And there it was: my island, Curva dos Dunas, exactly where old Simon Peace had positioned it. Curva dos Dunas — a Twist of Sand!
I looked at the formidable stretch of coast about twenty miles south of the mouth of the Cunene — what a fool I had been about the old man's dying words! Not south of north as I had thought. But south of — and there it was plain on the older chart — south of what the river used to be called, the Nourse. Twenty miles south of the Nourse lay the island, amongst the worst shoals and foul ground that could be charted anywhere. Most of them weren't anyway, not on the Admiralty map.
I studied Simon Peace's map in utter fascination. It was obvious that he had surveyed and charted the whole area himself. There, like a jewel set amid broken patterns of ore, was Curva dos Dunas. Guarded from the south by a needle-shaped rock (" ten feet at high tide, eight fathoms under "said the precise lettering in old Simon's hand) and protected farther south still by the Clan Alpine shoal, Curva dos Dunas was the most perfect hide-out anyone could wish for. North of it lay a series of shoals: the water shallowed with incredible abruptness from thirty-two to five fathoms in one place: on the landward side was a rock-strewn, hilly coast surmounted by high shifting dunes; a three-topped hill guarded a tiny beach marked "only sandy beach." This lay half at the back of the island, which seemed only a short distance from "the mainland itself. This mainland is known to sailors as the Skeleton Coast, a coastline beaten by high, thundering surf from the south-west; low, wind-blown scrub relieves the utter baldness of the dunes, and everywhere are the wicked shoals. The high dunes stretch northwards almost to the mouth of the Cunene (or Nourse as old Simon called it). The mouth itself is guarded by a most wicked constellation of shoals.
All this had been carefully charted, a labour which must have taken the old man years. The thought that he might have done it all in a sailing ship along that coast of death made me shudder and marvel at old Simon's intrepidity.
Curvas dos Dunas! The name rang like a bell.
I looked at the soundings and shuddered. It meant that I would have to go in through the shoals and pick off NP I as she lay there. "Discoloured water," said the chart. God! I knew what that meant: sand, stirred up from the shallows, and obscuring what little view there might be of channels. Channels! That was what I needed. There must be a channel in from the entrance — was there such a thing as a harbour? I checked the meticulous array of soundings. Seven, four, eight, fifteen, thirty fathoms — all in a jumble. If I took Trout in there I'd have her aground before I could say NP I. How did the Germans know about Curva dos Dunas? Well, that was probably easy enough to guess — the Admiralty charts were based on German ones compiled during their long occupation of South West Africa. I remembered that a German warship had done a survey before World War I, and the thorough German mind must have tucked away information like Curva dos Dunas for all the intervening years.
I knew quite instinctively that that was where NP I was lying low. I looked at the map again. On the seaward side of the stark little beach where the neat lettering said "three-topped hill," were two words. They said simply: "see inset." So the old man had made another map of the island, too? Where the devil was it? A brief look through the other crumpled charts and papers in my grip assured me that it was not there. I looked at the stiff parchment map: no, there was no inset. True, the chart would take me there, but on that wicked coast I would need more than just that. For by now the conviction was firm in my mind that I would take Trout in, whatever the cost.
The chart, laid out on the tiny table, crumpled itself and automatically I straightened it.
Then I saw.
The thick parchment had been split on the lower right-hand corner. With trembling fingers I felt. They met another edge of thin paper. Scarcely able to control my fingers and dreading that I should tear it, I slipped it out. I could have wept for joy. Silently I blessed old Simon. Curva dos Dunas! — a large-scale map with the entrance channel close to the ten-foot rock which I had first seen on the other chart.
The one I was now examining was a little masterpiece of cartography. The old sailor had taken bearings of the three-topped hill and the entrance channel in relation to the rock in the sea. Small wonder he had called it Curva dos Dunas — a Twist of Sand. The entrance channel curved like the whorls of a man's inner ear, swinging sharply north from the entrance and away from its first easterly direction, then doubling back almost on its own course; in between was a bar of what was marked as "hard sand." I thought what a brief end that sand-bar would make of a ship. The channel then swung round northwards in an irregular semi-circle — north, east, due south and then west again, debouching into a "harbour "contained in the enclosing arms of sand. It was thirty fathoms deep in places. It was something like the Jap base of Truk, in the Pacific, on a much smaller scale. What a funk-hole, I thought to myself. You could not winkle a submarine out of there with a can-opener, and it would be way out of range of the odd sea-search bomber of the South African Air Force at Walvis Bay. To the north lay neutral, largely unknown territory, and to the east the mainland appropriately known as the Skeleton Coast. Yes, that was where NP I was! I'd take Trout down that tortuous channel and sink the super U-boat with torpedoes in the deep water inside! Thank God that interminable box-search was at an end! I'd make for Curva dos Dunas and lie in wait for NP I.
Excitedly I got a ruler and made a rough calculation of my course to the island from Trout's present position. One hundred and sixty degrees. That would bring her nicely to the ten-foot rock — I'd call it Simon's Rock, in honour of the old sailor who might yet be my salvation — and, for that matter, the salvation of the fighting fleets and merchantmen in the North Atlantic. The thrill of the chase welled through my veins as I turned again to the beautifully drawn map of the channels into the "inner harbour "of Curva dos Dunas. My island! And in occupation by the most lethal submarine in the world! I could be there by late to-morrow…
The appalling significance of it struck me like an icy sea down the conning-tower hatch. One-six-oh! That was exactly the course we were steering! And we were on that course because — dear God! — could it be? Bissett had said the course was steady, and the sound was travelling steadily ahead of us at about seven knots. Course one-six-oh! The homeward-bound course of NP I to her base! Trout was, in fact, trailing along merrily, without any attempt at concealment, behind a nuclear-powered submarine!
I broke out in a cold sweat. The noise, that bursting bubble effect — it could well be that the Germans, with all their ingenuity, had abandoned the ordinary propeller and were using a form of hydraulic jet propulsion which ejected the water in exactly the same way that a squid sucks water into its gills and expels it again under high muscular pressure, thus providing its enormous speed and motive power. The thoughts tore through my brain. For a submarine fitted like that — and apparently all the power in the world with which to expel the water — it would be a double advantage, for those death-dealing, tired, trigger-happy men of the North Atlantic escort groups were accustomed to ordinary propeller noises and this new one would deceive them — at least at the outset. I knew hydraulic jet propulsion had been tried out with great success on shallow-draught small craft, but its application to anything else — well, that was a brand-new lesson for the North Atlantic.