. The swim was a revelation. The wing swam super light and was effortlessly manoeuvrable.
A block of lead like that of course has resistance in the water. Moreover it didn't make the handle look very handsome. How could I divide it across the middle? Sometimes you need a little bit of luck, very sometimes a huge setback. The second time I swam with the block of lead was also the last. At a robust manoeuvre the wing broke in two at the handle. Disillusioned I swam back to the stone pier and Dusty swam along with me.
How now? I bought two measures of steel (24x450 mm) and screwed them on either side across the handle onto the blades. The surface this took I gouged double deep, so the same measure of lead could go under it. Thus this problem was also overcome!
That turned out to be quite a job, also because at White Strand I do not have a table with a bench vice at my disposal. And so had to do everything on my knees on the pavement. The result fell short of my expectations and I thought this was because there was not enough lead in it. I bought an entire sheet of lead and went back to the drawing board. From this lead I cut a surface that covered the middle. This proved too heavy, the wing sank like a stone. So from front and rear, left and right I cut off equal pieces. After a few tries the wing kept afloat, but one half stuck higher out of the water than the other. I began cutting off pieces of lead, front and rear, from the heaviest half. After each time I checked the float balance in a beach pool. Finally I had removed nearly all of the lead from the heaviest side, but still the wing did not float in exact balance.
The swimming was nowhere near that with the block of diving lead in the middle. It became clear to me that all the weight had to be in the middle, without being in the way of my hands and as streamlined as possible. I removed the lead under the steel strips and calculated their surface. Added to that an estimate of the surface of lead that kept the wing from sinking and I would know the maximum surface of lead I could use. A winding of a long and narrow band of lead did not seem ideal. The edges could hinder my hands and the stack would not be very stable.
Then the idea came to let the strip of lead become ever wider, so I could keep bending the upper edges over the lower ones. This way you get a wrap that continues to overlap its forerunner and does not shove aside as they lock into each other.
Yesterday I swam with this for the first time. When I walked towards the water I felt the balance of the wing as a personal congratulation by Gravity herself. In the water I could swim from my middle, could effortlessly manoeuvre the wing and precisely dose the thrust at the moment desired.
I know, I have announced developments of the waterwing with enthusiasm before. But this one raises me right into dolphin heaven.
✹it may seem that the lighter material you use for the wing, the easier you swim. But you have to depart from the same volume, because a wing, thinner than 4 cm is too cutting and therefore unfit to handle. This displaces the same volume of water, but the buoyancy is stronger, so it needs more lead. The question now is: how light can a waterwing be and how much lead does it need to keep the wing easy to handle? So at the least imbalance the lighter side will not want to balloon up. The theoretical answer will be: the weight of the water the wing displaces minus its own weight. Thus you can experiment with wider and/or longer wings. The only limit then seems to be the surface that can be managed with muscle power. But transformation, for instance that at a higher speed the surface of the wing diminishes or that the blades move more to the rear, then becomes an option.